Tuesday, November 09, 2010

Sarcopenia or why we install railings by toilets

I attended a funeral last Friday. There was a fair amount of rising and falling to feet and to seats what with religious moments and a standing, whooping, foot-stomping ovation to Megan and her life well-lived. I've written before about funerals, and how I love a good one, but that is not the subject of this post.

My pew-mate was an older woman who carried more than a little extra weight and who struggled mightily to stand each time we were called upon to do so. In front of me sat a skinny woman, still older yet, who did not even attempt to get upright until it was time to leave the chapel. Two elderly friends of Megan, each losing physical ground in her own way, one to excess adiposity and osteoarthritis of knees and hips perhaps, the other to fraility and sarcopenia. The inability to rise from a seated position, however, be it in a kitchen chair, a living room recliner, or a toilet seat, is a big step on the road to dependence and demise.

Aging is filled with -penias as in osteopenia (loss of bone mass short of osteoporosis) and sarcopenia or loss of muscle mass. There are many factors that contribute to this age-related wasting away of muscles some of which not yet elucidated but not the least of which is inactivity brought on by injury, arthritis, and illness which in turn leads to weakness and fatigue which in turn fosters more inactivity.

In order to repair, regenerate, and develop muscles to propel ourselves up out of a chairs and off to the 'frig (or the gym!!), we depend on 'satellite' stem cells that reside on the surface of our muscle fibers. Reduced numbers of such cells coupled with their decreasing ability to do their job is the biological basis of sarcopenia. I've had patients seek out human growth hormone and human chorionic gonadotropin in order to boost muscle mass and reverse aging, but rats and researchers in Washington state and Israel have recently published findings that suggest a simpler, less expensive, more accessible way to get myogenic satellite cells. One word: Exercise!

Rodent models suggest nothing but bad news from aging satellite cells. Satellite cells are usually in a resting state in older animals but can be activated to repair and renew muscles after injury and illness. But satellite cells are more likely to generate fat (the lady next to me!) or fibrous connective tissue (the stringy, skinny lady in front of me!) than muscle fibers as they grow old. So what happens if rats work out instead of veg in front of the TV set?

The researchers confirmed that the older the rat, the fewer the satellite cells on their calf muscles. However, when the four-legged geezers were persuaded to hit the exercise wheel, this aging effect was corrected, and both males and females greatly increased the number of myogenic--muscle producing--cells. Better yet, this cellular change had a visible effect on the old coots with a favorable shift in their lean-to-fat content and on their level of "spontaneous locomotion." Svelte, toned, AND disinclined to sleep the day away in the wood shavings!

One of the ways I assess how my patients are faring is to greet them first in the waiting room. First of all, it's a good way to start the visit, but, in addition, I can watch them rise from their chairs and walk across the room and up two stairs to the hall. I am daily appalled by the way some of my long-time patients increasingly struggle with the task, even moreso by their seeming indifference or inattention to their inability to move with ease. Check out the way you spring from your pew, your toilet, your desk chair. Don't take "can't do it easily" for an answer.
1) Shefer, G et al. Reduced Satellite Cell Numbers and Myogenic Capacity in Aging Can Be Alleviated by Endurance Exercise. www.plosone.org.