Influence of high-velocity low amplitude manipulation of the lumbar spine on the activity of motor units of the erector spinal muscles with functional assessment in healthy young people

Introduction
High-velocity low amplitude (HVLA) manipulation is used worldwide by healthcare professionals. The literature reports that HVLA manipulation improves joint range of motion, re- duces joint surface compression, restores mus- cle-tissue balance, and reduces inflammation. Many possible reports on HVLA have been given in the last three decades.

Aims
This study aimed to assess the impact of HVLA manipulation of the L2-L4 level on the surface electromyography (sEMG) activity and functional efficiency assessed by the Duncan-Ely (D-E) test.

Material and methods
A group of 60 participants was randomized into 30 for the study and the con- trol group. The study group was randomized into two groups of 15 people. The average age of the study group was 23.77, and 23.07 years of the con- trol group. BMI among groups p=0.27. The project was a pre-test-post-test examining the main ef- fects of HVLA between measures and groups. The methodology used sEMG measurement of the erector spinal muscles using the Biering-Soren- son (B-S) test and normalization by maximum vol- untary isometric contraction (MVIC). In addition, D-E test was used to assess functional efficiency. Measurements and sEMG processing were sup- ported by MR® 3.16 Noraxon, ISEK, and SENIAM. The analyzes were done in Statistica v.13.1.

Results
After proving the normality of the dis- tributions for the B-S measurements pS-W>0.05 and the homogeneity of the variances from Lev- ene's test p>0.05, repeated measures ANOVA was used. ANOVA of sEMG measurements in two- group and three-group division was p>0.05. Del- tas of pre-test-post-test differences of the D-E test performed by M-WU test show the signifi- cance of both deltas p<0.05.

Conclusions
HVLA of the L2 to L4 level does not change the amplitude of the myoelectric activity of the erector spinal muscles in the B-S test, but it does improve the knee flexion range of motion in the population of young and asymptomatic people.