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America’s Trainer | Muscle & Body Magazine

Current opinion in skeletal muscle biology and exercise physiology is that “aerobic exercise has a negligible effect on skeletal muscle mass.” In my experience, I have rarely witnessed many bodybuilders put up a 30-mile cumulative running week.

But things may be changing, especially for sedentary individuals as they age.

“Aerobic exercise training is associated with improvements in aerobic capacity, cardiovascular function and metabolic regulation,” noted researchers at the Mayo Medical School, Endocrine Research Unit and Taylor University School of Natural and Applied Sciences in the April 2014 issue of Exercise and Sport Sciences Reviews.

None of that is surprising, but what caught my attention was that, according to the Mayo Medical School researchers: “Our findings suggest that aerobic exercise training is a viable exercise prescription to mitigate age-related decrements [loss] in muscle mass caused by catabolic [breakdown] mRNA expression [a blueprint for making protein or muscle].” Adding to that, these researchers make the bold statement that, “collectively, the benefits of aerobic exercise training on skeletal muscle health are underappreciated and not completely characterized.”

Research even suggests that “properly performed aerobic exercise leads to skeletal muscle hypertrophy that is compared to resistance exercise training.”

Muscle hypertrophy involves an increase in the size of skeletal muscle through an increase in the size of its component cells, which you might not expect from aerobic exercise.

“With the application of high-resolution imaging techniques (e.g., computed topography, magnetic resonance imaging), there is a growing body of evidence that aerobic exercise training can induce skeletal muscle hypertrophy in sedentary individuals aged 20–80 years old,” according to the study.

Sedentary And Aging People Benefit Most

The evidence seems to be strong that aerobic-exercise-type training (walking, jogging, cycling, kayaking) can cause muscle-fiber enlargement in sedentary individuals from 20–80 years old. This research point is quite significant relative to sarcopenia, which the U.S. National Library of Medicine says “is a term utilized to define the loss of muscle mass and strength…that occurs with aging.”

Sarcopenia tends to be at its highest after 65 years of age. Most people begin to lose modest amounts of muscle mass after age 30, but the resulting loss of strength increases exponentially with age. Sarcopenia is believed to play a major role in the pathogenesis of frailty and functional impairment that also occurs with old age.

Age-related muscle loss can be caused by a number of issues, including inactivity, suppressed ability to synthesize new proteins and reduced skeletal-muscle-fiber size and quantity.

The Mayo Medical School researchers qualified the intensity, duration and frequency of aerobic training to cause skeletal muscle enlargement, which “most likely depends on obtaining sufficient exercise intensity (70–80 % heart-rate reserve, or HRR), duration (30–45 minutes) and frequency (four or five days per week) to achieve a large number of muscle contractions that place a high volume/low load on skeletal muscle compared with traditional hypertrophic [enlargement] resistance exercise programs,” such as weight training.

HRR, noted by the researches relative to exercise intensity, is the difference between your maximum heart rate and your resting heart rate, which is used for exercise-heart-rate determination with the Karvonen formula, which takes a specific percentage of an individual’s training intensity and then adds back the resting heart rate.

A Possible Counter to Sarcopenia

In one study conducted more than 20 years ago, old and young men spent six months walking and running. They performed this exercise five times per week, with the exercise intensity and duration increasing progressively in two-week segments. The last two months consisted of exercise at 85% of their HRR for 45 minutes.

The findings suggested that old men (68-plus years) “could elicit a 9% increase in thigh cross-sectional area.” The research also showed that while old men saw an increase in skeletal muscle mass, young men did not. This could possibly be due to the duration and consistency of exercise, as the older men performed aerobic activity for longer periods of time.

In a study evaluating resistance training versus aerobic exercise, men and women, young and old, performed knee-extension exercises for 12 weeks to determine whether or not the two forms of exercise could comparably increase quadriceps muscle size. The resulting numbers indicated that “the gains in skeletal muscle volume after resistance exercise training are similar to 12 weeks of aerobic exercise training.

“Therefore, from investigations implementing 12 weeks of either resistance or aerobic exercise training, both modes of exercise have elicited a similar increase in quadriceps muscle volume, suggesting that both modes of exercise are equally effective at stimulating hypertrophy in the muscles used for 12 weeks.”

The concluding research determined that “multiple investigations demonstrate alterations in skeletal muscle molecular regulation and protein metabolism that are conducive for increased myofiber and whole muscle size after aerobic exercise training in sedentary individuals.”

In addition, it has been suggested that “aerobic exercise training should be acknowledged to increase skeletal muscle mass and be considered an effective countermeasure for muscle loss with advancing age.”

Get the Best of Both Worlds

While this meta-analysis offers much promise for all of us as we age, in the long run, I do not believe that aerobic training of a low-intensity/steady-state nature will come close to providing the benefits of full-body resistance training (e.g., weights, bands, isometrics) to preserve lean muscle mass in conjunction with adequate protein intake as we age gracefully.

So, do yourself a favor and start early. Don’t wait to exercise until you’re older and at higher risk for sarcopenia. In fact, why not just do both—resistance training and aerobic exercise—and hedge your bets? As always, seek medical advice whenever starting a new exercise program to determine whether or not you are healthy enough for additional stress-related activity.

One of the top trainers in the world, Mackie Shilstone has worked with such sports superstars as Roy Jones Jr., Serena Williams and Bernard Hopkins. You can learn more about Mackie by visiting his website at

Link:  America’s Trainer | Muscle & Body Magazine.