Isometric hip and knee torque measurements as an outcome measure in robot assisted gait training

Abstract

Background: Strength changes in lower limb muscles following robot assisted gait training (RAGT) in subjects with incomplete spinal cord injury (ISCI) has not been quantified using objective outcome measures. Objective: To record changes in the force generating capacity of lower limb muscles (recorded as peak voluntary isometric torque at the knee and hip), before, during and after RAGT in both acute and subacute/chronic ISCI subjects using a repeated measures study design. Methods: Eighteen subjects with ISCI participated in this study (Age range: 26-63 years mean age = 49.3 + 11 years). Each subject participated in the study for a total period of eight weeks, including 6 weeks of RAGT using the Lokomat system (Hocoma AG, Switzerland). Peak torques were recorded in hip flexors, extensors, knee flexors and extensors using torque sensors that are incorporated within the Lokomat. Results: All the tested lower limb muscle groups showed statistically significant (p<0.001) increases in peak torques in the acute subjects. Comparison between the change in peak torque generated by a muscle and its motor score over time showed a non-linear relationship. Conclusions: The peak torque recorded during isometric contractions provided an objective outcome measure to record changes in muscle strength following RAGT.

A novel adaptable isometric strength analysis and exercise development system design

“…22,23,30 Strength measurements in the field of medicine may be required in cases such as the diagnosis of diseases and injuries related to the neuro-muscular system, determination of treatment methods, and control of rehabilitation processes. [31][32][33][34]39,51 During the treatment and (or) posttreatment rehabilitation [40][41][42] of injured athletes 28 or sedentary individuals with orthopedic [35][36][37][38] and neurological [31][32][33][34] disorders, due to the limitation of movement caused by the functional disorders in the joints, benefits to the skeletal muscular system can be provided by isometric exercises and measurements. 51 Similarly, it is possible to predict the risk of injury that may occur in athletes via isometric muscle strength measurements.…”

“…26 From this point of view, observing the strength and power changes of athletes may play an important role in the training of elite athletes, in the regulation of competition preparations and training programs, [21][22][23]26,27 stages of return to sport during 28 and after the injury period. 16,29 In addition to strength and power measurement studies in the field of sports, 22,23,30 patients with neurological/neuromuscular [31][32][33][34] and orthopedic disorders, [35][36][37][38] physical therapy and rehabilitation patients, [39][40][41][42] the elderly, 8,43,44 children, [45][46][47] and various special groups [48][49][50] may also need to be observed the changes in strength and power. Strength and power measurements are used in all these groups, for development purposes, control purposes, 35,36,51 diagnosing diseases, 17,30,52 or planning treatments or creating normative data 17,20,47 by receiving feedback, etc.…”

“…1 Measuring muscle strength and power is important for evaluating the development of athletes' performance in the field of sports, 22,23,30 evaluating various patients, diseases, and treatment processes in the field of medicine. [31][32][33][34] Especially applications on static muscle strength measurement in the field of sports and medicine are frequently encountered. 35,64,67,74,80,[102][103][104][105][106] Concrete information could be acquired about the physiological condition of the muscle(s) evaluated by isometric contractile strength measurements.…”

Test–retest reliability of the electromyographic fatigue threshold for cycle ergometry

“…The amplitude (µVrms) value for the EMG signal was calculated as the average of the completed bursts from 10‐second epochs during the last 10‐seconds of each power output until participants reached voluntary fatigue . The EMG signals were bandpass filtered (fourth‐order Butterworth) at 10–500 H z .…”

Reliability of the log‐transformed EMG amplitude‐power output relationship for incremental knee‐extensor ergometry

“…The amplitude (microvolts root mean square, µVrms) value for the EMG signal was calculated as the average of the completed kick thrusts from 10‐s epochs during the last 10 s of each power output until the participants reached voluntary fatigue . The EMG amplitude from the MVIC was calculated for a 2‐s time period corresponding to seconds 2–4 of the 6‐s isometric muscle contraction .…”