The impact of fatigue on the intermittent high intensity exercise undertaken during participation in team sports has not been extensively studied. Team sports are characterised not only by intennittent exercise, but also by the contribution of a wide range of skills. This thesis describes a series of studies conducted in a controlled environment to assess the influence of fluid ingestion and fatigue on selected soccer skills. The aim of the first study was to examine the effect of 90-min of high intensity shuttle running with and without water ingestion on a socc er-dribb ling test. The subjects were allocated to two randomly assigned trials either ingesting or abstaining from fluid intake during a 90 min intennittent exercise protocol (Loughborough Intermittent Shuttle Test: LIST). In the absence of water ingestion soccer skill deteriorated (p < 0.05) by 5% but was maintained when fluid was ingested. The principal aim of the second study was to understand further the mechanisms contributing to the deterioration observed during the LIST. Subjects completed the LIST ingesting a 6.4% carbohydrate electrolyte solution (CHO), placebo (CON) or no fluid (NON). Free fatty acids, cortisol and aldosterone responses were lower (P < 0.01) at the end of exercise during both CHO and CON in comparison to NON. There was no difference in respiratory exchange ratio between trials. Fluid ingestion did not appear to cause a shift in substrate metabolism even though there were differences in plasma FFA concentrations. The consumption of carbohydrate during exercise has been shown to increase physical performance, capacity and cognitive function. The aim of the third study was to assess the influence of a 6.4 % carbohydrate-electrolyte (CHO) placebo (CON) or no fluid (NON) on passing and dribbling soccer skills following the LIST. During the NON trial performance of the dribbling test followed a similar pattern to that in the first study and performance of the passing test decreased (p < 0.05). This reduction in performance was prevented during the CHO and CON trials. The purpose of the final study was to identify whether a rehydration strategy following the LIST would result in a recovery of skill performance. Subjects were allocated to two randomly assigned trials either ingesting a volume of fluid equivalent to 150% (L) or 9% (S) of body mass loss during the LIST, over a2h recovery period. During the recovery period serum sodium and osmolality returned to resting concentrations in the L trial but remained elevated in the S trial (P < 0.05). Despite body mass returning to resting values following the rehydration period, performance of the skills tests remained impaired. Deterioration in skill test performance may have been related to a reduction in neuromuscular control either by a reduction in muscle glycogen or by an increase in muscle damage during the no fluid trials. The mechanism responsible for the deterioration in skill performance remains to be elucidated.

The impact of nutritional intervention on affective states has largely been ignored in the exercise-affect literature. For decades the impact of such interventions on perceptions of exertion has been well documented. However, Hardy and Rejeski (1989) assert that `what' a person feels, as measured by the rating of perceived exertion (RPE) scale, may be very different from `how' they feel, and that on its own the RPE provides limited information about the subjective experiences of individuals during exercise. This thesis describes a series of studies that assess the influence of various fluid ingestion regimes on both `how' and `what' a person feels. Seven studies were undertaken, incorporating a variety of exercise modes, including prolonged running (Study 1,3 & 7), prolonged cycling (Study 2& 4) and prolonged intermittent, high intensity exercise (Study 5,6 & 7). The relationship between fluid ingestion during exercise and affective states during and following exercise proved to be a complex one. The initial investigation (Study 1) showed that the ingestion of water during prolonged running resulted in an overall improvement in valence during the recovery period. A significant increase in activation was also noted in the water trial only, from pre to post exercise. Furthermore, subjective ratings of energy post-exercise were higher in the water trial, compared to the no water trial. In study 2 the beneficial effects observed in study 1 were not so apparent. In this instance the only significant change of interest was in energetic arousal, which was found to be higher 5 min post exercise in the water trial compared to the no water trial. When the ingestion of a CHO solution during exercise was compared to a placebo or flavoured water solution (Studies 3-7) the findings also varied. However, the observation of an enhanced affective profile following CHO ingestion in Study 4 and Study 5 highlights the importance of considering nutritional status and intervention when investigating the exercise-affect relationship. These studies have highlighted some important aspects in our understanding of the exercise-affect relationship alone. Firstly, a robust finding across all the studies was the observation of an almost uniformly positive shift in valence from the final within-exercise assessment to the post exercise assessments. Thus emphasising the dynamic nature of affect and the importance of repeated within exercise assessments. Secondly, moderate intensity exercise of a fixed duration was marked by highly variable inter-individual differences in the response of participants to the valence and activation dimensions. However, exercise to fatigue elicited a homogenous valence response as participants came closer to reaching their exercise capacity.

The aim of this study was to measure the degree of dehydration experienced during surf practice and examine the effect this might have on surfing performance, cognitive function and muscular endurance of elite surfers. Twelve male national and international level surfers volunteered to take part in the study. Their mean (± SD) age, body mass, height and surfing experience were 27.0 ± 3.3 years, 73.2 ± 7.1 kg, 1.7 ± 0.05 m and 21.0 ± 3.1 years, respectively. The participants were randomly assigned to one of two trials: no fluid ingestion (NF) or fluid ingestion (FI) during 100 min of surf practice in a steamer wetsuit. The experiment was designed to emulate not only the physical and cognitive demands of surfing but also the ambient environment in which it takes place. Before and immediately after surf practice, the participants had their hydration status measured, completed a cognitive test battery and upper and lower-body muscular endurance tests. Surfing performance was assessed during the first and last 20 min of practice. At the conclusion of the NF trial, participants showed a 3.9 ± 0.7% body mass (BM) loss, this was significantly greater (P < 0.05) than the 1.6 ± 0.7% BM loss seen at the end of the FI trial. In the NF trial, surfing performance decreased by 20.3 ± 7.1%, but showed a slight improvement in the FI trial (1.9 ± 10.2%). Of the six cognitive domains assessed (short-term memory, information processing speed, working memory, attention, visuomotor skill and visual acuity) all were significantly impaired when at a 3.9 ± 0.7% BM loss (P < 0.05) yet were unaffected at a 1.6 ± 0.7% BM loss. Information processing speed and working memory were the most strongly correlated to surfing performance (r = 0.74; P < 0.05). At the conclusion of the NF trial upper and lower-body muscular endurance were diminished by 21.2 ± 5.5% and 4.4 ± 5.8%, respectively. At the conclusion of the FI trial upper-body muscular endurance was reduced by 17.0 ± 4.1% while lower-body muscular endurance was marginally better (1 ± 3%). There was a significant difference in muscular endurance capacity between trials yet no significant correlation was observed between muscular endurance and surfing performance. The findings of this study suggest that surf practice for 100 min in a steamer wetsuit results in BM loss severe enough to significantly impair surfing performance, cognitive function and muscular endurance. Yet, when water is consumed during surf practice, surfing performance, cognitive function and lower body (but not upper-body) muscular endurance is maintained. Keywords: fluid ingestion, surf training, steamer wetsuit, hypohydration.