Why am I Getting So Weak? Muscle Wasting in RA
I was getting ready for bed the other night and had my shirt off. My wife grabbed my upper arm and with a joking voice said I needed to lift some weights. Oh the nerve! But she was right. I was just noticing the same thing not only a few minutes prior. Sure, recent elbow surgery kept me from using my right arm for some time now. And degeneration of cervical vertebrae resulting in nerve damage and surgery added to the mix. But there is clearly much more going on - this pattern of muscle wasting is evident all over my body with a noticeable reduction in muscle mass and strength especially in my legs. Since being diagnosed with RA, I’ve seen a steady decrease of muscle strength coupled with an increase in periodic pain and aching in muscle tissue. I thought that the aching could be caused by either overuse (comparatively speaking) or by biomechanical processes since the muscles are attached to RA-damaged joints via tendons. I can feel myself getting weaker as time goes on. During a follow-up visit about one of my ankle surgeries a few years back, the orthopedic surgeon noted in my chart that my calf muscles were getting atrophied. I no longer have the strength to open jars, dig a hole, take long walks, exercise, stand for more than a few minutes, or even maintain extended use of a muscle on a given task. Oh how I long for the days when I was 25, jogged 20-30 miles a week, and ran a landscaping business in the summer during my summer off from teaching high school. I was fit and had plenty of energy and muscles.
Impact of RA on joints & muscles
Since RA can impact joints, and joints are connected to muscles via soft tissue, it stands to reason that the destructive processes of the disease can impact muscles. In 1993, Young produced a model demonstrating the connection between joint damage and muscles.1 Muscles haven’t been a primary research topic but there have been a few studies over the years. As far back as 1951, researchers found that inflammation of arteries in muscle tissue was observed in RA patients (Sokoloff, et. al, 1951).2] According to a study by Ekdahl and Broman (1992), muscle strength in RA patients can be reduced by up to 75% of normal and have significantly reduced muscle function.3
In a study of 350 RA patients in Spain, weakness, muscle atrophy, and muscle inflammation were commonly observed in those suffering from RA (Miro, et al, 1996).4 A detailed research study by Helliwell and Jackson published in 1994 documented RA’s impact on muscle tissue. They concluded,
“Although there is significant muscle wasting in RA, it is likely that reduction in strength is also attributable to joint deformity and pain leading to inhibition of grip directly and, indirectly, by arthrogenous muscle inhibition. Doubts remain about the quality of muscle in RA”.5
Arthrogenous refers to “starting from a joint”.6
In addition to biomechanical problems, it is entirely plausible that biochemical processes involved with RA may negatively impact muscle tissue. According to one researcher, RA-related cytokines including tumor necrosis factor (TNF) that are the target of common RA biological treatments, are involved with breaking down the protein in muscles (Roubenoff, 2006).7 This breakdown of muscle mass, called cachexia, is accelerated in RA patients. According to Rall, et al (1996),
“Adults with RA have increased whole-body protein breakdown, which correlates with growth hormone, glucagon, and TNFα production. And although progressive resistance training led to improved strength and functional status in patients with RA and in controls, we saw no changes in protein metabolism or hormone levels as a result of the training intervention among any of the groups of subjects.”8
In other words, muscle breakdown continued even if the RA patient exercised. This mirrors a study by a group from Finland who noted that exercise helped RA patients’ muscle strength but not bone density (Hakkinen, et al., 2004).9
There are potentially serious consequences to RA induced muscle loss. Summers, et al. 2008 argued that RA muscle loss is under recognized by doctors. They also demonstrated that RA patients who show muscle wasting have a shorter life span.10
Can muscle wasting be reversed?
My suspicions about the biochemical impact and connectedness of RA impacted joints to decreasing muscle mass were both confirmed in the research literature. The question then remains as to what may be done to stop or reverse the impact of RA on muscles? Some argue that RA patients should engage in regular exercise in order to maintain muscle tone (see Mayo Clinic). In a 2003 review of research studies by Stenström and Minor (2003) on the impact of exercise on RA patients, it was found that most studies demonstrated that exercise positively impacted muscle strength without negatively impacting pain or daily activities.11 These results are interesting to me personally because every time I try to engage in exercise or strenuous activity, I feel worse and daily activities are limited. My physical therapist suggested trying swimming for low impact exercise. Always check with your doctor before starting an exercise program.
The evidence is clear – rheumatoid arthritis does impact muscle tissue. But more research is needed to identify the specific causes and to develop long-term solutions. Of course, a bona fide cure for RA might do the trick. Fortunately, there are still researchers seeking answers as attested to by the fact that funding is being provided to study muscles in RA patients (see recent grant award in the UK).
Quiz: Which is NOT a common risk factor for osteoporosis?