Forty articles were found through database searches. After we excluded duplicate articles (N=18), non-RCT articles, articles with a lower PEDro score (≤5), and articles not written in English (N=14), a total of 8 RCT articles were included in this systematic review.
Table 1 presents the quality of included studies. The mean PEDro score of included articles was 7.5 with a range of 6-8. All studies were randomized (100%), conducted concealed allocation (100%), and had baseline comparability (100%). All studies were analyzed between-group comparisons, with reported point estimates and variability (100%). All studies didn’t carry out blind subjects and blind therapist. Blind-assessors (87.5% of included articles), adequate follow-up (75% of included articles), and an intension-to-treat analysis (87.5% of included articles) were performed.
Table 2 provides the summarized information (including author, experimental design, participants, intervention, comparison, and outcome measures) for each RCT article. The ages of the experimental subjects ranged from 34-49 years of age5,6,7,8,9,10,11, 22). Only 1 RCT article discussed and compared Pilates and usual care/health education by age distribution5). For all other articles, the experimental and control groups showed a similar age distribution. Supervised Pilates intervention was included in most of the RCT articles, and the RCT Pilates programs lasted for 1 hour each time, 1-3 times per week for 6-12 weeks. A total of 6 weeks of exercise intervention were reported in 4 RCT articles5, 7, 11, 22), and 8 weeks in 2 RCT articles6, 9). The other 2 RCT articles used a 4-week intervention10) and a 12-week intervention8), respectively. Additionally, in 4 of 8 articles, Pilates equipment such as a Reformer was reportedly used6, 10, 11, 22).
For the following reasons, outcomes were not pooled into the meta-analysis. There was apparent clinical heterogeneity in the included RCT studies as shown by the conditions that were treated, frequency and duration of intervention with Pilates and other exercises, such as home exercise and education, administration of nonsteroidal anti-inflammatory drugs, use of Pilates equipment, the performance of follow-up, and evaluations of outcome measures over different periods (Table 2)18). In addition, the test for heterogeneity showed that significant statistical heterogeneity for pain relief: pilates exercise against minimal intervention and therapeutic training (i2=73%, p=0.001). Significant statistical heterogeneity was also observed when comparing improvements in functional ability with Pilates exercise versus minimal intervention and therapeutic training (i2=92%, p<0.001).
Among the included articles, 5 compared the effect of Pilates and minimal intervention (such as routine care and health education) on patients with CLBP (Table 3). After 4-12 weeks of Pilates or minimal intervention, all studies showed significant statistical differences for effects on pain relief5, 8,9,10, 23). However, only 2 of these 5 showed that the pain relief reached minimal clinically important differences (MCID)10, 23). Compared with no treatment, achieving MCID with treatment shows some clinical benefit. The Visual Analogue Scale (VAS) score for pain relief showing an MCID in patients with CLBP was reportedly 18 mm24); the MCID on the numeric rating scale (NRS) was 2 points18). The MCID on the Roland Morris Disability Questionnaire (RMDQ) for functional capacity in patients with CLBP was 2 points8, 25). In 3 of the 5 articles, patients indicated an improvement in functional ability with significant statistical differences after 4-12 weeks of Pilates or minimal intervention8, 10, 23), but two of them achieved MCID8, 23). After 4 and 12 weeks of Pilates, some functional abilities were maintained for up to 1210) and 24 weeks8), respectively8, 10).
Among included articles, 2 RCT studies compared the effects of Pilates and other exercise types on patients with CLBP (Table 4). In 1 of these, Pilates achieved significant statistical differences in the improvement in pain relief and functional ability after an 8-week training period, when compared with other exercise (stationary cycling), but MCID was not achieved in either study6); in the other study, the outcome measures of 6 weeks of Pilates and general exercise (including stationary bike, leg stretches, upper body weights, theraband, Swiss ball, and floor exercise) were similar11).
Among the included high-quality articles, only 1 compared the effects of mat-Pilates and equipment-based exercise on patients with nonspecific CLBP (Table 5). After 6 weeks of mat-Pilates training or 6 weeks using Pilates equipment, such as the Cadillac, Reformer, Ladder Barrel, or Step-chair, patients indicated similar improvements. However, after 24 weeks, there was greater improvement in the outcomes of functional ability and kinesiophobia in patients in equipment-based Pilates groups than in patients in the mat-Pilates group22).