Prospective Study
Copyright ©The Author(s) 2019. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Clin Cases. Oct 6, 2019; 7(19): 2976-2985
Published online Oct 6, 2019. doi: 10.12998/wjcc.v7.i19.2976
Immediate muscle strengthening by an end-effector type gait robot with reduced real-time use of leg muscles: A case series and review of literature
Chang Ho Hwang
Chang Ho Hwang, Department of Physical Medicine and Rehabilitation, Ulsan University Hospital, University of Ulsan College of Medicine, Ulsan 44033, South Korea
Chang Ho Hwang, Department of Biomedical Engineering, School of Electrical Engineering, University of Ulsan, Ulsan 44610, South Korea
Author contributions: Hwang CH substantially contribute all of (1) conception and design, acquisition of data, or analysis and interpretation of data; (2) drafting the article or revising it critically for important intellectual content; (3) final approval of the version to be published; (4) agreement to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.
Supported by the Research Project of Future Growth Engine Flagship Project, No: CN16040) by Minister of Science, ICT and Future Planning; the National Research Foundation of Korea grant funded by the Korea government (Ministry of Science, ICT and Future Planning), No. NRF-2017R1A2B4011478.
Institutional review board statement: This study was approval of the Institutional Review Board, No. UUH-2016-01-007.
Clinical trial registration statement: The clinical trial is registered with ClinicalTrials.gov, using identifier NCT02962453. Details can be found at https://clinicaltrials.gov/ct2/show/NCT02962453.
Informed consent statement: Informed written consent was obtained from the participants for publication of this report and any accompanying images.
Conflict-of-interest statement: The author declares no conflict of interest.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Corresponding author: Chang Ho Hwang, MD, PhD, Full Professor, Department of Physical Medicine and Rehabilitation, Ulsan University Hospital, University of Ulsan College of Medicine; Department of Biomedical Engineering, School of Electrical Engineering, University of Ulsan, 93 Daehak-ro, Nam-gu, Ulsan 44610, South Korea. chhwang1220ciba@gmail.com
Telephone: + 82-52-2507210 Fax: +82-52-2507211
Received: April 24, 2019
Peer-review started: May 8, 2019
First decision: August 1, 2019
Revised: August 27, 2019
Accepted: September 13, 2019
Article in press: September 13, 2019
Published online: October 6, 2019
Abstract
BACKGROUND

De-afferentation or non-weight bearing induces rapid cortical and spinal α-motor neuron excitability. Author supposed that an end-effector type gait robot (EEGR) could provide patients with a training condition that was specific enough to activate rapid cortical/spinal neuroplasticity, leading to immediate muscle strengthening. The electromyographic and biomechanical comparisons were conducted.

AIM

To compare the electromyographic activities of the thigh and shank muscles and isometric peak torque (PT) before and after walking training on a floor or in the end-effector gait robot.

METHODS

Twelve outpatients without ambulatory dysfunction were recruited. Order of two interventions (5-min training on a floor at a comfortable pace or training in an EEGR with non-weight bearing on their feet and 100% guidance force at 2.1 km/h) were randomly chosen. Isometric PT, maximal ratio of torque development, amplitude of compound motor action potential (CMAP), and area under the curve (AUC) were evaluated before and 10 min after both interventions.

RESULTS

The degree of PT improvement of the dominant knee flexors was larger in the EEGR than on the floor (9.6 ± 22.4 Nm/BW, P < 0.01). The EEGR-trained patients had greater PT improvement of the dominant knee extensors than those who trained on the floor (4.5 ± 28.1 Nm/BW, P < 0.01). However, all electromyographic activities of the thigh and shank muscles (peak CMAP, mean and peak AUC) were significantly lower for the use of the EEGR than walking on the floor.

CONCLUSION

Immediate strengthening of the knee flexors and extensors was induced after the 5-min EEGR training, despite reduced muscular use.

Keywords: Robotics, Rehabilitation, Muscles, Neuronal plasticity, Gait, Knee

Core tip: Just five-minute end-effector type robot-assisted gait training with non-weight bearing on their feet and 100% guidance force may induce immediate strengthening of the knee flexor and extensor muscles. Moreover, it may even reduce the real-time use of the thigh and calf muscles. It may be a useful tool to strengthen the leg muscles in the elderly or in patients with musculoskeletal injuries. As for its underlying mechanism, author supposes the rapid brain and spinal plasticity in theory.