Study two In 1996, another study analyzed five years of data from the South Shore YMCA's, Quincy, Mass., fitness classes (1,132 subjects, average age 51 years). During that time, 716 subjects met on Mondays, Wednesdays and Fridays to complete an eight-week program of strength and endurance exercise, and 416 participants performed the same training program on Tuesdays and Thursdays. The primary objective of this study was to determine the effects of twice-a-week and three-times-a-week strength-training sessions on the participants' body composition. The findings revealed that the three-day-per-week exercisers gained 2.5 pounds of lean muscle weight, and lost 4.6 pounds of fat weight. The two-day-per-week exercisers gained 2.2 pounds of lean muscle weight, and lost 4 pounds of fat weight. Surprisingly, the men and women who trained just twice a week experienced 88 percent as much muscle gain and 87 percent as much fat loss as those who trained three times per week (see Table 2). As in the first study, twice-a-week training proved to be a highly productive exercise protocol, even though in this study the Tuesday/Thursday participants performed only two-thirds as much work as the Monday/Wednesday/Friday subjects. The Tuesday/Thursday training program produced significant improvements in both lean and fat weight for these previously sedentary subjects. Because twice-a-week training is more time-efficient than traditional Monday/Wednesday/ Friday exercise programs, it is an excellent alternative for time-pressured individuals who have difficulty fitting strength training into their busy schedules. Other studies have demonstrated similar results, leading to the American College of Sports Medicine's recommendation to perform strength training two or three non-consecutive days per week.1,3

Study three

Although twice-a-week strength training may be acceptable for most people, a recent survey indicated that many adults may be limited to only one exercise day per week.6 For this reason, another study was conducted to compare the effects of one, two and three brief strength workouts a week on strength development.

The subjects in this study were 218 previously sedentary adults and seniors, average age 50 years, who enrolled in a 10-week beginning exercise program. During each training session, the participants performed about 25 minutes of strength training with 12 resistance machines, and about 25 minutes of endurance exercise (treadmill walking or stationary cycling). One hundred and three subjects trained on Mondays, Wednesdays and Fridays, 86 subjects trained on Tuesdays and Thursdays, and 29 subjects trained only on Saturdays. With respect to strength development, the three-day-per-week exercisers increased 21.2 pounds, the two-day-per-week trainees increased 15.5 pounds, and the one-day-per-week participants increased 15.5 pounds (see Table 3). All three training frequencies produced significant strength gains. Although they performed only two-thirds as much weekly exercise, the two-day trainees achieved 73 percent as much strength improvement as the three-day trainees. Even more impressive, the one-day trainees also attained 73 percent as much strength development as the three-day trainees, even though they performed only one-third as much weekly exercise.

The results of this study with adult and senior subjects were similar to the first study with college students. In both studies, the one-day and two-day trainees made almost identical strength gains, and these were about 73 percent as high as those attained by the three-day trainees.

While three strength-training sessions a week may be most productive for beginning participants, the findings from this study suggest that one or two relatively brief bouts of strength exercise may be sufficient for stimulating significant strength gains in previously sedentary adults and seniors. This is particularly impressive because the research subjects performed only one set of 12 resistance exercises, totaling about 25 minutes of strength training each session.

Because better results were attained with three weekly workouts, this is the recommended strength-training frequency for new exercisers. But individuals who cannot commit to a traditional Monday/Wednesday/Friday exercise schedule should do well with two evenly-spaced strength workouts per week. For time-pressured people who have difficulty fitting in two weekly workouts, a single strength-training session every seven days seems to be an effective alternative. However, once-a-week trainees must make every effort to avoid missing their workouts, as it is unlikely that an every-other-week exercise session will produce progressive strength development.

Study four

Recent research has demonstrated that impressive physical benefits can be attained from relatively brief and infrequent strength-training sessions. For example, several studies have shown similar strength gains from single-set and multiple-set training protocols.3 The following study, conducted with young athletes concurrently participating in sports activities, supports the training-frequency findings of the first three studies.

