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| 2. |
- Helge, E. Wulff, et al.
(författare)
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BMD in elite female triathletes is related to isokinetic peak torque without any association to sex hormone concentrations
- 2012
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Ingår i: Journal of Sports Medicine and Physical Fitness. - : Edizioni Minerva Medica. - 0022-4707 .- 1827-1928. ; 52:5, s. 489-500
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Tidskriftsartikel (refereegranskat)abstract
- Aim. Female endurance athletes suffering from low energy availability and reproductive hormonal disorders are at risk of low BMD. Muscle forces acting on bone may have a reverse site-specific effect. Therefore we wanted to test how BMD in female elite triathletes was associated to isokinetic peak torque (IPT) and reproductive hormone concentrations (RHC). A possible effect of oral contraceptives (OCON's) is taken into consideration. Methods. Eight female elite triathletes (training 8-24 hrs/wk) and seven sedentary controls, age 21-37 years, participated. Total body and regional BIVID (g.cm(-2)) were measured by DXA. IPT were measured during knee extension, and trunk extension and flexion (Nm). Serum RHC and biochemical bone markers were evaluated. Energy balance was estimated from 7-days training-and weighed food records. Results. Despite a high training volume, BMD in triathletes was not higher than in controls. In triathletes trunk flexion IPT, but not RHC, was a strong predictor of BMD in both total body and femur (0.70
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| 3. |
- Laurent, C M, et al.
(författare)
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Effect of gender on fatigue and recovery following maximal intensity repeated sprint performance
- 2010
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Ingår i: Journal of Sports Medicine and Physical Fitness. - 0022-4707 .- 1827-1928. ; 50:3, s. 243-253
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Tidskriftsartikel (refereegranskat)abstract
- Aim. This study investigated the effects of gender on repeated, maximal-intensity intermittent sprint exercise following variable day-to-day recovery periods.Methods. Sixteen volunteers (8 men, 8 women) performed four trials of high-intensity intermittent sprint exercise consisting of three bouts of eight 30 m sprints (total of 24 sprints). Following completion of the baseline trial, in repeated-measures design, participants were assigned, in counter-balanced order, variable recovery periods of 24, 48, and 72 h whereupon they repeated an identical exercise trial.Results. Results from a series of 4 (trial) x 3 (bout) repeated measures ANOVAs revealed men produced significantly (P < 0.01) faster times throughout all bouts and trials of repeated sprint exercise. Additionally, women exhibited significantly lower (P < 0.05) blood lactate concentration and significantly lower (P < 0.05) decrement in performance, indicating increased resistance to fatigue during repeated exercise sessions. There were no significant differences (P > 0.05) between genders for heart rate or rating of perceived exertion during or following trials. There were no significant differences for overall sprint performance within either gender among trials.Conclusions. These results indicate men, while able to produce higher absolute power outputs (i.e., lower sprint time), demonstrate higher decrement scores within a trial compared to women, thus suggesting women may recover faster and fatigue less. Also, gender differences affecting recovery within in a trial were observed to be diminished between trials (i.e., day-today recovery) of maximal intermittent sprint work evidenced by the observed stability of performance between trials following various recovery durations.
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- Mandroukas, A, et al.
(författare)
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Deltoid muscle fiber characteristics in adolescent and adult wrestlers.
- 2010
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Ingår i: Journal of Sports Medicine and Physical Fitness. - 0022-4707 .- 1827-1928. ; 50:2, s. 113-20
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Tidskriftsartikel (refereegranskat)abstract
- Our findings suggest that the observed muscle fiber profile in the deltoid muscle of wrestlers may represent an adaptation based on the mechanical and biochemical demands of the long-term training. Such adaptations are linked to the specific characteristics of the training program, the level and the previous training experience of the wrestlers.
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| 5. |
- Sperlich, Billy, et al.
(författare)
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Cardiorespiratory, metabolic and hormonal responses during open-wheel indoor kart racing
- 2014
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Ingår i: Journal of Sports Medicine and Physical Fitness. - 0022-4707 .- 1827-1928. ; 54:4, s. 475-480
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Tidskriftsartikel (refereegranskat)abstract
- AIM: This study aimed to quantify the cardiorespiratory, metabolic and hormonal responses of elite open-wheel indoor kart racers.METHODS: Ten male racers (age: 21±3 yrs; height: 1.92±0.06 m, body mass: 76.0±5.9 kg) participated in a racing tournament. Their peak oxygen uptake and heart rate were assessed by a ramp test (100 W, increase 30 W·min-1) in the laboratory. During the racing itself, the cardio-respiratory and accelerometer values were recorded and pre- and post-race levels of blood lactate and salivary cortisol were determined.RESULTS: The average peak values for all of the drivers with respect to oxygen uptake and heart rate were 4.5±0.8 L·min-1 (56.7±7.9 mL·min-1·kg-1) and 193±5 beats·min-1, respectively. Overall, 28.3±3.3 laps were completed during 30-min of racing. Acceleration forces for the entire test averaged 1.20±0.51 G (maximum: 3.30 G), declining from the first 10 min until the end of racing (P<0.03). The oxygen uptake (~20 mL·min-1·kg-1), heart rate (~133 beats·min-1), respiratory exchange ratio (~0.96) and ventilation (~70 L·min-1) observed indicated moderate cardio-respiratory responses. Blood lactate concentration was significantly higher after the race than before but remained at <2 mmol·L-1 (P<0.01; effect size: 1.62).CONCLUSION: There were no differences between salivary cortisol levels before and after the race (P<0.06; effect size: 0.49). Directly after the race, the drivers rated their perceived exertion on Borg’s scale as 11.1±1.3. The present data revealed that the psycho-physical exertion associated with a 30-min open-wheel indoor kart race is moderate.
