| 51. |
- da Silva, Julio Cézar Lima, et al.
(författare)
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Quadriceps and hamstring muscle activity during cycling as measured with intramuscular electromyography.
- 2016
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Ingår i: European Journal of Applied Physiology. - : Springer Science and Business Media LLC. - 1439-6319 .- 1439-6327. ; 116:9, s. 1807-1817
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: The aim of this study was to describe thigh muscle activation during cycling using intramuscular electromyographic recordings of eight thigh muscles, including the biceps femoris short head (BFS) and the vastus intermedius (Vint).METHODS: Nine experienced cyclists performed an incremental test (start at 170 W and increased by 20 W every 2 min) on a bicycle ergometer either for a maximum of 20 min or to fatigue. Intramuscular electromyography (EMG) of eight muscles and kinematic data of the right lower limb were recorded during the last 20 s in the second workload (190 W). EMG data were normalized to the peak activity occurring during this workload. Statistical significance was assumed at p ≤ 0.05.RESULTS: The vastii showed a greater activation during the 1st quadrant compared to other quadrants. The rectus femoris (RF) showed a similar activation, but with two bursts in the 1st and 4th quadrants in three subjects. This behavior may be explained by the bi-articular function during the cycling movement. Both the BFS and Vint were activated longer than, but in synergy with their respective agonistic superficial muscles.CONCLUSION: Intramuscular EMG was used to verify muscle activation during cycling. The activation pattern of deep muscles (Vint and BFS) could, therefore, be described and compared to that of the more superficial muscles. The complex coordination of quadriceps and hamstring muscles during cycling was described in detail.
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| 52. |
- D'Ascenzi, Flavio, et al.
(författare)
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Training-induced dynamic changes in left atrial reservoir, conduit, and active volumes in professional soccer players
- 2015
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Ingår i: European Journal of Applied Physiology. - : Springer. - 1439-6319 .- 1439-6327. ; 115:8, s. 1715-1723
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Tidskriftsartikel (refereegranskat)abstract
- Although left atrial (LA) enlargement is a recognized component of athlete's heart, dynamic cavity changes occurring during the training period remain to be elucidated. We aimed to investigate the adaptive changes of LA reservoir, conduit, and active volumes in elite athletes vs. controls and their response to different training loads. LA maximum, pre-P, and minimum volumes were assessed in 26 top-level athletes and 23 controls. In athletes, LA volumes were measured at pre-, mid-, end-training, and post-detraining time points using conventional 2D echocardiography. Athletes had larger maximum (27.5 +/- A 3.2 vs. 20.3 +/- A 5.8 mL/m(2), p = 0.001), pre-P (11.5 +/- A 0.9 vs. 9.8 +/- A 2.2 mL/m(2), p = 0.001), and minimum (6.6 +/- A 0.9 vs. 5.0 +/- A 1.2 mL/m(2), p < 0.001) LA indexed volumes, compared with controls. Total and passive emptying volume indices were also larger in athletes compared with controls (18.7 +/- A 3.1 vs. 15.3 +/- A 4.9 mL/m(2), p < 0.05 and 13.8 +/- A 2.9 vs. 10.5 +/- A 4.6 mL/m(2), p < 0.05, respectively), while active emptying volume was similar (p = 0.74). During training, LA maximum (p < 0.0001), pre-P (p < 0.0001), minimum (p < 0.0001), total (p < 0.005), and passive (p < 0.05) emptying volume indices progressively increased, while active emptying volume (p = 0.10) and E/e' ratio (p = 0.32) remained unchanged. After detraining, LA volume measurements were not different from pre-training ones. End-training left ventricular mass index was the only independent predictor of the respective maximum LA volume (beta = 0.74, p < 0.005). Top-level athletes exhibit a dynamic morphological and functional LA remodeling, induced by training, with an increase in reservoir and conduit volumes, but stable active volume. LA remodeling is closely associated with left ventricular adaptation to exercise and both completely regress after detraining.
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| 53. |
- Daussin, Frédéric N, et al.
(författare)
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Improvement of VO2max by cardiac output and oxygen extraction adaptation during intermittent versus continuous endurance training
- 2007
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Ingår i: European Journal of Applied Physiology. - New York, USA : Springer. - 1439-6319 .- 1439-6327. ; 101:3, s. 377-83
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Tidskriftsartikel (refereegranskat)abstract
- Improvement of exercise capacity by continuous (CT) versus interval training (IT) remains debated. We tested the hypothesis that CT and IT might improve peripheral and/or central adaptations, respectively, by randomly assigning 10 healthy subjects to two periods of 24 trainings sessions over 8 weeks in a cross-over design, separated by 12 weeks of detraining. Maximal oxygen uptake (VO2max), cardiac output (Qmax) and maximal arteriovenous oxygen difference (Da-vO2max) were obtained during an exhaustive incremental test before and after each training period. VO2max and Qmax increased only after IT (from 26.3 +/- 1.6 to 35.2 +/- 3.8 ml min(-1) kg(-1) and from 17.5 +/- 1.3 to 19.5 +/- 1.8 l min(-1), respectively; P < 0.01). Da-vO2max increased after both protocols (from 11.0 +/- 0.8 to 12.7 +/- 1.0; P < 0.01 and from 11.0 +/- 0.8 to 12.1 +/- 1.0 ml 100 ml(-1), P < 0.05 in CT and IT, respectively). At submaximal intensity a significant rightward shift of the Q/Da-vO2 relationship appeared only after CT. These results suggest that in isoenergetic training, central and peripheral adaptations in oxygen transport and utilization are training-modality dependant. IT improves both central and peripheral components of Da-vO2max whereas CT is mainly associated with greater oxygen extraction.
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| 54. |
- de Bruijn, Robert, et al.
(författare)
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Increased erythropoietin concentration after repeated apneas in humans
- 2008
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Ingår i: European Journal of Applied Physiology. - : Springer Science and Business Media LLC. - 1439-6319 .- 1439-6327. ; 102:5, s. 609-613
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Tidskriftsartikel (refereegranskat)abstract
- Hypoxia-induced increases in red blood cell production have been found in both altitudeadapted populations and acclimatized lowlanders. This process is mediated by erythropoietin (EPO) released mainly by the hypoxic kidney. We have previously observed high hemoglobin concentrations in elite breath-hold divers and our aim was to investigate whether apnea-induced hypoxia could increase EPO concentration. Ten healthy volunteers performed 15 voluntary maximal duration apneas, divided into three seriesof five apneas, each series separated by 10 min of rest. Apneas within series were separated by 2 min and preceded by 1 min of hyperventilation to increase apnea duration and arterial oxygen desaturation. When EPO concentration after serial apneas was compared to baseline values, an average maximum increase of 24% was found (P<0.01). No changes in EPO concentration were observed during a control day without apnea, eliminating possible effects of a diurnal rhythm or blood loss. We therefore conclude that serial apneas increase circulating EPO concentration in humans.
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| 55. |
- Debevec, Tadej, et al.
(författare)
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Acute short-term hyperoxia followed by mild hypoxia does not increase EPO production : resolving the "normobaric oxygen paradox''
- 2012
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Ingår i: European Journal of Applied Physiology. - : Springer Science and Business Media LLC. - 1439-6319 .- 1439-6327. ; 112:3, s. 1059-1065
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Tidskriftsartikel (refereegranskat)abstract
- Recent findings suggest that besides renal tissue hypoxia, relative decrements in tissue oxygenation, using a transition of the breathing mixture from hyperoxic to normoxic, can also stimulate erythropoietin (EPO) production. To further clarify the importance of the relative change in tissue oxygenation on plasma EPO concentration [EPO], we investigated the effect of a consecutive hyperoxic and hypoxic breathing intervention. Eighteen healthy male subjects were assigned to either IHH (N = 10) or CON (N = 8) group. The IHH group breathed pure oxygen (F(i)O(2) ~ 1.0) for 1 h, followed by a 1-h period of breathing a hypoxic gas mixture (F(i)O(2) ~ 0.15). The CON group breathed a normoxic gas mixture (F(i)O(2) ~ 0.21) for the same duration (2 h). Blood samples were taken just before, after 60 min, and immediately after the 2-h exposure period. Thereafter, samples were taken at 3, 5, 8, 24, 32, and 48 h after the exposure. During the breathing interventions, subjects remained in supine position. There were significant increases in absolute [EPO] within groups at 8 and 32 h in the CON and at 32 h only in the IHH group. No significant differences in absolute [EPO] were observed between groups following the intervention. Relative (∆[EPO]) levels were significantly lower in the IHH than in the CON group, 5 and 8 h following exposure. The tested protocol of consecutive hyperoxic-hypoxic gas mixture breathing did not induce [EPO] synthesis stimulation. Moreover, the transient attenuation in ∆[EPO] in the IHH group was most likely due to a hyperoxic suppression. Hence, our findings provide further evidence against the "normobaric O(2) paradox" theory.
