Recruitment Of Lower Extremity Musculature During The Biering-Sørenson Muscle Endurance Test

Abstract

In 1984, Biering-Sørenson found that individuals with less lumbar extensor muscle endurance had an increased occurrence of first episode low back pain. As a result, back endurance tests have recently been recommended for inclusion in health assessment protocols. However, different studies have reported markedly different values for endurance times both in healthy individuals as well as those suffering from chronic low back pain (LBP). The contribution of the Biceps Femoris and Gluteus Maximus musculature during this test may affect the endurance times and has not been reported to date. PURPOSE To examine the neuromuscular activity and fatigue characteristics of the Erector Spinae, Biceps Femoris, and Gluteus Maximus musculature during the Biering-Sørenson Muscular Endurance Test (BSME) performed by a LBP population. METHODS Twenty-seven males (n = 14) and females (n = 13) reporting chronic LBP performed the BSME while surface electromyography was used to quantify neuromuscular activity. Disposable silver-silver-chloride electrodes were placed in a bipolar arrangement over the right Biceps Femoris, Gluteus Maximus, and Erector Spinae muscles. Average median frequency (MF) and root mean square (RMS) was calculated for each 1 second epoch throughout the muscular endurance test. RESULTS The average endurance time was 115.5 seconds, with no significant difference found between males and females. Using a Kruskal-Wallis test, significant fatigue was shown in all muscle groups with a univariate analysis displaying a mean gender difference in the median frequency slope of the Gluteus Maximus muscle. RMS values were not found to increase with time to exhaustion in any of the three muscle groups. CONCLUSIONS These preliminary data indicate that the chronic LBP population recruited the Erector Spinae, Gluteus Maximus and Biceps Femoris muscles from the start of the BSME, a test designed to assess back endurance.