Effects of Cardiac Rehabilitation with Lumbar-Type Hybrid Assistive Limb on Muscle Strength in Patients with Chronic Heart Failure-A Randomized Controlled Trial

Background: Aiming to establish an effective tool in new cardiac rehabilitation programs, we investigated the use of a lumbar-type hybrid assistive limb (HAL) in patients with heart failure (HF) who had difficulty in walking at the usual speed of healthy subjects (approximate to 80 m/min). Methods and Results: We randomly assigned 28 HF patients (age, 73.1 +/- 13.8 years) to perform a sit-to-stand exercise with or without HAL. The sit-to-stand exercise was repeated as many times as possible as cardiac rehabilitation therapy over a period of 6-10 days. We measured 5 parameters before and after the completion of cardiac rehabilitation: B-type natriuretic peptide, Short Physical Performance Battery (SPPB), 6-min walking distance (6MWD), 30-s chair-stand test (CS-30), and isometric knee extensor muscle strength. The SPPB and 6MWD were significantly improved, and the CS-30 score was somewhat improved, after the exercise therapy in both the HAL and non-HAL groups. The knee extensor muscle strength improved significantly in the HAL group (0.29 +/- 0.11 to 0.35 +/- 0.11 kgf/kg, P<0.01), but showed no change in the non-HAL group (0.35 +/- 0.11 to 0.35 +/- 0.13 kgf/kg, P=0.40). Conclusions: The improved knee extensor muscle strength in the HAL group suggests that the lumbar-type HAL may be an effective tool for cardiac rehabilitation in HF patients with frailty, which is a predictor of poor prognosis in HF.