Jay Dicharry

The Effect of Running Shoes on Lower Extremity Joint Torques

To determine the effect of modern‐day running shoes on lower extremity joint torques during running.

A three-dimensional kinematic and kinetic comparison of overground and treadmill walking in healthy elderly subjects

BACKGROUND Instrumented treadmills offer a number of advantages for the biomechanical analysis of elderly gait, yet it is unclear how closely treadmill gait approximates overground gait. Although studies have indicated that the kinematics and kinetics of overground and treadmill gait are very similar in young adults, it still needs to be determined whether data collected in elderly adults during treadmill walking can be generalized to overground gait. The purpose of this study, therefore, was to compare the three-dimensional kinematics and kinetics of treadmill gait to overground gait in a group of healthy elderly subjects. METHODS Three-dimensional kinematic and kinetic data for 18 healthy, nondisabled elderly subjects, age 65-81 years, were collected for speed-matched overground and treadmill walking conditions. FINDINGS Overall, the kinematics and kinetics of gait during treadmill and overground walking in the elderly had very similar patterns. However, during treadmill walking elderly subjects showed greater cadence, smaller stride length and stride time as well as reductions in the majority of joint angles, moments and powers when compared to overground walking. INTERPRETATION The large increase in cadence suggests that an effective method of acclimation to treadmill walking still needs to be determined. Because of the differences, we believe that in order for instrumented treadmills to become a suitable tool for research and training purposes in healthy elderly, subjects must be adequately acclimated to the treadmill.

Changes in the coordination of hip and pelvis kinematics with mode of locomotion

Limited hip extension mobility has been proposed as a possible cause of both increased anterior pelvic tilt and subsequent exaggerated lumbar lordosis during walking and running. The purpose of the present study was to examine the coordinated sagittal plane kinematic patterns of the hip and pelvis during walking and running in a substantial group of adult recreational runners. The kinematics of 73 healthy adult runners (age: 34+/-11years) were examined on an instrumented treadmill at self-selected walking and running speeds using a three-dimensional motion capture system. Although stride length increased considerably from walking to running, the range of hip extension utilized during running was not significantly greater than that during walking. Thigh extension and anterior pelvic tilt were significantly greater during running than walking. Also, a significant positive correlation was found between hip extension and anterior pelvic tilt during both walking and running, indicating that anterior pelvic tilt was greater in subjects that displayed reduced utilized peak hip extension. Thus, compensations for the increased stride length during running seem to occur at the pelvis, and presumably in the lumbar spine, rather than at the hip. Considering the association between anterior pelvic tilt and lumbar lordosis, the present findings may have clinical relevance regarding the prevention and treatment of hamstring injuries and of injuries to the lumbar spine.

The Influence of Arch Supports on Knee Torques Relevant to Knee Osteoarthritis

PURPOSE Changes in footwear and foot orthotic devices have been shown to significantly alter knee joint torques thought to be relevant to the progression if not the development of knee osteoarthritis (OA) in the medial tibiofemoral compartment. The purpose of this study was to determine if commonly prescribed arch support cushions promote a medial force bias during gait similar to medial-wedged orthotics, thereby increasing knee varus torque during both walking and running. METHODS Twenty-two healthy, physically active young adults (age, 29.2 +/- 5.1 yr) were analyzed at their self-selected walking and running speeds in control shoes with and without arch support cushions. Three-dimensional motion capture data were collected in synchrony with ground reaction force (GRF) data collected from an instrumented treadmill. Peak external knee varus torque during walking and running were calculated through a full inverse dynamic model and compared. RESULTS Peak knee varus torque was statistically significantly increased by 6% (0.01 +/- 0.02 N.m.(kg.m)(-1)) in late stance during walking and by 4% (0.03 +/- 0.03 N.m.(kg.m)(-1)) during running with the addition of arch support cushions. CONCLUSIONS The addition of material under the medial aspect of the foot by way of a flexible arch support promotes a medial force bias during walking and running, significantly increasing knee varus torque. These findings suggest that discretion be employed with regard to the prescription of commonly available orthotic insoles like arch support cushions.

Lower limb joint kinetics in walking: The role of industry recommended footwear

The effects of current athletic footwear on lower extremity biomechanics are unknown. The aim of this study was to examine the changes, if any, that occur in peak lower extremity net joint moments while walking in industry recommended athletic footwear. Sixty-eight healthy young adults underwent kinetic evaluation of lower extremity extrinsic joint moments while walking barefoot and while walking in current standard athletic footwear matched to the foot mechanics of each subject while controlling for speed. A secondary analysis was performed comparing peak knee joint extrinsic moments during barefoot walking to those while walking in three different standard footwear types: stability, motion control, and cushion. 3-D motion capture data were collected in synchrony with ground reaction force data collected from an instrumented treadmill. The shod condition was associated with a 9.7% increase in the first peak knee varus moment, and increases in the hip flexion and extension moments. These increases may be largely related to a 6.5% increase in stride length with shoes associated with increases in the ground reaction forces in all three axes. The changes from barefoot walking observed in the peak knee joint moments were similar when subjects walked in all three footwear types. It is unclear to what extent these increased joint moments may be clinically relevant, or potentially adverse. Nonetheless, these differences should be considered in the recommendation as well as the design of footwear in the future.

