The Effect of Strenuous Exercise on Cognitive Function, Mood, Energy and Fatigue States in Trained Sporting Individuals

A growing body of research has been designed to further our understanding of how single bouts of exercise affect cognitive performance. Early work in this area led to the identification of several moderating factors that influence the exercise-cognition interaction, with two of these being exercise intensity and fitness level. The positive effects of moderate-intensity are well accepted having received substantial support in the literature. Due to receiving much less attention however, there is currently no clear consensus on the effects of high-intensity exercise, though theoretical, experimental and anecdotal literature converges towards an impairment in cognitive function. Compared to moderate intensities, strenuous exercise places much greater physiological demands on the human body and thus it has been suggested that individuals of greater fitness levels, and those accustomed to high-intensities that have undergone years of training and adaption, may respond differently to strenuous intensities compared to normal populations. Many sporting paradigms involve prolonged exercise, congested tournament fixtures and involve weeks of intensive training and thus the influence of these stressors on cognitive function and mood, energy and fatigue states in trained populations holds important implications for sports performance. The current PhD programme aimed to examine different strenuous exercise paradigms on cognitive function, mood, energy and fatigue states in trained sporting individuals, with a particular focus on three exercise models; prolonged exercise, congested exercise and intensified training. The series of investigations that set out to address this aim have led to many novel and interesting findings. To begin, study one conducted the first systematic review in this area of the literature. Amongst highlighting the limited research, evaluation of the existing literature suggested little effect of acute strenuous exercise on measures requiring simple cognitive processing in trained populations, but found there to be more ambiguity surrounding top-down higher-order processes. This is particularly interesting, as the exercise-cognition literature has predominantly focussed on simple processes; consequently, this chapter called for the assessment of multiple cognitive domains in future studies. The first experimental study, presented in Chapter 3, examined a prolonged strenuous exercise bout on cognitive function, mood, energy and fatigue states. In support of the previous chapter’s conclusions, a negative effect on executive function was found alongside reductions in mood and energy and significant increases in both physical and mental fatigue. Building on this, Chapter 4 explored the effect of repeated strenuous exercise bouts over two days on cognitive function, mood, energy and fatigue states. Results indicated that one day of congested strenuous exercise leads to a reduction in inhibitory response accuracy and choice reaction time in addition to having negative effects on mood, energy and fatigue states. The final experimental study of this thesis, presented in Chapter 5, investigated cognitive performance, mood, energy, fatigue, perceived sleep and physical performance during and following a chronic intensified training period. This paradigm led to significant reductions in physical performance and mood during the training weeks; however, cognitive function and sleep were not affected. The practical implications of each study are discussed in each respective chapter and highlight how the results can be applied in relevant situations. Collectively, the findings of this thesis provide novel information surrounding the effects of strenuous exercise on cognitive function, mood, energy and fatigue states in trained sporting populations. The current work has shown domain specific effects of strenuous exercise with a particular effect on top-down higher order cognitive processes. Similarly, deteriorations were observed in mood and energy states in each empirical chapter alongside significant increases in mental fatigue. Further work is required to: elucidate the mechanisms by which strenuous exercise exert these effects; to determine if these effects are observed in further exercise paradigms; and to identify methods by which cognitive function, mood, energy and fatigue states can be maintained in situations dependent upon optimal cognitive performance.