Title: VR-Based Training Increased Perceptual-Accuracy of Motor Effort at Higher Effort-intensities in Healthy Young Adults: Implications for Stroke and Neurologic Populations*
Author 1:
First Name: Emmanuel
Last Name: John
Organization: York College of Pennsylvania
Country: United States
Email: ejohn@ycp.edu
Author 2:
First Name: Rahul
Last Name: Soangra
Organization: Chapman University
Country: United States
Author 3:
First Name: Brian
Last Name: Bischoff
Organization: Chapman University
Country: United States
Email:
Author 4:
First Name: Sagar
Last Name: Jambusaria
Organization: Chapman University
Country: United States
Author 5:
First Name: Kristen K
Last Name: Abrajano
Organization: Chapman University
Country: United States
Author 6:
First Name: Kevin
Last Name: Llave
Organization: Chapman University
Country: United States
Author 7:
First Name: Kody
Last Name: Eckert
Organization: Chapman University
Country: United States
Author 8:
First Name: Moheb Shawky
Last Name: Yani
Organization: Chapman University
Country: United States
Topic(s): General Topics
Keywords: Sense of Motor Effort, VR-based Rehabilitation, Gamified Handgrip Training
Abstract: Background
Previous studies have shown that Virtual Reality (VR) training improves motor task performance. VRtasks entrains mirror neuron systems involved in both motor planning and motor learning. The ability to accurately predict (feedforward) motor effort required to accomplish a motor task is suggested to be centrally mediated using efferent copy of descending motor command signals. However, how VR-based unilateral handgrip effort game training could affect the perceptual accuracy of sense of motor effort(SOE) is unknown.

Purpose
Prior to future investigations in neurologic populations, the current study as a first step, seeks to understand how submaximal motor control handgrip training in a gamified VR environment, will influence changes in perceptual accuracies of SOE in healthy young individuals.

Methods
This 6-week VR training study utilized a robotic arm with a handgrip sensor (Armeo Spring®, Hocoma, DIH, Netherlands) in a VR gaming environment. Participants were comfortably seated with robotic arm-assisted weight support of their dominant upper extremities. The shoulder was slightly flexed and abducted, elbows flexed at 90, forearms in mid-prone, and wrists positioned at 25-30 of extension. Seat height was adjusted to keep the forearms in the horizontal plane. Participants first exerted 3Maximum Voluntary Contractions (MVC), as baseline, and were later asked to exert controlled handgrip force (effort) they perceived to be equivalent to 10%, 30%, 50%, 70% and 90% of MVC in a random sequence. Participants took part in 15 trials each week. The handgrip training involved playing 5-sets (3minutes each) of VR games (Monsters®, Hocoma) of varying precision handgrip motor control tasks, picking up monsters escaping from fi re to safety over a virtual cliff, 3-times a week for 6-weeks, totaling18 sessions. Perceptual accuracies of participants’ SOE handgrip efforts data were analyzed for variability and perceptual accuracy using percentage changes and standard deviations from theoretically expected SOE perceptual accuracies.

Results
Participants improved perceptual accuracies of their SOE for higher MVCs (70% and 90%). Perceptual errors reduced by 86.2% at 70%, and 44.2% at 90% MVCs. Although the errors were reduced for higher effort intensities, variability in handgrip effort increased with 6-weeks of training. Variability increased by 137% for 10% MVC, 42% for 30% MVC, 97% for 50% MVC, 81% for 70% MVC, 103% for 90% MVC.

Conclusion(s)
Participants improved perceptual accuracy of SOE after 6-weeks of VR-handgrip gamified training at higher intensity of effort, but not at lower effort levels. Variability increases post-VR training suggested that apparently healthy participants may have used multiple motor control strategies to generate more accurate SOE at higher levels of motor effort.

Implications
Further research is warranted to determine the effects, dosage, and modality of handgrip-VR-training protocols that can enhance precision motor control/SOE recovery after initial onset of motor paralysis or paresis in stroke and other neurologic lesions. Future studies should elucidate both the neural and neurophysiological mechanisms underlying how impaired perceptions of precision motor effort is mediated through VR-training to drive neuroplastic changes of motor recovery. The long-term retention of the training effects from improved SOE perceptual accuracies post-VR training is also needed.

*Previously presented at the World Physiotherapy Conference, Dubai, 2023