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| 56. |
- Debevec, Tadej, et al.
(författare)
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Separate and combined effects of 21-day bed rest and hypoxic confinement on body composition
- 2014
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Ingår i: European Journal of Applied Physiology. - : Springer Science and Business Media LLC. - 1439-6319 .- 1439-6327. ; 114:11, s. 2411-2425
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Tidskriftsartikel (refereegranskat)abstract
- This study tested the hypothesis that hypoxia exacerbates reductions in body mass observed during unloading. To discern the separate and combined effects of simulated microgravity and hypoxia, 11 healthy males underwent three 21-day campaigns in a counterbalanced fashion: (1) normoxic bed rest (NBR; FiO2 = 0.209; PiO2 = 133.1 +/- A 0.3); (2) hypoxic ambulatory confinement (HAMB; FiO2 = 0.141 +/- A 0.004; PiO2 = 90.0 +/- A 0.4; similar to 4,000 m); and (3) hypoxic bed rest (HBR; FiO2 = 0.141 +/- A 0.004; PiO2 = 90.0 +/- A 0.4). The same dietary menu was applied in all campaigns. Targeted energy intakes were estimated individually using the Harris-Benedict equation taking into account whether the subjects were bedridden or ambulatory. Body mass and water balance were assessed throughout the campaigns. Whole body and regional body composition was determined before and after the campaigns using dual-energy X-ray absorptiometry. Before and during the campaigns, indirect calorimetry and visual analogue scores were employed to assess the resting energy expenditure (REE) and perceived appetite sensations, respectively. Energy intakes were lower than targeted in all campaigns (NBR: -5 %; HAMB: -14 %; HBR: -6 %; P < 0.01). Body mass significantly decreased following all campaigns (NBR: -3 %; HAMB: -4 %; HBR: -5 %; P < 0.01). While fat mass was not significantly altered, the whole body fat free mass was reduced (NBR: -4 %; HAMB: -5 %; HBR: -5 %; P < 0.01), secondary to lower limb fat-free mass reduction. Water balance was comparable between the campaigns. No changes were observed in REE and perceived appetite. Exposure to simulated altitude of similar to 4,000 m does not seem to worsen the whole body mass and fat-free mass reductions or alter resting energy expenditure and appetite during a 21-day simulated microgravity.
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| 57. |
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| 58. |
- Dencker, Magnus, et al.
(författare)
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Daily physical activity and its relation to aerobic fitness in children aged 8-11 years.
- 2006
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Ingår i: European Journal of Applied Physiology. - : Springer Science and Business Media LLC. - 1439-6327 .- 1439-6319. ; 96:5, s. 587-592
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Tidskriftsartikel (refereegranskat)abstract
- A positive relationship between daily physical activity and aerobic fitness exists in adults. Studies in children have given conflicting results, possibly because of differences in methods used to assess daily physical activity and fitness. No study regarding daily physical activity and fitness in children has been published, where fitness has been assessed by direct measurement of maximum oxygen uptake and related to daily physical activity intensities by accelerometers. We examined 248 children (140 boys and 108 girls), aged 7.9-11.1 years. Maximum workload and maximal oxygen uptake (VO2PEAK) by indirect calorimetry were measured during a maximum bicycle ergometer exercise test. Exercise capacity was adjusted for body mass and (body mass)(2/3). Daily physical activity was evaluated by accelerometers, worn around the waist for 4 days. Mean accelerometer counts and time spent in vigorous physical activity were calculated. VO2PEAK was correlated with mean accelerometer counts (r=0.23 for boys and r=0.23 for girls, both P < 0.05), but somewhat better with time spent in vigorous activity (r=0.32 for boys, r=0.30 for girls, both P < 0.05). All results remained virtually the same regardless of the method used to adjust for differences in body size.
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| 59. |
- Dencker, Magnus, et al.
(författare)
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Gender differences and determinants of aerobic fitness in children aged 8-11 years.
- 2007
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Ingår i: European Journal of Applied Physiology. - : Springer Science and Business Media LLC. - 1439-6327 .- 1439-6319. ; 99, s. 19-26
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Tidskriftsartikel (refereegranskat)abstract
- Previous studies of gender differences in maximum oxygen uptake have come to different conclusions. Limited data exists where the determinants of maximum oxygen uptake have been evaluated in a comprehensive manner. Thus, we examined 248 children (140 boys and 108 girls), aged 7.9-11.1 years. Body composition was determined by dual-energy X-ray absorptiometry, measured variables were total body fat (TBF) and lean body mass (LBM). Maximal oxygen uptake (VO2peak) was measured by indirect calorimetry during a maximal cycle exercise test. Daily physical activity was assessed by accelerometers and duration of vigorous activity per day (VPA) was calculated. Left ventricular inner diastolic diameter (LVDD) was measured by echocardiography. Lung function was evaluated with spirometric testing and whole body plethysmography. Boys had between 8 and 18% higher values than girls for VO2peak, dependent upon whether VO2peak was expressed in absolute values or scaled to body mass, LBM or if allometric scaling was used. In multiple regression analysis absolute values of aerobic fitness were independently related to LBM, maximal heart rate (Max HR), gender, LVDD, and VPA. Furthermore, when VO2peak was scaled to body mass it was independently related to In TBF, Max HR, gender, VPA, and LVDD. Lung function had no relation to VO2peak. Our study concludes that body composition is the main predictor for VO2peak, in children aged 8-11 years, whereas VPA or LVDD has only a modest impact. Existing gender differences in VO2peak cannot be explained only by differences in body composition, physical activity, or heart size.
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| 60. |
- Domkin, Dmitry, et al.
(författare)
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Effect of ciliary-muscle contraction force on trapezius muscle activity during computer mouse work
- 2019
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Ingår i: European Journal of Applied Physiology. - : SPRINGER. - 1439-6319 .- 1439-6327. ; 119:2, s. 389-397
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Tidskriftsartikel (refereegranskat)abstract
- The present study aimed to identify whether or not an increase in ciliary-muscle contraction force, when the eye-lens is adjusted for viewing at a near distance, results in an increase in trapezius muscle activity, while performing a natural work task. Twelve participants, ranging in age from 21 to 32years, performed a computer-mouse work task during free gaze conditions. A moving visual target was tracked with a computer mouse on a screen placed at two different distances from the eyes, 25cm and 50cm. Tracking performance, eye accommodation, and bilateral trapezius muscle activity were measured continuously. Ciliary-muscle contraction force was computed according to a formula which takes into account the age-dependent, non-linear relationship between the contraction force of the ciliary muscle and the produced level of eye accommodation. Generalized estimating equations analyses were performed. On the dominant hand side and for the nearest screen distance, there was a significant effect of ciliary-muscle contraction force on the trapezius muscle activity (p<0.001). No other effects were significant (p>0.05). The results support the hypothesis that high visual demands, during computer mouse work, increase ciliary muscle contraction force and contribute to a raise of the sustained level of trapezius muscle activity. The current study specifically clarifies the validity of the relationship between ciliary-muscle contraction force and trapezius muscle activity and demonstrates that this relationship is not due to a general personality trait. We conclude that a high level of ciliary muscle contraction force can contribute to a development of musculoskeletal complaints in the neck-shoulder area.
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| 61. |
- Düking, Peter, et al.
(författare)
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Intra-individual physiological response of recreational runners to different training mesocycles : a randomized cross-over study
- 2020
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Ingår i: European Journal of Applied Physiology. - : Springer Science and Business Media LLC. - 1439-6319 .- 1439-6327. ; 120, s. 2705-2713
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: Pronounced differences in individual physiological adaptation may occur following various training mesocycles in runners. Here we aimed to assess the individual changes in performance and physiological adaptation of recreational runners performing mesocycles with different intensity, duration and frequency. Methods: Employing a randomized cross-over design, the intra-individual physiological responses [i.e., peak (V ˙ O 2 peak) and submaximal (V ˙ O 2 submax) oxygen uptake, velocity at lactate thresholds (V2, V4)] and performance (time-to-exhaustion (TTE)) of 13 recreational runners who performed three 3-week sessions of high-intensity interval training (HIIT), high-volume low-intensity training (HVLIT) or more but shorter sessions of HVLIT (high-frequency training; HFT) were assessed. Results: V ˙ O 2 submax, V2, V4 and TTE were not altered by HIIT, HVLIT or HFT (p > 0.05). V ˙ O 2 peak improved to the same extent following HVLIT (p = 0.045) and HFT (p = 0.02). The number of moderately negative responders was higher following HIIT (15.4%); and HFT (15.4%) than HVLIT (7.6%). The number of very positive responders was higher following HVLIT (38.5%) than HFT (23%) or HIIT (7.7%). 46% of the runners responded positively to two mesocycles, while 23% did not respond to any. Conclusion: On a group level, none of the interventions altered V ˙ O 2 submax, V2, V4 or TTE, while HVLIT and HFT improved V ˙ O 2 peak. The mean adaptation index indicated similar numbers of positive, negative and non-responders to HIIT, HVLIT and HFT, but more very positive responders to HVLIT than HFT or HIIT. 46% responded positively to two mesocycles, while 23% did not respond to any. These findings indicate that the magnitude of responses to HIIT, HVLIT and HFT is highly individual and no pattern was apparent.
