Due to the fact that many sports skills are performed in a fatigued state, there is a need to assess skilled performance in this condition. To date, much research examining the effect of fatigue on performance has been conducted in laboratory settings, vastly different from those encountered in the sporting field. The design of the current study was such that the investigators could carry out all experimental work in an appropriate field setting. While the conditions used in this investigation were appropriate for examining the effects of moderate and high intensity fatigue on basketball passing skills, the authors acknowledge that the fatiguing task is not without limitations in terms of ecological validity. We also acknowledge that the fatiguing task performed does not fatigue the muscle groups in the upper body to the same degree as the lower body. The justification for this type of fatiguing task however, is clearly outlined in the earlier sections of this paper. Furthermore, an appropriate basketball-specific fatigue protocol that truly replicates match play exercise patterns would have been utilised for this study but currently none exists. Future empirical work needs to carefully consider this so that the fatigue experienced is very similar to that experienced in match play. With respect to our results, the first notable finding was that the mean scores at rest were slightly higher in the novice players than the expert basketball players, possibly due to motivational factors. Additionally, the novice players were physically very fit, and demonstrated a very high intensity of effort during all testing. Fundamentally however, this study has demonstrated that there is a highly significant (p = 0.01) level of fatigue by level of skill interaction (Figure 5). The within and between-group statistical test results also show this to be true where the rate of decline in the basketball passing performance of the novice players is much greater than that in the expert players. The results support previous work where fatigue was also accompanied by a decline in skill (Al-Nakeeb et al., 2003; Berger and Smith-Hale, 1991; Davey et al., 2002; Lyons et al., 2006; Mohr, 2003). This research highlights however, that experts exhibited no statistical difference in performance following moderate fatigue. Finally, the expert players were better able to cope with high intensity fatigue conditions and maintain a higher level of performance compared to novice players. Comparison of our findings to previous investigations is difficult because of large variations in experimental designs from study to study. Add to this the distinct lack of research on fatigue in basketball, leaves researchers with a limited basis for comparing findings. Our findings do concur however, with those of Ivoilov et al., 1981 where basketball-shooting performance deteriorated following high intensity fatigue. This finding was consistent in both expert and novice players in the current research. Conversely, our findings are contrary to those of McMorris et al., 1994 where passing performance was significantly better following moderate fatigue than at rest. In our study however, there was a decline in passing performance following moderate intensity fatigue compared to rest in both groups but the decline was only statistically significant (p = 0.002) in the novice group. Mean performance scores in fact, were almost identical in the expert players at these two intensities (Table 1) suggesting that experts are able to compensate their performance at this intensity to ensure optimal performance. This compensation could take the form of recruitment of additional motor units and rotating between different synergist muscles to compensate for reduced muscular efficiency (Green, 1990). It seems therefore, that in expert players fatigue needs to be at a very high intensity for a significant deterioration in performance to be exhibited. Finally, McMorris et al., 1994 also found no difference between performance following moderate and high intensity fatigue. Again this is contrary to the current study where there was a significant (p = 0.038) difference in the performance of the expert players and a highly significant (p = 0.006) difference in the performance of the novice players. Fundamentally, while the passing test used by McMorris and colleagues is similar to this research, the fatiguing tasks are very different. Comparisons drawn therefore, must be interpreted with this is mind. As detailed previously, a number of theories have been developed attempting to explain the relationship between exercise, arousal and performance. Despite some limitations, the weight of the scientific evidence still continues to favour the Inverted-U theory (Landers and Arent, 2001). The results of this research however, do not conform to an inverted-U effect. Similarly, the results do not conform to Easterbrooks’ (1959) Cue Utilisation Theory, which would predict optimal performance at moderate levels of arousal. On the contrary, our results suggest that passing performance deteriorates in both experts and novices following moderate intensity fatigue. Again at high intensity fatigue the inverted-U theory and cue utilisation