Collegiate women's wrestling body fat percentage and minimum wrestling weight values: time for revisiting minimal body fat percent?

BACKGROUND: The estimation of body fat percentage (BF%) in wrestling is used to determine the minimum wrestling weight (MWW) and lowest allowable weight class (MWC) in which wrestlers are eligible to compete. A 12% minimum threshold is currently used for women wrestlers, yet a potential increase for safety has been discussed. Because of the novelty of collegiate women's wrestling, there is a paucity of literature available on the body composition norms of this population. The purpose of this study was to provide a descriptive summary of BF% and MWW values of female wrestlers and how MWW values would change with the use of different BF% thresholds. METHODS: Data from the 2022-2023 collegiate season were retrospectively analyzed resulting in a sample of 1,683 collegiate women wrestlers from the National Association of Intercollegiate Athletics (NAIA, n = 868) and the National Collegiate Athletics Association (NCAA, n = 815). All wrestlers completed skinfold assessments for weight certification at the start of the competition season. The skinfold values were used to estimate BF% using the Slaughter skinfold prediction equation. Frequency statistics and descriptive analysis were performed to compute normative MWW and BF% profiles. BF% thresholds of 12% (12MWW) and the BF% value defined as the lowest 5th percentile, which would be considered unusually lean, were used to determine the resulting MWW and MWC for each method. The lowest recorded weight and weight class division throughout the season was also recorded for each wrestler. RESULTS: There was a positively skewed (0.94) and platykurtic (1.86) distribution of MWW values. The median ± interquartile range BF% for all wrestlers was 27.4 ± 10.22%, with 17% BF representing the 5th percentile. Only 354 out of 1,579 (22.4%) wrestlers competed in their lowest allowable weight class, based on the 12MWW. Of these 354 wrestlers, the mean BF% was 21.3 ± 5.2% at weight certification with only n = 17 being at or below 12% body fat and an average weight loss of 11.1 ± 8.8 lbs. from the time of weight certification. Throughout the season, wrestlers competed at weights that were, on average (mean ± SD), 19.4 ± 16.9 lbs. higher than their 12MWW (95% CI: 18.6, 20.2 lbs. p < 0.001; effect size [ES] = 1.1), 13.4 ± 19.0 lbs. higher than the 17MWW (p < 0.001; ES = 0.70), and 8.7 ± 8.3 lbs. lower than their weight at the certification (95% CI: 8.3, 9.1 lbs. p < 0.001; ES = 1.1). CONCLUSIONS: Nearly all BF% values were well above the 12% threshold used to determine MWW. Increasing the minimum BF% threshold from 12% to 17% would affect a small percentage of wrestlers, likely reduce the need for excessive weight cutting, and minimize the deleterious health effects of an athlete at such a low BF%.

Post-Exercise Rehydration in Athletes: Effects of Sodium and Carbohydrate in Commercial Hydration Beverages.

The effects of varying sodium (Na) and carbohydrate (CHO) in oral rehydration solutions (ORS) and sports drinks (SD) for rehydration following exercise are unclear. We compared an ORS and SD for the percent of fluid retained (%FR) following exercise-induced dehydration and hypothesized a more complete rehydration for the ORS (45 mmol Na/L and 2.5% CHO) and that the %FR for the ORS and SD (18 mmol Na/L and 6% CHO) would exceed the water placebo (W). A placebo-controlled, randomized, double-blind clinical trial was conducted. To induce 2.6% body mass loss (BML, p > 0.05 between treatments), 26 athletes performed three 90 min interval training sessions without drinking fluids. Post-exercise, participants replaced 100% of BML and were observed for 3.5 h for the %FR. Mean ± SD for the %FR at 3.5 h was 58.1 ± 12.6% (W), 73.9 ± 10.9% (SD), and 76.9 ± 8.0% (ORS). The %FR for the ORS and SD were similar and greater than the W (p < 0.05 ANOVA and Tukey HSD). Two-way ANOVA revealed a significant interaction with the ORS having greater suppression of urine production in the first 60 min vs. W (SD did not differ from W). By 3.5 h, the ORS and SD promoted greater rehydration than did W, but the pattern of rehydration early in recovery favored the ORS.

