As we age, our muscles lose mass, our metabolism rates slow, and our bodies gain fat. While this is part of the natural aging process, a lot can be done to decrease the extent and rate of these changes. With a thoughtful fitness plan, it's possible to stay healthier for longer.
About the speaker: Wayne L Westcott is the fitness research director for the South Shore YMCA.
Decades of Degenerative Processes
Year by year, a person's body might change very little, but over time the consistent degeneration adds up. Aging takes a toll on our bodies in the following ways (average rate of change):
- Muscle loss: six pounds per decade
- Metabolic rate reduction: three percent per decade
- Fat gain: 16 pounds per decade
In part due to the cumulative effect of these changes, over 27 percent of American adults over the age of 65 are obese. That figure rises to approximately 70 percent when you include seniors who are overweight. As you'll see below, the three degenerative processes influence one another and sometimes have a cumulative effect.
Muscle loss increases to ten pounds per decade after age 50. It increases risk factors for obesity, diabetes, and cardiovascular disease. Muscle protein breakdown and synthesis are largely responsible for resting energy expenditure, which is about five or six calories per day per pound of untrained muscle tissue. Trained muscle tissue may have a resting energy expenditure of more than nine calories per pound per day. This means the more muscle you have, the higher your metabolism.Metabolism
Muscle loss is the largest contributor to the age-related decline in resting metabolic rate. Strength training and fitness focused on muscle gain can help to counteract the natural loss of muscle.
Resting metabolism accounts for 65 to 75 percent of daily calorie use among sedentary men and women. Consequently, metabolic rate reduction is generally accompanied by increased fat weight. The less muscle you have, the lower your metabolism will be and the more likely you'll be to gain body fat.
Reversing Muscle Loss
Numerous studies have shown that a basic program of resistance training can increase muscle mass in adults of all ages. Resistance training stimulates increased muscle protein turnover, which has a dual impact on resting metabolic rate, namely, a chronic adaptation and an acute response.
Chronic response: a three-pound increase in trained muscle tissue may raise the resting metabolic rate by more than 25 calories per day.
Acute response: increased energy requirements for 72 hours after a standard session of resistance exercises for remodeling the stressed muscle tissue.Reducing Body Fat
Several studies have shown that approximately three pounds of muscle gain and four pounds of fat loss can result after two-to-three months of strength training. Three 25-minute circuit strength training sessions per week may increase energy use by 5,400 calories per month. After 14 weeks of resistance exercise, 89-year-old nursing home residents increased strength by 60 percent, increased muscle mass by four pounds, and improved functional independence scores by 14 percent.Resisting Type-2 Diabetes
Resistance training is recommended for the prevention and management of Type II diabetes and metabolic disorders. The ADA recommends resistance exercise of all major muscles at least three days a week at high intensity.
Resistance training is at least as effective as aerobic endurance training for reducing some major cardiovascular disease risk factors. Resistance training also improves blood lipid profiles.Bone Mineral Density
10 million American adults have osteoporosis. Twenty percent of women and 15 percent of men will experience a bone fracture due to osteoporosis. Adults who do not perform resistance exercise may experience a one-to-three percent reduction of bone mineral density every year of life.Enhancing Mental Health
Resistance training can have mental health benefits as well as physical. Benefits of resistance training for mental health in adults include:
- Reduced symptoms of fatigue, anxiety, and depression.
- Reduced pain associated with osteoarthritis, fibromyalgia, and lower back issues.
- Improved cognitive abilities.
- Increased self-esteem.
- Aerobic activity plus resistance exercise produced greater cognitive improvement than aerobic activity alone. Ten weeks of strength and endurance exercise significantly improved physical self-concept, depression, and fatigue in adults and older adults. Ten weeks of resistance exercise reversed clinical depression in 80 percent of elderly subjects.
Reversing Aging Factors
Resistance training can even affect the body on a cellular level. Six months of resistance training reversed mitochondrial gene expression in older adults compared to that of younger adults.
Muscle is an endocrine organ, producing and releasing myokines, which work in hormone-like fashion, exerting specific endocrine effects on other organs.
Resistance training is effective for:
- Increasing insulin sensitivity and glucose control.
- Reducing resting blood pressure.
- Improving blood lipid profiles, bone mineral density, and cognitive ability.
- Reversing aging factors in skeletal muscle.
Everyone can benefit from resistance training, but older adults, in particular, can minimize and even reverse the degenerative processes of aging.