EXERCISE & PAIN
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EXERCISE & PAIN

Laurance Johnston, Ph.D.

A good workout can make many of us feel pretty good. Not only does it stimulate the release of feel-good molecules called endorphins, assuaging life’s trials and tribulations, but it promotes physical health in so many different ways, especially for individuals with spinal cord injury (SCI).

Foremost, it helps to maintain a healthy weight with a better fat-muscle ratio. Given post-injury muscle atrophy, this is an important issue. Our body-fat composition greatly influences our physiology and the development of disorders such as diabetes common in individuals with SCI. For diabetics, good old-fashion weightlifting is especially effective in pulling excessive sugar out of the blood where it is not needed into muscle tissue where it can fuel activity.

In addition, exercise profoundly influences the nervous system itself. For example, it stimulates the production of regeneration-stimulating nerve-growth factors and the differentiation of neuronal stem cells into mature nerve cells, replacing ones lost by injury and the entropy of aging, nurturing those that have survived. Due in part to these nervous-system influences, aggressive exercise programs have been shown to enhance functional recovery, even long after injury.

Finally, the focus of this update, studies suggest exercise can lessen SCI-associated pain, including not only the shoulder pain common to wheelchair living but also the more insidious neuropathic pain resulting from nervous-tissue damage. A summary of key studies are included below:

Studies

In 1999, Dr. Kathleen Curtis et al (California) examined the impact of a six-month, home-based, stretching and strengthening program on shoulder pain in 42 wheelchair users (35 with SCI). After study completion, subjects reported a 40% reduction in pain compared with 2% for controls.

In 2003, Dr Audrey Hicks and colleagues (Ontario) evaluated the influence of a nine-month exercise program on a variety of factors, including pain, in 34 individuals with SCI. Subjects were randomized either into a group participating in a twice weekly exercise program that involved both arm ergometry (i.e., cranking) and resistance training (i.e., weightlifting), or a control group offering bimonthly education session on topics like exercise physiology, osteoporosis, and relaxation techniques. Upon study completion, exercisers reported a modest reduction in pain while controls reported an increase.

In 2006, Dr. Deborah Nawoczenki and colleagues (New York) evaluated the benefits of an eight-week strengthening and stretching exercise program on existing shoulder pain in 21 manual wheelchair users with mostly SCI. Shoulder pain was significantly reduced after completion of the program.

In 2007, Dr. Mark Nash et al (Florida) examined the effects of circuit-resistance training on muscle strength, endurance, and shoulder pain in seven men with paraplegia.  The program consisted of training three times weekly for 16 weeks with resistance and endurance (arm-cranking) training. Shoulder pain decreased substantially by the end of the study.

In 2011, Dr. Sara Mulroy’s team (California) evaluated the effectiveness of an exercise intervention on shoulder pain in 80 manual wheelchair users with SCI. Subjects were randomized to either a 12-week home-based program of shoulder strengthening and stretching exercises together with strategies on how to optimize transfers, raises, and wheelchair propulsion; or a control group, which saw an instructional video reviewing shoulder anatomy, mechanisms of injury, and concepts in managing shoulder pain. As with the other studies, pain decreased substantially in the exercisers after finishing the program, a decline that persisted four weeks later. No change was noted in controls.

In 2012, Dr. Cecilia Norbrink and associates (Sweden) measured the benefits of an exercise program on both musculoskeletal and neuropathic pain in eight subjects with SCI. Subjects exercised with a double-poling ergometer adapted for persons with lower extremity impairments three times a week for 10 weeks. For the subjects with neuropathic pain, average pain decreased 40%. For those with musculoskeletal pain, pain virtually dissipated; all but one had no musculoskeletal pain at the end of the study; and the number of days per week with pain declined from an average of 5.5 to 0.7 days.

It is not especially surprising that exercise has the potential to reduce musculoskeletal pain through, for example, the strengthening and balancing of key muscles. However, because neuropathic pain is physiologically a totally different ballgame, the results are quite significant. The investigators noted that the impact of the exercise program on neuropathic pain is comparable to many of the drugs studied for treating neuropathic pain.

Conclusion

There are no magic bullets when it comes to SCI pain. Commonly prescribed pain-killing drugs often have only marginal long-term effectiveness and are laden with adverse side effects, but, nevertheless, seem relatively innocuous compared to some of the nerve-destroying surgeries that have been used in the past. Exercise is also no magic bullet, but studies suggest it, indeed, helps and without significant side effects. For individuals with SCI, perhaps the workout maxim “no pain, no gain” is less apropos than “you gain no pain” by exercising.   

Adapted from article appearing in April 2013 Paraplegia News (For subscriptions, call 602-224-0500) or go to www.pn-magazine.com

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