Elliptical Trainer Redesign to Diversify Muscles Recruitment

Abstract

This work aims to introduce simple-to-implement modifications to the elliptical trainer device to increase its utility with added new exercise options. The effectiveness of the introduced modifications was assessed on 51 subjects, with effectiveness representing the recruitment of a broader range of muscle groups with desired intensity levels. The improvements include a new in-phase mode, where bilateral body synchronization creates a skiing-like motion, and a variable range of motion through adjusting the stride length of a rotating-link mechanism. The impact of these modifications on muscle recruitment was assessed by recording surface electromyogram (sEMG) from eleven major muscles while performing a total of six exercise routines. The routines have various combinations of mode and intensity to cover the traditional mechanism and the newly- introduced mechanism adjustments for comparative analysis. The results have shown that increasing the stride length increases the demand on lower limbs muscles during the anti-phase mode while decreasing it on upper limb muscles. When comparing the two exercise modes, all muscle groups showed significantly higher activity in the in-phase mode except for thigh muscles (Hamstrings and Quadriceps). Hamstrings revealed significantly higher activity in the anti-phase mode, while Quadriceps showed no significantly different activity between the two modes. The introduced design modifications are shown to diversify the demand on major skeletal muscles hence improving its functionality at low added cost. Furthermore, these results can be exploited to implement gradual physiotherapeutic rehabilitation plans targeting various muscle groups with desired intensity levels.