ACUTE EFFECTS OF SPINAL MANIPULATION AND PASSIVE STRETCHING ON MUSCLE ACTIVATION AND FATIGABILITY

Emiliano Cè

1.2, Paolo Parente1

1Osteopathic Institute Take Care (TCIO)

, 2Dept. of Sports.Nutrition and Health Sciences, University of Milan, Italy

Introduction - Chronic low back pain (CLBP) patients are characterised by a reduction of trunk

flexion-extension range of motion (ROM) and an increased neuro-muscle activation and fatigability of

erector spinae (ES) muscles. High-Velocity Low-Amplitude (HVLA) impulse spinal manipulation and

passive stretching (PS) are commonly used as conservative therapies in CLBP rehabilitation. The aims

of the study were to assess: i) the effect of HVLA and PS on ES and hamstrings muscles activation,

and ii) the fatigability of ES and hamstrings muscles after the two manoeuvres in healthy subjects.

Material/Methods - Twenty young male participants underwent a monolateral HVLA at the level of

L5-S1 and a single application of PS of the ES muscle. Before and after the manoeuvres, five flexionextension

of the trunk and an one isometric contraction of ES and hamstrings muscles for 1 min were

performed. During tests, the electromyographic (EMG) signal was recorded and the root mean square

(RMS) and the mean frequency (MF) of the signal were calculated. Trunk flexion -extension ROM

was also measured.

Results - ROM increased significantly by 3% and 5% after HVLA and PS, respectively. The two

manoeuvres had no significant effects on hamstrings muscles. Conversely, in ES muscles a significant

anticipation of the end of neuro -muscle activation during flexion was observed after the two

interventions (-4.8 degree and -5.4 degree after HVLA and PS, respectively). During extension,

EMG RMS did not change, while EMG MF was reduced significantly after the two manoeuvres.

During the isometric test, no differences were observed in EMG RMS and MF in both muscles after

HVLA and PS.

Conclusion - In conclusion, both HVLA and PS increased trunk flexion -extension ROM of ES

muscles, through a change in motor units activation during flexion and extension and muscle -tendon

viscoelastic characteristics, but they did not have any effect on muscle fatigability.