Estimated moments at L5/S1 level and muscular activation of back extensors for six prone back extension exercises in healthy individuals

Abstract

The purpose of this study was to identify the prone back extension (PBE) exercises that offer the most resistance to the back extensor muscles. Twenty males with no previous history of low back injury performed two repetitions of eight exercises. These consisted of two maximal isometric voluntary activations (MVA) and six different PBE exercises. The participants, while lying prone on a bench, were asked to raise either their trunk or legs to the horizontal position and hold for one second (static phase) before returning to the original position. The exercises differed according to the particular segments that were raised into extension. To assess the PBE exercises, a biomechanical model was used to estimate the level of load resistance (%MVA) relative to the maximum voluntary activation strength (MVA). In addition, electromyography (EMG) was included to measure the level of muscle activity (%MVE) relative to the maximum voluntary activation EMG (MVE) value reached during the MVA. A significant relationship of 0.86 was found between the mass of the subject and the peak reaction moment during the MVA. Peak level of load resistance averaged around 50% MVA with the exception of exercise no. 5 where the subject had to raise in extension his trunk, legs and arms (65% MVA). The erector spinae (ES) activity level reached a peak value of 61% MVE for exercise no. 5. In the exercises where only the trunk was lifted, the peak level of ES was below 47% MVE and the average activity during the static phase reached approximately 26% MVE. For healthy individuals PBE exercises can be considered low intensity exercises (< 50% MVA; except exercise no. 5) and can be used to improve the endurance of the back muscles.

Isometric back muscle endurance: An EMG study on the criterion validity of the Ito test

“…Nonetheless, in the present study, the facts that in the test position of the Sorensen test, the hip extensor muscles were more activated than in the Ito test and that one hip extensor muscle contributed to holding time in the Sorensen test, but not in the Ito test, might result from differences between the two test positions in terms of position of the pelvis and the lumbar spine and might argue for better criterion validity of the Ito test than of the Sorensen test. The positions of both tests loaded the muscles below 50% MVC, which is in line with other studies (Moreau et al, 2001;Plamondon et al, 2002). However, the present study involved exclusively young participants.…”

“…The differences in muscle activity in the two test positions might be ascribed to the stabilization of the legs by three straps in the Sorensen test (Plamondon et al, 2002;Demoulin et al, 2006). The finding of the hip extensors contributing to endurance time in the Sorensen test is in accordance with previous studies (Moffroid et al, 1994;Kankaanpaa et al, 1998).…”

Comparison of Abdominal Muscle Activities with Vaginal Pressure Changes in Healthy Women

“…If the levator ani muscle is contracted by using only 19-34% of the slow-twitch fibers (type I) that comprise 70% of the levator ani muscle 13) , we would be able to accurately confirm the mobilization of pelvic floor muscles without overcompensating changes. In this way, we could devise an exercise program that allows the selective isometric contraction of the abdominal and pelvic floor muscles with appropriate strength.…”

Muscular Performance Assessment of Trunk Extensors: A Critical Appraisal of the Literature

“…Although spinal muscles are really solicited, most notably the multifidus muscle (Ng et al, 1997;Coorevits et al, 2008;Muller et al, 2010), the test solicits also the other muscles involved in extension of the trunk i.e. the hip extensor muscles (Kankaanpaa et al, 1998a;Plamondon et al, 2002;Plamondon et al, 2004;Champagne et al, 2008;Coorevits et al, 2008;Muller et al, 2010). However muscle fatigue of the hip extensor muscles (reflected by electromyographic parameters) is less correlated to the test holding time than back muscle fatigue (Coorevits et al, 2008).…”

“…Indeed, the elicited contractions were found to be no greater than 40-52% of the maximal voluntary contraction (MVC) (Mannion & Dolan, 1994;Ng et al, 1997;Plamondon et al, 1999;Muller et al, 2010) and the electromyographic (EMG) activity of the spinal erector muscles rarely exceeded 40% of its maximal value (Plamondon et al, 1999;Plamondon et al, 2002).…”