During physical rehabilitation from an injury, patients lose a lot of strength and endurance from overall fitness. Studies surrounding possible tools to rehabilitate and maintain fitness simultaneously are limited. During cardiac rehabilitation, heart rate must be monitored constantly due to risk of more heart related complications. Thus, being able to predict heart rate values prior to exercise is critical for cardiac rehab patients. This study was designed to investigate the correlation between amount of weight assisted and heart rate produced This study also evaluated the efficacy of the Lever Running System on maintaining fitness and promoting rehabilitation. Specifically, this study was undertaken to determine if the benefits of maintaining fitness outweigh the risks of injury during rehabilitation.