Since Dr. Kenneth Cooper published his first Aerobics book in 1968, there has been a major emphasis on physical fitness in the United States. We have experienced the running revolution of the 1970s, the aerobic dance movement of the 1980s, and the strength training interest of the 1990s. Today, most people are aware that exercise is good for their health, and is in fact 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 (1989), 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 five percent of the general public who do strength training.
Strength Training Misconceptions
Some of those who avoid strength exercise do so because they have heard that it may increase their blood pressure. Fortunately, this is not true. Although every adult should have physician approval before starting a strength program, research reveals that properly-performed strength exercise is similar to aerobic activity in terms of blood pressure response (Westcott 1983, 1985, 1987). That is, systolic pressure increases about 35 to 50 percent during exercise and returns quickly to resting levels after the activity session. More important, studies show that several weeks of strength training result in significant reductions in resting blood pressure (Holly and Harris 1987; Westcott, 1995a). For example, 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 3 mm Hg decrease in diastolic blood pressure (Westcott 1996). Sensible strength training, alone or in combination with endurance exercise, has beneficial effects on resting blood pressure.
Another reason many adults avoid strength exercise is the fear of increasing their bodyweight. 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 utilization during each training session. Second, it increases calorie use for several hours following exercise due to the afterburn effect (Melly 1993). Third, it increases calorie utilization all day long by adding new muscle tissue. This is because every pound of new muscle uses about 35 calories each day just for tissue maintenance (Campbell 1994).
A study of 1,132 adults revealed excellent body composition improvements after two months of strength and endurance exercise (Westcott 1996). As shown in Table 1, the men gained 3.7 pounds of muscle and lost 6.4 pounds of fat, and the women gained 1.7 pounds of muscle and lost 3.4 pounds of fat. Strength training, alone or in combination with endurance exercise, has beneficial effects on body composition.
Table 1. Changes in body weight and body composition for male and female program participants(N=1132).
|Age||Body Weight Pre (lbs.)||Body Weight Post (lbs.)||Body Weight Change (lbs.)||Percent Fat|
|Percent Fat Change (%)||Lean Weight Pre (lbs.)||Lean Weight Post (lbs.)||Lean Weight Change (lbs.)||Fat Weight Pre (lbs.)||Fat Weight Post (lbs.)||Fat Weight Change (lbs.)|
* Statistically significant change(p<.01)
Of course, there are a variety of health-related reasons to do strength exercise. These include increased bone density (Menkes 1993), improved glucose metabolism (Hurley, 1994), faster gastrointestinal transit (Koffler, 1992), better blood lipid levels (Stone 1992), reduced low back pain (Risch 1993), and less arthritic discomfort (Tufts 1994).
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.
Recommended Strength Training Program
The excellent results attained by the 1,132 research program participants (Westcott 1996) 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 (1990), is as follows:
Training Frequency: Two or Three Days Per Week
The standard strength training recommendation of three nonconsecutive days per week is sound, and should be followed whenever possible. However, in a large training study (Westcott 1996), the 416 subjects who did two strength workouts a week achieved almost 90 percent as much strength and muscle gain as the 716 subjects who did three strength workouts a week. For people who have difficulty getting to the gym three times a week, it is good to know that two strength workouts per week produces nearly as much training benefit.
Training Sets: One Set Per Exercise
One study (Westcott 1995a) found one-set and three-set training to be equally effective for increasing upper body strength, and another study (Starkey 1994) found one-set and three-set training to be equally effective for increasing 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.
Training Resistance: 75 Percent of Maximum
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.
Training Repetitions: 8 to 12 Reps Per Set
Research (Westcott 1993) indicates that most people can complete 8 to 12 controlled repetitions with 75 percent of their maximum resistance. Generally speaking, if you cannot perform at least 8 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 8 to 12 repetition range is recommended for safe and effective muscle development.
Training Progression: 12 by 5 Rule
Every strength training program needs a protocol for progressing to heavier weightloads. While it is important to periodically increase the exercise resistance, 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 complete 12 repetitions of an exercise in good form, you increase the resistance by 5 percent or less. The 12 by 5 procedure provides small but frequent training increments to progressively stress the muscular system.
Training Speed: Six-Second Repetitions
Unfortunately, there is little consensus on the best training speed for strength development. However, research indicates that slow movement speeds may be preferred over fast movement speeds, because they produce less momentum and more muscle tension. At 6 seconds each, 8 to 12 repetitions requires about 50-70 seconds of continuous muscle effort, which provides an excellent anaerobic stimulus for muscle building. We have obtained consistently good results training with 6-second repetitions, taking 2 seconds for the harder lifting movement and 4 seconds for the easier lowering movement (Westcott 1995b).
Training Range: Full Movement Range
Research (Jones 1988) indicates that 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.
Perhaps the most important aspect of a well-designed strength training program is to address all of the major muscle groups. A comprehensive training approach produces overall strength development and reduces the risk of muscle imbalance injuries. The recommended exercises and target muscle groups are:
Leg Extension Machine
Leg Curl Machine
Leg Press Machine
Quadriceps, Hamstrings, Gluteals
Double Chest Machine
Super Pullover Machine
Lateral Raise Machine
Biceps Curl Machine
Triceps Extension Machine
Low Back Machine
Four-Way Neck Machine
Neck Flexors and Extensors
It is advisable to perform one exercise for each major muscle group in order from larger to smaller muscles.
Basic and Brief Strength Exercise
During the past five years we have made careful pre and post training assessments on 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 in length, 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 men and women 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 the 749 women lost 3.4 pounds of fat weight and gained 1.7 pounds of lean (muscle) 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 decreased their average resting blood pressure by 3.1 mm Hg.
Another research finding is that the younger (ages 21-40), middle (ages 41-60), and older (ages 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 (highest percent 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.
Wayne L. Westcott, Ph.D., is fitness research director at the South Shore YMCA in Quincy, MA. and author of the new Nautilus book, Building Strength and Stamina.
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