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This study examined sweat rate, sweat sodium concentration [Na + ], and ad-libitum carbohydrate and fluid intakes in elite female soccer players during training ( n = 19) and a match ( n = 8); eight completed both for comparisons. Body mass (kg) was obtained before and after exercise to calculate sweat rate. The sweat [Na + ] was determined from absorbent patches on the thigh or back. Sweat rate, percentage body mass change, and sweat [Na + ] for 19 players during training were 0.47 ± 0.19 L·h -1 , +0.19 ± 0.65%, and 28 ± 10 mmol·L -1 , respectively. Sweat rate was higher during a match (0.98 ± 0.34 L·h -1 ) versus training (0.49 ± 0.26 L·h -1 , p = 0.007). Body mass losses were greater post-match (-1.12 ± 0.86%) than training (+0.29 ± 0.34%, p = 0.003). Sweat [Na + ] was similar for training (29 ± 9 mmol·L -1 ) and a match (35 ± 9 mmol·L -1 ) ( p = 0.215). There were no differences in match versus training carbohydrate intakes (2.0 ± 2.3 g·h -1 , 0.9 ± 1.5 g·h -1 , respectively, p = 0.219) or fluid intakes (0.71 ± 0.30 L·h -1 , 0.53 ± 0.21 L·h -1 , respectively, p = 0.114). In conclusion, female soccer players' sweat rates were higher during a match than during training, and carbohydrate intakes were below recommendations for matches and training.

Aim: The purpose of this study was to evaluate hydration status, fluid intake, sweat rate, and sweat sodium concentration in recreational tropical native runners., Methods: A total of 102 males and 64 females participated in this study. Participants ran at their self-selected pace for 30-100 min. Age, environmental conditions, running profiles, sweat rates, and sweat sodium data were recorded. Differences in age, running duration, distance and pace, and physiological changes between sexes were analysed. A p -value cut-off of 0.05 depicted statistical significance., Results: Males had lower relative fluid intake (6 ± 6 vs. 8 ± 7 mL·kg -1 ·h -1 , p < 0.05) and greater relative fluid balance deficit (-13 ± 8 mL·kg -1 ·h -1 vs. -8 ± 7 mL·kg -1 ·h -1 , p < 0.05) than females. Males had higher whole-body sweat rates (1.3 ± 0.5 L·h -1 vs. 0.9 ± 0.3 L·h -1 , p < 0.05) than females. Mean rates of sweat sodium loss (54 ± 27 vs. 39 ± 22 mmol·h -1 ) were higher in males than females ( p < 0.05)., Conclusions: The sweat profile and composition in tropical native runners are similar to reported values in the literature. The current fluid replacement guidelines pertaining to volume and electrolyte replacement are applicable to tropical native runners.

Hypohydration increases physiological strain and reduces physical and technical soccer performance, but there are limited data on how fluid balance responses change between different types of sessions in professional players. This study investigated sweat and fluid/carbohydrate intake responses in elite male professional soccer players training at low and high intensities in cool and hot environments. Fluid/sodium (Na + ) losses and ad-libitum carbohydrate/fluid intake of fourteen elite male soccer players were measured on four occasions: cool (wet bulb globe temperature (WBGT): 15 ± 7 °C, 66 ± 6% relative humidity (RH)) low intensity (rating of perceived exertion (RPE) 2-4, m·min -1 40-46) (CL); cool high intensity (RPE 6-8, m·min -1 82-86) (CH); hot (29 ± 1 °C, 52 ± 7% RH) low intensity (HL); hot high intensity (HH). Exercise involved 65 ± 5 min of soccer-specific training. Before and after exercise, players were weighed in minimal clothing. During training, players had ad libitum access to carbohydrate beverages and water. Sweat [Na + ] (mmol·L -1 ), which was measured by absorbent patches positioned on the thigh, was no different between conditions, CL: 35 ± 9, CH: 38 ± 8, HL: 34 ± 70.17, HH: 38 ± 8 ( p = 0.475). Exercise intensity and environmental condition significantly influenced sweat rates (L·h -1 ), CL: 0.55 ± 0.20, CH: 0.98 ± 0.21, HL: 0.81 ± 0.17, HH: 1.43 ± 0.23 ( p =0.001), and percentage dehydration ( p < 0.001). Fluid intake was significantly associated with sweat rate ( p = 0.019), with no players experiencing hypohydration > 2% of pre-exercise body mass. Carbohydrate intake varied between players (range 0-38 g·h -1 ), with no difference between conditions. These descriptive data gathered on elite professional players highlight the variation in the hydration status, sweat rate, sweat Na + losses, and carbohydrate intake in response to training in cool and hot environments and at low and high exercise intensities.

