The ages when men hit their physical peak vary, but according to Ask Men, a man hits his peak muscle mass in his 30s. When it comes to peak alertness and metabolism, the age of 25 seems to be the point when men start to slow down.
A person's peak of physical fitness varies on an individual basis. One man may not get into the best shape of his life until his 40s, when he finally starts taking his health seriously, while another man starts losing muscle mass when he leaves school and no longer participates in sports. There is also the question of what constitutes a physical peak. According to Ask Men, the average man reaches his maximum muscle mass in his 30s. By the age of 40, men start losing about 5lbs of muscle every 10 years.
According to Ask Men, after the age of 25 years old men get less deep sleep which can reduce how much human growth hormone they produce. This hormone is essential to building and maintaining muscle. Plus, a guy's metabolism starts to slow down by 5 percent every 10 years starting at this time. This double whammy means that men lose muscle while also gaining fat at a slow, but steady rate. Overall, a man's physical peak ranges between the age of 25 and 40 years old.