Compositional Aspects of Beverages Designed to Promote Hydration Before, During, and After Exercise: Concepts Revisited.

Hypohydration can impair aerobic performance and deteriorate cognitive function during exercise. To minimize hypohydration, athletes are recommended to commence exercise at least euhydrated, ingest fluids containing sodium during long-duration and/or high-intensity exercise to prevent body mass loss over 2% and maintain elevated plasma osmolality, and rapidly restore and retain fluid and electrolyte homeostasis before a second exercise session. To achieve these goals, the compositions of the fluids consumed are key; however, it remains unclear what can be considered an optimal formulation for a hydration beverage in different settings. While carbohydrate-electrolyte solutions such as sports drinks have been extensively explored as a source of carbohydrates to meet fuel demands during intense and long-duration exercise, these formulas might not be ideal in situations where fluid and electrolyte balance is impaired, such as practicing exercise in the heat. Alternately, hypotonic compositions consisting of moderate to high levels of electrolytes (i.e., ≥45 mmol/L), mainly sodium, combined with low amounts of carbohydrates (i.e., <6%) might be useful to accelerate intestinal water absorption, maintain plasma volume and osmolality during exercise, and improve fluid retention during recovery. Future studies should compare hypotonic formulas and sports drinks in different exercise settings, evaluating different levels of sodium and/or other electrolytes, blends of carbohydrates, and novel ingredients for addressing hydration and rehydration before, during, and after exercise.

Combining Anthropometry and Bioelectrical Impedance Analysis to Predict Body Fat in Female Athletes.

CONTEXT: Accurate methods for predicting the percentage of body fat (%Fat) in female athletes are needed for those who lose weight before competition. Methods mandated by sport governing bodies for minimal weight determination in such athletes lack validation. OBJECTIVE: To (1) determine whether combining anthropometry using skinfold (SF) thicknesses and bioelectrical impedance analysis (BIA) in a 3-compartment (3C) model would improve the prediction of %Fat in female athletes and (2) evaluate the Slaughter SF equation. DESIGN: Cross-sectional study. SETTING: Laboratory-based study during the preseason for collegiate sports. PARTICIPANTS: A total of 18 National Collegiate Athletic Association Division I female athletes were recruited from swim and gymnastics teams. MAIN OUTCOME MEASURE(S): We measured %Fat based on a 4-compartment (4C) criterion incorporating body density (air-displacement plethysmography), total body water (D2O dilution), and bone mineral mass (dual-energy x-ray absorptiometry) compared with predicted %Fat using SF alone (Slaughter equation), BIA (single frequency for total body water estimate), and combined SF and BIA (3C model). RESULTS: For the %Fat determined using the 4C criterion, the highest adjusted coefficient of determination and lowest prediction error (r2; ±standard error of estimate) were for the 3C model (r2 = 0.87; ±2.8%), followed by BIA (r2 = 0.80; ±3.5%) and SF (r2 = 0.76; ±3.8%; P values < .05 for all). Means differed for the %Fat determined using BIA (26.6% ± 7.5%) and the 3C (25.5% ± 7.2%) versus 4C model (23.5% ± 7.4%; analysis of variance and post hoc analyses: P values < .05). The SF estimate (24.0% ± 7.8%) did not differ from the 4C value. CONCLUSIONS: Combining SF and BIA might improve the prediction and lower the prediction error for determining the %Fat in female athletes compared with using SF or BIA separately. Regardless, the Slaughter equation for SF appeared to be accurate for determining the mean %Fat in these female athletes.

ACSM Expert Consensus Statement on Weight Loss in Weight-Category Sports.

ABSTRACT: Weight-category sports are defined by the requirement of a weigh-in before competition to provide performance equity and reduced injury risks by eliminating size discrepancies. Athletes in these sports try to gain a theoretical advantage by competing in weight divisions that are lower than their day-to-day body mass (BM), using a combination of chronic strategies (body-fat losses) and acute manipulations over a period of hours to days before weigh-in ("making weight"). Strategies to support safer practices include minimal competition weight classification based on preseason body composition, reductions in the period between weigh-in and competition, and prohibition of unhealthy weight loss techniques. At an individual level, expert guidance by a sports nutrition professional can help an athlete to establish a pragmatic and long-term approach to BM management, recognizing the nuances of their sport, to achieve favorable outcomes for both health and performance.