This study assessed the effect of carbohydrate intake on self-selected soccer-specific running performance. Sixteen male soccer players (age 23 ± 4 years; body mass 76.9 ± 7.2 kg; predicted VO 2max = 54.2 ± 2.9 mL∙kg -1 ∙min -1 ; soccer experience 13 ± 4 years) completed a progressive multistage fitness test, familiarisation trial and two experimental trials, involving a modified version of the Loughborough Intermittent Shuttle Test (LIST) to simulate a soccer match in a fed state. Subjects completed six 15 min blocks (two halves of 45 min) of intermittent shuttle running, with a 15-min half-time. Blocks 3 and 6, allowed self-selection of running speeds and sprint times, were assessed throughout. Subjects consumed 250 mL of either a 12% carbohydrate solution (CHO) or a non-caloric taste matched placebo (PLA) before and at half-time of the LIST. Sprint times were not different between trials (CHO 2.71 ± 0.15 s, PLA 2.70 ± 0.14 s; p = 0.202). Total distance covered in self-selected blocks (block 3: CHO 2.07 ± 0.06 km; PLA 2.09 ± 0.08 km; block 6: CHO 2.04 ± 0.09 km; PLA 2.06 ± 0.08 km; p = 0.122) was not different between trials. There was no difference between trials for distance covered ( p ≥ 0.297) or mean speed ( p ≥ 0.172) for jogging or cruising. Blood glucose concentration was greater ( p < 0.001) at the end of half-time during the CHO trial. In conclusion, consumption of 250 mL of 12% CHO solution before and at half-time of a simulated soccer match does not affect self-selected running or sprint performance in a fed state., Competing Interests: Ian Rollo is an employee of the Gatorade Sports Science Institute, a division of PepsiCo Inc. The views expressed in this manuscript are those of the authors and do not necessarily reflect the position or policy of PepsiCo Inc.

Intermittent sports (e.g., team sports) are diverse in their rules and regulations but similar in the pattern of play; that is, intermittent high-intensity movements and the execution of sport-specific skills over a prolonged period of time (~1-2 h). Performance during intermittent sports is dependent upon a combination of anaerobic and aerobic energy systems, both of which rely on muscle glycogen and/or blood glucose as an important substrate for energy production. The aims of this paper are to review: (1) potential biological mechanisms by which carbohydrate may impact intermittent sport performance; (2) the acute effects of carbohydrate ingestion on intermittent sport performance, including intermittent high-intensity exercise capacity, sprinting, jumping, skill, change of direction speed, and cognition; and (3) what recommendations can be derived for carbohydrate intake before/during exercise in intermittent sports based on the available evidence. The most researched intermittent sport is soccer but some sport-specific studies have also been conducted in other sports (e.g., rugby, field hockey, basketball, American football, and racquet sports). Carbohydrate ingestion before/during exercise has been shown in most studies to enhance intermittent high-intensity exercise capacity. However, studies have shown mixed results with regards to the acute effects of carbohydrate intake on sprinting, jumping, skill, change of direction speed, and cognition. In most of these studies the amount of carbohydrate consumed was ~30-60 g/h in the form of a 6%-7% carbohydrate solution comprised of sucrose, glucose, and/or maltodextrin. The magnitude of the impact that carbohydrate ingestion has on intermittent sport performance is likely dependent on the carbohydrate status of the individual; that is, carbohydrate ingestion has the greatest impact on performance under circumstances eliciting fatigue and/or hypoglycemia. Accordingly, carbohydrate ingestion before and during a game seems to have the greatest impact on intermittent sports performance towards the end of the game.