By Dov Michaeli
If you sampled any physiology or medical textbooks you’d find that after age 45 we lose about 1% muscle mass every year. Generations of physicians were raised on the belief that this is part of “normal aging”, nothing to worry about, and certainly not worth questioning –the facts are well-established, the biochemical processes underlying sarcopenia (muscle loss, in medical lingo) exhaustively studied. There were early studies challenging this fatalistic view; they showed that resistance training could slow or reverse “normal” aging. The problem was that most of those studies were poorly designed and were relegated to second and third line journals.
This has changed recently. I attribute the new interest in exercise and its effect on aging to the “aged boomers” tidal wave, the offspring of the “baby boomers” tsunami. Here is a whole generation that worshipped youth, adored their bodies, worked hard to ward off the signs of aging (Botox anyone?)-and they don’t like what they see in the mirror every morning. They are losing their gorgeous muscles that they worked so hard to develop, they are slowing down in their running, and their gait is losing its youthful springiness. There has got to be a quick fix!
Science to the rescue
With this kind of powerful constituency it was inevitable that the research funds spigot will open wide. And indeed, recent bountiful research has given the baby boomers what they sought –validation that aging as we knew it is no more.
The Institute of Medicine (IOM) added exercise recommendations to its dietary advice—essentially doubling the Surgeon General’s 1996 recommendation for moderate physical activity, from 1/2 to 1 hour daily. “Moderate physical activity” refers to movement such as walking, gardening, or bicycling. But this recommendation quickly gave way to something more vigorous: exercise, about 30 minutes a day of it, on average. While general physical activity is important for maintenance of energy balance and weight, exercise is designed to improve the five key components of physical fitness: cardio-respiratory endurance, muscle strength, muscle endurance, flexibility, and body composition. Resistance training, or weight training, is the best form of exercise to fulfill these requirements.
Strength training and medicine
One of the most persuasive experiments demonstrating the benefits if resistance exercise was done not with the elderly, but with patients with chronic renal failure. In such patients the kidneys lost their capacity to remove from the circulation the byproducts of protein metabolism, and those can be quite toxic when they reach high blood levels. So one remedy is obvious: restrict protein intake. But proteins are necessary to maintain our tissues, especially muscles. Indeed, patients with chronic kidney failure on protein restriction diet lose a large amount of their muscle mass. Tufts University researchers reported on a study involving a group of volunteers with this condition. About half the group engaged in resistance training, while the other half served as a control group.
Among the strength-trained participants—who exercised for 45 minutes (including warm-up and cool-down) three times per week for 12 weeks—measurements taken before and after the study period showed that, on average, total muscle fiber increased by 32 percent, and muscle strength increased by 30 percent. Those who did not exercise lost on average about 3 percent of their body weight, or about 9 pounds.
In addition, when compared to the control group, the exercisers reduced their blood levels of two key inflammation factors. Heart disease and vascular abnormalities (atherosclerosis, hypertension) have been shown to result from chronic inflammation.
The same research group studied patients with osteoarthritis who underwent the same exercise program as the patients with the kidney failure. Their balance improved by 55 percent, and muscle strength increased by 14 percent after a single 12-week program. Their flexibility improved by 17 percent, and their self-reported pain decreased by 30 percent. Sure beats any medical treatment for osteoarthritis I know of, and at a fraction of the cost.
Tufts University is now conducting a careful study of 3000 volunteers that is already revealing startling results: some of the volunteers older than 60 had doubled their leg strength and some older than 90 had put down their walking canes.
This improved body strength, the opposite effect of normal aging, was having a positive effect on activities of daily living. As participants reclaimed their muscles, they also regained their ability to climb stairs, clean house, grocery shop, and do other activities.
A post-doctoral study by Dr. Tim Henwood of the University of Queensland, Australia, investigated how people over the age of 65 responded to resistance training. The study had participants do a basic twice-weekly, machine-based resistance training program that targeted the major muscles of the upper and lower body. All training sessions were thoroughly supervised to promote motivation and correct technique.
