Dynapenic Obesity: Strength, Body Composition, And Physical Function In Women Diagnosed With Breast Cancer

Abstract

BACKGROUND: Breast cancer survivors (BCS) report more limitations performing activities requiring strength compared to women without a cancer history. Combined with obesity, BCS with dynapenia (poor muscle strength) may have greater risk of physical function (PF) difficulties; however, the prevalence and impact of dynapenic obesity (DO) in BCS remains unknown. PURPOSE: This study aimed to: 1) prospectively determine the prevalence of DO; 2) evaluate associations among DO, clinical factors, and resistance training (RT); and 3) determine if DO predicts PF in BCS from diagnosis to 2-year follow-up. METHODS: DO was operationalized as waist circumference (WC) ≥88 cm and poor grip strength, measured via dynamometry and categorized using ACSM normative values. RT participation was determined via interview and categorized as meeting/not meeting RT guidelines for cancer survivors. PF was self-reported as level of difficulty with tasks including standing in place, walking 2 blocks, and lifting objects. Assessments were conducted at diagnosis and repeated at 1- and 2-years post-surgery during scheduled oncology visits. Data were analyzed using descriptive statistics and linear regression. RESULTS: BCS (N=396, Mage=57.1±11.6 years, MBMI=29.2±6.2 kg/m2) had a mean WC of 96.2±17.6 cm and combined grip strength of 50.0±11.5 kg. The prevalence of DO was 18.3% at diagnosis, 28.2% at 1-year, and 34.5% at 2-year follow-up. DO was not associated with clinical factors (e.g., diagnosis stage, receipt of chemotherapy) at diagnosis. A weak, positive association between DO and age was observed at baseline (p=.009). Meeting RT guidelines at diagnosis was inversely associated with DO at baseline (p=.008) and 1-year (p=.05). Controlling for age and RT participation, DO at diagnosis significantly predicted PF difficulty at 1-year (β=.26, p=.007) and significantly predicted PF difficulty at 2-year follow-up (β=.15, p=.09). CONCLUSIONS: A significant proportion of BCS had high central adiposity and poor muscle strength from diagnosis to 1- and 2-year follow-up. DO significantly predicted PF difficulty after surgery, indicating the importance of strength and body composition prior to treatment. RT may be protective against DO; therefore, greater efforts to increase RT engagement in BCS are critically needed.