Background and aim: Musculoskeletal disorders in athletes, including spinal biomechanical dysfunctions, are believed to negatively influence symmetry. Spinal manipulative therapy (SMT) is recognised as a safe and effective treatment for musculoskeletal disorders, but there is little evidence about whether it can be beneficial in symmetry. Therefore, this study aimed to measure the effects of lumbar SMT in symmetry.
Methods: Forty asymptomatic athletes participated in the study. The randomisation procedure was performed according to the following group allocation: group 1 (SMT) and group 2 (SHAM). Each participant completed a physical activity questionnaire, and also underwent clinical and physical evaluation for inclusion according to eligibility criteria. Statistical significance (P<0.05) between groups and types of therapy were calculated by physical performance tests symmetry (static position, squat and counter movement jump (CMJ), pre- and post-SMT and SHAM. There were 14 trials of three symmetry tests for each participant, for a total of 560 trials.
Results: Lumbar SMT produced immediate effects in symmetry in the static position; however, the same effects were not found in squat and CMJ on symmetry 1. Therefore, our results showed a significant difference in pre- (mean 16.3%) and post-lumbar SMT (mean 3.7%) in static symmetry. However, symmetry 2 showed no statistical significant differences for any of the tests and intervention groups. No statistically significant effects in symmetry pre- to post-SHAM were found in any of the tests.
Conclusions: Statistically significant differences were found in lumbar SMT, but only for static symmetry. These findings suggest that SMT was effective in producing immediate effects in symmetry in the static position, but none in dynamic tests. Future studies could address our study's limitations.
Clinical trials register number: NCT03361592.
Keywords: biomechanics; exercise testing; lumbar spine; randomised controlled trial; rehabilitation; symmetry index.