Activation amplitude patterns do not change for back muscles but are altered for abdominal muscles between dominant and non-dominant hands during one-handed lifts

Abstract

It is assumed when lifting with the dominant hand that the relationship between contralateral and ipsilateral trunk muscle responses are similar to when lifting with the non-dominant hand. The purpose of this study was to quantify trunk muscle activation amplitude patterns during right- and left-handed lifts. Surface electromyography (EMG) and kinematic variables were recorded from 29 healthy subjects. Minimal trunk and pelvis motion was observed. Three principal patterns accounted for 95% of the variation in the EMG data indicating minimal variation in the pattern. Significant differences in scores captured different recruitment strategies for reach and hand. Selective and differential recruitment of back sites characterized lifts at greater distances from the body, whereas co-activation between internal oblique and back sites characterized lifts closer to the body. While the results showed no handedness effect for back muscles, the external oblique responded differently between right- and left-handed lifts. Specific recruitment strategies were used to account for subtle changes in reach and asymmetrical demands.

Activation amplitude and temporal synchrony among back extensor and abdominal muscles during a controlled transfer task: Comparison of men and women

“…4B) is consistent with the RMS amplitude pattern for the abdominal sites presented in our previous work and supports differential recruitment of the abdominal wall muscles for different activities (Butler et al, 2009b;Mirka et al, 1997;Moreside et al, 2008;Urquhart & Hodges, 2005). Higher activation observed for women could be explained by smaller abdominal fiber size (Mazis et al, 2009) and shorter muscle moment arm lengths in women resulting in lower muscular strength capabilities (Mannion et al, 1997;Marras et al, 2001).…”

“…With the exception of the multifidus (L52) the activation amplitudes (PC1 scores - Fig. 4B) gradually decreased from the upper lumbar levels to the lower levels consistent with erector spinae amplitudes reported for a task where the arms created reactive moment on the trunk (i.e., erector spinae amplitudes decreased from L1 to L4) (de Seze et al, 2008) and for both symmetrical (Butler et al, 2009a) and asymmetrical (Butler et al, 2009b) lift and replace tasks. This finding also supports an anatomical biomechanical model of the lumbar spine that estimated decreasing moment capability from L1 and L5 (Bogduk, Macintosh, & Pearcy, 1992) excepting that the multifidus site was high.…”

“…More recent studies confirm differential amplitude responses for back muscles such as the medial verses lateral erector spinae sites based on the direction of the applied external moment during static planar efforts (Butler, Hubley-Kozey, & Kozey, 2009a, 2009bThelen, Schultz, & Ashton-Miller, 1995;Vink, van der Velde, & Verbout, 1988). When the task becomes dynamic, representing more functional demands, the erector spinae responds in a systematic fashion by increasing or decreasing activation amplitudes that correspond to the consecutive levels of the spinal column (de Seze, Falgairolle, Viel, Assaiante, & Cazalets, 2008).…”

“…These findings are consistent with previous studies that examined muscle response to simple lift and replace exertions. Sagittal plane moments required more medial back extensor activations whereas more lateral sites were recruited for frontal plane moments (Butler et al, 2009a(Butler et al, , 2009bThelen et al, 1995;Vink et al, 1988) indicative of the CNS using the mechanical advantage of the more lateral sites in developing frontal plane moments. Significant differences between right and left muscle sites for the asymmetry pattern (PC2) for all back extensors support a trade off synergism related to loading location.…”

“…When the task becomes dynamic, representing more functional demands, the erector spinae responds in a systematic fashion by increasing or decreasing activation amplitudes that correspond to the consecutive levels of the spinal column (de Seze, Falgairolle, Viel, Assaiante, & Cazalets, 2008). Segments within abdominal muscles have been shown to have diverse activations with their relative muscle responses related to the magnitude (Lavender, Tsuang, Andersson, Hafezi, & Shin, 1992;Perez & Nussbaum, 2002) and direction of the external forces acting on the spine as well as whether the task is static or dynamic (Butler et al, 2009a(Butler et al, , 2009bde Looze, Groen, Horemans, Kingma, & van Dieën, 1999;Mirka, Kelaher, Baker, Harrison, & Davis, 1997;Moreside, Vera-Garcia, & McGill, 2008). Despite the stated importance of muscle synergies to respond to dynamically changing moments in an appropriate manner for protecting the spine from potentially damaging forces (Cholewicki & McGill, 1996;Panjabi, 2006), only a few studies have examined synergistic responses to dynamic perturbations by exploring the temporal patterns of the trunk musculature (Butler, Lariviere, Hubley-Kozey, & Sullivan, 2010;Hubley-Kozey, Hatfield, & Davidson, 2010;Hubley-Kozey & Vezina, 2002a;Lamoth, Meijer, Daffertshofer, Wuisman, & Beek, 2006;van der Hulst, Vollenbroek-Hutten, Rietman, & Hermens, 2010).…”