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| 62. |
- Eiken, Ola, et al.
(författare)
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Blood pressure regulation V : in vivo mechanical properties of precapillary vessels as affected by long-term pressure loading and unloading
- 2014
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Ingår i: European Journal of Applied Physiology. - : Springer Science and Business Media LLC. - 1439-6319 .- 1439-6327. ; 114:3, s. 499-509
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Forskningsöversikt (refereegranskat)abstract
- Recent studies are reviewed, concerning the in vivo wall stiffness of arteries and arterioles in healthy humans, and how these properties adapt to iterative increments or sustained reductions in local intravascular pressure. A novel technique was used, by which arterial and arteriolar stiffness were determined as changes in arterial diameter and flow, respectively, during graded increments in distending pressure in the blood vessels of an arm or a leg. Pressure-induced increases in diameter and flow were smaller in the lower leg than in the arm, indicating greater stiffness in the arteries/arterioles of the leg. A 5-wk period of intermittent intravascular pressure elevations in one arm reduced pressure distension and pressure-induced flow in the brachial artery by about 50%. Conversely, prolonged reduction of arterial/arteriolar pressure in the lower body by 5 wks of sustained horizontal bedrest, induced three-fold increases of the pressure-distension and pressure-flow responses in a tibial artery. Thus, the wall stiffness of arteries and arterioles are plastic properties that readily adapt to changes in the prevailing local intravascular pressure. The discussion concerns mechanisms underlying changes in local arterial/arteriolar stiffness as well as whether stiffness is altered by changes in myogenic tone and/or wall structure. As regards implications, regulation of local arterial/arteriolar stiffness may facilitate control of arterial pressure in erect posture and conditions of exaggerated intravascular pressure gradients. That increased intravascular pressure leads to increased arteriolar wall stiffness also supports the notion that local pressure loading may constitute a prime mover in the development of vascular changes in hypertension.
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| 63. |
- Eiken, Ola, et al.
(författare)
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Decompression strain in parachute jumpmasters during simulated high-altitude missions : a special reference to preoxygenation strategies.
- 2023
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Ingår i: European Journal of Applied Physiology. - : Springer Nature. - 1439-6319 .- 1439-6327.
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: Military parachute operations are often executed at high altitude, from an unpressurized aircraft compartment. Parachute jumpmasters (JM) are thus regularly exposed to 29,500 ft for 60 min. The aim was to investigate the decompression strain during a simulated JM mission at high altitude and to compare two strategies of preoxygenation, conducted either at sea-level or below 10,000 ft, during ascent to mission altitude.METHODS: Ten JM completed, on separate occasions, a 45-min preoxygenation either at sea-level (normobaric: N) or 8200ft (hypobaric: H), followed by exposure to 28,000 ft for 60 min, whilst laying supine and breathing 100% oxygen. At min 45 of the exposure to 28,000 ft, the JM performed 10 weighted squats. Decompression strain was determined from ultrasound assessment of venous gas emboli (VGE) during supine rest (5-min intervals), after three unloaded knee-bends (15-min intervals) and immediately following the weighted squats. The VGE were scored using a six-graded scale (0-5).RESULTS: In condition H, two JM experienced decompression sickness (DCS), whereas no DCS incidents were reported in condition N. The prevalence of VGE was higher in the H than the N condition, at rest [median(range), 3(0-4) vs 0(0-3); p = 0.017], after unloaded knee-bends [3(0-4) vs 0(0-3); p = 0.014] and after the 10 weighted squats [3(0-4) vs 0(0-3); p = 0.014]. VGE were detected earlier in the H (28 ± 20 min, p = 0.018) than the N condition (50 ± 19 min).CONCLUSIONS: A preoxygenation/altitude procedure commonly used by JM, with a 60-min exposure to 28,000 ft after pre-oxygenation for 45 min at 8200 ft is associated with high risk of DCS. The decompression strain can be reduced by preoxygenating at sea level.
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| 64. |
- Eiken, Ola, et al.
(författare)
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Effects of vision on energy expenditure and kinematics during level walking
- 2022
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Ingår i: European Journal of Applied Physiology. - : Springer Nature. - 1439-6319 .- 1439-6327.
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: We have previously observed substantially higher oxygen uptake in soldiers walking on terrain at night than when performing the same walk in bright daylight. The aims of the present study were to investigate the influence of vision on mechanical efficiency during slow, horizontal, constant-speed walking, and to determine whether any vision influence is modified by load carriage.METHODS: Each subject (n = 15) walked (3.3 km/h) for 10 min on a treadmill in four different conditions: (1) full vision, no carried load, (2) no vision, no carried load, (3) full vision with a 25.5-kg rucksack, (4) no vision with a 25.5-kg rucksack.RESULTS: Oxygen uptake was 0.94 ± 0.12 l/min in condition (1), 1.15 ± 0.20 l/min in (2), 1.15 ± 0.12 l/min in (3) and 1.35 ± 0.19 l/min in (4). Thus, lack of vision increased oxygen uptake by about 19%. Analyses of movement pattern, by use of optical markers attached to the limbs and torso, revealed considerably shorter step length (12 and 10%) in the no vision (2 and 4) than full vision conditions (1 and 3). No vision conditions (2 and 4) increased step width by 6 and 6%, and increased vertical foot clearance by 20 and 16% compared to full vision conditions (1 and 3).CONCLUSION: The results suggest that vision has a marked influence on mechanical efficiency even during entrained, repetitive movements performed on an obstacle-free horizontal surface under highly predictable conditions.
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| 65. |
- Eiken, Ola, et al.
(författare)
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G tolerance vis-à-vis pressure-distension and pressure-flow relationships of leg arteries
- 2012
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Ingår i: European Journal of Applied Physiology. - : Springer Science and Business Media LLC. - 1439-6319 .- 1439-6327. ; 112:10, s. 3619-3627
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Tidskriftsartikel (refereegranskat)abstract
- During increased gravitoinertial (G) load in the head-to-foot direction, pressures in dependent vascular beds are commonly raised to levels capable of distending precapillary vessels, which, in turn, may reduce arterial pressure, and hence compromise the capacity to withstand G load (G tolerance). We hypothesized that distensibility in precapillary leg vessels would be lower in a group of subjects possessing high G tolerance (H; n = 7; relaxed G tolerance = 6.6 ± 0.8 G) than in a group with low G tolerance (L; n = 8; G tolerance = 3.9 ± 0.3 G). The groups were matched with regard to gender, age, weight, height, and resting arterial pressure. Arterial pressure-distension and pressure-flow experiments were performed with the subject supine in a pressure chamber with a lower leg protruding to the outside. Increased intravascular pressure in the blood vessels of the outside leg was accomplished by stepwise increasing chamber pressure to 240 mmHg. Diameter and flow in the posterior tibial artery were measured by ultrasonographic/Doppler techniques. Pressure-induced increments in arterial diameter and flow were more pronounced (p < 0.03) in the L (14.1 ± 4.2% and 32 ± 21 ml/min respectively) than in the H (1.7 ± 5.0% and 1.6 ± 25 ml/min) group, and the pressure thresholds at which these increments commenced were lower (by 52 and 48 mmHg, respectively) in the L than in the H group (p < 0.04). Negative correlations were observed between G tolerance and the increments in diameter and flow (p < 0.02). Thus, the wall stiffness of precapillary leg vessels is greater in individuals with high relaxed G tolerance; whether a causal relationship exists remains to be established.
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| 66. |
- Eiken, Ola, et al.
