<div>We sought to establish whether torque pulses applied by an exoskeleton
to the hip and knee joint modulate propulsion mechanics and whether
changes in propulsion mechanics would be sustained after exposure to
torque pulses under user-driven treadmill control. We applied twelve
different formulations of torque pulses consecutively over 300 strides
to 24 healthy participants, and quantified the evolution of four outcome
measures – gait speed (GS), hip extension (HE), trailing limb angle
(TLA), normalized propulsive impulse (NPI) – before, during, and
immediately after training. We tested whether the pulse conditions
modulated propulsion mechanics during and after training relative to
baseline.</div>


<div>Metrics of propulsion mechanics significantly changed both during and
after training. After training, HE, NPI, and GS significantly increased
in eleven conditions, three conditions, and four conditions,
respectively.</div>


<div>Increases in HE during and after training were observed in conjunction
with hip/knee flexion pulses during early stance, or hip/knee extension
during late stance. Increases in NPI during training were associated
with hip/knee extension during early stance, or knee flexion during late
stance. Knee flexion during early stance resulted in positive
after-effects in NPI. Increases in GS were associated with the
application of hip flexion pulses.</div>


<div>Conditions exhibiting the largest positive changes in HE, and not NPI,
during training resulted in increased GS after training. Analysis of the
relationship between the effects measured during and after training
suggests that, when present, after-effects arise from retention of
training effects, and that retention is specific to the component of
propulsion mechanics affected by training.</div>