|Footwear is a necessary component of modern life, serving wide-ranging purposes from fashion apparel to personal protective equipment. Despite what would appear as an otherwise obscure addition of clothing or equipment for individuals, past research has indicated considerable footwear effects on spatiotemporal, kinematics, and kinetics during walking and running. Likewise, footwear has been implicated in altered lumbar and pelvic positioning while standing. While early gait-related research focused on descriptive information to examine the relative timing of body segments throughout the gait cycle, the relationship between trunk, pelvic, and lower extremity movements in maintaining forward momentum and increasing economy during gait is not yet fully understood. Furthermore, despite the considerable footwear effects on gait mechanics, it is not yet known whether footwear has a significant effect on segment synchronicity during walking. Therefore, the purposes of this investigation was: (1) to investigate the effects of velocity and cadence on lumbopelvic rhythm during overground walking; (2) to investigate the effects of footwear on lumbopelvic rhythm during gait; (3) to examine the effects of enhanced tactile feedback (i.e. barefoot, textured insole) on the onset of muscle activity at foot strike; (4) to examine the effects of spatiotemporal and footwear variation on the magnitude of lumbar (i.e. erector spinae) and lower extremity muscular activity (e.g. gluteus medius, biceps femoris, soleus, peroneus longus) during the stance phase of gait, and (5) to investigate differences in the kinematics and electromyography between males and females.
Results indicated significant increases in height normalized stride length, cadence, and velocity as spatiotemporal variables were manipulated from 75% of Normal, to Normal, and 125% of Normal. Results also indicated that altering velocity or cadence had a significant effect for TP mean, TP SD, TL mean, TL SD, PL mean, PL SD, Pelvic Rotation, Trunk Rotation, and Leg Rotation; however the influence of velocity appeared to be smaller in which significant differences were found only for TP mean, Pelvic Rotation, and Trunk Rotation. Likewise, normalized peak sEMG during the stance phase increased as velocity and cadence increased from 75% of Normal, to Normal, to 125% of Normal for lower extremity and lumbar musculature.
When examining footwear effects, results indicated that footwear had a significant effect on the preferred walking velocity, cadence, and normalize stride length of the participants. Specifically, the barefoot and barefoot-like condition (insole-only) exhibited a significantly shorter normalized stride length and lower velocity relative to both shod conditions (shod and insole-shod). Conversely, the present study found no significant footwear effect on normalized peak muscle activity during the stance phase or onset of muscle activity at foot strike. The only kinematic variable to display a significant footwear effect was the relative phase of the pelvis-leg, with barefoot and insole-only exhibiting greater asynchronicity than the shod and insole-shod conditions.
Finally, the present study revealed some gender differences are present during walking. For instance, females exhibited a significantly longer normalized stride length and higher cadence than males for the altered footwear conditions only. Conversely, there were no significant differences between males and females for during any of the altered walking velocity or cadence conditions. Relative phase differences were only found to be significantly different during the footwear conditions, with males exhibiting a significantly greater TP SD, indicating that the trunk-pelvis of males was significantly more variable than females when footwear was altered. Finally, no significant gender differences were noted for normalized peak muscle activity during the stance phase of walking during altered velocity, altered cadence, or altered footwear.