AUTHOR=Bjørke Ann Christin Helgesen , Buffart Laurien M. , Raastad Truls , Demmelmaier Ingrid , Stenling Andreas , Nordin Karin , Berntsen Sveinung 

TITLE=Exploring Moderators of the Effect of High vs. Low-to-Moderate Intensity Exercise on Cardiorespiratory Fitness During Breast Cancer Treatment – Analyses of a Subsample From the Phys-Can RCT

JOURNAL=Frontiers in Sports and Active Living

VOLUME=Volume 4 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/sports-and-active-living/articles/10.3389/fspor.2022.902124

DOI=10.3389/fspor.2022.902124

ISSN=2624-9367

ABSTRACT=Introduction
Results from the physical training and cancer randomized controlled trial (Phys-Can RCT), indicate that high intensity (HI) strength and endurance training during (neo-)adjuvant cancer treatment is more beneficial for cardiorespiratory fitness (CRF, measured as peak oxygen uptake [VO2peak]), than low-to-moderate intensity (LMI) exercise. Adherence to the exercise intervention and demographic or clinical characteristics of patients with breast cancer undergoing adjuvant treatment may moderate the exercise intervention-effect on VO2peak. In the present study, the objective was to investigate whether baseline values of VO2peak, body mass index (BMI), time spent in moderate- to vigorous-intensity physical activity (MVPA) and physical fatigue, age, chemotherapy treatment and the adherence to the endurance training moderated the effect of HI versus LMI exercise on VO2peak.
Materials and methods
We used data collected from a subsample from the Phys-Can RCT; women who were diagnosed with breast cancer and had a valid baseline and post-intervention VO2peak test were included (n = 255). The exercise interventions from the RCT included strength -and endurance training at either LMI or at HI, with similar exercise volume in the two groups. Linear regression analyses were used to investigate moderating effects using a significance level of p<0.10. Statistically significant interactions were examined further using the Johnson-Neyman (J-N) technique and regions of significance (for continuous variables) or box plots with adjusted means of post-intervention VO2peak (for binary variables).    
Results
Age, as a continuous variable, and adherence, dichotomized into < or > 58% based on median, moderated the effect of HI versus LMI on CRF (B = -0.08, 95% CI [-0.16, 0.01], pinteraction = 0.06, and B = 1.63, 95% CI [-0.12, 3.38], pinteraction = 0.07, respectively). The J-N technique and regions of significance indicated that the intervention effect (HI versus LMI) was positive and statistically significant in participants aged 61 years or older. Baseline measure of CRF, MVPA, BMI, physical fatigue, and chemotherapy treatment, did not significantly moderate the intervention effect on CRF.
Conclusion
Women with breast cancer who are older and who have higher adherence to the exercise regimen may have larger effects of HI exercise during (neo-)adjuvant cancer treatment on CRF.