The Effect of Strength Training During Chemotherapy in Women With Breast Cancer on Serum Cytokine Concentrations and Skeletal Muscle Autophagy-Related Proteins.

To evaluate whether strength training during chemotherapy alters (1) serum cytokines and (2) skeletal muscle autophagy- and heat-shock-related proteins in women with breast cancer. Exploratory analyses assessed associations between changes in physiological outcomes (muscle strength, cardiorespiratory fitness, and capillary density) and biomarker responses, and among cytokine changes. Women with breast cancer were randomized to strength training (n = 23) or usual care (n = 17). The training group completed supervised strength training twice weekly during chemotherapy; usual care maintained habitual physical activity. Assessments were performed pre-chemotherapy (T0) and post-chemotherapy/intervention (T1). Serum cytokines (IFN-γ, IL-1RA, IL-6, IL-8, IL-10, IL-17, MCP-1, TNF-α) were quantified, and muscle biopsies were analyzed for autophagy- and heat-shock-related proteins. In the strength training group, mean ± SD IL-6 increased from 1.21 ± 0.47 to 1.69 ± 0.71 pg/mL and IL-17 from 1.24 ± 0.25 to 2.18 ± 0.87 pg/mL. IFN-γ also increased in the training group (14.4 ± 8.6 to 28.8 ± 17.3 pg/mL), however, the group×time interaction was not statistically significant. In the usual care group, IL-6 and IL-17 decreased. No changes were observed in other cytokines or in autophagy- or heat-shock-related proteins. Exploratory analyses showed no associations between changes in strength and autophagy proteins, cardiorespiratory fitness and cytokines, or capillary density and cytokines. Strength training during chemotherapy did not alter selected skeletal muscle autophagy- or heat-shock-related proteins, despite group differences in IL-6 and IL-17 over time. The clinical and mechanistic significance of these cytokine shifts remains uncertain and should be evaluated in larger studies with additional time points and complementary immune and muscle outcomes.