Sleep disturbance and next-day physical activity in COPD patients.

Physical inactivity and sleep disturbance are more problematic in patients with chronic obstructive pulmonary disease (COPD) than in healthy individuals. The purpose of the study was to identify impacts of nighttime sleep on next-day physical activity in COPD patients. The study included 52 COPD patients reporting disturbed sleep. Sleep and physical activity were measured using an accelerometer for 5 days. Increased sleep latency was associated with less next-day physical activity during the afternoon (4-6 p.m.). Greater waking duration/times were associated with less next-morning (6-8 a.m.) physical activity. Greater total sleep time was associated with less next-morning (12-9 a.m.) physical activity, and greater sleep efficiency was associated with less next-morning (1-3 a.m.) and more next-evening (6-7 p.m.) physical activity. Results suggest that sleep disturbance had varying influences on next-day hourly physical activity. These results support the potential value of sleep management in promoting physical activity in COPD patients.

Comparative Analysis of Gut Microbiota Following Changes in Training Volume Among Swimmers.

Exercise can influence gut microbial community structure and diversity; however, the temporal dynamics of this association have rarely been explored. Here we characterized fecal microbiota in response to short term changes in training volume. Fecal samples, body composition, and training logs were collected from Division I NCAA collegiate swimmers during peak training through their in-season taper in 2016 (n=9) and 2017 (n=7), capturing a systematic reduction in training volume near the conclusion of their athletic season. Fecal microbiota were characterized using 16S rRNA V4 amplicon sequencing and multivariate statistical analysis, Spearman rank correlations, and random forest models. Peak training volume, measured as swimming distance, decreased significantly during the study period from 32.6±4.8 km/wk to 11.3±8.1 km/wk (ANOVA, p<0.05); however, body composition showed no significant changes. Coinciding with the decrease in training volume, the microbial community structure showed a significant decrease in overall microbial diversity, a decrease in microbial community structural similarity, and a decrease in the proportion of the bacterial genera Faecalibacterium and Coprococcus. Together these data demonstrate a significant association between short-term changes in training volume and microbial composition and structure in the gut; future research will establish whether these changes are associated with energy balance or nutrient intake.

Metabolic Rate during a Cognitive Vigilance Challenge at Alternative Workstations.

OBJECTIVE: The aim of this study was to compare energy expenditure (EE, kcal/min) at three workstations during an attention-demanding cognitive function task (Test of Variables of Attention or TOVA). Workstations included the seated desk (SIT), standing desk (STAND), and seated workstation designed to promote spontaneous movement (SWING). METHODS: Adult males (n = 11) and females (n = 13) were assessed for EE using VO2 and VCO2 per quarter of the 22-min TOVA. RESULTS: Average EE were 1.39 ±â€Š0.06 (SIT), 1.55 ±â€Š0.08 (SWING), and 1.44 ±â€Š0.08 (STAND). Main effects (P < 0.05) were seen for workstation (SWING, STAND > SIT), and quarter of TOVA (Q2 < Q1,Q3,Q4). TOVA errors and response times were not different for workstations but increased for Q3 and Q4. CONCLUSION: Spontaneous movement at an alternative workstation elevated EE 10% to 11% compared with sitting and could increase daily nonexercise activity thermogenesis without diminishing mental attention to desk work.

Effect of a novel workstation device on promoting non-exercise activity thermogenesis (NEAT).