Kinematics and Kinetics of Gait: From Lab to Clinic

Dynamic gait evaluation allows examination of the intrinsic and extrinsic factors affecting an individuals ability to walk or run. This article identifies the gait cycle so that common terminology can be used to discuss and compare walking and running. The range of motion, or kinematics, used during gait can be seen subjectively in the hallway of the clinic but can be further objectified in a motion analysis laboratory. Kinetics, or the forces that cause the body to move, are collected in a laboratory environment. Understanding the internal and external forces acting on the body, the mobility they produce at the joints, and the corresponding effect on biomechanics helps identify sources of dysfunction. A discussion on economy highlights factors affecting the ability to move with a given amount of energy cost.

Differences in Static and Dynamic Measures in Evaluation of Talonavicular Mobility in Gait

STUDY DESIGN Controlled laboratory study using a cross-sectional design. OBJECTIVES To compare the measurements of navicular drop during walking and running to those made clinically during a static position in a group of healthy young adults. BACKGROUND The navicular drop test is a common clinical measure of foot structure and, more specifically, of talonavicular joint function. Previous work has focused on static measurement to establish the relationship between navicular drop and various overuse injuries. However, loads on foot structure are dramatically increased during gait. Examining navicular drop dynamically is more reflective of the functional demands of the foot when walking and running. METHODS The navicular drop of 72 healthy runners was evaluated using 2 static methods. Results were used to classify individuals into groups and compared to dynamic measures of navicular drop made during walking and running. Three-dimensional motion capture and an instrumented treadmill were used to assess dynamic navicular mobility. A repeated-measures analysis of variance (ANOVA) was performed to examine differences between measurement conditions. Between-group differences were assessed with independent-samples t test (P<.05). RESULTS Static measures of navicular drop were not found to be uniformly predictive of dynamic function during walking or running. Functional navicular drop measurements underestimated the dynamic measures in all foot types, while subtalar neutral drop overestimated dynamic measures for individuals with neutral and hypermobile foot types. No differences in navicular drop were found between foot types during walking, and small differences were found in running only between the hypomobile and hypermobile foot types. Maximum foot deformation during gait occurs at the time of maximum ground reaction force. Significant differences in navicular drop between foot type groups measured statically become muted when looking at group differences while walking and running. CONCLUSIONS Differences in navicular mobility between foot type groups during walking and running indicate that factors other than static alignment affect dynamic foot mobility. Dynamic assessment of navicular mobility may be an effective tool to examine the interplay of how the extrinsic force demands of gait and intrinsic structure and neuromuscular control affect foot function in walking and running.

Effect of a supervised hip flexor stretching program on gait in elderly individuals.

To determine whether a 10‐week supervised hip flexor stretching program in healthy elderly subjects would increase peak hip extension, stride length and gait speed and reduce anterior pelvic tilt during walking.

Lower limb joint kinetics during moderately sloped running.

CONTEXT Knowledge of the kinetic changes that occur during sloped running is important in understanding the adaptive gait-control mechanisms at work and can provide additional information about the poorly understood relationship between injury and changes in kinetic forces in the lower extremity. A study of these potential kinetic changes merits consideration, because training and return-to-activity programs are potentially modifiable factors for tissue stress and injury risk. OBJECTIVE To contribute further to the understanding of hill running by quantifying the 3-dimensional alterations in joint kinetics during moderately sloped decline, level, and incline running in a group of healthy runners. DESIGN Crossover study. SETTING Three-dimensional motion analysis laboratory. PATIENTS OR OTHER PARTICIPANTS Nineteen healthy young runners/joggers (age = 25.3 +/- 2.5 years). INTERVENTION(S) Participants ran at 3.13 m/s on a treadmill under the following 3 different running-surface slope conditions: 4 degrees decline, level, and 4 degrees incline. MAIN OUTCOME MEASURE(S) Lower extremity joint moments and powers and the 3 components of the ground reaction force. RESULTS Moderate changes in running-surface slope had a minimal effect on ankle, knee, and hip joint kinetics when velocity was held constant. Only changes in knee power absorption (increased with decline-slope running) and hip power (increased generation on incline-slope running and increased absorption on decline-slope running in early stance) were noted. We observed an increase only in the impact peak of the vertical ground reaction force component during decline-slope running, whereas the nonvertical components displayed no differences. CONCLUSIONS Running style modifications associated with running on moderate slopes did not manifest as changes in 3-dimensional joint moments or in the active peaks of the ground reaction force. Our data indicate that running on level and moderately inclined slopes appears to be a safe component of training regimens and return-to-run protocols after injury.

Effect of a Supervised Hip Flexor Stretching Program on Gait in Frail Elderly Patients

To determine whether a 10‐week supervised hip flexor stretching program in frail elderly subjects would increase peak hip extension, stride length, and gait speed and reduce anterior pelvic tilt during comfortable and fast‐paced walking.