Type II muscle fibers (fast twitch) can decrease by as much as what percentage by the age of 80 in men who don't actively strength train?

Type II muscle fibers, also known as fast-twitch fibers, are crucial for activities that require quick bursts of power and strength, such as sprinting or heavy lifting. As individuals age, particularly those who do not engage in regular strength training, there is a substantial decline in muscle mass and overall muscular strength. Research indicates that by the age of 80, men who do not actively strength train can experience a decrease in their Type II muscle fiber composition by as much as 50%. This significant reduction is tied to the natural aging process, which includes factors like hormonal changes, reduced physical activity, and muscle atrophy. Therefore, maintaining an active strength training regimen is vital for promoting the preservation of muscle fibers and overall function in older adults, mitigating this age-related decline.