Effects of Speed and Visual-Target Distance on Toe Trajectory during the Swing Phase of Treadmill Walking

Abstract

Toe trajectory during swing phase is a precise motor control task that can provide insights into the sensorimotor control of the legs. The purpose of this study was to determine changes in vertical toe trajectory during treadmill walking due to changes in walking speed and target distance. For each trial, subjects walked on a treadmill at one of five speeds while performing a dynamic visual acuity task at either a "far" or "near" target distance (five speeds × two targets distances = ten trials). Toe clearance decreased with increasing speed, and the vertical toe peak just before heel strike increased with increasing speed, regardless of target distance. The vertical toe peak just after toe-off was lower during near-target visual acuity tasks than during far-target tasks, but was not affected by speed. The ankle of the swing leg appeared to be the main joint angle that significantly affected all three toe trajectory events. The foot angle of the swing leg significantly affected toe clearance and the toe peak just before heel strike.These results will be used to enhance the analysis of lower limb kinematics during the sensorimotor treadmill testing, where differing speeds and/or visual target distances may be used. Miller, Feiveson, Bloomberg 3

Minimum toe clearance adaptations to floor surface irregularity and gait speed

“…Overground MTC significantly increased with gait speed for all surfaces (p o0.0001, +4.0 mm/(m/s) for no obstacles surface). This finding is reasonable in that it indicates an adaptation to reduce trip risk during more hazardous gait conditions, but it contradicts the only other significant previous findings for MTC changes due to gait speed (-4.3 mm/(m/s), p o0.01) (Miller et al, 2009). This discrepancy was most likely due to differences in methodology (treadmill gait using single virtual toe marker vs. overground gait using hundreds of virtual toe markers) and task (concurrent dynamic visual acuity task vs. no concurrent task).…”

“…MTC has often been evaluated on a treadmill (Mills et al, 2008;Begg et al, 2007;Khandoker et al, 2008;Miller et al, 2009), which enables the rapid collection of a large number of consistent steps, but cannot account for ground height variations (e.g. changes in slope, level, or flatness), obstacles, and speed or direction changes of overground gait in real-world conditions.…”

The effects of everyday concurrent tasks on overground minimum toe clearance and gait parameters

“…While we did not detect a direct linear correlation between any gait parameter and MTC, there may be some relationship between task type, compensatory gait adaptations, and MTC that would be misrepresented by constant speed treadmill gait. Recent research has shown MTC on a treadmill to decrease at 4.3 mm per each additional m/s of gait speed [8], while earlier data of overground gait at different speeds reported MTC to be 8.9 mm at a toe speed of 3.6 m/s (slow cadence), 12.9 mm at 4.5 m/s (natural cadence), and 12.3 mm at 5.3 m/s (fast cadence) [14]. Despite some methodological differences, these contradictory findings indicate that speed-related changes in overground MTC do not appear to be equivalent to speed-related changes in treadmillobtained MTC.…”

“…Outliers (1.5-3*IQR) indicated by circles. captured here allows the point of minimum clearance between foot and ground to be selected from a large number of possible points rather than using a single [5,6,8] or only three [13] assumed points of minimum clearance. This level of accuracy may not ultimately prove to be necessary for all or even any experimental circumstances, but this should be verified experimentally rather than assumed to be the case.…”

“…MTC has generally been evaluated on a treadmill [5][6][7][8], which enables the rapid collection of a large number of consistent steps, but can not account for ground height variations, obstacles, and speed or direction changes of overground gait in real-world conditions. Moreover, studies that have recorded MTC overground did not attempt to account for the ground height variations of the laboratory [4].…”