Persistent pain is among the most common adverse effects to breast cancer and its treatments. It affects 25-60% of patients and can linger for several years as a source of considerable physical and psychological distress. Among other things, pain after breast cancer is a primary source of upper limb dysfunction and has been associated with greater levels of depression. These and other persistent pain-related issues collectively reduce the quality of life and perceived physical function of the patient, which is associated with increased breast cancer-related mortality. Unfortunately, there is currently a lack of knowledge on optimal management of persistent pain after breast cancer treatment. Consequently, the development of new and effective treatment strategies is of major clinical importance.
In our study conducted at Aalborg University, published in the February 2023 issue of Medicine & Science in Sports & Exercise®, we performed a randomized controlled trial to investigate the effect of a 12-week supervised resistance training program using free weights on persistent pain after treatment for breast cancer. We randomly allocated 20 survivors of breast cancer with self-reported pain into either a control group or an experimental group. The time frame for this study was six months (three-month intervention and three-month follow up). We assessed muscular strength, pain intensity during everyday life and mechanical pain sensitivity at baseline, three and six months. Participants allocated to the experimental group trained twice a week, in groups of two to four individuals, supervised by a certified strength and conditioning coach. They performed five multi-joint free weight exercises in sequential order, each for 2-4 sets separated by 3-5 minutes of rest. The number of repetitions decreased from 10-12 down to 2-4 over the course of the 12 weeks, while load started at 60% of 1RM and increased according to the individual training response.
The most important observations in this study were that our 12-week supervised resistance training program resulted in a 48% increase in 1RM, along with a 35% decrease in pain sensitivity. In addition, half the participants reported a decrease in everyday pain intensity of 20% or more. We found the gains in maximum strength largely remained following three months of detraining; however, the positive effects on pain had disappeared. Most notably, this suggests that resistance training can provide a clinically relevant improvement in persistent pain after breast cancer treatment. However, these benefits also appear to require consistent exposure and emphasize that resistance training for pain management is most likely a long-term commitment.
In short, resistance training is a valuable tool in the arsenal of clinical professionals to combat persistent pain after breast cancer. As previously highlighted by the American College of Sports Medicine, it is a safe and well tolerated exercise modality for this population, with an ever-growing base of evidence for its potential. For all these reasons, investigators at Aalborg University and elsewhere will continue to pursue this work in other clinical populations.
Gorm Henrik Fogh Rasmussen, PhD, is originally trained as a sports scientist with emphasis on biomechanics and neuroscience at Aalborg University, Denmark. His research area focuses on the clinical application of resistance exercise for managing adverse effects of cancer and its treatments, with a special emphasis on resistance training and pain. Dr. Rasmussen utilizes both qualitative and quantitative research methods in his work and completed his Ph.D. with supervision from Professor Pascal Madeleine (Dr. Scient, Ph.D.) and Associate Professor Mathias Kristiansen (Ph.D.).