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| 6. |
- Sperlich, Billy, et al.
(författare)
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Physiological effects of a new racing suit for elite cross country skiers
- 2011
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Ingår i: Journal of Sports Medicine and Physical Fitness. - 0022-4707 .- 1827-1928. ; 51:4, s. 555-559
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Tidskriftsartikel (refereegranskat)abstract
- AIM: The aim of this paper was to investigate the influence of the new cross country racing suit, designed for the Olympic Winter Games in Vancouver 2010, on cardio-respiratory, thermoregulatory and perceptual responses.METHODS: Six elite cross country skiers (29±6 years, peak oxygen uptake 73.2±6.9 mL·min-1·kg-1) performed two exercise bouts wearing either the 2009 or the 2010 racing suit. Bouts consisted of incremental testing on roller skis (12 km·h-1 at 5° inclination; 11 km·h-1 at 6° inclination and 12 km·h-1at 8° inclination for six minutes).RESULTS: During increasing intensities, significantly lower values were found for oxygen uptake, minute ventilation, RER and heart rate when wearing the new suit compared to the old one (P<0.05; effect sizes: 0.21-4.00). Core temperature was lower with the new suit during steps 2 and 3 (P<0.05, effect size: 1.22-1.27). Also, mean skin temperature was lower during the last increment (P<0.05, effect size: 0.87).CONCLUSION:The new 2010 racing suit, developed specifically for the Olympic Winter Games in Vancouver 2010, demonstrated lower values for oxygen uptake, minute ventilation, heart rate, skin and core temperature, ratings of thermal and sweat sensation when compared to the 2009 racing suit.
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| 9. |
- Dencker, Magnus, et al.
(författare)
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Aerobic capacity related to cardiac size in young children.
- 2013
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Ingår i: Journal of Sports Medicine and Physical Fitness. - 0022-4707. ; 53:1, s. 42-47
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Tidskriftsartikel (refereegranskat)abstract
- Aim:Aerobic capacity, defined as peak oxygen uptake (VO2PEAK), is generally considered to be the best single marker for aerobic fitness. We assessed if VO2PEAK is related to different cardiac dimensions in healthy young children on a population base. Methods: In a cross-sectional study, 245 children (137 boys and 108 girls) aged 8-11 years, were recruited from a population based cohort. VO2PEAK (ml/min-1/kg-1) was assessed by indirect calorimetry during a maximal exercise test. DXA-scan was used to measure lean body mass (LBM) and total fat mass (TBF). Echocardiography, with 2-dimensional guided M-mode, was performed in accordance with current guidelines. Left ventricular end-diastolic diameter (LVDD) and left atrial end-systolic diameter (LA) were measured, and left ventricular mass (LVM) was calculated. Results: Univariate correlations were found between VO2PEAK versus LVDD r=0.44 and LA r=0.27 (both P<0.05) and LVM r=-0.06 (NS) in boys. Corresponding values for girls were; 0.55, 0.34 (both P<0.05) and 0.11 (NS). Multiple regression analysis with VO2PEAK as dependent variable and inclusion of LBM, TBF, sex, age, Tanner stage, and maximal heart rate as independent variables showed that 67% of the total variance of VO2PEAK could be explained by these variables. Including LVDD or LA in the model, added 1% additional explained variance. Conclusion: Findings from this population based cohort of young healthy children show that multiple cardiac dimensions at rest are related to VO2PEAK. However, the different cardiac dimensions contributed very little to the added explained variance of VO2PEAK.
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| 10. |
- Dencker, Magnus, et al.
(författare)
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Importance of epoch length and registration time on accelerometer measurements in younger children.
- 2012
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Ingår i: Journal of Sports Medicine and Physical Fitness. - 0022-4707. ; 52:2, s. 115-121
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Tidskriftsartikel (refereegranskat)abstract
- AIM: The aim of this study was to investigate the effect of epoch length on accumulation of minutes of physical activity per day over a spectrum of intensities, and the effect that selection of number of hours of acceptable registration required per day had on number of days that were considered acceptable. METHODS: Participants were 696 children (369 boys and 327 girls) aged 6.7±0.4 yrs, from a population-based cohort. Physical activity was assessed by the Actigraph accelerometer for four days. RESULTS: Main findings were that epoch length had a profound impact on accumulation of minutes of physical activity per day for higher intensities, whereas it had no effect on mean counts per minute. The chosen number of hours for an acceptable registration per day heavily influenced the number of days that were considered acceptable. CONCLUSION: The findings in the present investigation should be taken into consideration when planning objective measurements of daily physical activity in younger children, and highlight the need for setting international recommendations for physical activity measurements with accelerometers, if different studies are to be comparable
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| 11. |
- Karlsson, Magnus, et al.
(författare)
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Groin pain and soccer players: male versus female occurrence.
- 2014
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Ingår i: Journal of Sports Medicine and Physical Fitness. - 0022-4707. ; 54:4, s. 487-493
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Tidskriftsartikel (refereegranskat)abstract
- Groin pain is common in soccer players. Comparison of results from different studies, especially between genders, is difficult as studies use different definitions and data collection procedures. Therefore we conducted a study of both male and female soccer players enabling direct gender comparison.
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