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Context: Exercises in motor development positions are employed to activate correct muscular patterns, but the effects on the activity of antagonist muscle pairs remain unknown. Objectives: To determine the effect of using exercises in motor development positions on the activity of antagonist muscle pairs. Another aim was to analyze if introducing some facilitators modifies the muscle activity in the different studied positions. Design: Controlled laboratory study using a single-group repeated measures design. Participants: A total of 21 right handed, healthy adults aged 41 years and older (10 males and 11 females). Setting: Workers of different departments at Maz Hospital. Intervention: Surface electromyography activity of muscle antagonist pairs upper trapezius/lower trapezius, serratus anterior/pectoralis major, and external abdominal oblique/lumbar paraspinal was measured in 3 positions: rest (supine decubitus), reflex turning 1, and modified Vöjta’s first position. Main Outcome Measures: Primary outcomes were mean normalized root mean square (averaged over 2 repetitions) of electromyography signals of antagonist muscle pairs in the 3 analyzed positions. Intraclass correlation coefficients (>.70) (model 3.2), type consistency, and 95% confidence interval were used to estimate the reliability and as exclusion criteria of measurements. Results: Analyzed positions had a significant effect on the activity of the muscles P < .001. There was a significant increase in the activity of the phasic musculature versus its tonic antagonists, except in the case of the external oblique/lumbar paraspinal in modified Vöjta’s first position. Adding possible facilitators such as gaze, breathing, or the combination of both did not show significant changes in the level of activation of the studied muscle groups. Conclusion: Ontogenetic developmental positions can be used to facilitate and improve the activation of phasic muscles.
Casas and Justes are with Rehabilitation, MAZ Hospital, Zaragoza, Spain. Calvo is with DXC Technology, Madrid, Spain.