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- Keramidas, Michail E., et al.
(författare)
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The effect of interval training combined with external pressure on thighs on maximal and submaximal performance
- 2009
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Ingår i: Acta Physiologica. - : John Wiley & Sons. - 1748-1708 .- 1748-1716. ; 197:S675, s. L47-L47
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Tidskriftsartikel (refereegranskat)abstract
- It is well known that a moderate reduction of muscle blood flow (low body positive pressure of 50 mmHg) during endurance continuous exercise training enhances the local aerobic muscle adaptations. The present study investigates the effect of interval training combined with thigh cuffs pressure of +90 mmHg on maximal and submaximal performance. Twenty untrained individuals (age = 23.0 ± 4.2 yrs; stature = 168.3 ± 9.6 cm; body mass = 64.2 ± 15.0 kg) were assigned either to control (CON) or to experimental (CUFF) training group. All participants carried out an incremental exercise test to exhaustion (VO2max), a 6-min constant test at 80% of VO2max (Sub80) and a constant power test (TF150) pre and post training. Furthermore, they obtained an incremental exercise test with cuffs inflated to external pressure of +90 mmHg (VO2maxPress) pre-training in order to be determined the training intensity. Both groups performed interval training on cycle-ergometers 3 d·wk-1 for 6 wks. The CON group trained on cycle ergometer without cuffs, whereas the CUFF group trained with cuffs on thighs pressurized to +90 mmHg (cuffs depressurized during active recovery) at the same relative intensity. In particular, each training session consisted of 2-min work bout at 90% of VO2max or VO2maxPress: 2-min active recovery bout at 40% of VO2max. Despite the unchanged VO2max, both groups increased significant PPO (CON: Pre = 207.2 ± 60.6 Watts, Post = 237.7 ± 77.2 Watts; CUFF: Pre = 182.3 ± 40.8 Watts, Post = 227.0 ± 37.7 Watts; P<= 0.05) that was accompanied by higher deoxygenation (DStO2) (CON: Pre = -15.3 ± 1.3%, Post = -29.1 ± 1.3%; CUFF: Pre = -21.6 ± 1.5%, Post = -42.4 ± 1.6%; P<= 0.05) measured with near infrared spectroscopy (NIRS); the deoxygenation was more pronounced on CUFF group (P<= 0.05) at the same relative PPO. Moreover, both groups reduced VO2 (P<= 0.05) during Sub80 without concomitant changes in DStO2. Also, CON and CUFF group improved TF150 by ~40% and ~32%, respectively; but there were no differences between training groups. It seems that 6-wks interval training combined with thigh cuffs pressure of +90 mmHg on exercised legs at the same relative intensity does not provide any additive effect on maximal and submaximal performance. However, despite the lower absolute training intensity of CUFF group, the enhanced PPO that was accompanied by higher DStO2 may reveal improvement of peripheral aerobic factors transferring and consuming O2.
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- Keramidas, Michail E., et al.
(författare)
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The effect of interval training combined with thigh cuffs pressure on maximal and submaximal exercise performance
- 2012
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Ingår i: Clinical Physiology and Functional Imaging. - : Wiley-Blackwell. - 1475-0961 .- 1475-097X. ; 32:3, s. 205-213
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of the study was to investigate the effect of interval training combined with a thigh cuffs pressure of +90 mmHg on maximal and submaximal cycling performance. Twenty untrained individuals were assigned either to a control (CON) or to an experimental (CUFF) training group. Both groups trained 3 days per week for 6 weeks at the same relative intensity; each training session consisted of 2-min work bout at 90% of VO(2max): 2-min active recovery bout at 50% of VO(2max). An incremental exercise test to exhaustion, a 6-min constant-power test at 80% of VO(2max) (Sub(80)) and a maximal constant-power test to exhaustion (TF(150)) were performed pre- and post-training. Despite the unchanged VO(2max), both groups significantly increased peak power output (CON: ∼12%, CUFF: ∼20%) that was accompanied by higher deoxygenation (ΔStO(2)) measured with near-infrared muscle spectroscopy. These changes were more pronounced in the CUFF group. Moreover, both groups reduced VO(2) during the Sub(80) test without concomitant changes in ΔStO(2). TF(150) was enhanced in both groups. Thus, an interval exercise training protocol under moderate restricted blood flow conditions does not provide any additive effect on maximal and submaximal cycling performance. However, it seems to induce peripheral muscular adaptations, despite the lower absolute training intensity.
