The Effects of Resistance Exercise on Testosterone

The Effects of Resistance Exercise on Testosterone

Original Study: Randomized controlled trial - Endocrine response to high intensity barbell squats performed with constant movement tempo and variable training volume.

This research study aimed to investigate the effects of resistance exercises with variable volume and constant intensity on the post-exercise concentrations of selected anabolic and catabolic hormones, specifically testosterone (T), growth hormone (GH), insulin-like growth factor (IGF-1), and cortisol (C). Twenty-eight experienced powerlifters participated in the study, performing barbell squats with a constant external load of 90% 1RM and different volumes of repetitions (3, 6, and 12 sets). Blood samples were collected before exercise, immediately after exercise, and one hour after exercise to analyze hormone levels.

The results indicated that the volume of training significantly influenced the hormonal response. Performing 6 and 12 sets of squats resulted in a significant increase in post-exercise GH levels (p<0.01). However, 6 sets of squats led to a decrease in post-exercise IGF-1 and cortisol levels (p<0.01). Interestingly, performing only 3 sets of squats caused an immediate post-exercise decrease in IGF-1 levels (p<0.01), but this decrease was not sustained after one hour of recovery. No other significant differences were observed in the analyzed variables. These findings support previous data suggesting that low training volume is a limiting factor for increased post-exercise hormone secretion.

Based on the study's outcomes, it can be concluded that the optimal volume of high-intensity strength exercise, in terms of endocrine response, is six sets. Both intentionally high volume (12 sets) and low volume (3 sets) did not effectively stimulate the endocrine responses in trained individuals. Notably, the hormonal responses of GH, cortisol, and IGF-1 were most pronounced with the 6 sets of squats, which may have a significant impact on muscle growth and tissue regeneration.

In conclusion, this research provides valuable insights into the relationship between exercise volume and the secretion of anabolic and catabolic hormones. The findings suggest that a moderate volume of six sets of squats is optimal for eliciting a favorable hormonal response in experienced powerlifters. These results can inform exercise programming and training protocols aimed at maximizing muscle growth and recovery in strength training athletes. Further studies are warranted to explore the long-term effects of variable training volumes on hormonal responses and performance outcomes in different populations.


Michal Wilk, Miroslav Petr, Michal Krzysztofik, Adam Zajac, Petr Stastny. (2018, October). Endocrine response to high intensity barbell squats performed with constant movement tempo and variable training volume. National Library of Medicine. Retrieved from