Bilateral level of effort of the plantar flexors, hip flexors, and extensors during gait in hemiparetic and healthy individuals.

BACKGROUND AND PURPOSE Muscle weakness is recognized as a key factor in gait performance of poststroke individuals, but its impact on lower-limb muscular effort has been scarcely studied. The aims of this study were to compare the level of effort of the lower limbs of hemiparetic and able-bodied individuals and to assess the effect of side, cadence, and muscle group. METHODS Seventeen chronic hemiparetic participants (7 females and 10 males) with a mean age of 60.5+/-13.4 years were assessed when walking. They were compared with a group of 14 able-bodied individuals. The level of effort was estimated from the muscular utilization ratio (MUR), which relates the walking moment of a given muscle group to its maximal potential moment. Peak MUR and MUR(area) were used as main outcome measures. RESULTS Hemiparetic individuals showed greater peak MUR values (45% to 78%) than the able-bodied subjects matched for cadence (24% to 63%). For both groups, the peak MUR values were similar between sides and increased with cadence. At self-selected cadence, the plantar flexors showed greater peak MUR values, whereas at maximal cadence, levels of effort for all muscles were equivalent. The MUR(area) values at the hip joint were greater for the hemiparetic group, and both groups had values that increased with cadence. Differences between sides and muscle groups were noted for the hemiparetic and healthy individuals, respectively. Large peak MUR values were associated with high MUR(area) values. CONCLUSIONS For a similar cadence, the levels of effort of hemiparetic individuals were greater than those of the able-bodied. In the presence of muscle weakness, similar bilateral levels of effort could mean that hemiparetic individuals relied on their sense of effort while walking.