Maximal Strength Training for Breast Cancer Patients Undergoing Adjuvant Treatment. Doctoral Thesis

Abstract

Objective. Breast cancer (BC) is the most frequently diagnosed type of cancer among women, with more than 2 million new cases and over 600 000 deaths annually (Bray et al., 2018), and its global incidence is steadily rising. BC patients through the cancer continuum experience complex health and psychosocial challenges. BC and anti-cancer treatment accompanied by an inactive lifestyle may further impair muscle strength and muscle force development characteristics. Historically, patients diagnosed with cancer were advises to rest and avoid vigorous activity following their diagnosis, but this dogma has changed markedly over the last 20 years as exercise oncology intervention studies have gained broad acceptance and acknowledgment. Strength training can optimally affect muscles and increased muscle strength may contribute to participation in daily activities, thus potentially improving the health-related quality of life (HRQoL). However, the optimal type, intensity and frequency of strength training, as a part of cancer care, that will most enhance muscle strength during anti-cancer treatment is yet unknown. Christensen et al. (Christensen et al., 2014) investigated newly confirmed (breast, gastric, colorectal, lung and pancreas) cancer patients and concluded that these patients had 0.9 kg lower muscle mass compared with healthy controls even before the initiation of anti-cancer treatment. Furthermore, during adjuvant chemotherapy, BC patients lost 1.3 kg lean body mass (LBM), and continued to lose LBM after therapy was completed. Ultimately, BC survivors evaluated after completion of primary therapy displayed 20–30% lower muscle strength compared with healthy counterparts. Most physical activity interventions for BC patients combine aerobic endurance training with strength training and diverse relaxation therapies, hence making it more complicated to evaluate the impact of training type. There has been a limited number of well-defined clinical trials on BC patients th