Limited clinical research has demonstrated that massage may provide safe and effective pain relief for persons with osteoarthritis (OA), a slowly progressive disease of the joints that afflicts roughly 27 million Americans. But, questions remain about the optimal frequency and length of massage sessions to produce best results. A recently reported study found that a 60-minute massage once per week may be most beneficial; however, some aspects of this trial were disappointing and cast doubt over the outcomes.
A team of researchers supported by the U.S. National Center for Complementary and Alternative Medicine (NCCAM) conducted a randomized controlled trial of massage therapy among 125 adults with OA of the knee [Perlman et al. 2012]. Participants were randomly assigned to either “Usual Care” (control) or one of 4 massage regimens, receiving treatments for either 30 or 60 minutes and once-weekly or twice-weekly for 4 weeks, and then all subjects received once-weekly treatments (either 30 or 60 minutes as before) for another 4 weeks. During the course of the study, each experimental group participant received a total of either 240, 360, 480, or 720 minutes of massage therapy.
A standardized protocol of Swedish massage was administered by licensed massage therapists at two clinical sites. Each protocol specified the standard strokes to be used and time allotted to various body regions during either a 30- or 60-minute regimen. All body regions were addressed, but special attention was focused on symptoms of knee OA. [While relaxation was no doubt a benefit of the approach, the protocol appeared to be structured for therapeutic effects and should not be confused with what most people think of as “spa massage.”]
The primary outcome measure was improvement from baseline on the Western Ontario and McMaster Universities Arthritis Index (WOMAC), which assesses dimensions of pain, functionality, joint stiffness, and global improvement using 24 questions. Secondary outcomes included pain measured on a 0-to-100 point visual analog scale (VAS), range of motion, and time to walk 50 feet. All assessments were performed at baseline, 8-, 16-, and 24-weeks.
In all, 119 participants completed the full 8 weeks of therapy, with 22 to 24 subjects in each of the 5 groups. Subjects were predominantly female, white, >63 years of age on average, marginally obese (mean BMI=31), and had moderate pain at baseline (mean VAS range 58-66).
Results at the primary endpoint of 8-weeks indicated that WOMAC global scores improved significantly (mean 24.0 points; 95% CI, 15–33) in the 60-minute massage groups as compared with Usual Care (mean 6.0; 95% CI, 0.1–13). WOMAC subscales of pain and functionality, as well as the VAS scores, also demonstrated significant improvements in the 60-minute groups compared with Usual Care. There were no statistically significant differences across groups in secondary measures of range of motion or 50-foot walk at 8-weeks. Furthermore, by 24 weeks (16 weeks after the end of therapy) no statistically significant differences (indicated by overlapping confidence intervals) were found in any outcome measure compared with Usual Care; although, there were some clinical improvements with moderate effect sizes, albeit not statisticlly significant, maintained over time in the 60-minute groups.
A dose-response curve based on WOMAC global scores demonstrated that benefits increased with greater total massage time over the 8 weeks of active therapy, but with a plateau at the 60-minute/week dose. In other words, 60-minute massages were better than 30 minutes; however, adding a second 60-minute massage each week was not of any advantage. Based on their findings, the authors concluded that the 60-minute, once weekly protocol seems to provide optimal effects, along with greatest economy and convenience for patients.
COMMENTARY: As we noted in an UPDATE last fall [here], consumers have a growing awareness of the health benefits of massage; in fact, 90% of individuals perceive massage as effective in reducing pain. At least one decent-quality study [reported here] demonstrated that massage therapy may be better than medication or exercise for easing discomfort and improving function in lower back pain. However, the type of massage that is best, the duration of therapy, and who might benefit most need further elaboration.
Outcomes of this present study by Perlman et al.  suggest that a 1-hour weekly massage may be most beneficial for knee OA; more or less massage time each week may not be of as much benefit. However, massage, by its nature, must be individualized to patient needs and the exact approach is difficult to define. Furthermore, the authors did not specify the number of massage therapists participating in their trial or if there might have been differences in effectiveness between them.
