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Acute doses of Sinemet ® (L-DOPA combined with carbidopa) previously failed to change prolonged exercise performance in a temperate environment, but it is not known whether acute doses of L-DOPA timed to reach C max during exercise will improve prolonged cycling performance in warm conditions. 10 physically active men (age 26 ± 4 y; height 1.76 ± 0.08 m; body mass 76.3 ± 10.6 kg; V O 2 peak 57 ± 8 ml/kg/min) were recruited for this study. Participants cycled for 1 h at 60% V O 2 peak followed by a 30 min exercise test, during which they were instructed to complete as much work as possible. Heart rate, skin and core temperature, as well as ratings of perceived exertion and thermal comfort were recorded throughout exercise and blood samples were collected at rest, 15 min intervals during the first hour of exercise and the end of the exercise test. Finger tap tests at the beginning and end of exercise were employed to examine fine motor control. There was no significant difference in the work done on placebo (314 ± 43 kJ) and L-DOPA trials (326 ± 48 kJ; p = 0.08). Prolactin concentrations were increased at the end of exercise in all trials (p

Exercise performance may be impaired following reductions in body water amounting to approximately 2% body mass. Post-exercise rehydration is an important factor to consider when a subsequent bout of exercise is to be undertaken. Drink volume and composition are important considerations with regards to fluid retention after exercise. The aim of this study was to examine retention of a sports drink and water when consumed with food in the post-exercise period. Seven healthy participants (3 male, 4 female) aged 21–41 y were dehydrated by (mean ± SD) 1.6 ± 0.3% body mass by intermittent cycling in the heat (35.0 ± 0.9°C, 51 ± 7% relative humidity). Participants then consumed a volume equal to 150% body mass loss of a commercially available sports drink or water with a standard meal designed to provide 30% of estimated daily energy expenditure. The drink was consumed in four equal boluses over a period of one hour with the meal consumed with the final three boluses. Urine volume and osmolality were measured before and after exercise and at hourly intervals for three hours after completion of the rehydration period. No significant differences between trials were observed for percentage body mass loss (p = 0.405), sweat loss (p = 0.376) or drink volume (p = 0.371). Cumulative urine volume following rehydration amounted to 765 ± 223 ml and 630 ± 231 ml (p = 0.244) and percentage of drink volume retained amounted to 53 ± 13% and 59 ± 15% (p = 0.336) during the water and sports drink trials, respectively. No difference (p > 0.05) in net fluid balance was observed between trials. The results of this study indicate that there is no difference in post-exercise fluid retention between water and a sports drink when consumed with a meal. The addition of a meal during the post-exercise period is likely to reduce the rate of fluid absorption, resulting in reduced urine production. This may explain the lack of a significant difference between trials.

Several studies have highlighted the beneficial effects of milk and dairy product consumption in the alleviation of exercise-induced muscle damage, post-exercise soreness sensations and indeed the satiating effects on subsequent appetite and energy intake in adult populations. The aim of this study was to assess the effects of skimmed milk as a recovery drink following exercise on subsequent appetite and energy intake in female recreational exercisers. Using a randomised cross-over design, nine female recreational exercisers (20±1 y) completed a test followed by two main exercise trials (matched for energy expenditure 1.78±0.14 v. 1.75±0.19 MJ; p =0.600). Main trials were conducted following a standardised breakfast and were carried out during the early follicular phase of the menstrual cycle. Following 30 minutes of moderate–vigorous cycling exercise (65% ) 600 mL of skimmed milk or 600 mL of orange juice (475 mL orange, 125 mL water), which were isoenergetic, was ingested followed 60 minutes later with an ad libitum pasta meal. Absolute energy intake was significantly less after consuming milk than after orange juice (2.39±0.70 v. 3.20±0.84 MJ, respectively; p =0.001). Relative energy intake (in relation to energy expenditure) was significantly lower after milk consumption compared to orange juice (0.61±0.72 v. 1.45±0.90 MJ, respectively; p =0.002). Relative energy intake (in relation to the energy content of the test beverages) was also significantly lower after milk consumption compared to orange juice (3.27±0.70 v. 4.13±0.84 MJ, respectively; p =0.003). There were no differences in AUC (x 3-h) subjective appetite parameters (hunger, fullness and desire to eat) between trials. In conclusion, the consumption of skimmed milk following 30 minutes of moderate-vigorous cycling exercise resulted in a reduction in subsequent energy intake, in female recreational exercisers.

