The effect of increasing sets (within one treatment session) and different set durations (between treatment sessions) of lumbar spine posteroanterior mobilisations on pressure pain thresholds

Spinal mobilisations are a common form of treatment intervention applied by physiotherapists in clinical practice to manage musculoskeletal pain and/or dysfunction. Previous research has demonstrated that mobilisations cause a hypoalgesic effect. However, there is very little research investigating the optimal treatment dose inducing this effect. To investigate the effect of the number of sets (up to 5) and different durations (30 vs. 60 s) on pressure pain thresholds (PPTs) at different sites. This single-blinded, randomised, same subject repeated measures crossover design included 19 asymptomatic healthy volunteers. The participants received 5 sets of either 30 or 60 s of postero-anterior mobilisations to L4 on different days. PPTs were measured immediately before, between and after the intervention at 4 different standardised sites. A 4-way ANOVA analysis revealed that there was no statistically significant difference between 30 versus 60 s of mobilisations. However, there was a tendency for PPT values to be higher for the 60 s intervention. All PPT measurements after the interventions were significantly higher than the baseline. Only the measurement after the 4th set of mobilisations was significantly higher than the measurement after the 1st set (p = 0.035). The results suggest that in order to induce the greatest local hypoalgesia, at least 4 sets of mobilisations are required. The different durations of 30 versus 60 s of mobilisation may not change the extent of the hypoalgesic effect.