We recently analyzed body composition data on more than 1,100 men and women who completed our eight-week Keeping Fit program during the past five years. The 716 subjects who strength trained three days per week gained 2.5 pounds of lean weight and lost 4.6 pounds of fat weight. The 416 subjects who strength trained two days per week gained 2.2 pounds of lean weight and lost 4.0 pounds of fat weight. On a comparative basis, the twice-a-week trainees added about 85 percent as much lean weight and lost about 85 percent as much fat weight as the three-times-a-week trainees. As illustrated in Figure 2, two strength sessions a week is almost as productive as three strength sessions a week with respect to body composition changes.

The Facts
Research (Westcott 1995) indicates that there is a direct relationship between the exercise effort and the recovery period required for optimum muscle development. That is, a harder exercise session produces more muscle microtrauma and requires more recovery time for the tissue-building processes to be completed. It is also clear that more advanced strength trainees need longer recovery and building periods than less advanced strength trainees, due to their greater exercise effort.

Our studies, conducted with previously untrained individuals, suggest that two or three strength workouts per week represent effective training protocols for increasing muscle strength and muscle mass. The rate of improvement for the two-a-day-a-week trainees was about 70 to 85 percent that of the three-day-a-week trainees, with less difference among middle-aged participants than among college students. These findings are consistent with those from the University of Florida (Braith et al. 1989). These researchers reported that two workouts a week produced about 75 percent as much strength development as three workouts a week.

In my opinion, beginning strength exercisers should be encouraged to perform three training sessions per week. However, those individuals who are unable to schedule three training days should be informed that two exercise sessions per week product excellent results. Although the rate of improvement may be slightly slower, the eventual training outcome should be similar. For persons who choose twice-a-week training, it is recommended that they space the exercise sessions as equally as possible, such as with a Monday-and -Thursday workout schedule.

Whether you exercise two or three days per week, you should achieve high levels of muscular fitness by applying the Nautilus strength-training principles. Perform one set of eight to 12 repetitions for each major muscle group. Train with a slow movement speed through a full movement range to the point of muscle fatigue. Whenever you can complete 12 repetitions with proper form, increase the exercise resistance by about 5 percent and continue your progress.

Table 1: Effects of two versus three exercise sessions per week on muscle strength and muscle mass.