Will We All Get Lou Gehrig's Disease?

Of course, the latest research suggests that Lou Gehrig did not have Lou Gehrig's disease.

That is, he did not die from amyotrophic lateral sclerosis, but rather from an aggravated case of motor-neuron disease, very likely induced by severe trauma. He got hit with too many line drives.

Fighters and football players also die from that sort of trauma.

What we don't often realize is that most of us will share their fate. That is, we will endure a variant of motor-neuron disease, although its etiology may be slightly different from that of athletes and it may not prove the principal cause of our demise.

Quite simply, as we age, we lose spinal neurons. These neurons innervate our major muscle groups.

When they lose their sources of nervous energy, the muscles die.

But they don't give up without a fight. They try to remodel themselves, enlisting the aid of satellite neurons.

The trouble is that the remodeled motor-neuron units are not as efficient as those they replace.

They don't fire as rapidly or with the same force as the original units.

They help us retain what are called type 1, or slow-twitch, muscle fibers. But they cannot save our type 2, or fast-twitch, ones.

Look at a chart of the death (apoptosis) of spinal neurons by age and you will note a steady decline from age forty to sixty-five and an accelerating decline thereafter.

That picture helps explain why we hit a wall at about age seventy.

After that age, though we may maintain our level of physical exertion, we cannot seem to maintain our musculature.

A few years ago, Goldman Sachs showed two pictures of the same man, aged sixty-five and seventy-five. At sixty-five, he was buff and toned. At seventy-five, although he performed the same level of exercise, his bodybuilder physique had evaporated. He was all flab.

To be sure, the death of spinal neurons is not the only cause of age-induced frailty.

The disease is, as they say, multifactorial, or polyetiological (I like that one).

Old age erodes our anabolic secretions ( e.g., testosterone, estrogen,  insulin growth factor).

It also decreases our capacity to take in and process enough high-quality protein--perhaps because, with age, our stomachs don't relax as much as they did when we were young.

Nevertheless, there is a growing professional consensus that age-related  loss of both muscle mass and muscle force (again, they are not the same thing) is primarily nerve related. 

By the time we enter our eighth decade, life has just hit us with too many line drives.