New Evidence on Skeletal Muscle Properties Encourages Exercise for Rheumatoid Arthritis Patients
From the ACSM Sports Medicine Bulletin
For patients with rheumatoid arthritis (RA), activities of daily living often are a struggle. They experience pain and swelling of the joints, fatigue and loss of muscle strength – all of which are characteristic for this common chronic joint disease caused by autoimmune inflammation of the joint lining. Improved clinical management of this disease has been achieved by the development of powerful disease-modifying antirheumatic drugs, which reduce progression of joint damage and deformity and enable many patients to maintain an active life in the community. But even patients with stable disease and minimal joint symptoms suffer limitations of physical function, often leading to work disability.
Recent studies have confirmed that significant muscle loss (termed rheumatoid cachexia) occurs in most patients with RA, often at an early stage of disease, and this contributes significantly to reduced strength and function. Major factors in this process include the catabolic effect of pro-inflammatory cytokines such as TNF and down regulation of factors anabolic for muscle, such as insulin-like growth factor I. We and others have demonstrated that intense exercise training can restore muscle mass and physical function without exacerbating disease activity. Thus, encouragement to exercise has increasingly become part of routine rheumatology care, and a growing number of patients – especially those with milder, well-controlled disease – attend public gyms.
Our recent research into the physiological and biomechanical properties of muscle in RA, published in the Dec. 2010 issue of Medicine & Science in Sports & Exercise, has shown that skeletal muscle parameters of patients with stable disease display similar characteristics to those of healthy people. Using methods that are routinely applied in exercise science, such as ultrasound and EMG, we demonstrated that though skeletal muscle mass tends to be reduced in patients with RA, muscle contractile properties, voluntary activation capacity, concentric force and power are not compromised. As a consequence, the force produced per unit muscle (i.e. muscle quality) is preserved, even in cachectic patients. The findings are consistent with, and provide an explanation for, the normal responses to resistance training (i.e. muscle hypertrophy and increased strength) observed in RA patients. These are important results for rheumatology health professionals and sports scientists involved in designing exercise training for RA patients, as they demonstrate that patients with RA are not resistant to the anabolic effects of exercise as previously thought. Rather, rheumatoid muscle should adapt to exercise training in a similar way as healthy muscle.
This is also encouraging news to impart to the people living with RA. Patients not only experience physical barriers to exercise such as pain and fatigue, but they often fear a lack of effect of exercise or even worry about a negative effect. Knowing about muscle characteristics and the benefits of exercise can help improve their perception of exercise training and motivate them to persist with this essential part of rehabilitation in RA, which is likely to lead to meaningful improvements in physical function and mortality for patients.