The use of acute responses of endocrine and immune biomarkers to highlight overreaching
AuthorsLeal, Diogo Luis Campos Vaz
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AbstractThe action of overtraining may lead to the different states of overreaching or the overtraining syndrome (OTS). Chronic maladaptation in endocrine and immune mechanisms, and performance decrements occur with the incidence of these states. Circulating cortisol and testosterone have been proposed as endocrine markers of overreaching/OTS. Salivary measurements of these hormones have been used as a non-invasive surrogate for circulating levels. Chapter 4 (study 1) on this Thesis examined the influence of consuming water 10 min, 5 min and 1 min before providing a saliva sample in diluting saliva and consequently providing invalid salivary cortisol and testosterone concentration levels. No trial effect was found. However, exercise-induced salivary cortisol and testosterone significantly elevated in response to the 10 min and 5 min trials only, with lower absolute-changes observed in the 1 min trial. No differences were found in the resting samples. It was suggested that consuming water up to 5 min before providing a saliva sample does not appear to influence the hormone concentrations at rest and during exercise. However, the recommended guidelines for saliva collection have been followed in the subsequent studies. Chapter 5 (study 2) examined the reproducibility of salivary cortisol and testosterone responses to a 30-min cycle named as the 55/80. This test has been proposed as a suitable indicator of hormonal alterations associated with overreaching/OTS. Reproducibility of salivary cortisol and testosterone to the 55/80 was confirmed by determining intra-individual coefficients of variation (CVi). However, the 55/80 is a cycle test and therefore, may not be appropriate for runners. Chapter 6 (study 3) focused on designing a 30-min, running bout (i.e. the RPEtreadmill) to reproduce the effects of the 55/80. The RPEtreadmill is a self-paced test and therefore, will not require aVO2maxtest to determine exercise intensities. An acute elevation of plasma and salivary testosterone, but not cortisol was observed in response to the RPEtreadmill. These responses have been shown to be reproducible. The data from Chapter 6 suggest that the RPEtreadmill may be a suitable tool to indicate hormonal alterations associated with overreaching/OTS. This led to the design of study 4 (Chapter 7). Plasma and salivary cortisol and testosterone responses were examined before and after a 12-day intensified-training period. Immunity markers (specifically salivary immunoglobulin A (SIgA), leucocyte subset proliferation and phagocytic activity) were examined before and after training. Plasma and salivary cortisol were unaffected by acute exercise and training. However, testosterone elevated to the RPEtreadmill Pre-Training, and these responses were reduced Post-Training. Total leucocytes and mucosal immunity were unaffected by exercise and training. However, increased upper respiratory tract infection symptoms were found Post-Training. Baseline phagocytic function was 47% lower Post-Training. This Thesis suggests that testosterone may be a more reliable exercise-stress marker. Moreover, the RPEtreadmill may be a suitable tool to highlight alterations in testosterone when in an overreached state in an attempt to avoid the incidence of OTS, and that this tool may be practically applied in the field of exercise science. Additionally, this Thesis shows that a 12-day intensified-training period induced a marked decrease in phagocytic responses, and therefore using the RPEtreadmill to highlight overreaching may be important to also prevent further impairments in immunity status.
CitationLeal, D.L.C.V. (2017) 'The use of acute responses of endocrine and immune biomarkers to highlight overreaching'. PhD thesis. University of Bedfordshire.
PublisherUniversity of Bedfordshire
TypeThesis or dissertation
DescriptionA Thesis submitted to the University of Bedfordshire, in fulfilment of the requirements for the degree of Doctor of Philosophy
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