Author(s): MACRAE, H., SABOU, V.R., TURNER, J.S.M., JAMES, L.J., ROLLO, I., RANDELL, R.K. , Institution: LOUGHBOROUGH UNIVERSITY , Country: UNITED KINGDOM, Abstract-ID: 2309

INTRODUCTION:
This study measured sweat rate and sweat sodium loss in elite female football players during habitual training. Few studies have explored these losses during female football training, limiting practitioners’ ability to provide evidence-based recommendations.
METHODS:
Twenty-two, Women's Super League (UK), female footballers (26 ± 3 y; 62.9 ± 6.1 kg) participated in this observational study. Testing took place during a high (HIGH) and low (LOW) intensity training session separated by 23 days (n=7 completed both sessions; n=10 completed modified/reduced training; n=6 completed 1 session). Sweat rate was estimated from changes in body mass, corrected for food/fluid intake and urine output. Food and fluid intake was ad-libitum but limited to breaks in training. Sweat sodium was measured using an absorbent sweat patch (ventral forearm). Individual training activity profiles were measured using a global positioning system. Data are presented as mean ± standard deviation. Where players did not complete both sessions in full, data were excluded from analysis between HIGH and LOW.
RESULTS:
Wet bulb globe temperature was 18.3 ± 0.6°C and 19.3 ± 0.2°C (P=0.104) for HIGH and LOW sessions, respectively. Total distance covered (9250 ± 391 vs 5420 ± 279 m; P<0.001) and high-speed running (HSR) (>5.3 m/s; 567 ± 75 vs 36 ± 33 m; P<0.001) were greater in HIGH vs LOW. HIGH resulted in greater sweat rate (0.9 ± 0.2 vs 0.6 ± 0.2 L/h; P=0.007), sweat sodium concentration (889 ± 173 vs 606 ± 114 mg/L; P=0.003), sweat sodium loss (797 ± 254 vs 354 ± 80 mg/h) and body mass loss (0.9 ± 0.2 vs 0.2 ± 0.6 %; P=0.017) (n=7). There was no difference between sessions for fluid (585 ± 180 vs 519 ± 188 mL/h; P=0.465) or carbohydrate (25 ± 13 vs 22 ± 8 g/h; P=0.627) intake. There was no correlation between sweat rate and sweat sodium concentration for those who completed both sessions (P=0.077) or when all data were analysed (P=0.135). There was a strong positive correlation between sweat rate and total distance covered (rs=0.665; P=0.001) and sweat sodium concentration and HSR (rs=0.612; P<0.001). There was a moderate positive correlation between sweat rate and HSR (rs=0.502; P=0.003) and a weak positive correlation between sweat sodium concentration and distance covered (rs=0.349; P=0.047).
CONCLUSION:
The hydration practices of the players were generally appropriate with only one player exceeding 2% body mass loss at the end of the high intensity session. However, high intensity training, which resulted in greater high-speed running and total distances, increased sweat rates and sweat sodium losses when compared with low intensity training in temperate conditions. These insights may be used to develop training specific hydration strategies.