Strength-training will not only make you stronger, it may also enhance bone density.
The fact that you may regularly run, walk, play tennis or ride a bike is not adequate to prevent an incremental loss of muscle mass and strength even in the muscles you’re using as well as those not adequately stressed by your usual activity. Strengthening all your skeletal muscles, not just the neglected ones, just may keep you from landing in the emergency room or nursing home after a fall.
Dr. Morley, among others, points out that adding and maintaining muscle mass also requires adequate nutrients, especially protein, the main constituent of healthy muscle tissue.
Protein needs are based on a person’s ideal body weight, so if you’re overweight or underweight, subtract or add pounds to determine how much protein you should eat each day.
Read more in the NY Times (paywall)