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; VO2 max: 46.3 +/- 7.5 mL.kg(-1).min(-1)) lost 2.0 +/- 0.3% BM cycling at similar to 75% VO2max (similar to 60 min, 24.2 +/- 0.9 degrees C) before commencing a 1 h recovery period with ad libitum access to one of 4 beverages: Water, Powerade (R) 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', similar to 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 mu-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. sigma- and tau-parameters) was unchanged across trials (p's>0.05). The effect on mu 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.