Study on design of rehabilitation device for athlete to reproduce running motions in consideration of body interlocking using planar linkage

Abstract

The current increase in health awareness has led to greater attention to exercise. However, the growing number of competitors in various sports has caused a concomitant increase in the number of injuries during matches. After an injury, an immediate return to competition is difficult. A related problem is the shortage of athletic trainers. Strong teams such as professional, corporate, and university teams retain athletic trainers who can create unified plans spanning from injury to recovery, including subsequent recurrence prevention. However, only a fraction of teams can maintain such support staff, and so measures to accommodate the increase in the competitive population in various sports are beginning to fall increasingly behind. Competitive sports are supported by the continued influx of amateur athletes, and so when members quit due to injury or injury aggravation, it is undesirable both for the individual and for the sport as a whole. Thus, there is a need to develop rehabilitation devices that can provide an environment in which the user can safely be rehabilitated while determining his or her own state of recovery even if no athletic trainer is available. Conventional rehabilitation devices have emphasized recovery of cardiopulmonary function or the function of specific joints, with little to no development of devices aiming for an early return to competition. Against this background, the objective of this study is to design and develop a rehabilitation device that prevents reduced range of motion in joints and also prevents decreased muscle strength and proprioception in athletic movements during the rehabilitation period. The device works by recreating a running action close to that used in daily life as a common movement in numerous sports. We demonstrate that the use of a planar linkage with one degree of freedom is effective in the design of such a device. This rehabilitation device uses a planar six-bar linkage to simulate the path of the legs during running. Furthermore, we investigate a design with a form that uses a slider crank mechanism with the motion of the arms during running as an input to create the proprioceptive sensation of a motion that includes not only the legs but the arms in a linked operation. We aim to develop a device that, by being used while seated in a saddle and employing adjustable links, can track a range of different leg pathways instead of being designed for a specific individual. Using a prototype device, we verify the reproduction of the running motion as well as the amounts of muscle activity when using the apparatus in order to investigate its utility as a rehabilitation device.