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- Kounalakis, S. N., et al.
(författare)
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The role of muscle pump in the development of cardiovascular drift
- 2008
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Ingår i: European Journal of Applied Physiology. - 1439-6319 .- 1439-6327. ; 103, s. 99-107
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Tidskriftsartikel (refereegranskat)abstract
- This study examined the role of muscle pump in the development of cardiovascular drift (CVdrift) during cycling. Twelve healthy males (23.4 ± 0.5 years, mean ± SE) exercised for 90 min with 40 and 80 pedal revolutions per minute (rpm) at the same oxygen consumption, in two separate days. CVdrift was developed in both conditions as indicated by the drop in stroke volume (SV) and the rise in heart rate (HR) from the 20th min onwards (ΔSV = −16.2 ± 2.0 and −17.1 ± 1.0 ml beat−1; ΔHR = 18.3 ± 2.0 and 17.5 ± 3.0 beats min−1 for 40 and 80 rpm, respectively, P < 0.05) but without difference between conditions. Mean cardiac output (CO2 rebreathing) was 14.7 ± 0.3 l min−1 and 15.0 ± 0.3 l min−1, and mean arterial pressure was 100.0 ± 1.0 mmHg and 96.7 ± 0.8 mmHg for 40 and 80 rpm, respectively, without significant changes over time, and without difference between conditions. Electromyographic activity (iEMG) was lower throughout exercise with 80 rpm (35.6 ± 1.2% and 11.0 ± 1.0% for 40 and 80 rpm, respectively). Similarly, total hemoglobin, determined with near-infrared spectroscopy (NIRS) was 58.0 ± 0.8 (AU) for 40 rpm and 53.0 ± 1.4 (arbitrary units) for 80 rpm, from 30th min onwards (P < 0.05), an indication of lower leg blood volume during the faster pedal rate condition. Thermal status (rectal and mean skin temperature), blood and plasma volume changes, blood lactate concentration, muscle oxygenation (NIRS signal) and the rate of perceived exertion were similar in the two trials. It seems that muscle pump is not an important factor for the development of CVdrift during cycling, at least under the present experimental conditions
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- Vanhees, L, et al.
(författare)
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Importance of characteristics and modalities of physical activity and exercise in the management of cardiovascular health in individuals with cardiovascular risk factors : recommendations from the EACPR. Part II.
- 2012
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Ingår i: European journal of preventive cardiology. - : Oxford University Press (OUP). - 2047-4881 .- 2047-4873. ; 19:5, s. 1005-33
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Tidskriftsartikel (refereegranskat)abstract
- In a previous paper, as the first of a series of three on the importance of characteristics and modalities of physical activity (PA) and exercise in the management of cardiovascular health within the general population, we concluded that, in the population at large, PA and aerobic exercise capacity clearly are inversely associated with increased cardiovascular disease risk and all-cause and cardiovascular mortality and that a dose–response curve on cardiovascular outcome has been demonstrated in most studies. More and more evidence is accumulated that engaging in regular PA and exercise interventions are essential components for reducing the severity of cardiovascular risk factors, such as obesity and abdominal fat, high BP, metabolic risk factors, and systemic inflammation. However, it is less clear whether and which type of PA and exercise intervention (aerobic exercise, dynamic resistive exercise, or both) or characteristic of exercise (frequency, intensity, time or duration, and volume) would yield more benefit for each separate risk factor. The present paper, therefore, will review and make recommendations for PA and exercise training in the management of cardiovascular health in individuals with cardiovascular risk factors. The guidance offered in this series of papers is aimed at medical doctors, health practitioners, kinesiologists, physiotherapists and exercise physiologists, politicians, public health policy makers, and individual members of the public. Based on previous and the current literature overviews, recommendations from the European Association on Cardiovascular Prevention and Rehabilitation are formulated regarding type, volume, and intensity of PA and regarding appropriate risk evaluation during exercise in individuals with cardiovascular risk factors.