(författare)
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Intraocular pressure and cerebral oxygenation during prolonged headward acceleration
- 2017
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Ingår i: European Journal of Applied Physiology. - : Springer. - 1439-6319 .- 1439-6327. ; 117:1, s. 61-72
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Tidskriftsartikel (refereegranskat)abstract
- Supra-tolerance head-to-foot directed gravitoinertial load (+Gz) typically induces a sequence of symptoms/signs, including loss of: peripheral vision-central vision-consciousness. The risk of unconsciousness is greater when anti-G-garment failure occurs after prolonged rather than brief exposures, presumably because, in the former condition, mental signs are not consistently preceded by impaired vision. The aims were to investigate if prolonged exposure to moderately elevated +Gz reduces intraocular pressure (IOP; i.e., improves provisions for retinal perfusion), or the cerebral anoxia reserve. Subjects were exposed to 4-min +Gz plateaux either at 2 and 3 G (n = 10), or at 4 and 5 G (n = 12). Measurements included eye-level mean arterial pressure (MAP), oxygenation of the cerebral frontal cortex, and at 2 and 3 G, IOP. IOP was similar at 1 (14.1 +/- 1.6 mmHg), 2 (14.0 +/- 1.6 mmHg), and 3 G (14.0 +/- 1.6 mmHg). During the G exposures, MAP exhibited an initial prompt drop followed by a partial recovery, end-exposure values being reduced by ae30 mmHg. Cerebral oxygenation showed a similar initial drop, but without recovery, and was followed by either a plateau or a further slight decrement to a minimum of about -14 mu M. Gz loading did not affect IOP. That cerebral oxygenation remained suppressed throughout these G exposures, despite a concomitant partial recovery of MAP, suggests that the increased risk of unconsciousness upon G-garment failure after prolonged +Gz exposure is due to reduced cerebral anoxia reserve.
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| 67. |
- Ekelund, Ulf, 1960-, et al.
(författare)
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Heart rate as an indicator of the intensity of physical activity in human adolescents
- 2001
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Ingår i: European Journal of Applied Physiology. - : Springer Science and Business Media LLC. - 1439-6319 .- 1439-6327. ; 85:3-4, s. 244-249
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Tidskriftsartikel (refereegranskat)abstract
- The aims of this study were, in a group of adolescents, firstly to identify the absolute heart rates (HR) and the percentages of maximal heart rates (HRmax) corresponding to 40%, 60% and 80% of peak oxygen uptake (PVO2), secondly to identify absolute and relative (%PVO2) oxygen uptakes (VO2) corresponding to HR of 120, 140 and 160 beats.min-1, and thirdly to examine a possible effect of fatness and fitness on the relationship between HR and VO2. The subjects were 127 (60 boys, 67 girls) adolescents with a mean age of 14.8 (SD 0.3) years. The HR and VO2 were measured by means of an incremental exercise test to exhaustion. Linear regressions were performed for the HR-VO2 and VO2-HR relationships using absolute and relative (%HRmax, %PVO2) data for each individual. From these regressions, target HR and VO2 were computed. Average target HR corresponding to 40%, 60% and 80% of PVO2 were: 119 (SD 9), 145 (SD 9), 171 (SD 8), and 120 (SD 10), 146 (SD 8), 172 (SD 8) beats.min-1 for boys and girls, respectively. Average VO2 corresponding to HR of 120, 140 and 160 beats.min-1 were: 22 (SD 5), 30 (SD 5), 38 (SD 6) and 18 (SD 4), 24 (SD 4), 31 (SD 4) mlO2.kg-1.min-1 for boys and girls, respectively. An analysis of covariance showed a significant fitness effect (P < 0.001) for predicted VO2 at all HR studied. The results suggest that the use of absolute HR to define exercise intensity levels when assessing young people's physical activity using HR monitoring detracts from the validity of the interpretation of the data.
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| 68. |
- Ekelund, Ulf, 1960-, et al.
(författare)
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Physical activity in relation to aerobic fitness and body fat in 14- to 15-year-old boys and girls
- 2001
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Ingår i: European Journal of Applied Physiology. - : Springer Science and Business Media LLC. - 1439-6319 .- 1439-6327. ; 85:3-4, s. 195-201
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this study was to examine the strength of the relationship between different variables of physical activity and aerobic fitness and body fat in adolescent boys and girls. Activity energy expenditure (AEE), time spent in a sedentary state, and time spent engaged in moderate and vigorous physical activity (MVPA, > or = 50% peak oxygen uptake, VO2peak) were assessed by the minute-by-minute heart rate monitoring method in 82 randomly selected 14- to 15-year olds (42 boys, 40 girls). Body fat was determined by measuring skinfold thicknesses. VO2peak was measured by indirect calorimetry. Somatic maturity level was determined by percentages of adult (i.e. 18 years) height attained at examination. AEE was related to aerobic fitness for both genders (boys, r = 0.30, P = 0.056; girls, r = 0.45, P = 0.003). For boys, there was a significant relationship between maturity level and VO2peak (r = 0.48, P < 0.001). For both genders, body fat was significantly and negatively related to VO2peak (r = -0.48 and r = -0.43, P < 0.01). Body fat and maturity explained 47% of the variation in VO2peak in boys, whereas AEE and body fat explained 22% of the variation in VO2peak in girls. No significant associations between physical activity variables and the data on body fat were observed. The total amount of physical activity (AEE) was related to VO2peak, at least in adolescent girls. Although VO2peak seems to be influenced by the maturity level in adolescent boys, the data support the promotion of a daily active lifestyle among young people.
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| 69. |
- Eklund, Linda M., et al.
(författare)
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Cold air exposure at -15 °C induces more airway symptoms and epithelial stress during heavy exercise than rest without aggravated airway constriction
- 2022
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Ingår i: European Journal of Applied Physiology. - : Springer. - 1439-6319 .- 1439-6327. ; 122:12, s. 2533-2544
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: Exposure to cold air may harm the airways. It is unclear to what extent heavy exercise adds to the cold-induced effects on peripheral airways, airway epithelium, and systemic immunity among healthy individuals. We investigated acute effects of heavy exercise in sub-zero temperatures on the healthy airways.Methods: Twenty-nine healthy individuals underwent whole body exposures to cold air in an environmental chamber at − 15 °C for 50 min on two occasions; a 35-min exercise protocol consisting of a 5-min warm-up followed by 2 × 15 min of running at 85% of VO2max vs. 50 min at rest. Lung function was measured by impulse oscillometry (IOS) and spirometry before and immediately after exposures. CC16 in plasma and urine, and cytokines in plasma were measured before and 60 min after exposures. Symptoms were surveyed pre-, during and post-trials.Results: FEV1 decreased after rest (− 0.10 ± 0.03 L, p < 0.001) and after exercise (− 0.06 ± 0.02 L, p = 0.012), with no difference between trials. Exercise in − 15 °C induced greater increases in lung reactance (X5; p = 0.023), plasma CC16 (p < 0.001) as well as plasma IL-8 (p < 0.001), compared to rest. Exercise induced more intense symptoms from the lower airways, whereas rest gave rise to more general symptoms.Conclusion: Heavy exercise during cold air exposure at − 15 °C induced signs of an airway constriction to a similar extent as rest in the same environment. However, biochemical signs of airway epithelial stress, cytokine responses, and symptoms from the lower airways were more pronounced after the exercise trial.
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| 70. |
- Ekman, Bertil, et al.
(författare)
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Growth hormone substitution titrated to obtain IGF-I levels in the physiological range in hypopituitary adults : Effects upon dynamic strength, endurance and EMG
- 2003
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Ingår i: European Journal of Applied Physiology. - : Springer Science and Business Media LLC. - 1439-6319 .- 1439-6327. ; 90:5-6, s. 496-504
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Tidskriftsartikel (refereegranskat)abstract
- We studied the effects of individualised growth hormone (GH) substitution, aiming at normal insulin-like growth factor I (IGF-I) levels, on biomechanical output and surface electromyogram (EMG) of isokinetic muscle strength and endurance performance in 18 hypopituitary adults and compared with 17 matched healthy controls. The muscle function tests consisted of isokinetic contractions of the right knee extensors, from which torque and EMG were recorded. Three patients were excluded from the final analysis of the muscle function tests due to technical errors and one control subject moved from the area during the study. We found that GH-deficient adults without GH substitution were weaker and had less endurance than healthy control subjects. At the group level, plasma levels of IGF-I were normalised but generally no significant effects upon biomechanical output and EMG were found after dose titration and 6 months of a constant GH dose. However, subjects with the largest changes in IGF-I had significantly better biomechanical output and EMG compared to those with small changes in IGF-I. This finding may indicate that the net increase in IGF-I levels is critical for improvements in biomechanical output, EMG and perception of fatigue to occur.
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| 71. |
- Elcadi, Guilherme H., 1966-, et al.