Dr. Henwood said “while many older people are encouraged to do basic aerobic exercise like walking to maintain their health, the benefits of increasing their muscle strength and power are as if not more important in the prevention of functional decline”.
“We saw some very significant increases, up to a 50 percent in muscle strength and power,” he said.
“However, the really important increases were those we saw in the participant’s functional ability.
“For this age group these increases are what allows them to keep successfully climbing stairs and getting out of chairs, thereby allowing them to retain their independence.”
And so on, and so on –literally hundreds of studies arriving at similar conclusions.
And now, for something different…
For the longest time body builders swore by certain food supplements that were supposed to help them bulk up. One of the most popular is creatine. Now, I feel compelled to admit that I have been more that dubious about the claims, and the presumed scientific basis for this supplement. After all, creatine phosphate serves as a transitory energy store in the muscle for the rapid buffering and regeneration of ATP. Its lifetime is measured in seconds. So how on earth could it cause increase in muscle bulk?
A study published on Oct. 3 in PLoS One, involved 19 men and 20 women who were 65 years or older and took part in a six-month program of regular resistance exercise training.
In the randomized double blind trial, some of the participants were given a daily supplement of creatine and linoleic acid (a naturally occurring fatty acid), while others were given a placebo. All participants took part in the same exercise program.
The exercise training resulted in improvements of functional ability and strength in all participants, but those taking the CrM (Creatine monohydrate) and CLA(Conjugated linoleic acid) showed even greater gains in muscle endurance, an increase in fat-free mass and a decrease in the percentage of body fat.
We all had the familiar sensation that after carrying something for a length of time the object is getting heavier and heavier. I always resolve to pack lighter on my next trip after lugging my suitcase across the length of O’Hare airport from terminal A to terminal F. The explanation, I thought, had to do with the buildup of lactic acid in the muscle, but I never gave it a second thought, until…
A paper in the May issue of Applied Physiology reported on a really unusual experiment. But first, some background. While it is well established that strength training is “good for you” many older people are unable to get the full benefits of such training because they suffer from conditions such as arthritis that prevent them from lifting enough weight to stimulate muscle growth. And, while younger men and women continue to produce significant amounts of muscle protein for hours after a resistance exercise workout, seniors receive a much smaller post-workout benefit. Now, anybody who watched really serious bodybuilders must have noticed that they may wear tight bands over their biceps. Turns out, this is not for decoration: moderately and temporarily restricting the flow of blood through muscles made light weights feel heavier.
A team of researchers from the University of Texas, Galveston, studied changes in the thigh muscles of seven older men (average age 70) when they performed four minutes of low-resistance leg extension exercises both with and without inflatable cuffs that reduced blood flow out of the muscles. Muscle protein synthesis was measured in each of the men by monitoring changes in a chemical tracer infused into the bloodstream. In addition, a series of biopsies yielded muscle samples that were analyzed to track alterations in biochemical pathways critical to muscle growth.
The cuffed subjects responded similarly to young people doing traditional high-intensity resistance exercise. The low-intensity exercise produced increases in protein synthesis, and activated two cellular pathways that stimulate protein synthesis and muscle growth in the post-exercise period.
Down to the cellular level
In a study published online in the October issue of PLoS ONE , researchers found that the number of muscle stem cells, called satellite cells increased after rats spent 13 weeks running on a treadmill for 20 minutes a day. (The blue dots shown on the muscle fibers in the image inset are muscle cells; the red dots represent satellite cells.) Younger rats showed a 20% to 35% increase in the mean number of stem cells per muscle fiber, while older rats showed a 33% to 47% increase. Since these cells regenerate muscles after injury or illness, the authors believe that the difference in stem cell numbers could explain why human exercisers have better muscle function than nonexercisers as they age. Better muscle quality could also delay sarcopenia, the decline in muscle mass that occurs with aging.
How to explain the effect of creatine supplementation? or restricted blood flow? or the fact that older people may have a higher rate of increase of stem cells than young ones? Beats me! But who cares – the practical conclusion is inescapable: go exercise; with or without creatine supplements, with or without a restrictive band –just do it!