Do people with musculoskeletal pain differ from healthy cohorts in terms of global measures of strength? A systematic review and meta-analysis.

The review found limited multi-joint strength data, and only four studies were eligible for meta-analysis. No included study had a healthy control group measured at baseline, so the meta-analysis used an online database of active community members. The active control database was self-filled and did not include medical records, so pain-free status could not be confirmed. Strength testing varied by exercise, load, repetition maximum and unit, and most studies used weight machines rather than free weights. Three of the four fibromyalgia studies used outdated diagnostic criteria, which may have included people with other nociceptive musculoskeletal pain. Pain interference during strength testing was reported in only one study, so it is unclear how pain affected the measured lifts. Study quality was mixed, with five poor PEDro scores, three fair, eleven good and one excellent. Ten studies included mixed gender groups without accounting for gender differences in strength. Sixteen included studies had funding or grants, and some did not clearly report conflicts of interest.

The review authors received no financial support. Among included studies, 16 had funding or grants, 12 reported no conflict of interest, and the remaining studies did not clearly state conflicts.

Do not conclude that all people with musculoskeletal pain have lower global strength. The review only pooled four fibromyalgia studies, and the differences were small. For knee osteoarthritis, chronic low back pain and rheumatoid arthritis, there were no baseline healthy control comparisons, so no strength difference can be claimed.