Upper Extremity Strength Imbalance after Mastectomy and the Effect of Resistance Training

The purpose of this non-randomized pre/post comparison trial was to explore the effect of resistance training (RT) on upper extremity strength imbalance in breast cancer survivors. Seventeen right-side dominant female breast cancer survivors (age: 58.2±2.7 years; BMI: 27.8±1.1 kg/m (2) ) with right-sided (RSM) or left-sided (LSM) mastectomy completed strength testing (30-second arm curl) before and after an 8-week RT program. At baseline, LSM (n=8) had equal strength bilaterally (right=16.8±1.1 repetitions; left=16.4±1.4 repetitions), whereas RSM (n=9) had impaired strength on the right (16.7±1.3 repetitions) compared to the left (18.6±1.1 repetitions) side ( p <0.01). After RT, RSM increased strength by 25% on the right (initially weaker) side and 19% on the left (initially stronger) side, which resolved the imbalance. By comparison LSM increased 19% on both sides that were initially equal in strength. Based on our findings, breast cancer survivors with dominant-side mastectomy are at risk for upper extremity strength imbalance that can be resolved with a relatively short-term RT program.