The older we become, the less likely we are to engage in physical activity of any kind. The numbers are staggering. In another 25 years, there will be 70 million Americans ages 65 and older. And those over age 85 are already growing faster than any other age group. But less than one-third of people over 65 perform regular exercise. By age 75, 40% have stopped doing any physical activity.
The cost of physical inactivity is enormous, not just to our health but also to our wallets. One analysis of the economic burden suggests that an average of $330 dollars per person can be saved in direct medical costs by maintaining physical activity and exercise. If the estimated 88 million Americans older than 14 years of age who are now considered inactive became regular exercisers, medical costs in the United States would decrease by as much as $76 billion.
The best physical-activity routine combines aerobic exercise three to five times a week and strength training two to three times a week. In this month's column, I will focus on strength training.
Muscle Size and Power
Aging, even in the absence of chronic illness, is associated with a loss of muscle mass and strength. Longitudinal population studies have shown that we lose an average of one-half pound of muscle mass per year starting after age 20. Just as significant is the decline in muscle power, which is good predictor of mobility and physical function in older people.
We can't completely hold back the loss of muscle size and strength, but we can markedly slow the decline no matter how old we are. Progressive resistance training (PRT), using free weights (barbells and dumbbells) or machines with adjustable tensions, increases muscle mass and power even in someone with chronic illness. Potential health benefits of PRT include better balance and steadier walking. That means fewer falls, improved mental alertness and fewer symptoms related to depression. PRT, like aerobic exercise, seems to improve immune function in some people.
Even the very old and frail benefit from resistance training, confirmed by a study published in the European Journal of Clinical Nutrition. The researchers put a group of deconditioned elders (aged 72 to 98) through a 10-week program of PRT. The exercise sessions were held three times per week; each session lasted 45 minutes. Muscle mass increased just a little, but muscle strength showed striking improvement after the 10 weeks. The participants improved their mobility scores and increased their frequency of self-motivated physical activity between sessions and after the program finished. The researchers demonstrated that PRT positively influences nerve signals to wake up previously underused muscles.
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Finding Your Strength Level
Most progressive-resistance-training programs are based upon your "one repetition max-out" weight combined with a set number of repetitions. The one repetition max-out is the maximum amount of weight that you can lift just once for each muscle exercise. Serious weight lifters go through a set of warm ups and increase the amount of weights to find the maximum weight they can lift once.
Instead, I suggest a gentler approach to find your one repetition max-out. For each muscle group that you are working, start the routine with a resistance or weight that you find easy to lift. Do 12 repetitions to warm up. Then move the resistance up one level. You should be able to perform eight repetitions with a little effort, but without straining. Note how much weight you used for the eight reps. Multiply that weight by a factor of 1.2 (this equates to a weight that is 20% higher). This is your estimated one repetition max-out. For example if you can chest press 50 pounds with eight repetitions, then your estimated one rep max-out is 60 pounds. This is probably less than you could lift if you really pushed it, but it is a safer target.
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One Example of a Strength Routine
There are many variations of successful progressive resistance-training routines. As an example, here is one that works the upper body:
- Chest press — Lying on a flat bench (you can lift feet up on the bench to prevent hyperextension of the spine), extend a barbell or dumbbells overhead, palms facing forward. Lower the weight until your elbows are parallel with your shoulders. (This primarily works the chest, but also the back of the arms and the front of the shoulders.)
- Shoulder press either with dumbbells or a barbell — This can be done standing or seated to prevent hyperextension of the spine. With an overhand grip, bring dumbbells or a barbell to shoulder level. Lift weight to a vertical position over your head. (This works all three parts of the shoulder as well as the back of the arms and upper back.)
- Triceps pushdowns — Stand facing a high pulley with a straight bar attachment. Stand with your feet hip-width apart and knees slightly bent. Take an overhand grip on the bar at shoulder-width. As you push the weight down, straightening your arms, keep your elbows close to your sides — do not let them splay out. Slowly bring the weight up until your hands are parallel with your elbows and repeat. (This works all muscles on the back of the arms.)
- Seated row — Sit facing the machine. Place your feet against the foot rests with your knees slightly bent. Grab the pulley in front of you and stretch until your back is straight. Keeping your back still, protract your shoulders as your bring the weight in front of you. This is the starting position. Begin the exercise by pulling the weight towards your torso to your lower rib cage. Keeping your arms close to the body, bring your elbows back, contracting your shoulder blades. (This works all the muscles in your back as well as the front of your arms and the back of your shoulders.)
- Biceps curls — Grab a barbell or dumbbells with an underhand grip. Extend your arms and bring your hands to slightly wider than shoulder width. Keeping your back straight and knees slightly bent, curl the weight up toward your chest and contract your biceps. Slowly extend arms to the starting position. (This works the front of the arms and the front of the shoulders.)
I recommend that you always do light aerobic exercise for about 10 minutes prior to starting a resistance-training session to warm up your muscles.
For each of the above exercises, perform a series based upon your estimated one rep max-out.
- Set the weight at 60% of your estimated one rep max-out. Do 12 reps.
- Move the weight up to 80% of your estimated one rep max-out. Do eight reps.
- Move the weight up to your max. Do only one or two reps.
- Move the weight back down to the 80% mark. Do eight more reps.
- Gently stretch that muscle group following the routine.
If you find that you can easily perform the routine in two successive sessions, you can increase your estimated one-rep max out by five to 10 pounds.
Every other day is the maximum frequency to perform resistance training. You need at least 48 hours to allow for muscle recovery.
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Howard LeWine, M.D. is chief editor of Internet publishing, Harvard Health Publications. He is a clinical instructor of medicine at Harvard Medical School and Brigham and Women's Hospital. Dr. LeWine has been a primary care internist and teacher of internal medicine since 1978.