Changes in muscle activation after reach training with gravity compensation in chronic stroke patients

Abstract

The objective of this study is to examine the effect of gravity compensation training on reaching and underlying changes in muscle activation. In this clinical trial, eight chronic stroke patients with limited arm function received 18 sessions (30 min) of gravity-compensated reach training (during 6 weeks) in combination with a rehabilitation game. Before and after training, unsupported reach (assessing maximal distance, joint angles and muscle activity of eight shoulder and elbow muscles) and the Fugl-Meyer assessment were compared. After training, the maximal reach distance improved significantly by 3.5% of arm length, together with increased elbow extension (+9.2°) and increased elbow extensor activity (+68%). In some patients, a reduced cocontraction of biceps and anterior deltoid was also involved, although this was not significant on group level. Improvements in unsupported reach after gravity compensation training in chronic stroke patients with mild to severe hemiparesis were mainly accompanied by increased activation of prime movers at the elbow, although in some patients, improved selective joint control may also have been involved. Gravity compensation seems to be a suitable way to provide active, task-specific treatment, without the need for high-tech devices. Further research on a larger scale, including control groups and combinations of arm support with functional hand training, is essential to enhance the potential of arm support to complement poststroke arm rehabilitation.

A cross-species neural integration of gravity for motor optimisation

“…We applied a simple and widely-used decomposition method to isolate the tonic (gravity-dependent force) and the phasic (inertial-dependent force) EMG components from the full EMG signal (Buneo et al, 1994; d’Avella et al, 2006, 2008; Flanders and Herrmann, 1992; Flanders et al, 1994, 1996; Olesh et al, 2017; Prange et al, 2009b, 2012; Russo et al, 2014). The tonic component emanates from the motionless rest-periods before and after the movement (Fig.…”

“…Such a neural policy is thought to facilitate the production of accurate movements to changing directions, amplitudes, durations, and loads, by merely scaling the inertial-dependent part of the motor command. Albeit based upon old literature, this influential Compensation hypothesis still guides current research in various fields such as motor control (d’Avella et al, 2008; Guigon et al, 2007; Kadmon Harpaz et al, 2014; Olesh et al, 2017; Russo et al, 2014), movement perception (Cook et al, 2013; Edey et al, 2019) or neuro-rehabilitation (Krabben et al, 2012; Prange et al, 2009a, 2009b, 2012; Raj et al, 2019).…”

Direction-dependent arm kinematics reveal optimal integration of gravity cues

“…The main benefit of a compensation strategy would be the simplification of motor planning by allowing for invariant trajectories (Hollerbach and Flash, 1982; Atkeson and Hollerbach, 1985). Current research in fields as diverse as neurorehabilitation, movement perception, or motor control modularity, assumes such a compensation principle (Prange et al, 2009, 2012; Cook et al, 2013; Russo et al, 2014). …”

Development of Activity-Related Muscle Fatigue during Robot-Mediated Upper Limb Rehabilitation Training in Persons with Multiple Sclerosis: A Pilot Trial

“…A possible solution to this phenomenon is to provide the patients with some assistance during the training to help them perform the exercise and sustain the training endurance which is important from a neural drive point of view. Such assistance can be gravity compensation of the arm, which is shown to provide support and be beneficial for the quality and active range of upper limb movement of MS (and other neurological) patients during their upper limb rehabilitation [ 16 , 27 , 28 ]. The level of such assistance is usually determined based on the muscle strength of the patient and only once at the beginning of the training.…”