Paraspinal muscle EMG fatigue testing with two methods in healthy volunteers. Reliability in the context of clinical applications.

OBJECTIVE

Comparison of the accuracy of surface electromyogram for back muscle endurance assessment with two different tests.

DESIGN

Test-retest measurements in 16 healthy volunteers on two separate occasions for each test under controlled conditions.

BACKGROUND

Back muscle endurance is considered important in low back pain rehabilitation. Reliability of paraspinal muscle endurance assessment is a pre-requisite for accurate and meaningful clinical applications of the technique.

METHODS

All participants performed each test twice. A direct comparison was made between two popular fatigue testing methods, the modified Biering-Sørensen and a 60% maximum voluntary isometric contraction in the upright position during which time fatigue was assessed from the electromyogram spectral and amplitude analysis.

RESULTS

Reproducibility of initial median frequency was excellent for both tests. Normalised median frequency slope values were more reliable with the 60% maximum voluntary contraction upright test. The clinical applicability of these measures in detecting significant differences after patient rehabilitation is recommended. Root mean square had very large between-day error for both tests.