Due to better detection and treatment, five-year breast cancer survival rates have improved; however, more women are likely to die of cardiovascular disease (CVD) than their cancer. Physical activity (PA) is an effective method for secondary prevention for chronic diseases, with aerobic-based and resistance exercise shown to improve aspects of cardiovascular health (CV health) in breast cancer survivors. However, it is unknown whether combined aerobic and resistance exercise training (circuit resistance training) improves CV health in breast cancer survivors. Therefore, the purpose of this study was to evaluate the effects of circuit resistance (CRT) on measures of CV health in breast cancer survivors. The primary aims were to investigate whether 12 weeks of CRT improves CV health in women previously treated with chemotherapy and/or radiation therapy compared to non-exercising controls and whether CRT improvements for CV health are associated with cardiovascular fitness (CVF) and muscle strength.
Thirty eight breast cancer survivors aged 35- 70 years with no previous resistance training experience were randomly assigned to the non-exercising control group (n=18) or the CRT intervention group (n=20). The exercise group performed CRT twice a week for 12 weeks while the control group carried on with normal life. Pulse wave analysis (PWA), pulse wave velocity (PWV), body composition, upper and lower body strength, CVF, and PA levels were measured before and after the intervention in both study groups.
Between group significant differences were found for central and peripheral rate pressure product (RPP) (central RPP; intervention group 7778.6 ± 2126.3 mmHg/bpm to 7245.2 ± 1301.6 mmHg/bpm vs. control group 6908.5 ± 1265.8 mmHg/bpm to 7191.5 ± 1347.4 mmHg/bpm, p<0.05; peripheral RPP intervention group 8576.2 ± 2616.4 mmHg/bpm to 7891.7 ± 1428.8 mmHg/bpm vs. control group 7522.8 ± 1458.2 mmHg/bpm to 7818.6 ± 1526.7 mmHg/bpm, p=0.05) and peripheral mean arterial pressure (pMAP) (intervention group 92.7 ± 9.9 mmHg to 89.2 ± 8 mmHg vs. control group 90.3 ± 7.6 mmHg to 90.9 ± 9.7 mmHg, p=0.05). Between group significant differences were also found for CVF; V ̇O2max (intervention group 29.0 ± 4.2 ml.kg-1.min-1 to 33.6 ± 3.7 ml.kg-1.min-1 vs. control 28.8 ± 3.8 ml.kg-1.min-1 to 27.8 ± 2.4 ml.kg-1.min-1, p<0.01), distance walked (intervention group 582.5 ± 108.0 m to 725.5 ± 82.7 m vs. control group 539.4 ± 100.6 m to 546.7 ± 121.3 m, p<0.01), maximal speed (intervention group 4.4 ± 0.9 km to 5.5 ± 0.7 km vs. control group 4.0 ± 0.7 km to 3.9 ± 0.5 km, p<0.01), rate of perceived exertion (RPE) (intervention group 5.6 ± 1.6 to 4.4 ± 1.0 vs. control group 4.2 ± 1.5 to 4.2 ± 1.0, p<0.05) and muscle strength; one repetition maximum (1RM) bench press (intervention group 22.7 ± 6.3 kg to 27.5 ± 5.6 kg vs. control group 22.1 ± 4.6 kg to 22.6 ± 5.3 kg, p<0.01), knee extension (intervention group 69.9 ± 27.2 Nm to 85 ± 19.7 Nm vs. control group 76.4 ± 22.8 Nm to 76.8 ± 28.3 Nm, p<0.05). No between group significant differences were found for central systolic blood pressure (cSBP), peripheral systolic blood pressure (pSBP), peripheral diastolic blood pressure (pDBP), arterial stiffness measures, hand grip strength and body composition. No significant between group correlation was found between CV health and the association with CVF and muscle strength.
Twelve weeks of CRT is an effective exercise modality for improving CVF and muscle strength in breast cancer survivors. It is also effective in decreasing measures of myocardial work load and mean arterial pressure (MAP).
