Intramuscular hormones affect muscle differently in genders

Recent studies highlight the role of sex hormones in skeletal muscle and how they change with age and exercise. These hormones, primarily testosterone in males and estrogen in females, fluctuate throughout a person's life and are produced not only by the gonads but also in muscles. A systematic review looked at how these hormones vary with age, how exercise impacts their levels, and whether they are linked to muscle strength and mass. Researchers examined data from four databases, selecting studies involving healthy males and females or rodent models that measured intramuscular sex hormones. The review included thirteen studies. It found that older males had lower levels of intramuscular testosterone compared to younger males. However, results for females about hormone levels before and after menopause were not clear. Interestingly, chronic exercise led to lower levels of androgens and estrogen in females, while in males, it increased androgen levels. For short, intense exercise, hormone levels did not change in humans but did increase in rodents. The findings suggest that intramuscular androgens are positively linked to muscle mass and strength in males. In contrast, the evidence for females regarding estrogen and androgens was mixed, showing inconsistent results related to muscle function and mass. Overall, the study indicates that age and exercise affect sex hormone levels differently between genders.