Muscular Strength Predicts Phase Angle in Breast Cancer Survivors

Abstract Phase angle (PhA) has emerged as a prognostic indicator of survival and quality of life (QOL) in cancer patients. Identifying measures of physical fitness that correlate with PhA can provide guidance towards optimizing cancer rehabilitation programs.PURPOSE: To examine the relationship between PhA and physical fitness in breast cancer survivors. METHODS: Sixty-three breast cancer survivors (60 ± 9 years, PhA 4.59±0.52, mean±SD) completed assessments for muscular strength, muscular endurance, cardiorespiratory endurance, flexibility, and body composition. PhA and body composition were measured using bioimpedance analysis (Inbody 770) at 50 KHz. The correlations between phase angle and measures of fitness were evaluated using Pearson coefficients. Simple and multiple linear regression was used to test if measures of muscular strength, muscular endurance, and cardiorespiratory endurance significantly predict PhA.RESULTS: Linear regression analysis showed that incline bench press 1-RM alone explains 28% (r2 = 0.28) of the variance in PhA. Multiple linear regression showed that incline bench press 1-RM, chair squat test repetitions, and predicted VO2peak explain 32% (r2 =0.32) of the variance in PhA. Incline bench press-1RM remained a significant predictor of PhA after adjusting for age (p=0.0001), while muscular endurance and cardiorespiratory endurance did not.CONCLUSION: Muscular strength is suggested to be a significant predictor of PhA in breast cancer survivors, while muscular endurance and cardiorespiratory endurance are not.IMPLICATIONS FOR CANCER SURVIVORS: The prioritization of muscular strength for improving PhA in exercise based cancer rehabilitation programs may be of importance.