BACKGROUND: Strategies to increase non-exercise activity thermogenesis (NEAT) through promotion of movement and energy expenditure at desk stations are needed to help overcome ill effects of prolonged sitting. OBJECTIVE: Examine the metabolic rate during three stages of a workstation: sitting, standing, and use of a device (HOVR®) that promotes leg movement while seated. METHODS: Participants (n = 16; mean ±standard deviation: age 26.1±6.0 years; BMI 24.7±4.3 kg/m2) were tested for VO2 and VCO2 for 15 min at each stage in this order: sitting only, sitting using the HOVR, and standing. Participants performed the same desk work to keep fine-motor activity consistent for the stages. Data collected during the final 5 min of a stage were averaged and analyzed as steady-state data. To evaluate the effect of each stage on cognitive function, the Stroop word-color test was administered after metabolic assessment as the stage continued. One-way ANOVA with repeated measures was used to compare stages for VO2 (L/min), metabolic equivalents (METs), respiratory exchange ratio (RER), and heart rate (p < 0.05). RESULTS: The ANOVA revealed significant differences between the mean values for each stage for each dependent variable (p < 0.05). Post hoc tests indicated VO2 differed for each stage (mean±SD in mL/kg/min: sitting, 4.13±0.56; sitting with HOVR, 4.82±0.74; standing, 4.50±0.53; p < 0.05). METs followed a similar pattern (sitting, 1.19±0.16; sitting with HOVR, 1.39±0.20; standing, 1.29±0.16; p < 0.05). An increase in Stroop Test scores was found as the stages progressed (p < 0.05). CONCLUSION: Modest movement while seated, i.e., use of HOVR, elevated metabolic rate by 17.6% compared to sitting and by 7% compared to standing and might be a reasonable strategy to help elevate NEAT during the workday.

Does Sport-Drink Use During Exercise Promote an Acute Positive Energy Balance?

Sports drinks have been implicated in contributing to obesity and chronic diseases by providing surplus calories and excess sugars. Using existing literature we compared energy intake from sports drinks consumed during exercise with the exercise-induced calorie expenditure to determine whether sports drink use might eliminate the energy deficit and jeopardize conditions for improved metabolic fitness. We identified 11 published studies that compared sport drink consumption to placebo during exercise with a primary focused on the effect of sport drinks or total carbohydrate content on enhancing physical performance. Energy expenditure (EE) was calculated using VO2, RER, and exercise duration for the exercise protocol. Energy ingestion (EI) was determined using the carbohydrate dosing regimen administered before and during the exercise protocol. A two-tailed t test was used to test whether the energy balance (EI-EE) was different from zero (alpha level = 0.05). Sport drink consumption during aerobic exercise of sufficient duration (≥ 60 min) did not abolish the energy deficit (p < .001). Mean ± SD were EE, 1600 ± 639 Cal; EI, 394 ± 289 Cal; and EI-EE,-1206+594 Cal; VO2, 3.05 ± 0.55 L/min; RER, 0.91 ± 0.04; exercise duration 110 ± 42 min. Ingesting sports drinks to enhance performance did not abolish the caloric deficit of aerobic exercise. Sports drinks can be used in accordance with research protocols that typically provide 30-60 g of carbohydrate per hour when exercising at adequate durations for moderate to high intensity and still maintain a substantive caloric deficit.

Exercise-induced trace mineral element concentration in regional versus whole-body wash-down sweat.

Simultaneous whole-body wash-down (WBW) and regional skin surface sweat collections were completed to compare regional patch and WBW sweat calcium (Ca), magnesium (Mg), copper (Cu), manganese (Mn), iron (Fe), and zinc (Zn) concentrations. Athletes (4 men, 4 women) cycled in a plastic open-air chamber for 90 min in the heat. Before exercise, the subjects and cycle ergometer (covered in plastic) were washed with deionized water. After the onset of sweating, sterile patches were attached to the forearm, back, chest, forehead, and thigh and removed on saturation. After exercise, the subjects and cycle ergometer were washed with 5 L of 15-mM ammonium sulfate solution to collect all sweat minerals and determine the volume of unevaporated sweat. Control trials were performed to measure mineral contamination in regional and WBW methods. Because background contamination in the collection system was high for WBW Mn, Fe, and Zn, method comparisons were not made for these minerals. After correction for minimal background contamination, WBW sweat [Ca], [Mg], and [Cu] were 44.6 ± 20.0, 9.8 ± 4.8, and 0.125 ± 0.069 mg/L, respectively, and 5-site regional (weighted for local sweat rate and body surface area) sweat [Ca], [Mg], and [Cu] were 59.0 ± 15.9, 14.5 ± 4.8, and 0.166 ± 0.031 mg/L, respectively. Five-site regional [Ca], [Mg], and [Cu] overestimated WBW by 32%, 48%, and 33%, respectively. No individual regional patch site or 5-site regional was significantly correlated with WBW sweat [Ca] (r = -.21, p = .65), [Mg] (r = .49, p = .33), or [Cu] (r = .17, p = .74). In conclusion, regional sweat [Ca], [Mg], and [Cu] are not accurate surrogates for or significantly correlated with WBW sweat composition.

