Since Dr. Kenneth Cooper published his first Aerobics book in 1968, there has been a strong emphasis on physical fitness in the United States. We’ve experienced the running revolution of the 1970s, the aerobic dance movement of the ’80s, and the strength-training boom of the ’90s. Today, most people are aware that exercise is good for their health and is an effective means of preventive medicine.
It is therefore hard to understand why so few people regularly participate in an exercise program. According to the United States Public Health Service Centers for Disease Control, less than 10 percent of all Americans perform enough physical activity to attain any measurable fitness benefits. Most of those who do exercise consistently are walkers and joggers, leaving less than 5 percent of the general public who do strength training.
There are numerous reasons why people avoid strength training – almost all of them myths. Some don’t do it because they have heard that it may increase their blood pressure. Fortunately, this is not true. Although every adult should have his or her doctor’s approval before starting a strength program, research reveals that properly performed strength exercise is similar to aerobic activity in terms of blood pressure response. That is, systolic pressure increases about 35 to 50 percent during exercise and returns quickly to resting levels after the session. More important, studies show that several weeks of strength training result in significant reductions in resting blood pressure. In a study I conducted and completed this year, 785 men and women who participated in a two-month program of strength and endurance exercise experienced an average 4 mm Hg decrease in systolic blood pressure and a 3 mm Hg decrease in diastolic blood pressure. Sensible strength training, by itself or in combination with endurance exercise, has beneficial effects on resting blood pressure.
Fear of increasing body weight is another reason many adults avoid strength exercise. They mistakenly believe that weight training is synonymous with weight gain. It is true that strength training adds muscle, but this is actually the best way to lose fat. In fact, strength exercise has a threefold impact on fat reduction. First, it increases calorie use during each training session. Second, it increases calorie use for several hours following exercise due to the afterburn effect. Third, it increases calorie use all day by adding new muscle tissue. This is because every pound of new muscle uses about 35 calories each day just for tissue maintenance.
Of course, there are a variety of health-related reasons to do strength exercise. These include increased bone density, improved glucose metabolism, faster gastrointestinal transit, better blood lipid levels, reduced low back pain, and less arthritic discomfort.
Perhaps the most prevalent misunderstanding about strength training, particularly for those who would like to do it, is the time requirement. Many adults simply do not have time to do the multiple-set workouts they have been told are necessary for strength development. Fortunately, time-efficient, single-set training can be just as productive as time-consuming multiple-set training when performed properly.
Basic and Brief Strength Exercise
During the past five years we have made careful pre-and post-training assessments of the 1,132 participants in our basic exercise program. These classes meet two or three days a week, one hour per session, with 25 minutes of strength exercise (11 Nautilus machines) and 25 minutes of aerobic activity (treadmill walking or stationary cycling).
The basic exercise program is two months long, which seems to be an ideal introductory period for previously sedentary adults. Over 90 percent of the participants rate their exercise class as highly satisfying, and about 80 percent join the YMCA after completing the program. In other words, the eight-week training period is sufficient to turn many inactive women and men into regular exercisers.
One reason for the positive lifestyle change is the excellent results attained by the program participants. As shown in Table 1, the 383 men lost 6.4 pounds of fat weight and gained 3.7 pounds of lean (muscle) weight for a 10-pound improvement in body composition, and the749 women lost 3.4 pounds of fat weight and gained 1.7 pounds of lean weight for a 5-pound improvement in body composition. At the same time, the men reduced their average resting blood pressure by 4.5 mm Hg, and the women reduced their average resting blood pressure by 3.1 mm Hg.
Another finding is that the younger (ages 21-40), middle (41-60), and older (61-80) adults all attained similar improvements in body composition and resting blood pressure. Just as important, those who began the program in the poorest shape (with the highest percentage of body fat) experienced the most fat loss and lean (muscle) gain. That is, the adults who had the greatest fitness needs made the greatest improvements.
A practical reason for the success of the basic exercise program is the time-efficient training requirements. The participants did only 25 minutes of strength exercise and 25 minutes of aerobic activity each training session. Even more helpful for many time-pressured adults, only two workouts a week were necessary for excellent results. As shown in Figure 1, the two-day and three-day exercisers made similar improvements in body composition and resting blood pressure after eight weeks of training.
In addition to an effective and efficient training program, most beginning exercisers appreciate small classes and attentive instructors. We conduct all of our classes in a separate exercise area, with six members and two instructors per class. This closely supervised setting facilitates the training process and produces an 85 percent compliance rate among program participants.
We have found that most adults can make time for a well-designed exercise program that takes a sensible and systematic approach to strength training. When the proper exercise principles are applied, excellent results can be achieved in just two 25-minute strength workouts per week.
The Strength-Training Program
The excellent results attained by the 1,132 research program participants required only 25 minutes of strength exercise, two or three days per week. The recommended strength-training protocol, based on the American College of Sports Medicine guidelines, is as follows:
The standard recommendation of three nonconsecutive days per week is sound, and should be followed whenever possible. However, in a large training study I completed this year, the 416 subjects who strength-trained twice a week achieved almost 90 percent as much strength and muscle gain as the 716 subjects who did strength workouts three days a week. For people who have a hard time getting to the gym three times a week, it is good to know that two strength workouts per week produce nearly as much training benefit.
Two separate studies have found that one-set training and three-set training are equally effective for increasing upper-and lower-body strength. If training time is limited, it is good to know that single-set strength exercise is just as productive as multiple-set workouts.
The exercise resistance should be high enough to produce a high rate of strength development and low enough to pose a low risk of injury. Empirical evidence clearly indicates that using 75 percent of maximum resistance meets both of these training criteria.
Research indicates that most people can complete eight to 12 controlled repetitions with 75 percent of their maximum resistance. Generally speaking, if you cannot perform at least eight repetitions the resistance may be too heavy, and if you can complete more than 12 repetitions the resistance may be too light. Working within the eight to 12 repetition range is recommended for safe and effective muscle development.
Every strength-training program needs a protocol for progressing to heavier workloads. While it is important to increase the exercise resistance periodically, it is equally important to do so gradually. A safe and productive progression is known as the 12 by 5 rule. That is, whenever you can complete 12 repetitions of an exercise in good form, you increase the resistance by 5 percent or less. The 12 by 5 procedure adds small but frequent weightload increments to progressively stress the muscular system.
Unfortunately, there is little consensus on the best training speed for strength development. Our research indicates, however, that slow movement may be preferred over fast movement, because a slow speed produces less momentum and more muscle tension. At six seconds each, eight to 12 repetitions require about 50 to 70 seconds of continuous muscle effort, which provides an excellent anaerobic stimulus for muscle building. We have obtained consistently good results training with six-second repetitions, taking two seconds for the harder lifting movement and four seconds for the easier lowering movements.
Full-range muscle strength is best developed through full-range exercise movements. In other words, the training effect is greatest within the exercised portion of the joint movement range. Full-range strength reduces injury risk and increases performance potential. Try to perform each repetition through a full range of movement, but never to a position of discomfort.
Wayne L. Westcott, Ph.D., is fitness research director at the South Shore YMCA in Quincy, Massachusetts, and author several books on strength training, including his most recent text, Strength Training Past 50.