An observational study of motion induced in the lumbar–pelvic complex during ‘harmonic’ technique: A preliminary investigation

BackgroundIn manual therapy, the ‘harmonic’ approach to inducing cyclical motion in different body regions has been described as distinct from rhythmic articulation, ‘harmonic’ techniques being further defined as those that bring about a state of resonance in body tissues. During application of ‘harmonic’ techniques, resonance is proposed to result from the technique operator ‘tuning in’ to the inherent frequency of the oscillating region. This study provides a quantitative analysis of the motion induced by a ‘harmonic’ technique and the notion of ‘tuning in’.ObjectivesTo provide a quantitative analysis of the oscillatory motion induced in the lumbar–pelvic complex by the application of a ‘harmonic’ technique and to compare the motion induced by two different operators.MethodsA ‘harmonic’ technique was applied to the lumbar–pelvic complex of 26 volunteers and the oscillatory motion filmed. An additional operator performed the technique on a subgroup (n = 12) of the sample to provide data for the comparisons of two operators.ResultsThe mean (SD) frequency of oscillation across all sessions was 1.17 Hz (0.10). The mean (SD) amplitude was 0.15 m (0.03). The mean (SD) inter-cycle variability of period was 2.45% (0.47). The mean (SD) inter-cycle variability of amplitude was 6.35% (2.06). There were no consistent intra-cycle relationship identified between period and amplitude. There was an inverse relationship between frequency and subject weight (Pearson's r = −0.66 (95% CI −0.84 to −0.32). The intra-class correlation coefficient (ICC) for inter-operator reliability of frequency was 0.93 (95% CI = 0.83 to 0.97). The ICC for inter-operator reliability of amplitude was 0.87 (95% CI = 0.69 to 0.94).ConclusionThe motion induced in the lumbar–pelvic complex using a modified harmonic technique displayed properties of harmonic motion. The inter-operator study demonstrated that two operators of different morphologies ‘tuned in’ to the same frequency of individual subjects. This supports the theory that motion arising from harmonic techniques is resonant.