National Athletic Trainers' Association position statement: safe weight loss and maintenance practices in sport and exercise.

OBJECTIVE: To present athletic trainers with recommendations for safe weight loss and weight maintenance practices for athletes and active clients and to provide athletes, clients, coaches, and parents with safe guidelines that will allow athletes and clients to achieve and maintain weight and body composition goals. BACKGROUND: Unsafe weight management practices can compromise athletic performance and negatively affect health. Athletes and clients often attempt to lose weight by not eating, limiting caloric or specific nutrients from the diet, engaging in pathogenic weight control behaviors, and restricting fluids. These people often respond to pressures of the sport or activity, coaches, peers, or parents by adopting negative body images and unsafe practices to maintain an ideal body composition for the activity. We provide athletic trainers with recommendations for safe weight loss and weight maintenance in sport and exercise. Although safe weight gain is also a concern for athletic trainers and their athletes and clients, that topic is outside the scope of this position statement. RECOMMENDATIONS: Athletic trainers are often the source of nutrition information for athletes and clients; therefore, they must have knowledge of proper nutrition, weight management practices, and methods to change body composition. Body composition assessments should be done in the most scientifically appropriate manner possible. Reasonable and individualized weight and body composition goals should be identified by appropriately trained health care personnel (eg, athletic trainers, registered dietitians, physicians). In keeping with the American Dietetics Association (ADA) preferred nomenclature, this document uses the terms registered dietitian or dietician when referring to a food and nutrition expert who has met the academic and professional requirements specified by the ADA's Commission on Accreditation for Dietetics Education. In some cases, a registered nutritionist may have equivalent credentials and be the commonly used term. All weight management and exercise protocols used to achieve these goals should be safe and based on the most current evidence. Athletes, clients, parents, and coaches should be educated on how to determine safe weight and body composition so that athletes and clients more safely achieve competitive weights that will meet sport and activity requirements while also allowing them to meet their energy and nutritional needs for optimal health and performance.

Core temperature and sweat responses in professional women's tennis players during tournament play in the heat.

CONTEXT: Tennis is often played in hot, humid environments, intensifying the thermoregulatory strain placed on the athletes. As a safety measure, some tennis organizations allow for a 10-minute break in play between the second and third sets when environmental conditions are extreme. However, the actual effect of these breaks in reducing core temperature is unknown. OBJECTIVE: To determine change in core temperature after a 10-minute break in play and assess fluid balance in professional female tennis players during tournament matches in the heat. DESIGN: Cross-sectional study. SETTING: A Women's Tennis Association Tour-sanctioned outdoor tournament on hard courts under hot conditions (30.3°C ± 2.3°C). PATIENTS OR OTHER PARTICIPANTS: Seven professional tennis players. MAIN OUTCOME MEASURE(S): Change in core temperature after a 10-minute break in tournament play, fluid intake, and sweat losses during match play. RESULTS: Core temperature was reduced from 38.92°C to 38.67°C (change of -0.25°C ± 0.20°C) when a break was taken (P  =  .02). Mean sweat rate during match play was 2.0 ± 0.5 L/h. During that time, mean fluid intake was 1.5 ± 0.5 L/h, resulting in a 1.2% ± 1.0% reduction in body mass. CONCLUSIONS: Female professional tennis players are subjected to high heat loads during match play in hot environments. However, a 10-minute break in play decreased core temperature in 6 of 7 players by an average of 0.25°C, indicating that the break provides practical benefits in the field. Furthermore, although mean sweat rate in this group of female tennis players was high, most athletes were still able to minimize mass loss to less than 2% of their prematch weight.

Carbohydrate exerts a mild influence on fluid retention following exercise-induced dehydration.

