# Resistance training-induced dihydrotestosterone is blunted in aging rat skeletal muscle

## TL;DR

This study shows that resistance training increases dihydrotestosterone in young rats but not in older rats, suggesting aging reduces this muscle response.

## Contribution

The study reveals that aging blunts resistance training-induced dihydrotestosterone production in rat skeletal muscle.

## Key findings

- Resistance training increased muscle mass in both young and old rats, but less so in older rats.
- Dihydrotestosterone levels in trained young rats were 35-fold higher than in sedentary controls.
- Dihydrotestosterone levels did not change significantly in trained old rats compared to sedentary ones.

## Abstract

This study aimed to investigate the influence of aging on steroid hormone production in skeletal muscles in response to resistance training. Male F344 rats, aged 4 months (young) and 22 months (old), were randomized into the sedentary and training groups. The training group performed resistance training by climbing a ladder with a load every three days for eight weeks. After the training period, the flexor hallucis longus muscle was dissection, and muscle steroid hormone levels were analyzed using liquid chromatography-tandem mass spectrometry. We found that resistance training significantly increased muscle mass in young and old rats, although the increase was less pronounced in the latter. In young, trained rats, muscle dihydrotestosterone levels were approximately 35-fold higher compared to sedentary controls (p < 0.01); dihydrotestosterone levels did not differ significantly between sedentary and trained old rats. These findings indicate that resistance training-induced dihydrotestosterone production is blunted in aging rat skeletal muscle.