ABSTRACT
Exercise guidelines for cancer survivors issued by multiple international organizations (Campbell KL et al, 2019) updated the recommendations that aerobic, combined aerobic plus resistance training, and/or resistance training could improve common cancer-related health outcomes (eg, anxiety, depression, fatigue, physical function, and health-related quality of life). Despite these guidelines, the majority of cancer survivors are not regularly physically active. A lack of awareness regarding available effective program to help facilitate exercise in cancer survivors was suggested to be a one of barriers to clinicians referring them to exercise. Furthermore, given that the COVID-19 pandemic has made getting sufficient exercise difficult, there is an urgent need for developing a home-based exercise program and its effectiveness among cancer survivors. Systematic review revealed that high-intensity interval training (HIIT) is a time-efficient method for increasing cardiovascular function in breast cancer survivors (Tsuji K et al, 2021), while all previous HIIT studies were lab-based supervised intervention. Recently, we originally developed 12-week home-based smartphone-supported HIIT program (habit-B program) and examined its effect on cardiorespiratory fitness among breast cancer survivors in Japan. Our single-blind single-center randomized controlled trial involved 50 sedentary women with stage I-IIa breast cancer. The results showed that home-based HIIT intervention can lead to improve cardiorespiratory fitness and muscle strength (Ochi E et al, 2021). Based on the pilot study, we are proceeding a multi-center RCT in stage I-III breast cancer survivors. Mobile health such as habit-B might become a solution, but we need more collaboration and care coordination with appropriate professionals as well as change in the behaviors of clinicians, cancer survivors, and those who deliver the rehabilitation and exercise program.
ABSTRACT
Background: A strategy for maintaining and/or improving cardiorespiratory fitness (CRF) in the growing population of cancer survivors is of major clinical importance in the COVID-19 era. With the aim of increasing CRF, recent studies have focused on the use of high-intensity interval training (HIIT) in supervised experimental settings, which appeared to be more beneficial than usual care in cancer survivors at all stages of treatment and aftercare. However, the effect of unsupervised HIIT on increasing CRF in breast cancer survivors is not known. Purpose: To determine whether the newly developed habit-B program, which involves home-based smartphone-supported HIIT using body-weight exercises, improves CRF in early-stage breast cancer survivors. We hypothesized that the habit-B program would improve VO2peak compared with a control group. Methods: This single-center, 12-week, parallel-group, single-blind, randomized controlled trial involved 50 women with stage I-IIa breast cancer, aged 20 to 59 years, who had completed initial treatment except for hormone therapy. Participants wore a smartwatch and were randomized to either the exercise or control group from May 27, 2019 through November 30, 2020. The planned sample size was 60 Spatients to detect the increase of 2.0 ml/kg/min change in VO2peak with a standard deviation of 2.6 ml/kg/min, one-sided significance level of 2.5% and 80% power. The exercise group underwent home-based HIIT using a smartphone and a Fitbit Versa thrice weekly for 12 weeks (three times per week). The primary outcome was the 12-week change in peak oxygen uptake (VO2peak;mL/kg/min) between the groups. Other outcomes included muscle strength, 6-min walk test, resting heart rate, physical activity, fatigue, safety, and quality of life. Results: Of the 50 participants, 44 (exercise group, n=23;control group, n=21) completed the CRF assessment and 6 did not because of issues related to the COVID-19 pandemic. The change in VO2peak increased significantly in the exercise group (0.9 [95%CI, 0.1 to 1.7]) compared with the control group (-0.8 [95%CI,-1.5 to-0.1]) (mean difference, 1.7 [95% CI, 0.7 to 2.7], p <.01). Leg strength also increased significantly in the exercise group compared with the control group (mean difference, 13.5 [95% CI, 2.9 to 24.1], p <.01). Changes in other outcomes were not significantly different between the groups. Conclusion: A home-based HIIT intervention can lead to improved cardiorespiratory fitness and muscle strength in early-stage breast cancer survivors;however, a multicenter pragmatic clinical trial is required to confirm the benefits of the habit-B program.