Rapid and complete rehydration, or restoration of fluid spaces, is important when acute illness or excessive sweating has compromised hydration status. Many studies have investigated the effects of graded concentrations of sodium and other electrolytes in rehydration solutions; however, no study to date has determined the effect of carbohydrate on fluid retention when electrolyte concentrations are held constant. The purpose of this study was to determine the effect of graded levels of carbohydrate on fluid retention following exercise-induced dehydration. Fifteen heat-acclimatized men exercised in the heat for 90 min with no fluid to induce 2-3% dehydration. After a 30-min equilibration period, they received, over the course of 60 min, one of five test beverages equal to 100% of the acute change in body mass. The experimental beverages consisted of a flavored placebo with no electrolytes (P), placebo with electrolytes (P + E), 3%, 6%, and 12% carbohydrate solutions with electrolytes. All beverages contained the same type and concentration of electrolytes (18 meq/l Na(+), 3 meq/l K(+), 11 meq/l Cl(-)). Subjects voided their bladders at 60, 90, 120, 180, and 240 min, and urine specific gravity and urine volume were measured. Blood samples were taken before exercise and 30, 90, 180, and 240 min following exercise and were analyzed for glucose, sodium, hemoglobin, hematocrit, renin, aldosterone, and osmolality. Body mass was measured before and after exercise and a final body mass was taken at 240 min. There were no differences in percent dehydration, sweat loss, or fluid intake between trials. Fluid retention was significantly greater for all carbohydrate beverages compared with P (66.3 +/- 14.4%). P + E (71.8 +/- 9.9%) was not different from water, 3% (75.4 +/- 7.8%) or 6% (75.4 +/- 16.4%) but was significantly less than 12% (82.4 +/- 9.2%) retention of the ingested fluid. No difference was found between the carbohydrate beverages. Carbohydrate at the levels measured exerts a mild influence on fluid retention in postexercise recovery.

Comparison of regional patch collection vs. whole body washdown for measuring sweat sodium and potassium loss during exercise.

This study compared simultaneous whole body washdown (WBW) and regional skin surface (REG) sweat collections to generate regression equations to predict WBW sweat Na(+) concentration ([Na(+)]) and K(+) concentration ([K(+)]) from single- and five-site REG sweat patch collections. Athletes (10 men, 10 women) cycled in a plastic chamber for 90 min in the heat. Before exercise, the subject and bike were washed with deionized water. After the onset of sweating, sterile patches were attached to the forearm, back, chest, forehead, and thigh and removed on saturation. After exercise, the subject and bike were washed with ammonium sulfate solution to collect all sweat electrolyte loss and determine the volume of unevaporated sweat. All individual patch sites and five-site REG (weighted for local sweat rate and body surface area) were significantly (P = 0.000) correlated with WBW sweat [Na(+)]. The equation for predicting WBW sweat [Na(+)] from five-site REG was y = 0.68x + 0.44 [r = 0.97, intraclass correlation coefficient (ICC) = 0.70] and did not differ between sexes. There were sex differences in the regression results between five-site REG and WBW sweat [K(+)] (men: y = 0.74x + 0.30, r = 0.89, ICC = 0.73; women: y = 0.04x + 3.18, r = 0.03, ICC = 0.00). Five-site REG sweat [Na(+)] and [K(+)] significantly overestimated that of WBW sweat (59 +/- 27 vs. 41 +/- 19 meq/l, P = 0.000 and 4.4 +/- 0.7 vs. 3.6 +/- 0.7 meq/l, P = 0.000, respectively). For both sexes, the best sites for predicting WBW sweat [Na(+)] and [K(+)] were the thigh (1 +/- 8 meq/l < WBW, P = 1.000, y = 0.75x + 11.37, r = 0.96, ICC = 0.93) and chest (0.2 +/- 0.3 meq/l > WBW, P = 1.000, y = 0.76x + 0.55, r = 0.89, ICC = 0.87), respectively. In conclusion, regression equations can be used to accurately and reliably predict WBW sweat [Na(+)] and [K(+)] from REG sweat collections when study conditions and techniques are similar to that of the present protocol.

Pregame urine specific gravity and fluid intake by National Basketball Association players during competition.

