Exercise-induced hypoalgesic effects of different types of physical exercise in individuals with neck pain: A systematic review and meta-analysis

OBJECTIVE

To evaluate the exercise-induced hypoalgesic (EIH) effects of different types of physical exercise in individuals with neck pain.

DESIGN

Systematic review with meta-analysis.

LITERATURE SEARCH

An electronic search of six databases was completed to include studies assessing EIH effects on neck pain.

STUDY SELECTION CRITERIA

Randomized controlled trials, controlled trials, and observational studies that assessed before and immediate after-effects of a single session of physical exercise in people with neck pain were included. Two reviewers independently screened records, extracted outcomes, assessed the risk of bias, and rated the quality of evidence using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach.

DATA SYNTHESIS

EIH is characterized by increased pain threshold, pain tolerance, and/or decreased sensitivity to painful stimuli or unpleasantness, which may last up to 30 min after a single bout of exercise. EIH is usually measured with quantitative sensory testing (QST) and is mostly taken as the difference between pre- and postexercise pressure pain threshold (PPT). Data were pooled and analyzed using a fixed-effect meta-analysis.

RESULTS

Eleven articles were included in this review; nine with low risk of bias and two with some concerns about the risk of bias. Three studies with chronic whiplash-associated disorders (WAD) were included in the meta-analysis; isometric exercise had a larger EIH effect at the local testing site compared with submaximal aerobic exercises (MD = -0.21, [95% CI = -0.43, 0.00], p = 0.05, I²  = 92%), submaximal aerobic and isometric exercises had equal EIH effects at the remote testing site (MD = 0.01, [95% CI = -0.33, 0.35], p = 0.95, I²  = 0%), and submaximal aerobic exercises exerted comparably larger EIH effect at the remote testing site than local testing site (MD = -0.01, [95% CI = -0.20, 0.18], p = 0.93, I²  = 56%). The certainty of evidence (GRADE) for these analyses was low to very low. According to the descriptive analysis of the studies of chronic nonspecific neck pain, isometric and range of motion (ROM) exercises have shown EIH effects. Active stretching exercises have illustrated contradictory effects.

CONCLUSION

Isometric and ROM exercises exerted hypoalgesia at local and remote sites. A larger EIH effect following submaximal aerobic exercises was exerted at the remote testing site compared with the local site.