The aim of this study was to investigate sweat loss in elite short track speed skaters across 6 different training sessions over a three day period, and sweat sodium loss in one on ice training session. Nine male and three female elite short track speed skaters participated in the study (age 22±3 years, Body Weight: 68.1±10.2 kg). Six training sessions, comprising of an on ice speed session (Sp), on ice endurance session (En), on ice speed endurance session (SpEn), off ice strength session (St), a 40 minute aerobic off ice session (Ae) and an off ice sport specific conditioning session (SpCo). Sweat loss was calculated for each session by weighing the participants before and after each training session, as well as weighing fluid/ food consumed and urine produced during training. Sweat sodium concentration [Na + ] was calculated from forehead sweat patch analysis during En. Whole body sodium loss was calculated from sweat loss and [Na + ] for En. A One Way ANOVA was used to compare sweat loss in different training sessions. There was a difference in sweat loss between training sessions (F 5,66 =4.24, P=0.02), with both En (700±248 ml) and SpEn (681±304 ml) being different from St (299±162 ml). However, sweat loss in SP (514±242 ml), Ae (572±267 ml) and SpCo (522±128 ml) was not different from other sessions. During all sessions, no participants lost more than 2% in body weight, suggesting participants adequately consumed fluid during training to prevent dehydration. During En sweat sodium loss was 1.9±0.6 g, with a mean [Na + ] of 51±16 mmol/L. In conclusion, short track speed skaters consume adequate fluid to maintain fluid balance during a range of training sessions.

Angiotensin I-converting enzyme (ACE) plays a pivotal role in whole body fluid balance and the degradation of bradykinin. A common allelic variant with a 287 base pair insert has been identified on the ACE gene. The homozygous insertion genotype ( II ) corresponds with lower basal serum ACE concentrations compared to the heterozygous ( WI ) and homozygous wild type genotypes ( WW ). Higher circulating levels of ACE may decrease vasodilation; affecting blood flow and sweat loss during exercise. A genotype-independent rise in ACE activity following 20 min of exercise has been reported, but the response to prolonged exercise is unknown. The aim was to examine the influence of ACE genotype on the serum ACE response to exercise in the heat. Healthy Caucasian males ( n =45, 18–45 y) completed 60 min of cycle exercise at (mean ± SD) 62 ± 5% VO 2max in 30.5 ± 0.3°C, with fluid ad libitum . Fluid intake and sweat loss were recorded. Venous blood samples were drawn pre, mid, and postexercise for the determination of serum ACE concentration and ACE genotype. Basal serum ACE concentrations were dependent on ACE genotype ( WW : 215 ± 57 ng.ml -1 ; WI : 158 ± 28 ng.ml -1 ; II : 106 ± 29 ng.ml -1 , P -1 , 166 ± 29 ng.ml -1 and 115 ± 30 ng.ml -1 for WW , WI and II , respectively ( P ACE genotype ( P = 0.321). No differences were found for mean fluid intake ( WW : 613 ± 388 ml; WI : 753 ± 385 ml; II : 862 ± 421 ml, P = 0.31), or sweat loss ( WW : 1013 ± 257 ml; WI : 1048 ± 254 ml; II : 1257 ± 675 ml, P = 0.28). Serum ACE concentration increased independently of ACE genotype within 30 min exercise at 30.5°C. Coupled with the lack of genotype effect on sweat loss and fluid intake, these results suggest ACE genotype plays little role in fluid balance during exercise.

Milk has been shown to be an effective post-exercise rehydration solution, but the specific effects of milk protein on rehydration after exercise are unknown. This study examined the effects of milk protein on rehydration after exercise in the heat, via the comparison of carbohydrate and carbohydrate-milk protein solutions matched in terms of energy density and electrolyte content. Eight male subjects (mean±SD: age 21±3 years, height 1.78±0.08 m, body mass 75.7±11.6 kg) lost 1.9±0.2% of their initial body mass via intermittent exercise in a warm environment (35±0.1°C, 50.9±2.1% RH). Subjects then rehydrated with 150% of their body mass loss over 1 h, with either a 65 g/l carbohydrate solution (C) or a 40 g/l carbohydrate, 25 g/l milk-protein solution (CP). Urine samples were collected before and after exercise and for 4 h after rehydration. After rehydration, total cumulative urine output was greater for trial C (1212±310 ml) than trial CP (931±254 ml) (p