The Relationship between Muscle Activity and Muscle Grade of the Trunk Flexors Using Manual Muscle Testing with Electromyography

Abdominal muscle activation: An EMG study of the Sahrmann five-level core stability test

Background

Sahrmann five-level core stability test protocol has been used to evaluate the ability of the core muscles to stabilize the spine. However, validation studies on the Sahrmann protocol are limited.

Objective

The purpose of this study was to compare the different levels of Sahrmann five-level core stability (levels 1-5) on the muscle activity of rectus abdominis (RA), external oblique (EO), and transverse abdominis/internal oblique (TrA/IO).

Methods

Twenty-two asymptomatic male participants aged 21.3 6 ± 1 .59 years were recruited. Participants were instructed to perform maximum voluntary contraction (MVC) and five levels of Sahrmann five-level core stability test guided with a pressure biofeedback unit (PBU). The surface electromyography (EMG) data of each muscle during five levels of Sahrmann five-level core stability test were normalized as a percentage of MVC.

Results

Results showed significant differences in the normalized EMGs of RA [ χ 2 (4) = 64.80, p < 0 .001], EO [ χ 2 (4) = 58.11, p < 0 .001], and TrA/IO [ χ 2 (4) = 56.00, p < 0 .001] between the five levels of Sahrmann five-level core stability test. Post-hoc analysis revealed Sahrmann levels 5 and 3 have significantly higher abdominal EMG signals than levels 4, 2, and 1 ( p < 0 .001).

Conclusion

In conclusion, the Sahrmann five-level core stability test differs according to the level of Sahrmann tests. Significantly higher abdominal muscle activities were observed during levels 3 and 5. Therefore, the classification exchange in levels 3 and 4 of the Sahrmann five-level core stability test should be reconsidered in the future.