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The oxygen consumption (VO₂) of 30 (10 females, 20 males) legally blind adolescents and their sighted controls were compared for treadmill walking (3 mph, 4.8 km/h) and running (6 mph, 9.6 km/h). The VO₂ of the visually impaired subjects averaged 24.4% and 10.8% higher than those of their same-sex age-matched controls, and 42.8% and 11.2% higher than the American College of Sports Medicine (ACSM) norms for walking (p<.01) and running (p<.05), respectively. The normal association between aerobic capacity and locomotor energy costs was evident among the sighted controls (r= .44, p<.05) but insignificant (r=.35, p>.05) for the visually impaired subjects. The energy costs of both walking and running were highest among the totally blind subjects, and decreased toward normal as a function of residual vision among the legally blind subjects. The energy costs of walking and running for blind adolescents are higher than both those of sighted controls and the ACSM norm values.

Crossing moving obstacles requires different space-time adjustments compared with stationary obstacles. Our aim was to investigate gait spatial and temporal parameters in the approach and crossing phases of a moving obstacle. We hypothesized that obstacle speed affects gait parameters, which allow us to distinguish locomotor strategies. Ten young adults walked and stepped over an obstacle that crossed their way perpendicularly, under three obstacle conditions: control—stationary obstacle, slow (1.07m/s) and fast speed (1.71m/s) moving obstacles. Gait parameters were different between obstacle conditions, especially on the slow speed. In the fast condition, the participants adopted predictive strategies during the approach and crossing phases. In the slow condition, they used an anticipatory strategy in both phases. We conclude that obstacle speed affects the locomotor behavior and strategies were distinct in the obstacle avoidance phases.

Healthy young adults transition between level and hill surfaces of various angles while walking at fluctuating speeds. These surface transitions have the potential to decrease dynamic balance in both the anterior-posterior and medial-lateral directions. Hence, the purpose of the current study was to analyze modifications in temporal-spatial parameters during hill walking transitions. We hypothesized that in comparison with level walking, the transition strides would indicate the adoption of a distinct gait strategy with a greater base of support. Thirty-four participants completed level and hill trials on a walkway with a 15-degree portable ramp apparatus. We collected data during 4 transition strides between level and ramp surfaces. In support of our hypothesis, compared with level walking, the base of support was 20% greater during 3 out of the 4 transition strides. In short, our results illustrate that healthy young adults did adopt a distinct gait strategy different from both level and hill walking during transitions strides.

In speed skating, the conventional skate has been replaced by the klapskate, in which the shoe can rotate around a hinge between shoe and blade. It has been hypothesized that the improved performance with klapskates vs. conventional skates can be attributed to the difference in the anterior/posterior position of the foot’s center of rotation relative to the ice. This study investigated the effect of the position of the foot’s center of rotation on push-off mechanics in speed skating. Eight elite speed skaters skated four 2000-m trials on instrumented klapskates at a fixed velocity. In each trial the hinge was placed at a different position between the 5th metatarso-phalangeal joint and the tip of the toes. 3-D kinematics and pushoff forces were measured to analyze push-off kinematics and kinetics. Shifting the hinge from the most posterior to the more anterior positions resulted in a delayed onset of foot rotation and longer duration of push-off. This delay coincided with an increase in angular displacement and peak angular velocity of the knee and hip joint, an increase in the flexing knee joint moment at the end of the push-off, and a reduction in work generated at the knee joint. Total work per stroke was similar for the various hinge positions. Besides the similar work per stroke, the observed effects are in accordance with the differences between klapskating and conventional skating. It was concluded that the position of the foot’s center of rotation affects the timing of foot rotation, and therefore the balanced pattern of segmental rotations. Although it could not be proven in this study, it was shown that this constraint could affect work per stroke and might explain the difference between klapskates and conventional skates.

Functional knee braces used during rehabilitation from injury and surgery to the anterior cruciate ligament (ACL) have been reported to provide a strain-shielding effect on the ACL in healthy people while standing, reduce quadriceps electromyoraphy in ACL-deficient individuals, and alter joint torque patterns in people with ACL reconstruction during walking. These results led to the hypothesis that functional knee braces protect a reconstructed ACL during dynamic activity by reducing the anterior shear load applied to the knee. This hypothesis was tested by investigating the effects of a functional knee brace on lower extremity muscle forces and the anteroposterior shear force at the knee joint during the stance phase of walking in people with ACL reconstruction. Ground reactions and sagittal plane video were recorded from 9 ACL-reconstructed individuals as they walked with and without a functional knee brace, and from 10 healthy people without the functional knee brace. Inverse dynamics were used to calculate the net joint torques in the lower extremity during the stance phase. Hamstrings, quadriceps, and gastrocnemius muscle and knee anteroposterior shear force were then predicted with a sagittal-plane mathematical model. Compared to healthy individuals, those with ACL reconstruction walked with 78% more hamstrings impulse and 19% less quadriceps impulse (both p < .05). The functional knee brace produced an additional 43% increase in hamstrings impulse and an additional 13% decrease in quadriceps impulse in the ACL group. Peak anterior knee shear force and anterior impulse were 41% lower and 16% lower in ACL vs. healthy individuals, respectively. The functional knee brace further reduced the peak knee shear force and impulse 28% and 19%, respectively, in the ACL group. It was concluded that a functional knee brace protects a reconstructed ACL during walking by altering muscle forces and reducing the anterior shear force applied to the knee joint.

