The Effects of Repeated, Consecutive High-Intensity Exercise on Cognitive Performance in Well-Trained Team Sports Players

Abstract

Improvements in cognitive performance and mood are generally accepted following moderate intensity exercise; however, the impact of high-intensity exercise is less clear. Given that professional team sports are performed at high or maximal intensity, which can be further compounded during periods of intensified periods of competition, investigations into the effect of such exercise on cognition are needed. PURPOSE: To determine the effect of repeated high-intensity exercise on cognitive function, mood and perceptions of both physical and mental energy, and fatigue. METHODS: In a counterbalanced crossover design, twenty-four well-trained, sub-elite rugby players (mean ± SD age, height, mass were 20.7 ± 1.9 yrs, 181.7 ± 5.5 cm, 88.2 ± 9.0 kg, respectively) completed a series of repeated sprints (20 x 20 m, three times per day for two consecutive days) or a seated control. Prior to and following each set of sprints or equivalent control duration, a selection of cognitive tests including simple reaction time, four-choice reaction time (FCRT), Corsi blocks and Stroop task (ST) were completed in addition to visual analogue scales assessing mood, energy and fatigue. Repeated-measures ANOVAs were conducted with pairwise comparisons where necessary (α = 0.05). RESULTS: No changes were observed in any cognitive, mood, energy or fatigue measures after one single high-intensity session. However, compared to the control, ST accuracy was lower in the exercise condition (-0.6 %, P < 0.05) which was largely due to a sharp decline at bout 3 on day 1 that continued throughout day 2. Additionally, FCRT was slower on day 2 (+2.2 %) whilst feelings of alertness (-12 %), contentedness (-5 %), and physical (-22 %) and mental (-24 %) energy were reduced and ratings of physical (+22 %) and mental (+40 %) fatigue increased (all day 2 vs. day 1, P < 0.05). No changes were observed in the control condition. CONCLUSION: Intensified periods of exercise have detrimental effects on cognitive performance, mood and perceptions of physical and mental energy, and fatigue. The deleterious effects on these parameters could be contributing to increased injury rates during fixture congestion alongside decrements in performance. Player rotation may help alleviate these effects whilst also prompting further research into cognitive recovery strategies.