At self-selected walking speeds, elderly compared with young adults generate decreased joint torques and powers in the lower extremity. These differences may be actual gait-limiting factors and neuromuscular adaptations with age or simply a consciously selected motor pattern to produce a slower gait. The purpose of the study was to compare joint torques and powers of young and elderly adults walking at the same speed. Twelve elderly and fourteen young adults (ages 69 and 21 yr) walked at 1.48 m/s over a force platform while being videotaped. Hip, knee, and ankle torques and powers were calculated from the reaction force and kinematic data. A support torque was calculated as the sum of the three joint torques. Extensor angular impulse during stance and positive work at each joint were derived from the torques and powers. Step length was 4% shorter and cadence was 4% higher in elderly adults (both P < 0.05) compared with young adults. Support angular impulse was nearly identical between groups, but elderly adults had 58% greater angular impulse and 279% more work at the hip, 50% less angular impulse and 39% less work at the knee, and 23% less angular impulse and 29% less work at the ankle compared with young adults (t-test, all P < 0.05). Age caused a redistribution of joint torques and powers, with the elderly using their hip extensors more and their knee extensors and ankle plantar flexors less than young adults when walking at the same speed. Along with a reduction in motor and sensory functions, the natural history of aging causes a shift in the locus of function in motor performance.

https://www.physiology.org/doi/pdf/10.1152/jappl.2000.88.5.1804

Age causes a redistribution of joint torques and powers during gait

Biomechanical gait alterations independent of speed in the healthy elderly: Evidence for specific limiting impairments

A kinematic comparison of overground and treadmill walking.

Forces that are repeatedly applied to the body could lead to positive remodeling of a structure if the forces fall below the tensile limit of the structure and if sufficient time is provided between force applications. On the other hand, an overuse injury could result if there is inadequate rest time between applied forces. Running is one of the most widespread activities during which overuse injuries of the lower extremity occur. The purpose of this article is to review the current state of knowledge related to overuse running injuries, with a particular emphasis on the effect of impact forces. Recent research has suggested that runners who exhibit relatively large and rapid impact forces while running are at an increased risk of developing an overuse injury of the lower extremity. Modifications in training programs could help an injured runner return to running with decreased rehabilitation time, but it would be preferable to be able to advise a runner regarding injury potential before undertaking a running program. One of the goals of future research should be to focus on the prevention or early intervention of running injuries. This goal could be accomplished if some easily administered tests could be found which would predict the level of risk that a runner may encounter at various levels of training intensity, duration, and frequency. The development of such a screening process may assist medical practitioners in identifying runners who are at a high risk of overuse injury.

Impact and overuse injuries in runners.

HRELJAC, A., R. N. MARSHALL, and P. A. HUME. Evaluation of lower extremity overuse injury potential in runners. Med. Sci. Sports Exerc., Vol. 32, No. 9, pp. 1635‐1641, 2000. Introduction: The purpose of this study was to identify biomechanical and anthropometric variables that contribute to overuse injuries in runners. Methods: Comparisons were made between a group of runners who had sustained at least one overuse running injury and a group of runners who had been injury free throughout their running careers. Groups were well matched in important training variables. Synchronized kinetic and rearfoot kinematic variables of both feet were collected by filming subjects running over a force platform at a speed of 4 mzs 21 . Results: The injury-free group demonstrated significantly greater posterior thigh (hamstring) flexibility, as measured by a standard sit and reach test. This was the only anthropometric variable in which the groups differed. Within each group, there were no significant differences between left and right foot landing for any biomechanical variable. Biomechanical variables that demonstrated significantly lower values for the injury free group were the vertical force impact peak and the maximal vertical loading rate, with the maximal rate of rearfoot pronation and the touchdown supination angle showing a trend toward being greater in the injury free group. Conclusion: These results suggest that runners who have developed stride patterns that incorporate relatively low levels of impact forces, and a moderately rapid rate of

Evaluation of lower extremity overuse injury potential in runners

Treadmills are often used in research projects to simulate overground locomotion, assuming that locomotion is similar on a treadmill and overground. The purpose of this investigation was to determine whether a treadmill could be used to simulate overground locomotion. Twenty-two subjects ran on four different surfaces: overground and three treadmills that differed in size and power. The kinematics of the right leg and foot were studied using two high-speed Locam cameras (lateral and posterior view). The subjects ran in two different shoes at four different speeds (3.0-6.0 m.s-1). The differences in the kinematics between treadmill and overground running could be divided into systematic and subject dependent components. Subjects systematically planted their feet in a flatter position on the treadmill than overground. Most of the lower extremity kinematic variables, however, showed inconsistent trends for individual subjects, depending on the individual subject's running style, running speed, and shoe/treadmill situation. The differences were substantial. It is not yet understood how the human locomotor system adapts to a particular treadmill running situation. However, it is concluded that individual assessment of running kinematics on a treadmill for shoe or shoe orthotic assessment may possibly lead to inadequate conclusions about overground running.

A kinematic comparison of overground and treadmill running.

The purpose of this investigation was to determine whether a graded response in gait kinematics, kinetics, and EMG occurs as shoe heel height increases. Four different shoes, including one flat shoe and three shoes with high heels, were tested in this investigation. The average heel heights of the four shoes were 1.4 cm, 3.7 cm, 5.4 cm, and 8.5 cm. Kinematics, kinetics, and muscle EMG were measured during the stance phase of gait on 13 healthy female subjects while wearing each of these 4 shoes. Systematic increases in the active vertical, propulsive, and braking forces were found as shoe height increased. Ankle and knee flexion and soleus and rectus femoris activity showed a graded response as heel height increased. One surprising result was the behavior of the maximal vertical impact force peak and the maximal loading rate during heel impact. The vertical impact force peaks and the maximal vertical loading rates were highest for the shoe with 3.7 cm heel height and lowest for the flat shoe and the shoe ...

The Influence of High Heeled Shoes on Kinematics, Kinetics, and Muscle EMG of Normal Female Gait

Gait characteristics as a function of age and gender

Purpose:The purpose of this study was to quantify changes in foot eversion and tibial rotation during running resulting from systematic changes of material composition of five shoe inserts of the same shape.Methods:Tests were performed with 12 subjects. The inserts had a bilayer design using

Veronica Fisher

Papers

A kinematic comparison of overground and treadmill running.

The Influence of High Heeled Shoes on Kinematics, Kinetics, and Muscle EMG of Normal Female Gait

Gait characteristics as a function of age and gender

Effect of shoe insert construction on foot and leg movement.

External loads throughout a 45 minute run in stress fracture and non-stress fracture runners