Strength Training Adaptations in Breast Cancer Survivors Across Recovery Phases: A Longitudinal Quasi-Experimental Study

Breast cancer survival has increased substantially in recent years, leading to a growing need to address long-term physical sequelae and functional impairments. Strength training is recognized as an effective intervention for improving physical function in this population; however, the influence of recovery phase on training outcomes re-mains unclear. This study aimed to explore the longitudinal changes in handgrip strength following an 8-week supervised strength training program and to determine whether these observed variations follow an exploratory association according to the time elapsed since surgery. A quasi-experimental, longitudinal, and prospective design was conducted with 30 breast cancer survivors stratified into three recovery phases (≤6 months, 7–12 months, ≥13 months). Participants completed an 8-week supervised strength training program, and handgrip strength was assessed before and after the intervention. A linear mixed model was used to analyze the effects of time, hand condition, and recovery phase using maximum trial values. Significant improvements in handgrip strength were observed across all cohorts, with greater absolute adaptations in the late recovery phase (+3.80 kg, p < 0.001) compared to the intermediate (+2.87 kg, p < 0.001) and early (+2.25 kg, p = 0.015) phases. A persistent inter-limb strength deficit was present on the operated side. These preliminary findings suggest that resistance training induces strength modifications across all recovery strata, though absolute adaptations vary by time elapsed since surgery.