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- Geladas, N.D., et al.
(författare)
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Maximal oxygen uptake may be limited by sensation of muscle oxygenation
- 2010
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Ingår i: Open Sports Medicine Journal. - : Bentham Science Publishers Ltd.. - 1874-3870. ; 4, s. 9-16
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Tidskriftsartikel (refereegranskat)abstract
- Background: The aim of the present study was to investigate the effects of restricted muscular oxygenation on VO2max, peak power output (PPO), and maximum heart rate (HRmax).Methods: Six young healthy male subjects participated in four testing sessions within a 2-week period. On four separate days, participants performed stepwise incremental exercise tests to exhaustion (VO2maxNor) on a cycle ergometer under control condition and with thigh cuffs inflated to external pressure of 60, 90 and 120 mmHg, respectively (Cuff60, Cuff90, Cuff120), following a counterbalanced order. Respiratory gas exchange responses, heart rate and near infrared spectroscopy (NIRS) measurements of muscle oxygenation from rectus femoris muscle were continuously monitored during the four tests.Results: A decrease proportional to the degree of cuff inflation was observed in VO2max (Nor = 42.9 ± 3.7, Cuff60 = 34.5 ± 5.8, Cuff90 = 33.4 ± 3.5, Cuff120 = 31.2 ± 6.8 ml·kg-1·min-1; p<0.05). Lower values of PPO (Nor= 298 ± 64, Cuff60 = 252 ± 35, Cuff90 = 213 ± 26, Cuff120 = 210 ± 20 Watts, P<0.05) and HRmax (Nor = 183.7 ± 4.8, Cuff60 = 177.5 ± 7.7, Cuff90 = 168.8 ± 14.0, Cuff120 = 170.8 ± 17.1 beats·min-1, p<0.05) were recorded in cuff conditions. Final values of muscle deoxygenation and rate of perceived exertion were not different among the four conditions.Conclusions: It appears that with cuff application, muscle oxygenation is compromised leading to premature sensation of maximum effort, which in turn prevents the heart and the muscle from attaining their maximum capacity.
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- Keramidas, Michail E., et al.
(författare)
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Forearm-finger skin temperature gradient as an index of cutaneous perfusion during steady-state exercise
- 2013
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Ingår i: Clinical Physiology and Functional Imaging. - : Wiley-Blackwell. - 1475-0961 .- 1475-097X. ; 33:5, s. 400-404
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this study was to examine whether the forearm-finger skin temperature gradient (Tforearm-finger), an index of vasomotor tone during resting conditions, can also be used during steady-state exercise. Twelve healthy men performed three cycling trials at an intensity of similar to 60% of their maximal oxygen uptake for 75min separated by at least 48h. During exercise, forearm skin blood flow (BFF) was measured with a laser-Doppler flowmeter, and finger skin blood flow (PPG) was recorded from the left index fingertip using a pulse plethysmogram. Tforearm-finger of the left arm was calculated from the values derived by two thermistors placed on the radial side of the forearm and on the tip of the middle finger. During exercise, PPG and BFF increased (P<0.001), and Tforearm-finger decreased (P<0.001) from their resting values, indicating a peripheral vasodilatation. There was a significant correlation between Tforearm-finger and both PPG (r=-0.68; P<0.001) and BFF (r=-0.50; P<0.001). It is concluded that Tforearm-finger is a valid qualitative index of cutaneous vasomotor tone during steady-state exercise.
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