Extended Data Fig. 10: Immediate recovery of trunk control.

Step 1, Participant P2 performing repeated front pull movement on a medicine ball without stimulation (black/EES OFF) and with EES targeting the T12 dorsal root (red/EES ON). Radius of curvature of the lumbar region is measured at position 3, which is the most difficult position for the participants to stabilize. Exercises were repeated 4-5 times in each condition (EES OFF/ON). Step 2, Representation of the trunk muscles engaged in the execution of the task (gray) and EES targeted muscles (red), together with the electrode configuration to target the subset of these muscles affected by the SCI. Step 3, Bar plots reporting the radius of curvature of the lumbar region at position 3 and the execution time of the whole exercise for each participant (n = 5 repetitions per participant, two-tailed Mann–Whitney test, Lumbar curvature (p = 0.0079 for all three participants), Execution time (P1: p = 0.0159, P2: p = 0.0079, P3: p = 0.0079), *, p < 0.05; **, p < 0.01). Step 4, Participant P2 performing repeated lumbar lordosis correction in four-point kneeling position in the absence of stimulation (black/EES OFF) and with a stimulation program that targeted trunk, abdominal and gluteus muscles to stabilize the four-point kneeling position (red/EES ON). Radius of curvature of the lumbar region is measured at the time of maximal contraction and maximal relaxation of the lower back. Exercises were repeated 4-5 times in each condition (EES OFF/ON). Step 5, Same as Step 2. Step 6, Bar plots reporting the lumbar curvature without and with stimulation (n = 6 (P1), n = 4 (P2), n = 6 (P3) repetitions, two-tailed Mann–Whitney test, P1: p = 0.0022, P2: p = 0.0286, P3: p = 0.0022, *, p < 0.05; **, p < 0.01). Step 7, Participant P2 performing repeated front shoulder raise in the absence of stimulation (black/EES OFF) and with EES (red/EES ON). Exercises were repeated 4-5 times in each condition (EES OFF/ON). Step 8, Same as Step 2. Step 9, Changes in position of the wrist in the vertical plane during the front shoulder raise movement, showing improved symmetry and range of motion with EES turned on. The bar plot reports the execution time of this task with (n = 7) and without EES (n = 6), and in 5 healthy individuals for comparison (n = 5 repetitions, two-tailed Mann–Whitney test, p = 0.0082, **, p < 0.01). Step 10, Dips lifting hip. In the absence of stimulation, the participant (P1) is able to lift his own body-weight but is not able to lift his pelvis (black). With EES, he is able to activate his lower abdominal and oblique muscles to lift his pelvis on both sides. Step 11, The participant (P1) is using a torso rotation machine at the gym. In the absence of stimulation, he is able to rotate to both sides lifting 10 kg. EES enables him to perform this exercise with twice this weight as represented on the bar plot.