No abstract

BackgroundScientific data on the performance of collegiate female tennis players during the menstrual phases are scarce.Trial designDouble-blind, counter-balanced, crossover trials were conducted to examine whether tennis performance was affected during menstruation, with and without dehydroepiandrosterone sulfate (DHEA-S) supplementation.MethodsTen Division 1 collegiate tennis players (aged 18–22 years) were evenly assigned into placebo-supplemented and DHEA-supplemented (25 mg/day) trials. Treatments were exchanged among the participants after a 28-day washout. Tennis serve performance was assessed on the first day of menstrual bleeding (day 0/28) and on days 7, 14 and 21.ResultsMood state was unaltered during the menstrual cycles in both trials. The lowest tennis serve performance score (speed times accuracy) occurred on day 14 (P=0.06 vs day 0; P=0.01 vs day 21) in both placebo and DHEA trials. Decreased performance on day 14 was explained by decreased accuracy (P=0.03 vs day 0/28; P=0.01 vs day 21), but not velocity itself. Isometric hip strength, but not quadriceps strength, was moderately lower on day 14 (P=0.08). Increasing plasma DHEA-S (by ~65%) during the DHEA-supplemented trial had no effects on mood state, sleep quality or tennis serve performance.ConclusionWe have shown that menses does not affect serve performance of collegiate tennis players. However, the observed decrement in the accuracy of serve speed near ovulation warrants further investigation.

Altitude training is a frequently used method for enhancing endurance performance in athletes. But its acute effect on carbohydrate metabolism in cardiac muscle is unknown. In this study, we determined the acute effect of an exercise-hypoxia challenge on glycogen storage and GLUT4 protein expression in heart muscle. Sixteen male Sprague-Dawley rats were assigned to one of two groups: control (CTRL) and exercise-hypoxia (EX+HY). The exercise protocol consisted of swimming for 180 min twice, with a 45-min rest interval. Five hours after the exercise, the EX+HY rats were exposed to a 14% O(2) systemic hypoxia under normobaric condition for 12 h. After this hypoxia exposure, the EX+HY and control rats were given glucose orally (1 g/kg body weight) with stomach tube and recovered under normal condition for 16 h. Ventricular portion of the heart was used to determine the levels of glycogen, GLUT4 mRNA, and GLUT4 protein after recovery. We found that myocardial glycogen level was lowered by the exercise-hypoxia challenge (51% below control, p < 0.05), while GLUT4 mRNA was dramatically elevated (approximately 400% of the control level, p < 0.05). The acute exercise-hypoxia treatment did not affect GLUT1 protein level in the same tissue. The novel finding of the study was that the exercise-hypoxia treatment significantly induced GLUT4 gene expression in the cardiac muscle. This acute response appears to be associated with a sustained glycogen depletion of the muscle.

Several lines of evidence suggest that dehydroepiandrosterone sulphate (DHEA-S) is invariably consumed following different types of acute stress, implicating its role in stress coping and recovery. The role of DHEA-S in the mood adjustment against negative outcome for athletic competition has not previously been investigated. In the current study, 14 elite golfers participating in a major national golf tournament were subsequently divided into two groups according to their competition outcomes: made the cut (n=8) and failed to make the cut (n 8). The Profile of Mood States (POMS) inventory and plasma concentrations of DHEA-S and cortisol were measured 1 day before the beginning of competition (baseline) and 1, 3, and 5 days after the players' final competition, in the morning (08.00-08.30 h) under fasted conditions. Results showed that the total mood disturbance scores and DHEA-S were not changed for the group that made the cut throughout the entire observation period. DHEA-S concentration for the group that failed to make the cut fell significantly below baseline values on day 1 and remained lower for 5 days. The Depression subscale of the POMS for the group that failed to make the cut was increased only on day 1 post-competition, reflecting a situational reaction to the event. Cortisol concentration for the group that made the cut fell significantly below baseline values on day 1 only after competition and no change was observed for the group that failed to make the cut. In conclusion, although the overall mood state post-competition was well-maintained for those golfers who had a negative competition outcome, plasma DHEA-S concentration was reduced for 5 days, suggesting that it has a role in the coping mechanism against psychological challenge.

No abstract