Éditeur(s) : HAL CCSD Human Kinetics
Résumé : International audience
In order to study the acclimatization process over 14 days of exposure to tropical climate, 9 triathletes performed 4 outdoor indirect continuous multistage tests in both thermoneutral and tropical conditions. The thermoneutral test (TN, 14 C, 45% rh) was performed before traveling to the tropical area (Martinique, FWI). The tropical tests were performed 2, 8, and 14 days after arrival (32.9 C, 78% rh). During each trial, we measured tympanic temperature, sweat rate, body mass loss, heart rate (HR), and performance. The results showed that 1) the mean tympanic temperature was greater in T2 (P < .001), T8 (P < .01) and T14 (P < .01) than in TN and significantly lower in T14 than in T2 (P < .05); 2) the mean sweat rate was significantly greater (P < .001) in T2, T8 and T14 than in TN and significantly greater (P < .05) in T8 and T14 than in T2; 3) the body mass loss after trials was significantly greater (P < .001) in T2, T8 and T14 than in TN and significantly greater (P < .05) in T8 and T14 than in T2; 4) the mean HR and HR at rest were significantly higher (P < .005) in T2 than in TN, T8, T14 and the mean HR was significantly lower (P < .05) in T14 than in the other trials; and 5) the performance time was significantly lower in T2 (P < 0.02), T8 (P < 0.03) and T14 (P < 0.05) than in TN. We concluded that 14 days of exposure.
ISSN: 1066-7814

hal-00720075
https://hal.univ-antilles.fr/hal-00720075
https://hal.univ-antilles.fr/hal-00720075/document
https://hal.univ-antilles.fr/hal-00720075/file/02.Voltaire_551_.pdf

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Seven male subjects volunteered to participate in an investigation of whether the diurnalincrease in core temperature influences the effects of pre-cooling or passivewarm-up on muscular power. Morning (07:00-09:00 h) and afternoon (17:00-19:00 h) evaluation of maximal power output during a cycling sprint was performed on different days in a control condition (room at 21.8 °C, 69% rh), after 30 min of pre-cooling in a cold bath (16 °C), or after 30 min of passivewarm-up in a hot bath (38 °C). Despite an equivalent increase from morning to afternoon in core temperature in all conditions (+0.4 °C, P < 0.05), power output displayed a diurnalincrease in control condition only. A local cooling or heating of the leg in a neutral environment blunted the diurnal variation in muscular power. Because pre-cooling decreases muscle power, force and velocity irrespective of time-of-day, athletes should strictly avoid any cooling before a sprint exercise. In summary, diurnal variation in muscle power output seems to be more influenced by muscle rather than core temperature.
ISSN: 1440-2440

hal-00706159
https://hal.univ-antilles.fr/hal-00706159
DOI : 10.1016/j.jsams.2007.09.008

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
This study compared the conventional parameters of anaerobic cycling power in physically active non-cyclists using the Pro-Race® system and a traditional chainring. The force--velocity test was chosen for this purpose because it is the shortest validated cycling laboratory test in which each parameter of maximal anaerobic power can be estimated. The power output (Wmax) and the force at whichWmax is produced (Fopt) were significantly improved with the eccentric chainring (1100±227W versus 1006±197W and 1.39±0.15 N/kg body mass versus 1.13±0.16 N/kg body mass with the eccentric and round designs, respectively; P < 0.006 and P < 0.0004, respectively). The power gained (delta power) was significantly correlated with the eccentric chainring Fopt (r = 0.649; P < 0.05), the mid-thigh circumference (r = 0.685; P < 0.05), the estimated lean thigh volume (r = 0.765; P < 0.01) and the estimated lean lower limb volume (r = 0.665; P < 0.05). We concluded that the eccentric chainring significantly improved the estimated anaerobic power output during a force--velocity test by increasing the force component, Fopt. Cautious interpretation of our results suggests that the subjects with physical attributes that contribute to developing high forces may have a significant advantage in performing with the eccentric chainring.
ISSN: 1440-2440

hal-00703458
https://hal.univ-antilles.fr/hal-00703458
DOI : 10.1016/j.jsams.2007.06.004

Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
Facts -The capacity to exercise is markedly reduced in hot environments. -High humidity imposes further physiological strain on the body. -The combination of exercise and hot environments increases the risk of heat illness and heatstroke. Recommendations for players -Fluid intake should be sufficient to restrict body mass loss to o2% of the pre-exercise mass. -A minimum of 1-2 weeks of acclimatization should be undertaken before playing in a hot environment. Recommendations for organizers -Perform pre-participation screenings before competing in the heat. -Watch at-risk individual (e.g. sickle cell trait, vascular disease) and observe signs and symptoms if WBGT > 28°C. -Add additional fluid breaks and foresee medical coverage if WBGT > 30°C. -Reconsider event if WBGT > 32°C. Future research should investigate -The optimal cooling strategies prior and during sporting activities, i.e., halftime in football games. -The influence of acclimatization on football performance. -The impact of heat on decision making in players and match officials. -The impact of heat on spectators from cooler regions.
ISSN: 0905-7188

hal-00706256
https://hal.univ-antilles.fr/hal-00706256