Frontal and sagittal plane analyses of the stair climbing task in healthy adults aged over 40 years: what are the challenges compared to level walking?

Objective. This study compared stair climbing and level walking in healthy adults aged over 40 years. Design. Eleven subjects performed at their comfortable speed. Background. The number of parameters studied during stair climbing has been limited, in particular in the frontal plane. Methods. Time–distance parameters and three-dimensional kinematic data were obtained using foot-switches and an Optotrak system. Ground reaction forces were collected with a force platform embedded in the second step of the staircase or in the ground for level walking. Relative angles were calculated using a Cardanic rotation matrix and the net moments and the powers at the ankle, knee and hip joints were estimated with an inverse dynamic approach. Results. A significant longer mean cycle duration and a shorter proportion of time in stance was obtained for stair climbing as compared to level walking. Profiles of the frontal plane joint angles, moments and powers indicated a different action of the hip abductors across tasks to control the pelvis in stance. Profiles of the sagittal plane confirmed the dominant role of the knee extensors during stair climbing but revealed also a knee-hip energy generation pattern that allows the avoidance of the intermediate step. Conclusions. Results suggest environment specific adaptations of the neuro-musculo-skeletal system that should be considered in the rehabilitation of stair climbing in patients.