Aging and Muscle Loss: Use It, Don’t Lose It!
Muscle loss is an expected and usual part of the aging process; however, it is something that can be reduced or prevented with the proper amount and type of exercise. The most dominant cause of muscle loss associated with aging is inactivity. The main reason for this is that muscle nerves and their related fibers depend on each other. In someone who is inactive, there is an interruption in this muscle and nerve connection, and therefore the muscle fibres begin to shrink (Harris & Kravitz, 2014.)
The results of inactivity extend to diminished function in the remaining neurons. However, exercise has the opposite effect, as muscle contractions trigger the release of muscle growth factors, promoting protein synthesis and growth in muscles. Both cardiovascular and resistance exercises are important in preventing the muscle/nerve loss associated with both aging and inactivity. This includes both moderate- and high-intensity exercise.
What level of exercise is appropriate for preventing muscle loss? Well, according to Harris & Kravitz, you can begin with 2.5 hours of moderate cardiovascular exercise, eventually increasing to up to 5 hours per week. For vigorous cardiovascular exercise, begin with 75 minutes per week, increasing to 2.5 hours for greater benefit. Muscle strengthening activities should be of moderate or high intensity, and include all muscle groups, at least twice per week.
Although myths circulate that it is difficult to increase muscle size with increased age, in fact, with proper resistance training and sufficient protein intake it is common for older adults to gain muscle. It is important to note that what you eat or do not eat will also affect muscle wastage. As we age, we often lose our appetites or sense of hunger, thereby decreasing our food intake by approximately 25% (Sayer et al., 2013.) This results in inadequate protein and micronutrient intake. Older adults with low vitamin D intake also are more likely to experience sarcopenia (muscle loss.) Sayer et al. suggest that seniors should supplement their diets with 700-1000 IU of Vitamin D per day in order to reduce the effects of muscle loss and related falls.
Harris, E. and Kravitz, L. What is sarcopenia, and can we turn back the clock? IDEA Fitness Journal; February, 2014.
Sayer, A.A., et al. 2013. New horizons in the pathogenesis, diagnosis and management of sarcopenia. Age and Ageing, 42 (2), 145–50.