This two-part study was conducted with young female figure skaters, who were concurrently spending several hours a week practicing and competing in their sport. Due to school and a heavy on-ice training schedule, the girls were limited to one or two strength-training sessions per week. The younger girls performed one set of 10 strength exercises on child-sized machines, and the older girls performed one set of 10 strength exercises on standard resistance machines.

Sixteen girls, with an average age of 10 years, completed the first study, training one or two days per week under the supervision of a personal trainer. As shown in Table 4, these skaters made significant improvements in muscle strength (31 lbs. to 43 lbs.) and vertical jump height (10.2 in. to 11.5 in.). Ten girls, with an average age of 11 years, completed the second study, training only one day a week under the supervision of a personal trainer. As presented in Table 5, these skaters attained significant improvements in muscle strength (35 lbs. to 50 lbs.) and standing long jump distance (4.53 ft. to 4.85 ft.).

The findings from these studies indicate that training just one or two days per week is sufficient stimulus for significant strength development. Unlike the first study, however, these results were obtained with relatively brief and low-volume workouts (one set of 10 exercises every seven days). Consequently, there appears to be little risk of overtraining associated with this strength-training protocol. In fact, for in-season athletes, performing more than one or two strength workouts a week may lead to overtraining.

In addition to improving muscle strength and physical performance, the young athletes learned how to properly perform strength exercises during their weekly workouts. After 10 Saturdays of supervised strength training, the girls were fully functional in the exercise facility and capable of training independently. There have been no injuries in any of the training-frequency studies, indicating that one or two strength workouts a week offers a safe and efficient approach to muscle conditioning. Therefore, personal trainers who give clients the option of one- or two-day-per-week strength-training programs can provide practical and productive alternatives to the traditional Monday/Wednesday/Friday exercise schedule.

Summary

Based on the findings from these four studies, strength training only one or two days a week is a safe and effective means for attaining significant improvements in muscle strength and body composition. Because strength gains in beginning participants have a large motor learning component, increases in muscle strength may be more dependent on training frequency than are improvements in body composition. There is evidence that for many time-pressured people, less-frequent strength workouts may make the difference between training with good results or not training at all. For these reasons, personal trainers should consider presenting potential clients with scheduling options with different exercise frequencies.

The studies' research findings are summarized as follows:

Study 1: College-age subjects who strength trained once and twice a week had similar strength improvements (24.7 lbs. vs. 22.8 lbs.), which represented about 73 percent as much strength development as the subjects who trained three days per week (32.7 lbs.).

Study 2: Adult and senior subjects who strength trained two days a week experienced 88 percent as much muscle gain (2.2 lbs. vs. 2.5 lbs.) and 87 percent as much fat loss (4.0 lbs. vs. 4.6 lbs.) as subjects who strength trained three days a week.

Study 3: Adult and senior subjects who strength trained once and twice a week had equal strength improvements (15.5 lbs.), which represented about 73 percent as much strength development as the subjects who trained three days per week (21.2 lbs.).

Study 4: Young female figure skaters who strength trained one or two days a week made significant improvements in muscle strength (41 percent) and jumping performance (11 percent).

REFERENCES

1. American College of Sports Medicine. The recommended quantity and quality of exercise for developing and maintaining cardiorespiratory and muscular fitness in healthy adults. Medicine and Science in Sport and Exercise 22: 265-274, 1990.

2. Braith, R., J. Graves, M. Pollock, S. Leggett, D. Carpenter and A. Colvin. Comparison of two versus three days per week of variable resistance training during 10 and 18 week programs. International Journal of Sports Medicine 10: 450-454, 1989.

3. Feigenbaum, M., and M. Pollock. Prescription of resistance training for health and disease. Medicine and Science in Sport and Exercise 31 (1): 38-45, 1999.

4. Westcott, W. Effects of varied frequencies of weight training on the development of strength. Master's thesis, The Pennsylvania State University, University Park, Pa., 1974.

5. Westcott, W., and J. Guy. A physical evolution: Sedentary adults see marked improvements from training as little as two days a week. IDEA Today 14 (9): 58-65, 1996.

6. Westcott, W. Wanted: Better health, supervision, and expertise. Perspective 24 (5): 40-42, 1998.

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