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- Sperlich, Billy, et al.
(författare)
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Biomechanical, cardiorespiratory, metabolic and perceived responses to electrically assisted cycling.
- 2012
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Ingår i: European Journal of Applied Physiology. - : Springer. - 1439-6319 .- 1439-6327. ; 112:12, s. 4015-4025
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Tidskriftsartikel (refereegranskat)abstract
- The aims of the present study were to characterize the effects of cycling in varying terrain with the assistance of an electric motor with respect to (1) power output, velocity, and electromyography (EMG) signals; (2) cardiorespiratory parameters; (3) energy expenditure (EE); (4) rate of perceived exertion (RPE) and enjoyment and to compare these effects with those of non-assisted cycling. Eight sedentary women (age: 38 ± 15 years, BMI: 25.3 ± 2.1 kg m(-2)) cycled 9.5 km on varying terrain (change in elevation: 102 m, maximum incline: 5.8 %) at their own pace, once with and once without motorized assistance, in randomized order. With electrical assistance, the mean power output (-29 %); EMG patterns of the m. biceps femoris (-49 %), m. vastus lateralis (-33 %), m. vastus medialis (-37 %), and m. gastrocnemius medialis (-29 %); heart rate (-29.1 %); oxygen uptake (-33.0 %); respiratory exchange ratio (-9.0 %); and EE (-36.5 %) were all lower, whereas the mean cycling speed was higher (P < 0.05) than that without such assistance. In addition, following assisted exercise the mean blood lactate concentration and RPE were lower (P < 0.05) and ratings of enjoyment higher (P < 0.05). Moreover, motorized cycling was associated with (1) lower EMG with higher power output and speed; (2) less cardiorespiratory and metabolic effort; (3) lower respiratory exchange ratio; (4) lower RPE with more enjoyment; and (5) sufficient EE, according to present standards, to provide health benefits. Thus, electrically assisted cycling may represent an innovative approach to persuading reluctant sedentary women to exercise.
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| 2. |
- Sperlich, Billy, et al.
(författare)
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Exercising in a Hot Environment : Which T-shirt to Wear?
- 2013
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Ingår i: Wilderness & environmental medicine (Print). - : Elsevier BV. - 1080-6032 .- 1545-1534. ; 24:3, s. 211-220
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Tidskriftsartikel (refereegranskat)abstract
- Objective. The aim of this study was to investigate thermoregulatory, cardiorespiratory, metabolic, and perceptual responses while running in a hot environment (31.7 degrees +/- 1.0 degrees C; 42% +/- 3% relative humidity) and wearing T-shirts made from different fiber types. Methods.-Eight well-trained men performed 4 tests wearing either a T-shirt made of 100% polyester with 4, 6, or 8 channels, or one made of 100% cotton. Each test consisted of 30 minutes running at 70% of peak oxygen uptake, followed by a ramp test to exhaustion and 15 minutes of recovery. Results.-There were no differences in skin, core, and body temperatures between fiber types during submaximal and high-intensity running (best P = .08). During recovery, body temperature and shivering/sweating sensations were lower when wearing 4- and 6-channel fibers (P <= .04) compared with cotton. The relative humidity at the chest and back were lower for all polyester T-shirts compared with cotton during and after submaximal and maximal running (P <= .007). Heart rate (best P = .10), oxygen uptake (P = .95), respiratory exchange ratio (best P = .93), ventilation (best P = .99), and blood lactate concentration (best P = .97) did not differ between the fiber types. Nor were any differences in time to exhaustion (best P = .76), ratings of perceived exertion (best P = .09), thermal sensation (best P = .07), or sensation of clothing wetness (best P = .36) discovered. Conclusions.-Although statistical analysis revealed lower shivering/sweating sensations while wearing 4- and 6-channel fiber shirts during recovery, with an improved chest and back microenvironment for all polyester T-shirts, the question remains whether these differences are of any practical relevance because the performance of the well-trained men was unaffected.
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| 3. |
- Sperlich, Billy, et al.
(författare)
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Is leg compression beneficial for alpine skiers?
- 2013
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Ingår i: BMC Sports Science, Medicine and Rehabilitation. - : Springer Science and Business Media LLC. - 2052-1847. ; 5:1
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Tidskriftsartikel (refereegranskat)abstract
- Background:This study examined the effects of different levels of compression (0, 20 and 40 mmHg) produced byleg garments on selected psycho-physiological measures of performance while exposed to passive vibration (60 Hz,amplitude 4-6 mm) and performing 3-min of alpine skiing tuck position.Methods:Prior to, during and following the experiment the electromygraphic (EMG) activity of different muscles,cardio-respiratory data, changes in total hemoglobin, tissue oxygenation and oscillatory movement ofm. vastuslateralis, blood lactate and perceptual data of 12 highly trained alpine skiers were recorded. Maximal isometric kneeextension and flexion strength, balance, and jumping performance were assessed before and after the experiment.Results:Thekneeangle(−10°) and oscillatory movement (−20-25.5%) were lower with compression (P<0.05inall cases). The EMG activities of thetibialis anterior(20.2-28.9%),gastrocnemius medialis(4.9-15.1%),rectus femoris(9.6-23.5%), andvastus medialis(13.1-13.7%) muscles were all elevated by compression (P< 0.05 in all cases).Total hemoglobin was maintained during the 3-min period of simulated skiing with 20 or 40 mmHg compression,but the tissue saturation index was lower (P< 0.05) than with no compression. No differences in respiratory parameters,heart rate or blood lactate concentration were observed with or maximal isometric knee extension and flexionstrength, balance, and jumping performance following simulated skiing for 3 min in the downhill tuck positionwere the same as in the absence of compression.Conclusions:These findings demonstrate thatwith leg compression, alpine skiers could maintain a deeper tuckposition with less perceived exertion and greater deoxygenation of thevastus lateralismuscle, with nodifferences in whole-body oxygen consumption or blood lactate concentration. These changes occurred withoutcompromising maximal leg strength, jumping performance or balance. Accordingly, our results indicate that theuse of lower leg compression in the range of 20-40 mmHg may improve alpine skiing performance by allowing adeeper tuck position and lowering perceived exertion.
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