Effects of Resistance versus High-Intensity Interval Training on Myokines and Cancer Cell Suppression in Breast Cancer Survivors: A Randomized Trial.

[PURPOSE] Reducing recurrence and mortality is crucial for breast cancer survivors. We investigated the effects of a 12-wk resistance training (RT) versus high-intensity interval training (HIIT) program on myokines, cytokines secreted by skeletal muscle cells at rest in response to muscle contraction, and cancer cell inhibition.

[METHODS] Twenty-eight survivors of breast cancer (age = 55.5 ± 8.8 yr, body mass index = 27.9 ± 5.1 kg·m -2 , time since diagnosis = 31 ± 12.3 months) were randomly allocated to a 12-wk supervised moderate to high-intensity RT ( n = 14) or HIIT ( n = 14) program 3 d·wk -1 . Resting blood was collected before and after exercise program (at least 48 h before the first and after the last exercise session) to measure serum levels of myokines (decorin, interleukin 6 [IL-6], secreted protein acidic and rich in cysteine [SPARC], and oncostatin M [OSM]) and triple negative MDA-MB-231 cell growth in vitro , using real-time cellular analysis to determine growth rate.

[RESULTS] Exercise attendance was 85% for RT and 81% for HIIT. Serum levels of SPARC for RT and OSM for HIIT significantly ( P < 0.05) increased (11% to 15%) after 12 wk, with no significant differences between groups. MDA-MB-231 cell growth was significantly ( P < 0.05) reduced for both RT and HIIT by 22% and 25%, respectively, with no significant difference between groups. Reductions in MDA-MB-231 cell growth in HIIT were associated with improvements in lean and fat mass.

[CONCLUSIONS] A program of RT or HIIT can increase levels of myokines (an effect considered beneficial given their potential cancer-suppressive effects) and inhibit growth of MDA-MB-231 cells in survivors of breast cancer. In addition, the development of the antitumor environment may be mediated by exercise-related changes in muscle strength and body composition.