Resumen de Low-Load vs. High-Load Resistance Training to Failure on One Repetition Maximum Strength and Body Composition in Untrained Women

Taylor K. Dinyer, Byrd M. Travis, Matthew J. Garver, Alex J. Rickard, William M. Miller, Steve Burns, Jody L. Clasey, Haley C. Bergstrom

• This study examined the effects of resistance training (RT) to failure at low and high loads on one repetition maximum (1RM) strength and body composition (bone- and fat-free mass [BFFM] and percent body fat [%BF]) in untrained women. Twenty-three untrained women (age: 21.2 +/- 2.2 years; height: 167.1 +/- 5.7 cm; body mass: 62.3 +/- 16.2 kg) completed a 12-week RT to failure intervention at a low (30% 1RM) (n = 11) or high (80% 1RM) (n = 12) load. On weeks 1, 5, and 12, subjects completed 1RM testing for 4 different exercises (leg extension [LE], seated military press [SMP], leg curl [LC], and lat pull down [LPD]) and a dual-energy x-ray absorptiometry scan to assess body composition. During weeks 2-4 and 6-7, the subjects completed 2 sets to failure for each exercise. During weeks 8-11, the subjects completed 3 sets to failure for each exercise. The 1RM strength increased from week 1 to week 5 (LE: 18 +/- 16%; SMP: 9 +/- 11%; LC: 12 +/- 22%; LPD: 13 +/- 9%), week 1 to week 12 (LE: 32 +/- 24%; SMP: 17 +/- 14%; LC: 23 +/- 26%; LPD: 25 +/- 13%), and week 5 to week 12 (LE: 11 +/- 9%; SMP: 7 +/- 9%; LC: 10 +/- 7%; LPD: 11 +/- 11%) in each exercise, with no significant differences between groups. There were no significant changes in BFFM (p = 0.241) or %BF (p = 0.740) for either group. Resistance training to failure at 30% 1RM and 80% 1RM resulted in similar increases in 1RM strength, but no change in BFFM or %BF. Untrained women can increase 1RM strength during RT at low and high loads, if repetitions are taken to failure.