theory would predict that performance should return to baseline level when in the current study performance deteriorated significantly compared to rest in both groups. In terms of explaining the expert-novice differences however, Drive Theory, developed by Hull, 1943 potentially provides an explanation for the novice players’ results. Within the novice group there was a progressive decline in basketball passing performance as arousal or fatigue intensity increased. This agrees with Drive Theory, which would also predict such an effect because in the novices’ habit patterns are not strongly formed. Drive Theory also predicts optimal performance at low arousal levels in the novices’, which mirrors our findings. At high levels of fatigue however, performance will deteriorate due to the fact that habit strength is low and so incorrect responses are likely to dominate in the novices. Again our findings show this to be the case. However, the basketball passing performance of the experts in this study is contrary to what Hull, 1943 and Oxendine, 1984 would hypothesise. In experts, because habit patterns are strongly formed, basketball passing should be optimal at a high level of arousal (following high intensity fatigue) especially for simple skills such as that employed in this study. However, in our research, there was in fact, a highly significant (p = 0.006) deterioration in basketball passing compared to rest. The results of this study may be better explained however, in terms of the Multi-Dimensional Allocation of Resources Theory (Kahneman, 1973) that predicts a deterioration in performance following high intensity exercise, as cognitive effort cannot focus attention solely on task-relevant information. Within both the novice and expert groups this was clearly the case. From Table 1 it is clear that in the expert group, performance declined by 5.30 ± 1.24 while in the novice group performance declined by 10.90 ± 1.22. Consequently, while the distractibility referred to by Kahneman, 1973 is evident in both groups, it is higher in the novices. Both groups therefore, are unable to ignore perceptions of pain, distress and fatigue and focus on the passing test. This divided attention ultimately leads to a deterioration in passing performance, which is clearly evident in both groups. Experts however, despite a significant decline in passing performance following high intensity fatigue seem better able to focus on task relevant information, thereby maintaining a higher standard of performance than the novice players. More specifically, the performance of both groups at rest can also be explained based on this theory. According to Kahneman, 1973 performance at rest can be optimal if cognitive effort can allocate sufficient resources to the task. In the present investigation this was found to be true for both groups. There is also a possibility that the novice players allocated additional resources at rest, thereby achieving a slightly higher rest score than that of the expert players. Further research is warranted therefore, to preclude any definitive statements regarding the theoretical effects of fatigue on performance. Trying to identify the physiological mechanisms underlying fatigue effects on performance in this research is both challenging and highly complex. Additionally, mechanisms of fatigue are still not understood and most likely involve multiple sites (Lee et al., 2000). These mechanisms, underlying causes and sites have been argued and counter argued elsewhere in the scientific literature. McKenna, 2003 points out however, that in most cases fatigue predominantly occurs in the periphery and given the nature of the fatigue task in this study, it is likely that causes lie in the periphery. The details of peripheral impairments due to fatigue can be found in reviews published elsewhere (Coggan and Coyle, 1991; Enoka and Stuart, 1992; Fitts and Metzger, 1993). The likelihood that the deterioration in motor performance can be traced to a single common event or process however, now appears naïve (Green, 1990). Despite this, the following points need consideration in terms of the present research findings. Firstly, the fatiguing task in this study was very much an anaerobic-type task and very demanding of energy as was the passing test. The fatiguing task impacted heavily on a number of major muscle groups in the lower body such as the quadriceps and gastrocnemius. It is likely therefore, that muscle glycogen degradation in large muscle groups such as the quadriceps, which were then subsequently used in the passing task, was one causative factor. In the debriefing sessions participants often remarked following the high-intensity fatigue session that by the end of the passing-test they had nothing left in their legs. Given the fatiguing task and the ensuing passing task it is most likely that the participant would have experienced a disproportionate decrease in muscle glycogen, leading to reduced ATP resynthesis. Combined, these would certainly have limited performance on the basketball passing task following high intensity fatigue in both groups of players. Given the anaerobic nature of the fatiguing task it is likely that metabolic by-products such