Resistance training can provide many benefits, including increased muscle mass; decreased adipose tissue; and improved metabolism, bone density, strength, and mobility. However, data are limited on the association between resistance training and the development or exacerbation of lymphedema, a common and potentially debilitating consequence of breast cancer treatment. In a recent study reported in JAMA Network Open, Shamsesfandabadi et al examined the association between resistance training and lymphedema among breast cancer survivors.
Study Details
The prospective cohort study enrolled 115 women aged 20 to 89 years treated for ductal carcinoma in situ or invasive breast cancer. Participants were recruited from three studies—EXERT-BC, EXERT-BCN, and EXERT-C—between September 2022 and March 2024 at the Allegheny Health Network. Eligibility required sufficient physical function to participate in supervised, group-based resistance training, while exclusion criteria included severe comorbid conditions or ongoing cytotoxic chemotherapy (except in EXERT-C).
All participants underwent a thrice-weekly, 3-month, dose-escalated resistance training program. The regimen included compound, multi-joint movements designed to induce muscle hypertrophy and strength through progressive overload. Exercises included squats, presses, deadlifts, and rows. Adherence was closely monitored, with participants required to attend at least 75% of the sessions to be considered compliant.
Lymphedema was assessed both clinically and via bioimpedance analysis (BIA) at baseline and postintervention. BIA enabled differentiation between intracellular water (ICW), extracellular water (ECW), and total body water (TBW), yielding an “edema index” (ECW/TBW ratio) used to monitor lymphedema progression. A clinical diagnosis was defined as a discrepancy in arm circumference of more than 3% compared with preoperative ipsilateral arm measurements. Additional measures included lean mass and body fat composition. Data were analyzed using the Wilcoxon signed-rank test (when normal distribution could not be assumed) or the paired t test (for variables following a normal distribution).
Key Findings
The cohort had a median age of 54 years (range = 24–71 years), and 15 women (13%) had clinical lymphedema at study enrollment. Among the participants, 83% had undergone sentinel lymph node biopsy and 12% had had axillary lymph node dissection. Of the 115 patients, 4 underwent bilateral surgery, limiting contralateral arm comparisons. Fluid assessment was reported for the remaining 111 patients.
Resistance training significantly increased lean mass in both affected and unaffected upper extremities. Lean mass in affected arms increased from a median of 5.45 lb (95% confidence interval [CI] = 5.34–5.67 lb) to 5.64 lb (95% CI = 5.40–5.84 lb, P < .001). Total body water and intracellular fluid volumes also increased, reflecting improved muscle mass. The mean edema index improved from 0.385 (95% CI = 0.384–0.386) to 0.383 (95% CI = 0.382–0.385, P < .001), indicating a reduction in lymphedema-associated fluid imbalance. No protocol-limiting injuries were reported, and no patient experienced a self-described or clinical worsening of lymphedema at the end of the study.
The authors concluded: “In this cohort study of breast cancer survivors, intense resistance training did not exacerbate lymphedema and was associated with improvements in fluid balance and lean mass in the upper extremities. These findings suggest support for the inclusion of structured resistance exercise as part of breast cancer treatment and survivorship care.”
Colin E. Champ, MD, CSCS, of the Department of Radiation Oncology, Allegheny Health Network, Pittsburgh, Pennsylvania, is the corresponding author for the JAMA Network Open article.
Disclosure: For full disclosures of all study authors, please visit jamanetwork.com.
