Extended Data Fig. 4: Torque raw data for all joints, functions and subjects and effect of fatigue in maximum torque.

a, Experimental set up to measure isometric torques for knee extension and flexion. b-f Maximum voluntary contraction in all muscles, sessions and subjects that we could reliably measure (torque above 4 N): SMA01 Hip (b), SMA01 Knee (c), SMA02 Hip (d), SMA03 Hip (e) and SMA03 (f). Each point corresponds to one repetition and the square represents the mean across repetitions. g, We used a multivariable linear regression analysis to study the effect of fatigue in our measurements of torque (see Methods). For SMA01, we found that the largest regressor was the repetition indicating that SMA01 was fatiguing after only a few repetitions of maximum voluntary contractions. Given that we always started with SCS OFF trials, our results could be underestimating the assistive effect of SCS (Fig. 3a-c). Indeed, we found for SMA01 right knee extension, the interaction between the SCS and the repetition number was significant indicating that SCS increased maximum torque when SMA01 was fatigued. In SMA03 we reduced the trial duration time from 5 to 2 seconds and we found that the repetition number had no impact indicating that direct comparison between SCS OFF and ON trial is probably not affected by the repetition number. h,Torque traces for SCS ON and SCS OFF fatigued repetition (after more than 12 repetitions of maximum voluntary contraction) in day 12 (See supplementary methods for more information). i, Maximum torque at right knee extension produced by SMA01 in fatigued trials for each session. j, Data from all sessions pooled where we tested the maximum torque in fatigued condition. All error bars show the mean and 95% confidence interval of the mean, computed with bootstrap (N = 10,000).