Why am I losing muscle as I age?

DEAR DOCTOR K:

I’m in my 60s. Despite exercising regularly, I have been losing muscle as I get older. Why does this happen, and is there anything I can do about it?

DEAR READER:

As the years pass, muscle mass generally shrinks and strength declines. It happens to all of us as we age — even Arnold Schwarzenegger. The key to slowing this process is strength and power training.

There are basically two reasons that our muscle mass starts to shrink. The first is “sarcopenia” — age-related muscle loss. This usually begins at around age 35 and occurs at a rate of 1 percent to 2 percent a year for the typical person. After age 60, it can accelerate to 3 percent a year. On average, adults who don’t do regular strength training can expect to lose 4 to 6 pounds of muscle per decade.

The second reason our muscle mass starts to shrink is that, as we grow older, more of us use our muscles less. We don’t spend as much time at sports as when we were younger. For most of us, our work doesn’t require that we use our muscles much. Strength and power training can prevent, and even reverse, some of this loss.

The nerve-signaling system that recruits muscle fibers for tasks also deteriorates with age and lack of use. Again, power training and strength training may help restore these neural pathways and reverse this effect.

So exactly what is strength and power training? Strength training refers to exercises that build muscle by harnessing resistance — an opposing force that muscles must strain against. Putting more than the usual amount of load on your muscles makes them stronger. Power training exercises increase power, which is the product of both strength and speed.

It’s worth the effort to incorporate strength and power training into your exercise regimen. Strong muscles have an effect on more than just the way people look or move. Strong muscles pluck oxygen and nutrients from the blood much more efficiently than weak ones. Basically, they don’t have to work as hard, so the heart doesn’t have to work as hard to supply oxygen and nutrients to the muscles. That puts less strain on the heart.

Strong muscles are also better at sopping up sugar in the blood, keeping blood levels of sugar in the healthy range. In addition, strong muscles also help the body stay sensitive to insulin. This helps prevent or control Type 2 diabetes.

Strong muscles enhance weight control, too. That’s because the more muscle you have, the higher your resting metabolic rate.

People with stronger muscles are less likely to fall. And when they do take a tumble, they are less likely to sustain a serious injury.

Finally, it’s now becoming clear that regular strength and power training — like aerobic exercise — protects against heart disease and strokes. These two conditions are important causes of premature death.

Our muscles naturally start to weaken early in adult life. But don’t curse that fact — reverse it, instead. You can do a lot.