Long-Term Side Effects of Breast Cancer on Force Production Parameters.

ABSTRACT: Bertoli, J, de Souza Bezerra, E, Dias Reis, A, Amice da Costa Barros, E, Gobbo, LA, and Forte Freitas Júnior, I. Long-term side effects of breast cancer on force production parameters. J Strength Cond Res 36(5): 1450-1458, 2022-Breast cancer treatments have long-term side effects, which are associated with muscle strength reduction, negatively affecting the quality of life and increasing the chances of a sedentary life style. The aim of this study was to analyze the effects of types of surgery and hormone therapy on muscle strength parameters in breast cancer survivors compared to women without cancer (control). Eighty-three women, 42 breast cancer survivors and 41 control women, volunteered to participate in this study. Subjects performed maximal isometric voluntary contractions, so that force parameters of the right and left shoulder abductor, trunk extensor, and preferred knee extensor-flexor muscles could be evaluated. Overall, breast cancer survivors presented a lower absolute and normalized maximal force (Fmax) for all muscle groups compared with control. The right shoulder abductor muscles of breast cancer survivors presented a significantly lower absolute and normalized rapid force index (RFI) than control. When compared according to hormone therapy treatment, in breast cancer survivors undergoing aromatase inhibitor, all strength parameters except for normalized RFI demonstrated lower values for the right and left shoulder abductors, trunk, and knee extensors compared with control and tamoxifen. When separated by surgery type, breast cancer survivors who underwent quadrantectomy and radical mastectomy presented lower values for some strength parameters for the left and right shoulder abductors, except for trunk extensor muscles, in which quadrantectomy and total mastectomy presented lower strength parameters. It is recommended that breast cancer survivors should be encouraged to perform supervised strength training programs for different muscle groups to improve Fmax and RFI, aiming to reduce muscle weakness and pain, and improve functional capacity and quality of life.

Effect of exercise training and detraining in autonomic modulation and cardiorespiratory fitness in breast cancer survivors.

BACKGROUND: Breast cancer is one of the leading causes of death worldwide. Heart rate variability (HRV) has attracted scientific community attention in different pathologies, becoming thus an ultimate importance tool in both clinical and research setting, being a good predictor of cardiac events and mortality risk and also used in physical exercise and sports in general. The aim of the present study was to evaluate 12 weeks of exercise training and six weeks of detraining in cardiorespiratory capacity, and autonomic modulation in breast cancer patients. METHODS: The sample was composed of 18 females (9 controls and 9 exercised), (aged 30-60 years). The HRV in the time and frequency domain was performed using an electrocardiogram before, after 12 weeks of the session of exercise training and after six weeks of detraining. Shapiro-Wilk and Mann-Whitney tests were made. RESULTS: No significant changes in time domain were found. In the frequency domain, 12 weeks of exercise training promote a decrease in LF (nu) and decrease in HF (nu) Index. The exercise training period promoted a decrease in LF/HF. The autonomic data returned to baseline levels after the detraining period. However, cardiorespiratory capacity remained increased after the detraining period. CONCLUSIONS: These data demonstrated that exercise training can be used to prevent autonomic dysfunction in breast cancer patients, but detraining promotes loss of all autonomic benefits.