as lactic acid contributed to the deterioration seen in the performance in both groups at a high intensity. Exercise induced accumulation of lactic acid in skeletal muscle and the resulting decrease in cellular pH have been widely considered to contribute to fatigue (Westerblad et al., 1991; Fitts, 1994). Again while not directly measured in our study, lactic acid in the legs was frequently cited by the participants in the debriefing sessions. There are clearly many other metabolic factors that have potential to disrupt energy provision and muscular contraction but discussion of these is beyond the remit of this work. From observation of the testing and post-test briefing sessions the following points also need consideration. It is very clear in some participants that the distractibility cited by Kahneman, 1973 was a factor in limiting performance. In both groups it was also evident following high intensity fatigue, that players were experiencing a degree of discomfort and subsequent disruption in motor control. The novice players particularly had difficulty maintaining balance and postural stability immediately following both fatigue conditions, a finding not uncommon in the scientific literature (Vuillerme et al., 2002; Johnston et al., 1998). Consequently, decreased postural stability on the part of the players should not be overlooked as a factor influencing performance while fatigued. Secondly, information provided by the novice players in the debriefing sessions frequently revealed a feeling of ’weakness’ in their legs and a distinct lack of power, following fatigue at a high intensity. The lack of power could be due to a number of physiological reasons but also due to the fact that when muscles undergo repeated shortening contractions a greater force loss is evident than with repeated isometric contractions (James et al., 1995, cited in Cairns et al., 2005). The fatigue task in this research certainly required repeated shortening contractions and so this may account for the distinct lack of power. In the case of this research, the lack of power manifested itself through weak or inaccurate passes, subjects losing control of the ball and on some occasions players stepping over the restraining line all of which decreased the score obtained. Weaker passes were those where the ball was not passed with sufficient power or force against the wall for the rebounding ball to be caught by the participant before bouncing. Therefore, the decline in performance on the basketball passing test could be due directly or indirectly to the inability of the specific muscle groups to cope with the demands of the task in terms of speed, accuracy or both. This point is crucial in that the test relied on a combination of speed and accuracy (as is often the case in sports) and ultimately performance deteriorated. There are possible implications here for coaching and training in basketball. Linked to this somewhat was the observation that following high intensity total body fatigue there was a detrimental impact on the players reaction to the ball rebounding off the wall which manifested in the form of players fumbling the ball. This is similar to the findings of Legros et al., 1992. This was particularly evident again in the novice players following high intensity fatigue. In the novices, it is clear that under conditions of intense exercise, essential elements in performance such as handball coordination and movement cannot be integrated properly and so performance level deteriorates. This may be a determining factor that separates expert and novice players during performance. The third point which is crucial to note is that the design of this study may provide some evidence as to why a decline in performance was evident following both fatigue intensities in both groups. Fatigue is considered to be a continuous rather than a failure-point phenomenon (Cairns et al., 2005). Speed of recovery can be an issue if measurements are not made immediately on exercise cessation. McMorris and Graydon, 2000 highlighted this in a previous study, where reaction time was hypothesised to decrease following maximal exercise (due to reduced acetylcholine, potassium, ATP, and phosphocreatine in muscle). However, as the mean task time was 2.33min, a significant amount of replenishment most likely had occurred. Astrand et al. (2003) also add that replenishment of these chemicals following exercise is especially fast in trained athletes. Plasma concentrations of epinephrine for example, are known to dissipate quickly when exercise is stopped (Kjaer, 1989) with as much as a 35% reduction within 1 minute and a 50% reduction within 2-3 minutes. It is also acknowledged that recovery in muscular strength is fast in trained athletes following exercise. However, it is extremely unlikely that such recovery was a factor in this study because passing performance was conducted immediately following (3-4 seconds) fatigue and the total duration of the passing test was 30 seconds. Consequently, this research has allowed the researcher to investigate the immediate effect of fatigue on performance. Replenishment of chemicals or recovery in muscular strength/power is therefore unlikely given our design. |