Most older individuals are well aware that they need regular aerobic exercise, such as walking, swimming, or running, to strengthen their heart and lungs and tone their bodies, but many dismiss weight training (also called resistance training) as an activity predominantly for the young or the vain. However, it is the only type of exercise that can substantially slow, and even reverse, the declines in muscle mass, bone density, and strength that were once considered inevitable consequences of aging. Unlike aerobic, or endurance, activities, which improve cardiovascular fitness and require moving large muscle groups hundreds of times against gravity, weights provide so much resistance that muscles gain strength from only a few movements. Resistance is usually provided by free weights or machines, but individuals can also get stronger by exercising in water.
People shouldn't experience pain while lifting weights, but it's normal to feel some soreness the next day. Experts believe that as muscles are challenged by the resistance of a weight, some of their tissue breaks down; as the muscles heal, they gradually increase in strength and size. Although muscles should be worked until they are fatigued, common sense will dictate when it's time to stop. If you feel joint or nerve pain, or are putting a tremendous amount of strain on any part of the body, you're probably going overboard and can harm yourself. Because strains, sprains, and tissue damage can take weeks or even months to heal, preventing injury should be a priority. Although many older people who are inactive but want to get moving may think that a pair of walking shoes is a wiser investment than a set of weights, the opposite may actually be true, say fitness experts. People who have been sedentary for long periods are at high risk for falls because their muscle tone is weak, flexibility is often limited, and balance may be precarious. To reduce the risk of falls and injury, people over 60 who haven't recently been active should begin by strengthening their legs, arms, and trunk muscles with 3-4 weeks of weight training 2-3 times a week before walking long distances or engaging in other aerobic exercise.
Because aerobic activity and strength training are each important for health, the ACSM recommends that able adults do both on a regular basis; 20 to 60 minutes of aerobic activity is advised 3 to 5 days a week and weight training should be done for 20 to 30 minutes 2 to 3 times a week. The guidelines also suggest that people perform stretching exercises -- which increase the range of motion, or amount of movement, of joints -- a minimum of 2 to 3 times a week.
In general, as people grow older, their muscle fibers shrink in number and in size (atrophy) and become less sensitive to messages from the central nervous system. This contributes to a decrease in strength, balance, and coordination. Although there is no question that people experience at least some of these declines at about age 40, the extent to which they occur depends on a number of factors, including genetics, diet, smoking and alcohol use, and -- most important -- physical activity level. Indeed, recent research has indicated that inactivity is responsible for the majority of age associated muscle loss. Fortunately, resistance exercise can reverse much of this decline by increasing the size of shrunken muscle fibers.
It is also well known that weight training can increase bone mass, which lowers the risk of developing osteoporosis and fractures. Strength training adds more weight to the skeleton by building muscle; this stimulates the bones to strengthen and grow to bear the heavier load on the muscles. Once achieved, much of the gain can be maintained through weight-bearing endurance activities such as brisk walking, stair climbing, and aerobics. Resistance exercise can also help older people live independently by giving them the strength they need to perform everyday tasks. There is even evidence that resistance exercise can help people sleep better and can improve the mood of mildly to moderately depressed individuals. And because proper strength training doesn't apply stress directly to joints, it is ideal for people with arthritis; indeed, rheumatologists often recommend it. Although it cannot reverse arthritic changes, lifting weights helps alleviate symptoms by strengthening the muscles, tendons, and ligaments that surround joints.