CONTEXT: Urine specific gravity (USG) has been used to estimate hydration status in athletes on the field, with increasing levels of hypohydration indicated by higher USG measurements (eg, greater than 1.020). Whether initial hydration status based on a urine measure is related to subsequent drinking response during exercise or athletic competition is unclear. OBJECTIVE: To determine the relationship between pregame USG and the volume of fluid consumed by players in a professional basketball game. DESIGN: Cross-sectional study. SETTING: Basketball players were monitored during Summer League competition. PATIENTS OR OTHER PARTICIPANTS: Players (n = 29) from 5 teams of the National Basketball Association agreed to participate. MAIN OUTCOME MEASURE(S): Pregame USG was measured for each player on 2 occasions. Athletes were given ad libitum access to fluid during each game and were unaware of the purpose of the study. Volume of fluid intake was measured for each player. To assess sweat loss, athletes were weighed in shorts before and after each game. RESULTS: Sweat loss ranged from 1.0 to 4.6 L, with a mean sweat loss of 2.2 +/- 0.8 L. Fluid intake ranged from 0.1 to 2.9 L, with a mean fluid intake of 1.0 +/- 0.6 L. Pregame USG was greater than 1.020 in 52% of the urine samples collected and was not correlated with fluid volume consumed during either of the games (r = 0.15, P = .48, and r = 0.15, P = .52, respectively). CONCLUSIONS: Approximately half of the players began the games in a hypohydrated state, as indicated by USG. Fluid intake during the game did not compensate for poor hydration status before competition. Furthermore, sweat losses in these players during games were substantial (greater than 2 L in approximately 20 minutes of playing time). Therefore, both pregame and during-game hydration strategies, such as beverage availability and player education, should be emphasized.

Core temperature and metabolic responses after carbohydrate intake during exercise at 30 degrees C.

CONTEXT: Carbohydrate ingestion has recently been associated with elevated core temperature during exercise in the heat when testing for ergogenic effects. Whether the association holds when metabolic rate is controlled is unclear. Such an effect would have undesirable consequences for the safety of the athlete. OBJECTIVE: To examine whether ingesting fluids containing carbohydrate contributed to an accelerated rise in core temperature and greater overall body heat production during 1 hour of exercise at 30 degrees C when the effort was maintained at steady state. DESIGN: Crossover design (repeated measures) in randomized order of treatments of drinking fluids with carbohydrate and electrolytes (CHO) or flavored-water placebo with electrolytes (PLA). The beverages were identical except for the carbohydrate content: CHO = 93.7 +/- 11.2 g, PLA = 0 g. SETTING: Research laboratory. PATIENTS OR OTHER PARTICIPANTS: Nine physically fit, endurance-trained adult males. INTERVENTION(S): Using rectal temperature sensors, we measured core temperature during 30 minutes of rest and 60 minutes of exercise at 65% of maximal oxygen uptake (Vo(2) max) in the heat (30.6 degrees C, 51.8% relative humidity). Participants drank equal volumes (1.6 L) of 2 beverages in aliquots 30 minutes before and every 15 minutes during exercise. Volumes were fixed to approximate sweat rates and minimize dehydration. MAIN OUTCOME MEASURE(S): Rectal temperature and metabolic response (Vo(2), heart rate). RESULTS: Peak temperature, rate of temperature increase, and metabolic responses did not differ between beverage treatments. Initial hydration status, sweat rate, and fluid replacement were also not different between trials, as planned. CONCLUSIONS: Ingestion of carbohydrate in fluid volumes that minimized dehydration during 1 hour of steady-state exercise at 30 degrees C did not elicit an increase in metabolic rate or core temperature.

Daily fluid turnover during preseason training in U.S. college football.

The authors measured 24-h fluid-turnover (FTO) rate during 6 d of preseason training in U.S. college football players. Players, training (T, n = 9, full gear and contact drills) and reference (R, n = 4, conditioning without gear or contact), ingested a deuterium oxide (D(2)O) dose and provided urine samples every 24 h for analysis of D(2)O. During one approximately 2.3-h practice (wet-bulb globe temperature 24.6 degrees C), body-mass change, urine production, and voluntary fluid intake were measured to calculate gross sweat loss (GSL). Average FTO was 10.3 +/- 2.2 L/d for T and 7.0 +/- 1.0 L/d for R. GSL was 3.4 +/- 1.5 L for T and 1.7 +/- 1.3 for R (P > 0.05). By Day 6, body mass decreased significantly in T (-2.4 +/- 1.3 kg, P < 0.05) but not in R (0.38 +/- 0.95 kg). With preseason training under moderate environmental stress, football players had high FTO and sweat rates, which might have contributed to a loss of body mass during preseason football training.