Probably, such an analysis would not have been fruitful anyway, since this study with fewer than 25 subjects per group completing the 8 weeks of active therapy was statistically underpowered. The authors concede that, “A sample size of 125 individuals in five arms was based on budgetary and logistical constraints.” It seems disappointing that a federal agency, NCCAM in this case, would not invest sufficient funding to pursue a study of adequate size to produce more definitive and reliable results. This size deficiency casts doubt on the outcomes in at least several ways…
- As is usually the case with small group sizes, there were large variances in the outcome data, as indicated by wide confidence intervals; so, it cannot be assumed that the outcomes are accurate and true estimates of what might be found in a larger population of patients with knee OA.
- If groups had been larger, more significant benefits of shorter, 30-minute, massages might have emerged. At the same time, however, beneficial effect sizes for all groups might have diminished — but there is no way of knowing this for certain.
- Although the magnitude of effects was strongest after 8 weeks, there were some persisting beneficial effects at 24 weeks; however, these did not achieve statistical significance, which might only have been due to inadequate groups sizes for distinguishing such effects.
Additionally, as the authors note, the “truly optimal dose” might differ from the 4 studied; however, they believe that the frequency and duration of massage sessions that were assessed conform well to those currently in use and advocated by massage therapists. However, the trial was limited to Swedish massage, which precludes generalizability to other techniques.
Of some interest, a concise scientific rationale for the therapeutic effects of massage in relieving pain has never been fully elucidated, and Perlman et al. discuss some of the possibilities:
“Increased blood circulation to the muscles promoting gas exchange and delivery of nutrients and removal of waste products has long been thought to be one of the outcomes and benefits of massage, and recent studies support this effect. There is some evidence for the promotion of a relaxation response and shift to parasympathetic nervous system activation, with reduced heart rate, blood pressure, biochemical (including blood and salivary stress hormones, endorphins, and serotonin) and brain activation changes, associated with reduced anxiety. This may be mediated through the activation of mechanoreceptors in the deep tissues innervated by alpha beta fibers with subsequent central nervous system (CNS) effects on the pituitary gland and limbic system and/or other mechanisms.”
“The need for moderate pressure to achieve many of the effects of massage therapy may support this mechanism, deserves further investigation, and supports light touch as an appropriate active control for future trials. A recent study comparing a single session of Swedish massage to light touch showed significant neuroendocrine and immune system changes over time, with differing patterns and degree in the massage and control intervention. Other potential outcomes and mechanisms of massage therapy's effectiveness include decreasing muscle strain, balancing muscle tension across the joint, positive mechanical changes in muscles, increased joint flexibility and proprioception, increased lymphatic circulation, immunologic and inflammatory changes, improved sleep, and blocking pain signals.”
A better understanding of massage mechanisms of action, in diverse clinical models of pain, would be helpful for optimizing application of this modality. For example, Perlman and colleagues theorize, “if massage enhances regional blood flow, it might be that a follow-up massage too soon (ie, within one week) actually attenuates benefit by applying pressure to slightly engorged tissue. Thus, there might be an optimal periodicity to massage, with suboptimal effects seen with dosing outside this purported ideal.”
Furthermore, if there are changes in neuroendocrine and inflammatory status, or pain generation and sensitivity, or musculature strain or balance fostered by massage, these also might reach an optimal state that persists for some time and are not enhanced by further massage within a specific time period. So, clearly, there is much more research needed for maximizing the benefits of therapeutic massage for pain management — and, hopefully, it will be better funded to yield higher quality research evidence.
REFERENCE: Perlman AI, Ali A, Njike VY, Hom D, Davidi A, et al. Massage Therapy for Osteoarthritis of the Knee: A Randomized Dose-Finding Trial. PLoS ONE. 2012;7(2):e30248 [free article available here].