Much has been learned about the characteristics of gait in overground and treadmill walking. However, there are many contexts in which overground or treadmill walking might not be possible, such as in home-based physical therapy. In those cases, a surrogate task to index gait behavior would be a valuable tool. Thus, the purpose of this study was to evaluate the stride behavior characteristics of stationary stepping compared with treadmill walking. Healthy young adults (N = 10) preformed two 15-minute tasks: (1) treadmill walking and (2) stationary stepping. Several stride behavior characteristics were recorded, including the number of strides taken, minimum and maximum knee angle, stride interval mean, stride interval standard deviation, and detrended fluctuation analysis (DFA) alpha of the stride interval time series. The results showed that stride behavior was similar between tasks when examined at the group level. However, when individual level analyses were used to examine the reliability of each metric between tasks, poor reliability was observed in most metrics, indicating that stationary stepping may not be an appropriate surrogate task for overground or treadmill walking. These results are discussed in the context of a gait dynamics framework, with attention to task constraints that may have influenced the findings.

Individuals must constantly modify their gait patterns to safely transition between different surfaces. The goal of the current study was to determine if gait changes could be detected two steps from a transition, and whether these changes scaled with the angle of the hill. We hypothesized that during the anticipation of uphill walking and the aftereffect of downhill walking, the magnitude of kinetic and electromyography changes would be greatest at steep hill angles and fewer steps from the transition. We collected force and electromy-ography data as participants walked on the level ground before an uphill ramp and after a downhill ramp. As hypothesized, there were significant main effects for both the number of steps and angle of the hill for the first vertical GRF peak, as well as lateral gastrocnemius and vastus lateralis activity. Overall, our results indicate that when transitioning to and from hills, anticipation and aftereffect responses occur at least two steps from the transition and are scaled to the angle of the hill.

Weighted vests have been used primarily as behavioral interventions for children and adolescents with autism. Contemporary research has begun to examine weighted vest effects on movement. Previous research in children with neurotypical development revealed 15% body mass loads modified spatial-temporal gait characteristics; however, a value applicable to children and adolescents with autism has not been established. The purpose of this study was to establish an appropriate mass value by examining spatial-temporal gait parameters in children and adolescents with autism with various loads in a weighted vest. Nine children and adolescents with autism, aged 8–17, walked without a weighted vest, with 5%, 10%, 15%, and 20% body mass while spatial-temporal data were captured. Repeated-measures analysis of variance (α = .05) were conducted among conditions for each variable, with a Holm–Bonferroni method correction. Analysis revealed significant decreases in right step length, but no differences in stride width, left step length, double-limb support time, or stride velocity were observed. Due to insignificant findings, an appropriate mass value could not be determined for weighted vests for children with autism. However, unchanged spatial-temporal gait parameters with increasing loads could be clinically relevant as weighted vest loads of 10% are typically used for behavioral interventions.

This study investigated the differences between 5 commonly used methods to calculate leg stiffness over a range of running velocities. Thirteen male, habitually rearfoot, recreational runners ran on a force instrumented treadmill for a 5-minute running session. Each session consisted of 30-second intervals at 6 progressively faster speeds from 2.5 m·s⁻¹ through 5.0 m·s⁻¹ with each interval speed increasing by 0.5 m·s⁻¹. Two-way within-factors repeated-measures analyses of variance were used to evaluate leg stiffness and length. A one-way repeated-measures analysis of variance was used to evaluate the slope of each trend line of each model across speeds. Pearson correlations were used to compare the relationship between the different computational methods. The results indicated that the direct stiffness methods increased with speed whereas the indirect stiffness methods did not. The direct methods were strongly correlated with each other as were the indirect methods. However, there were no strong correlations between the direct and indirect methods. These differences can be mostly attributed to how each individual stiffness method calculated leg length. It is important for researchers to understand these differences when conducting future studies and comparing past studies.