(författare)
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Shoulder and forearm oxygenation and myoelectric activity in patients with work related muscle pain and healthy subjects
- 2013
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Ingår i: European Journal of Applied Physiology. - New York : Springer. - 1439-6319 .- 1439-6327. ; 113:5, s. 1103-1115
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Tidskriftsartikel (refereegranskat)abstract
- We tested hypotheses of (i) reduced oxygen usage, oxygen recovery, blood flow and oxygen consumption; and (ii) increased muscle activity for patients diagnosed with work related muscle pain in comparison to healthy controls. Oxygenation was measured with near infrared spectroscopy (NIRS), and muscle activity with EMG for the extensor carpi radialis (ECR) and trapezius descendens (TD) muscles. Eighteen patients with diffuse neck-shoulder-arm pain and seventeen controls (matched in age and sex) were equipped with NIRS and EMG probes. After determining an individual’s maximum voluntary contraction (MVC) force, short term (20 sec) isometric contractions for the ECR and TD of 10%, 30%, 50% and 70% MVC generated ∆StO2% and StO2% recovery (Rslope) from NIRS, and RMS%max from EMG signals. In addition, upper arm venous (VO) and arterial (AO) occlusions generated slopes of total hemoglobin (HbTslope) and deoxyhemoglobin (HHbslope) for the resting ECR as surrogates of blood flow and oxygen consumption, respectively. Mixed Model analyses, t-tests, and Mann-Whitney test were used to assess differences between groups. There was no significant difference in MVC between groups for either muscle. Also, ∆StO2%, Rslope for either muscle, and ECR-HbTslope were not different between groups, thus our hypotheses of reduced oxygen use, recovery, and blood flow for patients were not confirmed. However, patients had a significantly lower ECR-HHbslope confirming our hypothesis of reduced consumption. Further, there was no difference in RMS%max during contractions meaning that the hypothesis of increased activity for patients was not confirmed. When taking into account the number of NIRS variables studied, differences we found between our patient group and healthy controls (i.e. in forearm oxygen consumption and shoulder oxygen saturation level) may be considered modest. Overall our findings may have been impacted by the fact that our patients and controls were similar in muscle strength, which is in contrast to previous studies.
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| 72. |
- Elcadi, Guilherme H., 1966-, et al.
(författare)
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The relationship between oxygenation and myoelectric activity in the forearm and shoulder muscles of males and females
- 2011
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Ingår i: European Journal of Applied Physiology. - : Springer. - 1439-6319 .- 1439-6327. ; 111, s. 647-658
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Tidskriftsartikel (refereegranskat)abstract
- The aim was to investigate the relationship between oxygen saturation (StO(2)%) measured with near-infrared spectroscopy (NIRS) and myoelectric activity (root mean square, RMS) for the extensor carpi radialis (ECR) and trapezius muscles. In addition, gender differences were examined for submaximal (10-70% MVC) and sustained (10% MVC for 5 min) isometric contractions. Thirteen males and 15 females participated. Changes in StO(2)% (a dagger StO(2)%) and RMS, expressed as percentages of maximum, were calculated for each submaximal contraction. A good correlation between a dagger StO(2)% and RMS was seen for the ECR (r = -0.53) and a moderate correlation seen for the trapezius muscle (r = -0.44). The ANOVA showed a significant decrease in ECR-a dagger StO(2)% over force with females demonstrating a tendency for larger changes than males. ECR-RMS increased over force with no impact of gender. For the trapezius, a dagger StO(2)% decreased over force but was not gender dependent. Trapezius-RMS increased over force with females demonstrating a tendency for greater change than males. For the sustained contraction, ECR-StO(2)% changed over time but was not gender dependent. ECR-RMS increased over time with females showing a greater response than males. Trapezius-StO(2)% changed over time and differed between genders, i.e., males increased while females decreased. RMS increased over time similarly for both genders. In conclusion, our data show that the ECR and trapezius aerobic demands during isometric contractions are negatively correlated to electromyography (EMG) RMS. The present study also suggests some gender specificity for forearm and shoulder myoelectric activity and oxygenation for submaximal and sustained contractions.
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| 73. |
- Elert, Jessica, 1954-, et al.
(författare)
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Lack of gender differences in the ability to relax between repetitive maximum isokinetic shoulder forward flexions : A population-based study among northern Swedes
- 2000
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Ingår i: European Journal of Applied Physiology. - : Springer Science and Business Media LLC. - 1439-6319 .- 1439-6327. ; 83:4-5, s. 246-256
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the present study was to analyse the effects of gender and age in a population-based sample of clinically healthy subjects on: (1) strength, endurance and perception of fatigue, (2) mean frequency (MNF) of the electromyogram (EMG), and (3) the ability to relax between active contractions (signal amplitude ratio, SAR) of the surface EMG of an isokinetic shoulder forward flexion test. With this aim we have analysed aspects of the validity of MNF as an indicator of fatigue, using peak torque as a criterion variable. The subjects were 27 men and 28 women (age range: 20-60 years), who were obtained by random sample from the official census lists (participation rate: 66%). The peak torque and surface EMG of two portions of the trapezius, deltoid and infraspinatus muscles were recorded throughout 100 repetitive maximal isokinetic shoulder forward flexions. No significant differences in the perception of fatigue and relative endurance levels of peak torque and work were found between males and females. Males were significantly stronger than females and, on average, females produced approximately 60% of the output of the males, 76% after normalisation for body mass. The men had significantly lower MNF endurance levels for three of the investigated muscles. When controlled for age and body mass, the men had a significantly higher MNF of the deltoid muscle than did the females. These differences were only found for the deltoid muscle. Significant correlations existed between the MNF of the four muscles and biomechanical output, indicating criterion validity for the MNF variable with respect to fatigue. There were no significant effects of gender or age on the ability to relax between repetitive contractions (SAR). The higher prevalence of musculoskeletal complaints of the neck-shoulder region in females cannot be explained by a higher intrinsic muscle tension. Age, gender, body mass index and biomechanical output can have significant effects upon MNF. These effects are important considerations in the interpretation of MNF, for instance in ergonomic situations.
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| 74. |
- Elia, Antonis, et al.
(författare)
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Erythropoietic responses to a series of repeated maximal dynamic and static apnoeas in elite and non-breath-hold divers
- 2019
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Ingår i: European Journal of Applied Physiology. - : Springer. - 1439-6319 .- 1439-6327. ; 119:11-12, s. 2557-2565
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: Serum erythropoietin (EPO) concentration is increased following static apnoea-induced hypoxia. However, the acute erythropoietic responses to a series of dynamic apnoeas in non-divers (ND) or elite breath-hold divers (EBHD) are unknown.METHODS: Participants were stratified into EBHD (n = 8), ND (n = 10) and control (n = 8) groups. On two separate occasions, EBHD and ND performed a series of five maximal dynamic apnoeas (DYN) or two sets of five maximal static apnoeas (STA). Control performed a static eupnoeic (STE) protocol to control against any effects of water immersion and diurnal variation on EPO. Peripheral oxygen saturation (SpO2) levels were monitored up to 30 s post each maximal effort. Blood samples were collected at 30, 90, and 180 min after each protocol for EPO, haemoglobin and haematocrit concentrations.RESULTS: No between group differences were observed at baseline (p > 0.05). For EBHD and ND, mean end-apnoea SpO2 was lower in DYN (EBHD, 62 ± 10%, p = 0.024; ND, 85 ± 6%; p = 0.020) than STA (EBHD, 76 ± 7%; ND, 96 ± 1%) and control (98 ± 1%) protocols. EBHD attained lower end-apnoeic SpO2 during DYN and STA than ND (p < 0.001). Serum EPO increased from baseline following the DYN protocol in EBHD only (EBHD, p < 0.001; ND, p = 0.622). EBHD EPO increased from baseline (6.85 ± 0.9mlU/mL) by 60% at 30 min (10.82 ± 2.5mlU/mL, p = 0.017) and 63% at 180 min (10.87 ± 2.1mlU/mL, p = 0.024). Serum EPO did not change after the STA (EBHD, p = 0.534; ND, p = 0.850) and STE (p = 0.056) protocols. There was a significant negative correlation (r = - 0.49, p = 0.003) between end-apnoeic SpO2 and peak post-apnoeic serum EPO concentrations.CONCLUSIONS: The novel findings demonstrate that circulating EPO is only increased after DYN in EBHD. This may relate to the greater hypoxemia achieved by EBHD during the DYN.
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| 75. |
- Elia, Antonis, et al.
(författare)
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Physiology, pathophysiology and (mal)adaptations to chronic apnoeic training: a state-of-the-art review
- 2021
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Ingår i: European Journal of Applied Physiology. - : Springer. - 1439-6319 .- 1439-6327. ; 121:6, s. 1543-1566
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Tidskriftsartikel (refereegranskat)abstract
- Breath-hold diving is an activity that humans have engaged in since antiquity to forage for resources, provide sustenance and to support military campaigns. In modern times, breath-hold diving continues to gain popularity and recognition as both a competitive and recreational sport. The continued progression of world records is somewhat remarkable, particularly given the extreme hypoxaemic and hypercapnic conditions, and hydrostatic pressures these athletes endure. However, there is abundant literature to suggest a large inter-individual variation in the apnoeic capabilities that is thus far not fully understood. In this review, we explore developments in apnoea physiology and delineate the traits and mechanisms that potentially underpin this variation. In addition, we sought to highlight the physiological (mal)adaptations associated with consistent breath-hold training. Breath-hold divers (BHDs) are evidenced to exhibit a more pronounced diving-response than non-divers, while elite BHDs (EBHDs) also display beneficial adaptations in both blood and skeletal muscle. Importantly, these physiological characteristics are documented to be primarily influenced by training-induced stimuli. BHDs are exposed to unique physiological and environmental stressors, and as such possess an ability to withstand acute cerebrovascular and neuronal strains. Whether these characteristics are also a result of training-induced adaptations or genetic predisposition is less certain. Although the long-term effects of regular breath-hold diving activity are yet to be holistically established, preliminary evidence has posed considerations for cognitive, neurological, renal and bone health in BHDs. These areas should be explored further in longitudinal studies to more confidently ascertain the long-term health implications of extreme breath-holding activity.
