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Angle-specific muscle activation on a multi-modal exercise system: A ten-muscle surface EMG analysis of sex-related differences
Azmi, Rida Strong, Sydnie Scraper, Samantha
Azmi, Rida
Strong, Sydnie
Scraper, Samantha
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2026-04-24
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Azmi, Rida; Strong, Sydnie; Scraper, Samantha; Van Ravenhorst-Bell, Heidi A. 2026. Angle-specific muscle activation on a multi-modal exercise system: A ten-muscle surface EMG analysis of sex-related differences. -- In Proceedings: 25th Annual Undergraduate Research and Creative Activity Forum. Wichita, KS: Wichita State University.
Abstract
Across muscles, surface EMG (sEMG) generally increases with steeper angles, indicating greater muscle activation. Changes in body or joint angles alter load distribution and muscle engagement, enhancing strength, stability and functional performance. Additionally, research has demonstrated sex-related differences attributed to variations in muscle mass distribution and strength levels between males and females. Purpose: To compare sEMG amplitude across ten muscles during standardized exercise on the Challenger at three device angles: Power Sled, Power Stairs, and Power Climb. In addition, sex related differences were evaluated. Methods: Thirty-four healthy young adults completed a single 60-min session. Participants performed standardized, simultaneous upper- and lower-limb dynamic movements on the Challenger at three device angles—Power Sled, Power Stairs, and Power Climb. The same movement pattern was used at each angle while sEMG was recorded on ten specific muscle groups. Device resistance was fixed at level 5 (scale: 1 = easiest, 10 = hardest). Ratings of perceived exertion (Borg 6–20) were obtained after each angle condition. Results: A mixed repeated-measures ANOVA analyzed Angle x Muscle activation on ten muscle groups, and between subject gender. Alpha set at p<.05, Post Hoc comparison with Bonferroni-adjustment (p<.017), if warranted. Significant main effects were observed for Muscle, Angle, and Gender, along with a significant Muscle × Angle interaction (p < .05); no significant gender interactions were found. Conclusion: The significant main effects and Muscle x Angle interactions demonstrated that muscle activation was angle-dependent and influenced by joint positioning. Biomechanics and angle-specific recruitment patterns were found to be consistent across sexes, regardless of males presenting with greater overall muscle activation. In conclusion, exercise prescription in use with this multi-modal system should consider joint positioning to optimize muscle targeting and training outcomes. However, further research with a broader and more diverse population is needed to examine longitudinal adaptations.
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Presented to the 25th Undergraduate Research and Creative Activity Forum (URCAF) held in Woolsey Hall, Wichita State University, April 24, 2026.
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Wichita State University
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URCAF;v.25