MEDICAL AREA   

Medicina dello Sport 2019 March;72(1):67-78

DOI: 10.23736/S0025-7826.18.03294-5

Copyright © 2018 EDIZIONI MINERVA MEDICA

language: English, Italian

Effects of time-of-day strength training on plasma testosterone and cortisol concentrations in male amateur athletes

Majdi BOUAZIZI ¹, Sarah CHÉOUR ², Chouaib CHÉOUR ², Nicola L. BRAGAZZI ^{3, 4}, Julien S. BAKER ⁵, Salah SOUISSI ¹, Fairouz AZAIEZ ², Maamer SLIMANI ^{3, 4}, Foued CHÉOUR ⁶ ✉

¹ Faculty of Sciences of Bizerte, University of Carthage-Tunisia-Zarzouna, Zarzouna, Tunisia; ² Higher Institute of Sport and Physical Education of Sfax, University of Sfax, Sfax, Tunisia; ³ Department of Health Sciences (DISSAL), School of Public Health, Genoa University, Genoa, Italy; ⁴ Section of Psychiatry, Department of Neuroscience, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health (DINOGMI), Genoa University, Genoa, Italy; ⁵ Institute of Clinical Exercise and Health Science, University of the West of Scotland,, Hamilton, UK; ⁶ Institute of Applied Biology of Médenine, Médenine, Tunisia

BACKGROUND: The purpose of the present study was to examine the effects of time-of-day-strength training on plasma testosterone (T) and cortisol (C) concentrations in male amateur athletes.
METHODS: Forty-five male athletes (age, 21.2±0.3 years; height, 1.75±0.14 m; weight, 72±1.52 kg) participated in the present study. They were subjected to strength training of the knee extensor and flexor muscles. Following this, they were randomly assigned into three groups: morning strength training group (MSTG, 07:00-08:00 hours, N.=15), afternoon strength training group (ASTG, 16:00-17:00 hours, N.=15) and morning and afternoon strength training group (MASTG, 07:00-08:00 and 16:00-17:00 hours, N.=15). The concentration of T and C for each athlete was collected in all three conditions in the morning, noon and afternoon, before and after 8 weeks of strength training. The effects of group, time of the day and pre- to post-training were verified by a 3-way analysis of variance with repeated measures.
RESULTS: Our results indicate that strength training induces an increase of plasma T/C ratio in both groups of athletes who have always trained for only one session per day mainly in the afternoon compared with the MASTG (P<0.05). However, a reduction of the plasma T/C ratio was observed in the athletes who have always trained successively in the morning and in the afternoon (P<0.05). Plasma T/C ratio exhibit circadian rhythmicity in all groups showing a low level in the morning, whereas in the afternoon an increased value was more noted (P<0.05).
CONCLUSIONS: From an applied perspective, this study suggests that amateur athletes should train at the afternoon to maximize their performance gain.

KEY WORDS: Resistance training - Testosterone - Hydrocortisone - Circadian rhythm - Athletes