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| 76. |
- Elia, Antonis, et al.
(författare)
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Six weeks of dynamic apnoeic training stimulates erythropoiesis but does not increase splenic volume
- 2021
-
Ingår i: European Journal of Applied Physiology. - : Springer Science and Business Media Deutschland GmbH. - 1439-6319 .- 1439-6327. ; 121:3, s. 827-838
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: This study examined the influence of dynamic apnoea training on splenic volume and haematological responses in non-breath-hold divers (BHD). Methods: Eight non-BHD performed ten maximal dynamic apnoeas, four times a week for six weeks. Splenic volumes were assessed ultrasonically, and blood samples were drawn for full blood count analysis, erythropoietin, iron, ferritin, albumin, protein and osmolality at baseline, 24 h post the completion of each week’s training sessions and seven days post the completion of the training programme. Additionally, blood samples were drawn for haematology at 30, 90, and 180 min post session one, twelve and twenty-four. Results: Erythropoietin was only higher than baseline (6.62 ± 3.03 mlU/mL) post session one, at 90 (9.20 ± 1.88 mlU/mL, p = 0.048) and 180 min (9.04 ± 2.35 mlU/mL, p = 0.046). Iron increased from baseline (18 ± 3 µmol/L) post week five (23 ± 2 µmol/L, p = 0.033) and six (21 ± 6 µmol/L; p = 0.041), whereas ferritin was observed to be lower than baseline (111 ± 82 µg/L) post week five (95 ± 75 µg/L; p = 0.016), six (84 ± 74 µg/L; p = 0.012) and one week post-training (81 ± 63 µg/L; p = 0.008). Reticulocytes increased from baseline (57 ± 12 × 109/L) post week one (72 ± 17 × 109/L, p = 0.037) and six (71 ± 17 × 109/L, p = 0.021) while no changes were recorded in erythrocytes (p = 0.336), haemoglobin (p = 0.124) and splenic volumes (p = 0.357). Conclusions: Six weeks of dynamic apnoeic training increase reticulocytes without altering mature erythrocyte concentration and splenic volume.
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| 77. |
- Elia, Antonis, et al.
(författare)
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Skeletal muscle, haematological and splenic volume characteristics of elite breath-hold divers.
- 2019
-
Ingår i: European Journal of Applied Physiology. - : Springer. - 1439-6319 .- 1439-6327. ; 119:11-12, s. 2499-2511
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: The aim of the study was to provide an evaluation of the oxygen transport, exchange and storage capacity of elite breath-hold divers (EBHD) compared with non-divers (ND).METHODS: Twenty-one healthy males' (11 EBHD; 10 ND) resting splenic volumes were assessed by ultrasound and venous blood drawn for full blood count analysis. Percutaneous skeletal muscle biopsies were obtained from the m. vastus lateralis to measure capillarisation, and fibre type-specific localisation and distribution of myoglobin and mitochondrial content using quantitative immunofluorescence microscopy.RESULTS: Splenic volume was not different between groups. Reticulocytes, red blood cells and haemoglobin concentrations were higher (+ 24%, p < 0.05; + 9%, p < 0.05; + 3%, p < 0.05; respectively) and mean cell volume was lower (- 6.5%, p < 0.05) in the EBHD compared with ND. Haematocrit was not different between groups. Capillary density was greater (+ 19%; p < 0.05) in the EBHD. The diffusion distance (R95) was lower in type I versus type II fibres for both groups (EBHD, p < 0.01; ND, p < 0.001), with a lower R95 for type I fibres in the EBHD versus ND (- 13%, p < 0.05). Myoglobin content was higher in type I than type II fibres in EBHD (+ 27%; p < 0.01) and higher in the type I fibres of EBHD than ND (+ 27%; p < 0.05). No fibre type differences in myoglobin content were observed in ND. Mitochondrial content was higher in type I than type II fibres in EBHD (+ 35%; p < 0.05), with no fibre type differences in ND or between groups.CONCLUSIONS: In conclusion, EBDH demonstrate enhanced oxygen storage in both blood and skeletal muscle and a more efficient oxygen exchange capacity between blood and skeletal muscle versus ND.
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| 78. |
- Elmer, Steven
(författare)
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Eccentric arm cycling: physiological responses and potential applications for clinical andathletic populations
- 2013
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Ingår i: Journal of applied physiology. - : Springer Science and Business Media LLC. - 8750-7587 .- 1522-1601 .- 1439-6319 .- 1439-6327. ; 113:10, s. 2541-2552
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Tidskriftsartikel (refereegranskat)abstract
- INTRODUCTION:Eccentric leg cycling has served as an important research model for investigating multi-joint eccentric actions and as an effective rehabilitation and training modality for improving locomotor muscle function (e.g., quadriceps size, strength, mobility). While there are more than 30 reports documenting physiological responses to eccentric leg cycling, physiological responses to eccentric arm cycling (ECarm) have not been clearly established.PURPOSE:We tested the hypothesis that ECarm could be performed with lower levels of metabolic and cardiorespiratory demand and perceived exertion compared to traditional concentric arm cycling (CCarm).METHODS:Eight individuals performed ECarm and CCarm at 40, 80, and 120 W (~9 min, 60 rpm) while expired gases and muscle activation patterns were recorded.RESULTS:Oxygen consumption, cardiac output, heart rate, and ventilation were 25-50 % lower during ECarm compared to CCarm (all P < 0.05). Further, only low-to-moderate levels of whole-body and arm-specific perceived exertion were required to perform ECarm which was not the case for CCarm (8-12 vs. 9-16 Borg values, both P < 0.05). Differences in oxygen consumption and total upper body muscle activity between ECarm and CCarm were strongly related (r (2) = 0.75, P < 0.01). Coordination of ECarm involved triceps brachii, deltoideus anterior, and external oblique muscles, whereas CCarm involved all of these muscles along with contributions from biceps brachii, deltoideus posterior, and trapezius transversalis.CONCLUSIONS:These results highlight the high-force, low-cost nature of multi-joint eccentric actions and extend the application of eccentric cycling to the upper body. ECarm may be useful for exercising elbow, trunk, and shoulder musculature while minimizing metabolic and cardiorespiratory strain and perceived exertion.
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| 79. |
- Elmer, Steven J, et al.
(författare)
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Fatigue is specific to working muscles : no cross-over during single-leg cycling in trained cyclists
- 2013
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Ingår i: European Journal of Applied Physiology. - : Springer Science and Business Media LLC. - 1439-6319 .- 1439-6327. ; 113:2, s. 479-488
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Tidskriftsartikel (refereegranskat)abstract
- Fatigue induced via a maximal isometric contraction of a single limb muscle group can evoke a "cross-over" of fatigue that reduces voluntary muscle activation and maximum isometric force in the rested contralateral homologous muscle group. We asked whether a cross-over of fatigue also occurs when fatigue is induced via high-intensity endurance exercise involving a substantial muscle mass. Specifically, we used high-intensity single-leg cycling to induce fatigue and evaluated associated effects on maximum cycling power (P max) in the fatigued ipsilateral leg (FATleg) as well as the rested contralateral leg (RESTleg). On separate days, 12 trained cyclists performed right leg P max trials before and again 30 s, 3, 5, and 10 min after a cycling time trial (TT, 10 min) performed either with their right or left leg. Fatigue was estimated by comparing exercise-induced changes in P max and maximum handgrip isometric force (F max). Mean power produced during the right and left leg TTs did not differ (203 ± 8 vs. 199 ± 8 W). Compared to pre-TT, FATleg P max was reduced by 22 ± 3 % at 30 s post-TT and remained reduced by 9 ± 2 % at 5 min post-TT (both P < 0.05). Despite considerable power loss in the FATleg, post-TT RESTleg P max (596–603 W) did not differ from pre-TT values (596 ± 35 W). There were no alterations in handgrip F max (529–547 N). Our data suggest that any potential cross-over of fatigue, if present at all, was not sufficient to measurably compromise RESTleg P max in trained cyclists. These results along with the lack of changes in handgrip F max indicate that impairments in maximal voluntary neuromuscular function were specific to working muscles.
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| 80. |
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| 81. |
- Enocson, A. G, et al.
