Endocrine response to high intensity barbell squats performed with constant movement tempo and variable training volume
Abstract
OBJECTIVE: Research indicates that among the many elements of resistance exercise protocols, training volume and total training load are the key factors for post-exercise increase in the secretion of testosterone (T), growth hormone (GH), insulin-like growth factor (IGF-1) and cortisol (C). This study aim is to deter - mine the effect of resistance exercises of variable volume and constant intensity and movement tempo on post-exercise concentrations of selected anabolic and catabolic hormones.
MATERIALS AND METHODS: Totally 28 experienced powerlifters (27.8 +- 2.9 years, with 6.64 +- 1.29 years of training experience, average body mass of 85.3 +- 3.3 kg and body height of 165.8 +- 10.3 cm) who compete at the national and international level performed three repetition of barbell squats with a constant extremal load of 90% 1RM and variable volume (3, 6 and 12 sets of squats) in three stages (pre-exercise, immediately post exercise, and 1h after exercise) over three consecutive weeks. Venous blood samples (10ml) were collected from the antecubital vein, to determine pre- and post-exercise biochemical values of the analyzed variables (T, GH, IGF-1, C) at rest, immediately after the cessation of the last set of squats, and after 60 minutes of recovery.
RESULTS: T test showed that performing 6 and 12 sets resulted in increases post exercise GH (p<0.01). Performing 6 sets of squats resulted in post exercise decrease (p<0.01) in IGF-1 and C.
Performing 3 sets of squats resulted in immediate post exercise decrease of IGF-1 (p<0.01), which did not last 1h after exercise. There were no other significant differences in analysed variables, with the training volume of three sets of three reps, confirming previous data suggesting that low volume is the limiting factor in obtaining significant differences in post-exercise levels of selected hormones.