Effect of age and activity level on lower extremity gait dynamics: an introductory study.

Elderly adults should perform exercises that maintain or improve balance to reduce risk of injury from falls. Bone fractures secondary to falls in the elderly, particularly sedentary females, continue to pose a major health and economic problem. A greater understanding of the processes that contribute to the propensity for falling may be obtained by considering changes in gait biodynamics with age and activity level. Therefore, the purpose of this study was to quantify the relationships between age/activity level and selected biodynamic parameters of the lower extremity during normal gait. Seventeen healthy women, 9 young and 8 elderly, were divided into groups of 9 active and 8 sedentary subjects. Three-dimensional (3D) video motion and force platform kinematic and kinetic data were collected from the hip, knee, and ankle of the right lower extremity as the subjects walked at self-selected speeds. Data were analyzed as functions of age and activity level by using a 2-way analysis of variance. As expected, our results show that the elderly group had significantly greater (p < 0.05) functional and mobility limitations in their lower extremity joints than did the younger group. Significant, age-related lower-limb gait alterations were manifested primarily at the ankle, whereas activity-related alterations were manifested most prominently at the hip. The knee showed the fewest changes accompanying age or activity level. Thus, age and activity level affect gait, which may have a role in the subsequent development of a predisposition to gait-related imbalances and resultant falling and increased hip fracture risk. Strength and conditioning professionals may consider these factors related to age and activity level when individualizing exercise regimens for their older, or sedentary, clients. Prophylactic physical activities involving specific, controlled 3D body movements may help prevent abnormal lower-limb joint kinematics (and their hypothetically coupled, intrinsic postural control strategies), thereby reducing fall and fracture propensity.