Abstract
Title: THE LOSS OF MUSCLE SYNERGY AFTER A SORENSEN TASK IN YOUNG ADULTS WITH ADOLESCENT IDIOPATHIC SCOLIOSIS
Authors: Sun ER1, Tsang SMH1, Chan RYH1, Ma ACF1, Chan JCL1, Cheung TSK1, Wong RWY1, Fu ACL2
1 Department of Rehabilitation Sciences, The Hong Kong Polytechnic University, Hong Kong.
2 School of Medicine and Health Sciences, The University of Sydney, Australia
Introduction
Muscle synergy patterns refer to the coordinated activation among muscle groups that work together to achieve a specific movement or task. Understanding the impact of specific tasks and muscle fatigue on muscle coordination in AIS provides insights into the underlying mechanisms contributing to the associated postural abnormalities and functional limitations.
Objectives
This cross-sectional study investigated the impact of a Sorensen task on the number of muscle synergies of regional paraspinal muscles during various arm elevation tasks in young adults diagnosed with AIS. We hypothesised that (1) Sorensen task will lead to the significant reduction of the number of muscle synergies; (2) the number of synergies in the paraspinal muscles on the convex side will be significantly larger than on the concave side of the scoliotic curve.
Methods
15 young female adults who were diagnosed with idiopathic scoliosis (Cobb angle: 30.1 deg (SD:12.1 deg); 13/15 having thoracolumbar curve, one thoracic and one lumbar curve) were recruited. Surface EMG of 16 bilateral regional erector spinae muscles (at the 4th cervical, 4th and 9th thoracic, and 1st lumbar spine levels), deltoids, upper and lower trapezius were recorded during the arm elevation tasks (left, right, bilateral shoulder flexions followed by shoulder abduction in the same sequence). Same tasks were performed under non-weighted and 2kg-weighted conditions carried by the participant’s hands, before and after a Sorensen task. The number of muscle synergies of muscles during the corresponding arm elevation tasks was calculated using Nonnegative Matrix Factorization. A two-way ANOVA with Bonferroni correction was conducted to analyze the time- (pre-Sorensen vs. post-Sorensen) and load-effects (non-weighted vs. 2kg-weighted) on the number of muscle synergies. Paired t-test was used to compare the number of muscle synergies between concave and convex sides.
Results
An example of the muscle synergy pattern separated by Nonnegative Matrix Factorization (Fig. 1A) multiplied by muscle synergy amplitude (Figure 1B) is presented. Results of the two-way ANOVA indicated that insignificant time-effect on the outcome (ps > 0.05). However, the significant load-effect revealed in concave-side abduction with a significantly lower synergy number when performing the task with a load compared to without a load (p < 0.01). Post-hoc analysis revealed that the significantly lower synergy number over both sides when performing the loaded bilateral flexion task compared to the unloaded trial (p = 0.024, Fig. 1C). Significant time-and-load interactions were observed in the synergy number during concave abduction (p < 0.01, Fig. 1D). Furthermore, the paired t-test result showed that the synergy number of the convex-side paraspinal muscles was significantly larger than that of the concave side during the bilateral flexion task (p = 0.002).
Authors: Sun ER1, Tsang SMH1, Chan RYH1, Ma ACF1, Chan JCL1, Cheung TSK1, Wong RWY1, Fu ACL2
1 Department of Rehabilitation Sciences, The Hong Kong Polytechnic University, Hong Kong.
2 School of Medicine and Health Sciences, The University of Sydney, Australia
Introduction
Muscle synergy patterns refer to the coordinated activation among muscle groups that work together to achieve a specific movement or task. Understanding the impact of specific tasks and muscle fatigue on muscle coordination in AIS provides insights into the underlying mechanisms contributing to the associated postural abnormalities and functional limitations.
Objectives
This cross-sectional study investigated the impact of a Sorensen task on the number of muscle synergies of regional paraspinal muscles during various arm elevation tasks in young adults diagnosed with AIS. We hypothesised that (1) Sorensen task will lead to the significant reduction of the number of muscle synergies; (2) the number of synergies in the paraspinal muscles on the convex side will be significantly larger than on the concave side of the scoliotic curve.
Methods
15 young female adults who were diagnosed with idiopathic scoliosis (Cobb angle: 30.1 deg (SD:12.1 deg); 13/15 having thoracolumbar curve, one thoracic and one lumbar curve) were recruited. Surface EMG of 16 bilateral regional erector spinae muscles (at the 4th cervical, 4th and 9th thoracic, and 1st lumbar spine levels), deltoids, upper and lower trapezius were recorded during the arm elevation tasks (left, right, bilateral shoulder flexions followed by shoulder abduction in the same sequence). Same tasks were performed under non-weighted and 2kg-weighted conditions carried by the participant’s hands, before and after a Sorensen task. The number of muscle synergies of muscles during the corresponding arm elevation tasks was calculated using Nonnegative Matrix Factorization. A two-way ANOVA with Bonferroni correction was conducted to analyze the time- (pre-Sorensen vs. post-Sorensen) and load-effects (non-weighted vs. 2kg-weighted) on the number of muscle synergies. Paired t-test was used to compare the number of muscle synergies between concave and convex sides.
Results
An example of the muscle synergy pattern separated by Nonnegative Matrix Factorization (Fig. 1A) multiplied by muscle synergy amplitude (Figure 1B) is presented. Results of the two-way ANOVA indicated that insignificant time-effect on the outcome (ps > 0.05). However, the significant load-effect revealed in concave-side abduction with a significantly lower synergy number when performing the task with a load compared to without a load (p < 0.01). Post-hoc analysis revealed that the significantly lower synergy number over both sides when performing the loaded bilateral flexion task compared to the unloaded trial (p = 0.024, Fig. 1C). Significant time-and-load interactions were observed in the synergy number during concave abduction (p < 0.01, Fig. 1D). Furthermore, the paired t-test result showed that the synergy number of the convex-side paraspinal muscles was significantly larger than that of the concave side during the bilateral flexion task (p = 0.002).
| Original language | English |
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| Publication status | Published - 22 Jun 2024 |