The effectiveness of spinal manipulative therapy (SMT) for improving athletic performance in healthy athletes (or anything else for that matter) is unclear. The objective of this systematic review was to systematically review the literature on the effect of SMT on performance-related outcomes in asymptomatic adults.
The authors searched electronic databases from 1990 to March, 2018. Inclusion criteria was any study examining a performance-related outcome of SMT in asymptomatic adults. Methodological quality was assessed using the SIGN criteria. Studies with a low risk of bias were considered scientifically admissible for a best evidence synthesis.
Of 1415 articles screened, 20 studies had low risk of bias, seven were randomized crossover trials, 10 were randomized controlled trials (RCT) and three were RCT pilot trials. Four studies showed SMT had no effect on physiological parameters at rest or during exercise. There was no effect of SMT on scapular kinematics or transversus abdominus thickness. Three studies identified changes in muscle activation of the upper or lower limb, compared to two that did not. Five studies showed changes in range of motion (ROM). One study showed an increase lumbar proprioception and two identified changes in baropodometric variables after SMT. Sport-specific studies showed no effect of SMT except for a small increase in basketball free-throw accuracy.
The authors, who are all affiliated to the Canadian Memorial Chiropractic College, concluded that the preponderance of evidence suggests that SMT in comparison to sham or other interventions does not enhance performance-based outcomes in asymptomatic adult population. All studies are exploratory with immediate effects. In the few studies suggesting a positive immediate effect, the importance of such change is uncertain. Further high-quality performance specific studies are required to confirm these preliminary findings.
I think, this says it (almost) all: yet another lucrative claim made by many chiropractors and osteopaths turns out to be not backed up by good evidence. The only thing worth adding is the fact that only 4 of the studies mentioned adverse effects. This means the vast majority of studies failed to comply with this basic requirement of research ethics – and this really says it all!