Intensified training and salivary hormone response to high-intensity exercise

Cortisol (C) and testosterone (T) are commonly suggested as markers of overreaching and the unexplained underperformance syndrome (UPS) as taken together they highlight the body s state of stress by indicating the body s catabolic/anabolic balance. Research in this area has focused on the resting concentrations of these hormones and provided inconsistent findings with increases, decreases and no changes reported when individuals are compared in an overreached state with a normally trained state. Little attention has been given to the exercise-induced responses of these hormones and whether this could be a reliable marker of overreaching/UPS. Overreaching will only occur with an intensification of training so the aims of the studies in this thesis were to determine the effects of intensified training on the exercise-induced responses of salivary and plasma C and T concentrations. Study 1 (Chapter 4) determined the salivary and plasma C, T and plasma adrenocorticotrophic hormone (ACTH) concentration responses in physically fit, healthy males to a double-bout cycle to fatigue protocol devised by Meeusen et al. (2004). They reported blunted exercise-induced hormonal responses to this protocol when well-trained cyclists were overreached compared with a normally trained state. Study 1 concluded that the exercise-induced responses of the salivary and plasma C and plasma ACTH concentrations were unaffected by a 4-day intensified training period. Blunted exercise-induced salivary and plasma T concentrations were found post-training but were due to blunted resting, basal T concentrations post-training compared with pre-training. The double-bout cycle to fatigue protocol did not elicit large C or T responses and so was not ideally suited to highlight alterations in the exercise-induced hormone responses. A high-intensity, short-duration exercise protocol (called the 55/80 bout) was established in Chapter 5 which induced robust elevations of salivary and plasma C and salivary T concentrations when in a normal trained state. Such a protocol could highlight any adaptations in the exercise-induced responses of C and T concentrations. It was also concluded that salivary and plasma C concentrations positively correlated if the peak post-exercise values were compared but not so with the salivary and plasma T concentrations. Chapter 6 and Chapter 7 concluded that blunted responses of the salivary C (Chapter 6) and T (Chapter 6 and Chapter 7) concentrations to a 55/80 bout occurred after an intensified endurance training period (~10 days). These results indicate that the 55/80 bout could be a useful detection tool of exercise-induced alterations in salivary C and T concentrations caused by an elevation of training loads in both recreationally active and elite athlete populations. The reproducibility of the salivary hormonal responses to the 55/80 bout needed to be established before it could be concluded that this was indeed a useful tool. Chapter 8 concluded that the responses of both salivary C and T concentrations to the 55/80 bout were reasonably reproducible with intra-individual variations of 12% (salivary C) and 7% (salivary T) reported. Chapter 8 also concluded that a familiarisation 55/80 bout was needed to reduce the variation in the responses of both salivary C and T concentrations. The final experimental chapter examined the response of salivary C and T over a competitive season in elite male triathletes and concluded that the 55/80 bout was unable to highlight any adaptations in the salivary C and T exercise-induced responses. This was suggested to be due to the low numbers of participants in this study and the ability of the triathletes to cope well with the elevations in training loads over the season. In conclusion, the studies in this thesis suggest that the exercise-induced responses of salivary C and T do alter due to an intensification of training loads. This alteration presents as a blunting of the exercise-induced responses of these salivary hormones. The 55/80 cycle bout can highlight this blunted response in both recreationally active and elite athlete male populations and therefore may be a useful tool to examine exercise-induced adaptations in salivary C and T concentrations caused by periods of intensified training

Reproducibility of acute steroid hormone responses in men to short-duration running

PURPOSE: Progressively overloading the body to improve physical performance may lead to detrimental states of overreaching/overtraining syndrome (OTS). Blunted cycling-induced cortisol and testosterone concentrations have been suggested to indicate overreaching following intensified-training periods. However, a running-based protocol is yet to be developed or demonstrated reproducible. This study develops two 30-min running protocols: (i) 50/70 (based on individualised physical capacity) and (ii) RPETP (self-paced) and measures the reproducibility of plasma cortisol and testosterone responses. METHODS: Thirteen recreationally active, healthy males completed each protocol (50/70 and RPETP) on three occasions. Venous blood was drawn Pre-, Post- and 30 min Post-Exercise. RESULTS: Cortisol was unaffected (both p > 0.05; 50/70: η2 = 0.090; RPETP: η2 = 0.252) whilst testosterone was elevated (both p < 0.05; 50/70: 35%, η2 = 0.714; RPETP: 42%, η2 = 0.892,) with low intra-individual coefficients of variation (CVi) as mean ± standard deviation (50/70: 7 ± 5%; RPETP: 12 ± 9%). Heart rate (50/70: ES = 0.39; RPETP: ES = -0.03), speed (RPETP: ES = -0.09) and rating of perceived exertion (50/70: ES = -0.06) were unchanged across trials (all CVi < 5%, p < 0.05). RPETP showed greater physiological strain (p < 0.01). CONCLUSIONS: Both tests elicited reproducible physiological and testosterone responses, but RPETP induced greater testosterone changes (likely due to increased physiological strain) and could therefore be considered a more sensitive tool to potentially detect OTS. Advantageously for the practitioner, RPETP does not require a priori exercise-intensity determination, unlike the 50/70, enhancing its integration into practice

Effect of the perception of breakfast consumption on subsequent appetite and energy intake in healthy males

Purpose: This study aimed to assess the effects of consuming a very-low-energy placebo breakfast on subsequent appetite and lunch energy intake.  Methods: Fourteen healthy males consumed water-only (WAT), very-low-energy, viscous placebo (containing water, low-calorie flavoured squash, and xanthan gum; ~ 16 kcal; PLA), and whole-food (~ 573 kcal; FOOD) breakfasts in a randomised order. Subjects were blinded to the energy content of PLA and specific study aims. Venous blood samples were collected pre-breakfast, 60- and 180-min post-breakfast to assess plasma acylated ghrelin and peptide tyrosine tyrosine concentrations. Subjective appetite was measured regularly, and energy intake was assessed at an ad libitum lunch meal 195-min post-breakfast.  Results: Lunch energy intake was lower during FOOD compared to WAT (P Conclusion: Consuming a very-low-energy placebo breakfast does not alter energy intake at lunch but may reduce cumulative energy intake across breakfast and lunch and attenuate elevations in subjective appetite associated with breakfast omission.  Trial registration: NCT04735783, 2nd February 2021, retrospectively registered.</p