Comparison of 2 vs 3 days/week of variable resistance training during 10- and 18-week programs

The purpose of this study was to evaluate the effectiveness of resistance training performed either 2 days/week or 3 days/week. One hundred and seventeen sedentary volunteers were randomly assigned to one of the two training groups or a control group. Twenty-two men (27 +/- 5 years) and 22 women (26 +/- 5 years) trained for 10 weeks. Twenty-five men (26 +/- 5 years) and 22 women (24 +/- 5 years) trained for 18 weeks. Twenty-six subjects served as controls and did not train. Training consisted of a single set of variable resistance bilateral knee extensions performed to volitional fatigue with a weight load that allowed seven to ten repetitions. Prior to and immediately following training, isometric strength was evaluated at 70, 85, 100, 115, 130, 145, 160, and 171 degrees of knee extension with a Nautilus knee extension tensiometer. All groups who trained showed a significant increase in peak isometric strength when compared with controls (P less than 0.01). Groups that trained 3 days/week increased peak isometric strength (10 weeks = 21.2%; 18 weeks = 28.4%) to a greater extent (P less than 0.05) than groups that trained 2 days/week (10 weeks = 13.5%; 18 weeks = 20.9%). We conclude that resistance training 2 days/week significantly improves knee extension isometric strength; however, the magnitude of strength gain is greater when training is performed 3 days/week. These data indicate that the adult exerciser (18 to 38 years) training 2 days/week may derive approximately 80% of the isometric strength benefits achieved by those training 3 days/week.