Hormonal and metabolic responses of older adults to resistance training in normobaric hypoxia.

ABSTRACT

PURPOSE: In young adults, the hormonal responses to resistance exercise are amplified by normobaric hypoxia. Hormone concentrations and metabolism are typically dysregulated with age, yet the impact of hypoxia on these responses to resistance exercise are uncharacterised. Therefore, this study aimed to characterise the acute and chronic hormonal and metabolic responses of older adults to resistance training in normobaric hypoxia. METHODS: Adults aged 60-75 years completed 8 weeks of resistance training in either normoxia (20.9% O2; n = 10) or normobaric hypoxia (14.4% O2, n = 10) twice weekly at 70% of their predicted 1-repetition maximum. Growth hormone, glucose, lactate, insulin, homeostatic model assessment of insulin resistance (HOMA-IR), cortisol, total testosterone, adrenaline, noradrenaline and dopamine were quantified at pre- and post-training, and in the 60 min following the first training session (untrained state) and the last training session (trained state). RESULTS: Eight weeks of training in hypoxia did not affect the resting levels of the hormones or physiological factors measured. However, hypoxia significantly blunted the acute growth hormone response in the 15 min following the last training session at week eight (43.87% lower in the hypoxic group; p = 0.017). This novel and unexpected finding requires further investigation. All other hormones were unaffected acutely by hypoxia in the 60 min following the first and the last training session. CONCLUSION: Chronic resistance training in normobaric hypoxia supresses the growth hormone response to exercise in older adults. All other hormones and metabolic markers were unaffected both acutely and chronically by hypoxia.