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. Author manuscript; available in PMC: 2022 Aug 1.
Published in final edited form as: IEEE Trans Biomed Eng. 2021 Jul 16;68(8):2389–2399. doi: 10.1109/TBME.2020.3039404

Fig. 5:

Fig. 5:

Subject S4: Magnitude (a) and directions (b) of possible double and triple, quadruple, and quintuple muscle combinations. Magnitude and direction were calculated from measured force in the A/P and M/L directions. Each graph shows the result when the muscle is activated alone followed by the result when the muscles are co-activated (Com) along with a black line indicating perfect vector addition. Percent difference between the linear combination and measured combination is shown above each graph. Error bars are standard deviation (n=10). A direction of 0° is directly right, 90° is purely anterior, 180° is directly left, and 270° is purely posterior. Acronyms: LES - left lumbar erector spinae, LQL - left quadratus lumborum, RGX - right gluteus maximus, RIL - right iliopsoas, RHS - right hamstring semimembranosus.