As You Age, Preserve Your Fast-Twitch Muscle Fibers

They’re important

All illustrations by the author.

Sedentary individuals can lose up to 3–8% of muscle per decade after the age of 30, and this rate accelerates further after 60.

Another example of muscle loss magnitudes with aging, by Burford et al.

The image below depicts a cross-section of the thigh muscle in a young individual around the age of 23 (IMAGE A), and in an older inactive individual around the age of 71 (IMAGE B).

Images from this study

As we can see, the older individual’s thigh volume and density are lower than that of the younger individual.

Now, what actually occurs within the muscle during this deterioration?

Broadly, muscles contain slow-twitch and fast-twitch fibers.

Slow-twitch muscle fibers produce low amounts of force but are highly fatigue resistant (they can sustain force production for very long).