A study Investigating the effects of osteopathic muscle energy technique on the viscoelasticity of skeletal muscle

Abstract

This study was performed to investigate the effects of an osteopathic treatment technique (muscle energy technique) on the viscoelasticity of skeletal muscle (biceps brachii). Fifteen 18-30 year old healthy non obese right handed male volunteers participated. Data collection was undertaken over four days with each subject attending two sessions separated by an interval of 1 day. On day one, three measurements of muscle viscoelasticity (stiffness, power of resistance) were taken from each individual participant’s left biceps brachii muscle. Measurements were made using a purpose designed force dial viscoelastometer. This device is designed to perform incremental compression of tissue and to calculate stress - strain data for muscle tissue during periods of controlled deformation. On day two, three measurements were again taken followed by five 10 second cycles of muscle energy technique on the subject’s left biceps brachii muscle; three further measurements were again taken post intervention. Analysis of deflection and resistance of the measuring probe was then plotted as a linear equation (y = kx +b). The deformed muscle tissue was conceptually modelled and represented using 3 subsequent springs in series, representing 3 different compartments (layers) of skeletal muscle. Indices of total compressive stiffness of skeletal muscle and specific power of resistance during tissue compression were calculated using multiple mathematical formulas. A comparative statistical analysis between pre-intervention and post-intervention data was performed with the single tailed paired samples t-test from the software program SPSS 12.0.1 for Windows. There was no significant difference in stiffness (95% CI = -0.06419 to 0.23786 degrees; t = 1.233; df = 14; P < 0.238) and power of resistance (95% CI = -0.00804 to 0.01988 degrees; t = -0.910; df = 14; P < 0.378) between pre-intervention and post-intervention states. After intervention the stiffness and power of resistance of the biceps brachii muscle did not decrease. The Cohen’s d post-hoc test showed that the effect size of the intervention was considered to be small, low, minor. No significant individual difference was demonstrated in terms of the stiffness (95% CI = -0.36715 to 0.07369 degrees; t = -1.428; df = 14; P < 0.175) and power of resistance (95% CI = -0.02503 to 0.01245 degrees; t = -0.719; df = 14; P < 0.484) between pre-intervention (baseline) trials for each subject. This study demonstrates that muscle energy technique did not decrease indices of viscoelasticity (stiffness and power of resistance) of the biceps brachii muscle. These findings encourage further research on the physiological background of MET.