Reduced flexibility over the neuromotor control of paretic leg muscles may impact the extent to which individuals post-stroke modulate their muscle activity patterns to walk along curved paths. The purpose of this study was to compare lower-limb movements and neuromuscular strategies in the paretic leg of individuals with stroke with age-matched controls during curved walking. Participants walked at their preferred walking velocity along four different paths of increasing curvature, while lower-limb kinematics and muscle activity were recorded. A second group of able-bodied individuals walked along the four paths, matching the walking speed of the stroke group. The stroke group showed reduced lower-limb joint excursion and disordered modulation of foot pressure during curved walking, accompanied by reduced modulation of muscle activity patterns. In the inner leg of the curve in control subjects, the posteromedial muscles (medial gastrocnemius and medial hamstrings) showed decreased electromyographic amplitude as path curviture increased. Conversely, activity of the posterolateral musculature of the outer leg was decreased with increasing path curvature. Activity in the tibialis anterior and gluteus medius was also modulated with path curvature. However, in the stroke group, we found reduced modulation of muscle activity in the paretic leg during curved walking. The extent of modulation was also associated with the level of physical impairment due to stroke. The results of this study provide further knowledge about neuromuscular control of locomotor adaptations post-stroke.

Muscle activity during the swing phase of walking is influenced by proprioceptive feedback pathways. Previous studies have shown that feedback and anticipatory motor commands contribute to locomotor adaptive strategies to prolonged exposure to a resistance against leg movements during walking. The purpose of this study was to determine whether people with motor-incomplete spinal cord injuries (SCI) modulate flexor muscle activity in response to different levels of resistance in a similar way as uninjured controls. A second purpose was to determine whether people with motor-incomplete SCI have the capacity to form anticipatory motor commands following exposure to resistance. Subjects walked on a treadmill with the Lokomat robotic gait orthosis. The Lokomat applied different levels of a velocity-dependent resistance, normalized to each subject's maximum voluntary contraction of the hip flexors. Each condition consisted of 20 steps against resistance followed by 20 steps without. Electromyography and kinematics of the lower limb were recorded. Although both groups responded to the resistance with an overall increase in rectus femoris activity during swing, the SCI group showed weak modulation of muscle activity to different levels of resistance. Following removal of the resistance, both groups showed aftereffects, but they were manifested differently. Controls responded to the removal of resistance with a high step, whereas the SCI subjects exhibited increased step length. The size of the aftereffect was related to the amount of added resistance. In addition, the SCI group showed a negative relationship between the size of the aftereffect and locomotor function.

Due to lack of high-quality, consistent research on the effects of exercise for persons with vertebral fractures, no definitive conclusions can be drawn from this systematic review. Positive trends were identified with regard to improvements in strength and balance, with no increase in pain following exercise protocols. Future research is needed in this area.

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