Mounting evidence supports the safety of weight lifting after breast cancer

The chronic and intractable condition of breast cancer related lymphedema is a major cause of fear among women diagnosed with breast cancer [1]. The lack of a clear incidence pattern and the lack of a prevention or cure are possibly major contributing factors. This may have caused a precautionary approach in postsurgical care, including recommendations for patients to avoid strenuous and repetitive upper limb activities as well as heavy lifting after surgery. Studies appearing around the turn of the millennium challenged this precautionary approach, and in 2010 the most prominent contribution to the evidence of safety of resistance training was offered by Schmitz and colleagues [2]. They examined the progressive introduction of resistance training to both a population at risk of incident lymphedema, and a population with manifest lymphedema at risk of exacerbation. In both populations, they found no increased risk from participating in moderate load resistance training initiated more than one year post-surgery. Although further clinical trials have supported the findings by Schmitz and colleagues, the evidence up until recently concerned populations mainly at low risk for lymphedema [3].

In the current issue of Acta Oncologica, Bloomquist and colleagues bring documentation that resistance training with heavy loads is safe in terms of lymphedema risk [4]. Participants received adjuvant taxane based chemotherapy and were physically inactive before the diagnosis with breast cancer, and thereby, according to study inclusion criteria, at least two known risk factors for lymphedema were present in the study population [5,6]. The intervention group participated in a 12-week supervised progressive resistance training intervention, whereas the control group was instructed to a walking intervention. Although lymphedema was a secondary outcome of the trial, the study has strong methodology and utilize objective outcome measurements for lymphedema detection and arm volume change. The results therefore contribute novel findings to the evidence base, with documentation that not only is progressive resistance training with heavy loads safe, but it is safe also for a population at high risk for lymphedema.

Another high-risk population was examined by our group in the recently completed LYCA study [7,8]. We tested if lymphedema could be prevented with early initiated (2 weeks post-surgery) moderate load progressive resistance training in breast cancer patients who had undergone axillary lymph node dissection and received radiotherapy to the axilla. We, too, found no difference in the incidence of lymphedema between the intervention and control groups.

With the recent trials reported, the accumulating evidence documents the safety of resistance training, both with high loads, in high-risk groups, in the early post-operative setting and during taxane based chemotherapy. This growing evidence base might bring an end to the fear and reluctance of women to engage in heavy load resistance exercises and activities, although that heavily relies on health professionals bringing updated knowledge to the patients across the continuum of care and the different health professions that patients encounter.

The rationale for bringing resistance training into breast cancer postoperative care is conceivable. Scarring and fibrosis from surgery and adjuvant treatment have direct and indirect effects on the biomechanics of the scapulothoracic and scapulohumeral joints [9]; joints that are largely dependent on muscle synergies to function optimally [10]. The impact may be reflected in the frequently reported musculoskeletal complaints in the shoulder girdle after BC surgery [11–13]. Theoretically, patients could therefore benefit from targeted and guided strengthening upper body exercises to regain full function as a component in rehabilitation. Other well-documented benefits of resistance training are improved skeletal health, weight management, improved comorbidity- and inflammatory status [14–16], and further, exercise in general is associated with favorable cancer treatment outcomes, survival and recurrence rates [17].

Despite the evidence that heavy load resistance training is safe, gaps in the knowledge about pathophysiology of lymphedema persist and a substantial number of women are affected by the condition. No conservative preventive methods have yet been found effective [18], although emerging studies offer promise of prospective surveillance for the early detection and timely management of swelling to detain it at an acceptable state [19,20]. Further encouraging, valid self-monitoring methods have been developed in order to ensure a wide public reach of surveillance at a low cost [21,22]. Nonetheless, the effect of prospective surveillance has yet to be examined in a randomized clinical trial [23].

Implications for future research include the uncovering of which patients develop lymphedema and why. This would in turn allow for targeted attention and closer surveillance in relevant individuals. Furthermore, it will enable the study of subgroup effects of interventions in women who are predisposed to lymphedema.

However, the current level of knowledge about risk factors for lymphedema offer an opportunity to use exercise, dietary and weight management interventions to target not only lymphedema, but also other vital outcomes such as comorbidity, survival and recurrence.

This opportunity calls for a more integrative clinical approach, incorporating a prospective surveillance model and updated knowledge on effects of exercise in the existing rehabilitation programs.

Disclosure statement

No potential conflict of interest was reported by the authors.