Physiological and Psychological Fatigue in Extreme Conditions: Overtraining and Elite Athletes

Abstract

This article will review relevant mechanisms and markers associated with overtraining syndrome (OTS), and discuss signs and symptoms, differential diagnosis, and current assessment tools for fatigue within the context of overtraining. The findings are drawn from original research and review articles referenced by PubMed and ScienceDirect databases. Sources were selected for their contributions to the current knowledge of biological, psychological, and molecular mechanisms. Data were reviewed for relevance to OTS and then evaluated against criteria that included significant OTS outcomes and findings. Information was systematically analyzed to identify patterns, dependencies, connections, and causal factors. Comparative analysis was confounded by inconsistent metrics, terminology, and variable methodology; potential biomarkers, treatment and prevention approaches, and future research directions are identified. Diagnosing OTS is difficult because underlying cause(s) are unknown; one must exclude other factors that degrade performance and mood status. Many studies are confounded by inadequate experimental designs, poor measures of performance, and different methods for characterizing OTS. OTS is complex because the demands of excessive training in combination with other biologic, psychological, and social stressors are difficult to quantify. However, changes in mood are always noted. Interrelations among dietary patterns; social, psychological and physiological profiles; and the neuroendocrine, immune, and central nervous systems are complex and not adequately elucidated.

Fitness level impacts salivary antimicrobial protein responses to a single bout of cycling exercise

“…Given the potential link between sAMPs and the autonomic nervous system, sAMPs may prove to be a useful tool for determining URTI susceptibility or overtraining, as alterations in the autonomic nervous system are thought to contribute to overtraining (Purvis et al 2010).…”

Facilitation of postural limb reflexes in spinal rabbits by serotonergic agonist administration, epidural electrical stimulation, and postural training

“…The difference between the oscillatory EMG activity in the control group and that in the other groups was significant in the 2nd and 3rd periods. *P Ͻ 0.05; **P Ͻ 0.01; ***P Ͻ 0.001. from the phenomenon of "overtraining" (Purvis et al 2010). Animals of this group were subjected to many more tilts in each experimental session (ϳ440 tilts) compared with the DOIϩSPT group (ϳ120 tilts) or the EESϩSPT group (ϳ190 tilts).…”

Lipid Replacement Therapy with a Glycophospholipid Formulation with NADH and CoQ10 Significantly Reduces Fatigue in Intractable Chronic Fatiguing Illnesses and Chronic Lyme Disease Patients

“…Fatigue and especially chronic fatigue have been described as a multidimensional sensation, and clinical studies have determined the extent of fatigue in aging and in various medical conditions (neurological, respiratory, coronary, musculoskeletal, metabolic, autoimmune and gastrointestinal diseases, cancer, infections) [3,[5][6][7]. Most patients consider fatigue to be a loss of overall energy and inability to perform even simple tasks without exertion [3,4].…”