(författare)
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Signal intensity of MR-images of thigh muscles following acute open- and closed chain kinetic knee extensor exercise – index of muscle use
- 2005
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Ingår i: European Journal of Applied Physiology. - : Springer Science and Business Media LLC. - 1439-6319 .- 1439-6327. ; 94:4, s. 357-363
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Tidskriftsartikel (refereegranskat)abstract
- Exercise-induced shifts in signal intensity (SI) of magnetic resonance (MR) images were examined to assess indirectly muscle use in closed- and open-chain knee extensor exercises. Eight men performed five sets of 8–12 repetitions in the leg press (LP) and the seated knee extension (KE) exercises at 50, 75 and 100%, respectively of the 5·10 repetition maximum (RM) load. Prior to exercise and after each load setting, images of the thigh were obtained. The increase in SI (D SI) of the quadriceps at 100% load was greater (P<0.05) after KE (32.1±9.0%) than after LP (21.9±9.2%). Regardless of load, the four individual muscles of the quadriceps showed similar changes in SI after LP. The three vastii muscles showed comparable increases in SI after KE. M. rectus femoris showed greater (P<0.05) D SI than the vastii muscles at 100%. Neither exercise produced increase in SI of mm. semimembranosus, semitendinosus, gracilis or biceps femoris. Mm. adductor magnus and longus showed increased (13.3±6.5%; P<0.05) SI after LP, but not after KE, at 100% load. The present data also infer greater involvement of the quadriceps muscle in the open-chain knee extension than in the closedchain leg press exercise. The results of the current investigation also indicate similar over-all use among the three vastii muscles in LP and KE, but ifferential m. rectus femoris use between the two exercises. This report extends the merits of the MR imaging technique as an aid to study individual muscle involvement in a particular exercise task.
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| 82. |
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| 83. |
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| 84. |
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| 85. |
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| 86. |
- Fernandez-Gonzalo, R., et al.
(författare)
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Muscle damage responses and adaptations to eccentric-overload resistance exercise in men and women
- 2014
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Ingår i: European Journal of Applied Physiology. - : Springer Science and Business Media LLC. - 1439-6319 .- 1439-6327. ; 114:5, s. 1075-1084
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: This study assessed markers of muscle damage and training adaptations to eccentric-overload flywheel resistance exercise (RE) in men and women. Methods: Dynamic strength (1 RM), jump performance, maximal power at different percentages of 1 RM, and muscle mass in three different portions of the thigh were assessed in 16 men and 16 women before and after 6 weeks (15 sessions) of flywheel supine squat RE training. Plasma creatine kinase (CK) and lactate dehydrogenase (LDH) concentrations were measured before, 24, 48 and 72 h after the first and the last training session. Results: After training, increases in 1 RM were somewhat greater (interaction P < 0.001) in men (25 %) than in women (20 %). Squat and drop jump height and power performance at 50, 60, 70 and 80 % of 1 RM increased after training in both sexes (P < 0.05). Power improvement at 80 % of 1 RM was greater (interaction P < 0.02) in men than women. Muscle mass increased ~5 % in both groups (P < 0.05). CK increased in men after the first training session (P < 0.001), whereas the response in women was unaltered. In both sexes, LDH concentration was greater after the first training session compared with basal values (P < 0.05). After the last session, CK and LDH remained at baseline in both groups. Conclusions: These results suggest that although improvements in maximal strength and power at high loads may be slightly greater for men, eccentric-overload RE training induces comparable and favorable gains in strength, power, and muscle mass in both men and women. Equally important, it appears muscle damage does not interfere with the adaptations triggered by this training paradigm. © 2014 Springer-Verlag Berlin Heidelberg.
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| 87. |
- Flodgren, Gerd, 1961-, et al.
(författare)
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Changes in interstitial noradrenaline, trapezius muscle activity and oxygen saturation during low-load work and recovery
- 2009
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Ingår i: European Journal of Applied Physiology. - : Springer Science and Business Media LLC. - 1439-6319 .- 1439-6327. ; 107:1, s. 31-42
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Tidskriftsartikel (refereegranskat)abstract
- Both physical as well as mental demands result in an increased activity in the sympathetic nervous system (SNS) with changes in blood-pressure and heart-rate. Through local release of catecholamines, e.g. noradrenaline (NAd) SNS exerts various actions at the muscle level. The aims of this study were to investigate the effects of low-load repetitive work alone and in combination with mental demands on local muscle interstitial noradrenaline concentration [NAd]i, muscle activity and oxygenation, assessed with microdialysis, surface electromyography, and near-infrared spectroscopy, respectively. Healthy females (n = 15) were exposed to (1) 30 min repetitive work (RW) and (2) 30 min repetitive work with superimposed mental load (RWML) on two different occasions. Muscle [NAd]i and muscle activity increased significantly in response to RW, but did not increase further during RWML. For RW, [NAd]i was found to be inversely correlated to muscle activity. Oxygenation decreased significantly during work, independently of occasion. Our findings indicate that low-load work causes significantly increased trapezius muscle [NAd]i in healthy females, and short periods of superimposed mental load do not add to this increase and further, that both muscle activity and oxygenation were unaffected by the superimposed mental load.
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| 88. |
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| 89. |
- Flueck, M, et al.
(författare)
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Linking genes with exercise: where is the cut-off?
- 2010
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Ingår i: European journal of applied physiology. - : Springer Science and Business Media LLC. - 1439-6327 .- 1439-6319. ; 110:6, s. 1095-1098
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 90. |
- Fransson, Dan, 1980, et al.
(författare)
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Skeletal muscle and performance adaptations to high-intensity training in elite male soccer players : speed endurance runs versus small-sided game training
- 2018
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Ingår i: European Journal of Applied Physiology. - : Springer. - 1439-6319 .- 1439-6327. ; 118:1, s. 111-121
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Tidskriftsartikel (refereegranskat)abstract
- To examine the skeletal muscle and performance responses across two different exercise training modalities which are highly applied in soccer training. Using an RCT design, 39 well-trained male soccer players were randomized into either a speed endurance training (SET; n = 21) or a small-sided game group (SSG; n = 18). Over 4 weeks, thrice weekly, SET performed 6-10 x 30-s all-out runs with 3-min recovery, while SSG completed 2 x 7-9-min small-sided games with 2-min recovery. Muscle biopsies were obtained from m. vastus lateralis pre and post intervention and were subsequently analysed for metabolic enzyme activity and muscle protein expression. Moreover, the Yo-Yo Intermittent Recovery level 2 test (Yo-Yo IR2) was performed. Muscle CS maximal activity increased (P < 0.05) by 18% in SET only, demonstrating larger (P < 0.05) improvement than SSG, while HAD activity increased (P < 0.05) by 24% in both groups. Na+-K+ ATPase alpha(1) subunit protein expression increased (P < 0.05) in SET and SSG (19 and 37%, respectively), while MCT4 protein expression rose (P < 0.05) by 30 and 61% in SET and SSG, respectively. SOD2 protein expression increased (P < 0.05) by 28 and 37% in SET and SSG, respectively, while GLUT-4 protein expression increased (P < 0.05) by 40% in SSG only. Finally, SET displayed 39% greater improvement (P < 0.05) in Yo-Yo IR2 performance than SSG. Speed endurance training improved muscle oxidative capacity and exercise performance more pronouncedly than small-sided game training, but comparable responses were in muscle ion transporters and antioxidative capacity in well-trained male soccer players.
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| 91. |
- Fransson, Per-Anders, et al.
(författare)
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Balance Control and Adaptation during Vibratory Perturbations in Middle-Aged and Elderly Humans.
- 2004
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Ingår i: European Journal of Applied Physiology. - : Springer Science and Business Media LLC. - 1439-6327 .- 1439-6319. ; 91:5-6, s. 595-603
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Tidskriftsartikel (refereegranskat)abstract
- The objective was to investigate if healthy elderly people respond and adapt differently to postural disturbances compared to middle-aged people. Thirty middle-aged (mean age 37.8 years, range 24–56 years) and forty healthy elderly subjects (mean age 74.6 years, range 66–88 years) were tested with posturography. Body sway was evoked by applying pseudorandom vibratory stimulation to the belly of the gastrocnemius muscles of both legs simultaneously. The tests were performed both with eyes open and eyes closed. The anteroposterior body sway was measured with a force platform and analyzed with a method that considers the adaptive changes of posture and stimulation responses. The results showed that middle-aged people generally used a different postural control strategy as compared to the elderly. The elderly responded more rapidly to vibratory perturbation, used more high-frequency (>0.1 Hz) motions and the motion dynamics had a higher degree of complexity. Moreover, the elderly had diminished ability to use visual information to improve balance control. Altogether, despite having an effective postural control adaptation similar to that of middle-aged people, the elderly had more difficultly in withstanding balance perturbations. These findings suggest that the balance control deterioration associated with aging cannot be fully compensated for by postural control adaptation.
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| 92. |
- Fransson, Per-Anders, et al.
