Comparing the effects of low and high load resistance exercise to failure on adaptive responses to resistance exercise in young women

The aim of this study was to compare the effect of 6 weeks of resistance training to volitional failure at low (30% 1 repetition maximum (RM)) or high (80%1RM) loads on gains in muscle size and strength in young women. Thirteen women (age: 29.7 +/- 4.7years; height 166.7 +/- 6.4cm; weight 64.2 +/- 12.2kg) completed 2 training sessions per week for 6 weeks and muscle strength (1RM), muscle thickness (ultrasound) were measured before and after training. Training comprised 1 set to volitional failure of unilateral leg extensions and bicep curls with each limb randomly assigned to train at either 80% 1RM or 30% 1RM. Increases in muscle thickness [arms: 6.81 +/- 3.15% (30% 1RM), 5.90 +/- 3.13% (80% 1RM) and legs: 9.37 +/- 5.61% (30% 1RM), 9.13 +/- 7.9% (80% 1RM)] and strength [arms: 15.4 +/- 12.2% (30% 1RM), 18.26 +/- 12.2% (80% 1RM) and legs: 25.30 +/- 18.4 (30% 1RM), 27.20 +/- 14.5 (80% 1RM)] were not different between loads. When resistance exercise is performed to volitional failure gains in muscle size and strength are independent of load in young women.