Effects of acute aerobic exercise, dehydration and ad libitum fluid consumption on mood and choice reaction time in trained females: A distributional analysis

This study investigated the effect of acute aerobic exercise, dehydration and fluid intake on choice reaction time (CRT) and the ex-Gaussian CRT distribution. On 4 separate occasions, 8 trained females (body mass [BM]: 61.8±10.7 kg; VO_{2 max}: 46.3±7.5 mL·kg^-1·min^-1) lost 2.0±0.3% BM cycling at ~75% VO_2max (~60 min, 24.2±0.9°C) before commencing a 1 h recovery period with ad libitum access to one of 4 beverages: Water, Powerade^® Isotonic (SD), Up&Go Energize^TM (HP-MILK) and Up&Go Reduced Sugar^TM (LS-MILK). Participants had an additional 15 min to consume food (e.g. muesli bars, fruit, bread and condiments) ad libitum at the end of the 1 h period. CRT and mood (concentration and alertness) were assessed 'Pre-Exercise', ~5 min 'Post-Exercise' and 'Post-Recovery'. Median CRT decreased Post-Exercise (401±48 ms) compared to Pre-Exercise (420±48 ms, p=0.025) and Post-Recovery values (427±49 ms, p=0.050). This improvement was localized to the μ-component of the ex-Gaussian CRT distribution (Pre-Exercise: 393±40 ms; Post-Exercise: 366±47 ms; Post-Recovery: 395±52 ms, p=0.018); the spread and skew of the distribution (i.e. σ- and τ-parameters) was unchanged across trials (p's>0.05). The effect on μ was relatively consistent across each exercise occasion (Hedges' g range: 0.32-0.63). No changes in mood were identified across time (p's>0.05). While beverage intake was similar across treatments (p=0.351), differences in total (i.e. food plus fluid) energy (p=0.014) and carbohydrate (CHO) (p<0.001) consumption were observed. Still, the type of beverage consumed did not affect mood, CRT or the ex-Gaussian CRT distribution (p's>0.05). Acute aerobic exercise provides a cognitive performance benefit, which appears to outweigh any adverse effects imposed by dehydration in the immediate post-exercise period in trained females.