(författare)
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Changes in multi-segmented body movements and EMG activity while standing on firm and foam support surfaces.
- 2007
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Ingår i: European Journal of Applied Physiology. - : Springer Science and Business Media LLC. - 1439-6327 .- 1439-6319. ; 101:1, s. 81-89
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Tidskriftsartikel (refereegranskat)abstract
- Postural control ensures stability during both static posture and locomotion by initiating corrective adjustments in body movement. This is particularly important when the conditions of the support surface change. We investigated the effects of standing on a compliant foam surface using 12 normal subjects (mean age 26 years) in terms of: linear movements at the head, shoulder, hip and knee; EMG activity of the tibialis anterior and gastrocnemius muscles and torques towards the support surface. As subjects repeated the trials with eyes open or closed, we were also able to determine the effects of vision on multi-segmented body movements during standing upon different support surface conditions. As expected, EMG activity, torque variance values and body movements at all measured positions increased significantly when standing on foam compared with the firm surface. Linear knee and hip movements increased more, relative to shoulder and head movements while standing on foam. Vision stabilized the head and shoulder movements more than hip and knee movements while standing on foam support surface. Moreover, vision significantly reduced the tibialis anterior EMG activity and torque variance during the trials involving foam. In conclusion, the foam support surface increased corrective muscle and torque activity, and changed the firm-surface multi-segmented body movement pattern. Vision improved the ability of postural control to handle compliant surface conditions. Several essential features of postural control have been found from recording movements from multiple points on the body, synchronized with recording torque and EMG.
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| 93. |
- Fritz, Jesper, et al.
(författare)
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A 5-year exercise program in children improves muscle strength without affecting fracture risk.
- 2016
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Ingår i: European Journal of Applied Physiology. - : Springer Science and Business Media LLC. - 1439-6327 .- 1439-6319. ; 116:4, s. 707-715
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Tidskriftsartikel (refereegranskat)abstract
- High level of physical activity (PA) is associated with great muscle strength and high fracture risk. This prospective controlled population-based study evaluated how a pediatric PA intervention program influenced muscle strength and fracture risk.
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| 94. |
- Frohm, Anna, et al.
(författare)
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A new device for controlled eccentric overloading in training and rehabilitation
- 2005
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Ingår i: European Journal of Applied Physiology. - : Springer Science and Business Media LLC. - 1439-6319 .- 1439-6327. ; 94:1-2, s. 168-174
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this work was to evaluate a device that allows for eccentric overload to be applied under controlled and safe conditions and it is applicable in exercises commonly used in training and rehabilitation. The machine contains a barbell, which is lowered and raised by a motor, following a predetermined velocity profile. It is capable of handling heavy loads (> 500 kg) and is instrumented with a sensor to measure the velocity of the barbell and two scales to measure the vertical component of the ground reaction force. The velocity recordings of the built-in displacement sensor were found to correspond well with those obtained using a motion-capture system. Applying known weights on each scale demonstrated linearity with respect to magnitude and independence regarding location of application. The velocity of the barbell was found to be dependent on the load on the barbell and on the resisting force produced by the individual training in the machine. The combined man-machine reliability was tested using a group of habitually active males (n = 13, 2855 years) performing squats. Peak voluntary resisting force and position at peak resistance were recorded on two occasions, showing no significant differences and a coefficient of variation of 9% and 22%, respectively. Preliminary observations from training in the machine have been positive both for increasing performance in top athletes and for causing pain relief in patients with diffuse knee problems. The possibility of feedback of the force under each foot makes individual dosage of training load possible, which is valuable, e.g. in rehabilitation of a unilateral injury.
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| 95. |
- Gago, Paulo, et al.
(författare)
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Post activation potentiation can be induced without impairing tendon stiffness.
- 2014
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Ingår i: European Journal of Applied Physiology. - : Springer Science and Business Media LLC. - 1439-6319 .- 1439-6327. ; 114:11, s. 2299-2308
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: This study aimed to investigate conditioning effects from a single 6-s plantar flexion maximal voluntary isometric contraction (MVIC) on Achilles tendon stiffness (ATS) and twitch properties of the triceps surae in athletes.METHODS: Peak twitch (PT), rate of torque development (RTD), rising time (RT10-90%) and half relaxation time (HRT) were measured from supramaximal twitches evoked in the plantar flexors of 10 highly trained athletes. Twitches were evoked before and at seven occasions during 10 min of recovery after a 6-s MVIC. In a second session, but at identical post-conditioning time points, ATS was measured at 30 and 50 % of MVIC (ATS30% and ATS50%) using an ultrasonography-based method.RESULTS: The magnitude and duration of the conditioning MVIC on muscle contractile properties were in accordance with previous literature on post activation potentiation (PAP), i.e., high potentiation immediately after MVIC, with significant PAP for up to 3 min after the MVIC. While PT and RTD were significantly enhanced (by 60.6 ± 19.3 and 90.1 ± 22.5 %, respectively) and RT10-90% and HRT were reduced (by 10.1 ± 7.7 and 18.7 ± 5.6 %, respectively) after conditioning, ATS remained unaffected.CONCLUSIONS: Previous studies have suggested that changes in stiffness after conditioning may interfere with the enhancements in twitch contractile properties. The present study, however, provided some evidence that twitch enhancements after a standard PAP can be induced without changes in ATS. This result may suggest that athletes can use this protocol to enhance muscle contractile properties without performance deficits due to changes in ATS.
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| 96. |
- Gao, Chuansi, et al.
(författare)
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Cooling vests with phase change materials: the effects of melting temperature on heat strain alleviation in an extremely hot environment
- 2011
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Ingår i: European Journal of Applied Physiology. - : Springer Science and Business Media LLC. - 1439-6327 .- 1439-6319. ; 111:6, s. 1207-1216
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Tidskriftsartikel (refereegranskat)abstract
- A previous study by the authors using a heated thermal manikin showed that the cooling rates of phase change material (PCM) are dependent on temperature gradient, mass, and covering area. The objective of this study was to investigate if the cooling effects of the temperature gradient observed on a thermal manikin could be validated on human subjects in extreme heat. The subjects wore cooling vests with PCMs at two melting temperatures (24 and 28°C) and fire-fighting clothing and equipment, thus forming three test groups (vest24, vest28 and control group without the vest). They walked on a treadmill at a speed of 5 km/h in a climatic chamber (air temperature = 55°C, relative humidity = 30%, vapour pressure = 4,725 Pa, and air velocity = 0.4 m/s). The results showed that the PCM vest with a lower melting temperature (24°C) has a stronger cooling effect on the torso and mean skin temperatures than that with a higher melting temperature (28°C). Both PCM vests mitigate peak core temperature increase during the resting recovery period. The two PCM vests tested, however, had no significant effect on the alleviation of core temperature increase during exercise in the heat. To study the possibility of effective cooling of core temperature, cooling garments with PCMs at even lower melting temperatures (e.g. 15°C) and a larger covering area should be investigated.
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| 97. |
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| 98. |
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| 99. |
- Gerdhem, Paul, et al.
(författare)
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Accelerometer-measured daily physical activity among octogenerians: results and associations to other indices of physical performance and bone density
- 2008
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Ingår i: European Journal of Applied Physiology. - : Springer Science and Business Media LLC. - 1439-6327 .- 1439-6319. ; 102:2, s. 173-180
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Tidskriftsartikel (refereegranskat)abstract
- Information on objectively assessed physical activity in elderly people is scarce. The aim of this study was to investigate accelerometer measures in elderly women, and its relation to other indices of physical activity and bone density. A subset of 57 women, all 80 years old, (range 80.0-80.7) of the Malmo OPRA study was equipped with an MTI accelerometer for a period of 5-7 days. A 7-day activity log was used. At baseline a self-assessment questionnaire was used and isometric muscle strength (knee), gait speed, balance and bone density measurements [dual-energy X-ray absorptiometry (total body, hip, and spine), and quantitative ultrasound of the calcaneus] were measured. About 14% (8 out of 57) had a moderate to vigorous physical activity (MVPA) (>1,952 counts per min [CPM]) exceeding 30 min/day. The median CPM was 18. When compared to questionnaire data, the correlation between MVPA and physical activity was 0.50 (P < 0.001). The corresponding result for CPM was 0.48, P < 0.001. When compared to the activity log, the correlation between MVPA and physical activity away from home was 0.49 (P < 0.001). The corresponding result for CPM was 0.55, P < 0.001. The correlation between MVPA and gait speed was 0.41 (P = 0.002). The corresponding result for CPM was 0.40, P = 0.002. There were no correlations to the measurements of muscle strength, balance or bone density (all P >/= 0.07). Accelerometers can be used for measuring of physical activity also of the elderly. Questions on daily physical activity correlated modestly with accelerometer results in elderly women. Accelerometer results were not correlated to measures of balance, muscle strength and bone density.
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| 100. |
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