Carol Ewing Garber, PhD is Clinical Exercise Physiologist and Director, Human Performance Laboratory, Memorial Hospital of Rhode Island, and Clinical Associate Professor of Medicine, Brown University School of Medicine.
Muscular strength declines with age, although there is variability in the rate of decline in various muscle groups. There is a decrement in muscle strength of approximately 30% between the ages of 20 and 70 years in both men and women, with much of the loss in strength occurring after age 45-50 years and during menopause, although estrogen replacement therapy may attenuate this loss in women.1,2 There are few data available on strength in those older than 70 years, a serious lapse in our knowledge base.1,2
Many studies have demonstrated that significant increases in muscular hypertrophy and strength result from resistance training in healthy and frail old participants.1,2,3 The relative magnitude of the strength increases in the elderly appear to be similar to younger subjects, when differences in initial strength are considered.2,3 In older adults, these increases in strength often translate into improvements in the ability to ambulate and to carry on the activities of daily living.3,4 Thus, older individuals can benefit greatly from participation in a regular program of resistance training exercise.2,3,5 The American College of Sports Medicine (ACSM) recommends strength training for all healthy adults, including elders.2,3 The American Heart Association recommends resistance training for patients with stable cardiovascular disease.6
Types of resistance training
Resistance training exercise generally involves lifting weights, all or part of one's body weight, or moving the body against some externally imposed resistance such as elastic resistance bands or a strength training machine, i.e., Nautilus machine. Resistance training involves two types of muscular contraction: isometric and isotonic contractions. Isometric, or static, exercise involves muscular contraction without shortening of the muscle or movement of the limb and usually occurs at the beginning and at the end of the range of exercise. Isotonic, or dynamic, exercise involves muscular contraction accompanied by movement of the limb. The isotonic contraction can be concentric, where the muscle shortens, or eccentric, where the muscle length lengthens, usually when moving against gravity or against heavy resistance, i.e. walking down stairs, or lowering a heavy weight. Eccentric contractions generally result in greater muscle soreness and should be minimized, particularly in the earlier phases of an exercise training program.
Current ACSM recommendations for resistance training suggest exercising at a "sufficient intensity to improve muscular strength and endurance and to maintain fat-free mass."2 Exercises for all the major muscle groups should be included and the program of exercise should be individualized and progress gradually. One set of 10-15 repetitions of each exercise two to three days per week is recommended for adults over age fifty. The amount of resistance can be determined by the amount of weight or resistance that can be lifted comfortably at least 10 times.
Stretching exercises are strongly recommended before and after performing the resistance exercises and it is helpful to warm the muscles by performing some light aerobic or calisthenic activity before engaging in the resistance exercises. Many patients will benefit from individualized instruction by an exercise physiologist as they begin a resistance training program. Many YMCA's, health clubs and other community facilities offer these services for older adults. For home exercise, common household objects can be used for resistance training. Cans of various sizes, milk jugs with varying amounts of water added, bicycle tubes, or elastic bungee cords (without metal hooks) can all become the older person's training tools. Hand, wrist and ankle weights of varying weight can be purchased inexpensively at many department stores. Older adults often do better with attachable wrist and ankle weights that allow for adjustment in the amount of weight.
How much weight?
To determine the appropriate amount of weight for each exercise, the patient should choose a weight that can be lifted comfortably 10 times. It is expected that there may be great variability in the amount of weight that an individual can lift with different muscle groups. The exercises should feel "somewhat hard" to "hard" and the patient should not strain to complete the exercises. To improve exercise adherence, it is usually best with new exercisers to begin with a less intense exercise program (lower resistance and repetitions) that will be easily tolerated. A gradual progression, generally with increases in the amount of weight or resistance every 2-4 weeks, is usually well tolerated by most patients. A good gauge for readiness for progression is when the patient can lift the weight or repeat an exercise 20 times, and the level of intensity feels "fairly easy."
Patients need to understand that they may experience some muscle soreness 24-48 hours following exercise at the beginning and when increasing a resistance training program, but that this should not be severe or incapacitating. If they do experience severe soreness, a reduction in the amount of resistance and/or repetitions on a subsequent exercise session is probably indicated. Mild fatigue is not uncommon in the early stages of exercise, but the patient should not experience inordinate fatigue. Excessive fatigue is often a symptom of over-training at an intensity or duration of exercise that is too high, or it may be a symptom of exercise intolerance in some patients, such as those with heart failure.
An exercise program should begin at a level consistent with the patient's habitual physical activity during normal daily activities and leisure activities. That is, an individual who does little physical activity in the course of his/her day generally needs to begin with low intensity exercise with fewer repetitions, while someone who is active throughout the day, including lifting and walking or moving about, can begin at a higher intensity of effort. A sample (conservative) exercise progression is shown in Table 1. For individuals who are very deconditioned, it is often reasonable to have them start with calisthenic exercises or have them perform the motions without any weight or resistance for a week or two. Then light weights or resistance can be added gradually, as tolerated. Patients who are active can start with more exercise, according to their habitual activity.
Prior to recommending exercise training, contraindications to exercise,6 co-morbidities, and/or problems with balance, vision, and cognition must be considered. To minimize falls, patients with balance problems can exercise while in a sitting position. Patients with visual impairments will need instruction in audio or large print format. Patients with cognitive issues need close supervision and frequent repetition of instructions. Older adults with chronic health problems such as coronary artery disease, COPD, or diabetes mellitus may benefit from medically supervised programs.
Physicians can do much to provide encouragement for older patients to begin a comprehensive exercise program, including resistance training. Many older patients, with few exceptions, can safely engage in resistance training and can realize substantial improvements in strength, balance, and the ability to carry out activities of daily living.
Side Note: Do It For You