Causes of extreme fatigue in underperforming athletes - a synthesis of recent hypotheses and reviews

Abstract

The Olympic motto citius, altius, fortius (faster, higher, stronger) epitomises the goal of athletic training. As athletes strive to improve their performance, inevitably their training load increases. Frequently their training strategies are successful and their performance improves. However, substantial anecdotal as well as experimental evidence 17,18 links intensified training, for an extended period, with a chronic decrement in athletic performance. This reduced performance may manifest as an athlete failing to improve/maintain his/her previous performances, despite undergoing more intensive training, or an athlete reporting an inability to regain previous form following a vigorous competition.Athletes must undergo significant amounts of physiological as well as psychological stress during training in order to provide sufficiently potent stimuli for appropriate adaptations to occur. To ensure that the athlete adapts favourably to the training load imposed, adequate rest is a crucial part of any training programme. If rest is not sufficient and the exercise stress alone or combined with other stressors (health, nutritional, environmental or psychological) is too great, the athlete may fail to adapt (maladapt) and enter a state of 'overreaching'. If the athlete continues training with insufficient rest, and in addition is exposed to further stressors (mentioned above), then a state of chronic underperformance may occur. This condition has been referred to as overtraining syndrome (OTS), but has also been referred to as staleness or burnout syndrome. 22It should be noted that although the condition of 'overreaching' may be a precursor to overtraining, certain coaches and athletes regard this condition as an integral part of training to achieve a supercompensatory effect. 22 However, if an athlete is overreached, approximately 2 weeks of rest should result in a return to previous performance levels or even improved performance. 22 In contrast, the OTS athlete will not recover in 2 weeks. It may take months for this athlete to recover, and in some instances the individual may never recover. 22OTS is commonly reported to occur in around 10 -20% of elite endurance athletes 32 and affects up to 65% of longdistance runners at some point in their athletic career. 28 This condition should therefore not be regarded as a marginal problem but as an important and frequent event in the athletic community. 22 Redefinition of overtraining syndromeAlthough the aetiology of OTS remains elusive the term 'overtraining syndrome' may be a misnomer, since it implies that exercise is the sole causative factor of the syndrome. The recent redefinition of the syndrome focuses not only on the outcome, but also implies that the cause may be multi- REvIEW ARTIClECauses of extreme fatigue in underperforming athletesa synthesis of recent hypotheses and reviews AbstractThe underperformance syndrome (UPS), previously known as the overtraining syndrome (OTS), has been defined as a persistent decrement in athletic performance capacity despite 2...

Exercise and the Regulation of Endocrine Hormones

“…It should be noted that recently it has been proposed to use the Decreased ratio of free testosterone to cortisol ratio of more than 30% Elevated cortisol levels term "unexplained underperformance syndrome" rather than the OTS in order to account for the role life stresses can play as just training load alone may not be the total causative factor in the syndrome development. [29][30][31][32] The research in exercisers (i.e., athletes) who are overreachingovertraining suggests that the endocrine system's hormonal responses seem to occur in two phases: an initial hyperactivity phase, followed by a latter hypoactivity phase (see Table 4). 27,28,33,34 In the hyperactivity phase, elevations in the circulating levels of hormones such as adrenocorticotrophic hormone, cortisol, prolactin, and catecholamines have been reported at rest and/or in response to an acute exercise session, 27,[33][34][35][36] although these hormonal findings are not completely universal.…”

“…Interestingly, it should be noted that in some situations during "overreaching," if the athlete is given short-term rest and recovery Decreased maximal lactate response to exercise BP, blood pressure; HR, heart rate; ?, too little, or conflicting, data exist to make conclusive statement. [25][26][27][28][29][30][31][32] (2 weeks), they may actually compensate with greater than normal adaptations and enhancements of performance. 25 The hypoactivity phase seems to more closely correspond to the "overtraining" status and/or with the occurrence of the OTS.…”

“…Proinflammatory cytokines (hormone-like substances with endocrine actions), part of the immune system, such as IL-6, tumor necrosis factor-α, and IL-1β in turn act upon multiple levels of the hypothalamicpituitary-adrenal axis, most notably the hypothalamic paraventricular nucleus where CRF production occurs. 31,32 The neuropeptide CRF influences adrenocorticotrophic hormone secretion (and the whole hypothalamic-pituitary-adrenal axis) and can also affect mood, sexual, and additional immune functions, 33,35 either directly acting on brain sensitive regions or indirectly via the sympathetic nervous system. 26,27,35 Furthermore, the cytokine changes noted may facilitate a suppression of the cell-mediated aspects of the adaptive immune system.…”

“…This creates an increased risk for infection and the so-called "sick response or sickness behavior" which is associated with many of the characteristics found in overtrained athletes. 30,31,40 As these systems interact, the negative events of overtraining intensify, and the athlete spirals downward from being healthy and physically fit to syndrome development and psychophysiologically compromised. 25,[41][42][43] 6.…”