Author(s): GROSPRETRE, S., RUFFINO, C.1, JOURNOT, P.1, MARUSIC, U.3,4, WOLLESEN, B.5, Institution: C3S - EA4660, Country: FRANCE, Abstract-ID: 958

INTRODUCTION:
The duration of arm-reaching movements depends on target distance and size, as modeled by Fitts in 1954 through a linear relationship between target difficulty and movement duration (1). Thus, increasing execution speed compromises accuracy and vice versa. Both elite sports performance and daily tasks rely on managing this speed-accuracy trade-off. This study aimed to examine how a virtual reality (VR) exergame can improve this motor competence.
METHODS:
Twelve healthy young participants (23.4 years old, 4 females) completed three sessions on separate days in a random order to assess the effects of three VR interventions: control condition (CONT), accuracy-focused (ACC), and speed-focused (SPE). The control condition consisted of a neutral immersive VR video. ACC and SPE involved playing the VR rhythm game "Beat Saber” (Beat Games, Prague), where players cut approaching cubes with two virtual sabers. In ACC, cubes were at minimum size, cutting tolerance was reduced, and speed was moderate. In SPE, cube size and display speed were maximized, while cutting tolerance increased. Each intervention (CONT, ACC, SPE) lasted 15 minutes. Before and immediately after each session, participants performed a Fitts’ pointing task with their right arm, targeting four difficulty levels (determined by Fitts formula) on a large vertical touchscreen (120 × 70 cm). Standing participants extended their arm to touch targets in four directions: UP, DOWN, RIGHT, and LEFT. Throughout the experiment, variation of electromyographic (EMG RMS) activity of 5 shoulder muscles and three-dimensional hand acceleration were recorded.
RESULTS:
CONT induced no changes in pointing times or muscle activations. In RIGHT and LEFT pointing, SPE reduced pointing time for the largest target (low difficulty), increasing Fitts’ slope (P<0.001). Conversely, ACC reduced pointing time for the smallest targets (high difficulty), decreasing Fitts’ slope (P<0.001). UP pointing remained unaffected. For DOWN pointing, SPE increased pointing time in difficult targets (P=0.011), whereas ACC reduced pointing time in easier targets (P=0.006). Muscle activation strategies and deceleration patterns varied between ACC and SPE. Arm accelerometry confirmed that the game used primarily involves horizontal and downward movements.
CONCLUSION:
VR exergaming acutely modifies motor strategies by adjusting the speed-accuracy trade-off, as reflected in changes to Fitts’ slope. These effects are intervention-dependent: accuracy training improved precise targeting, while speed training enhanced performance on simpler tasks. However, the speed-focused session impaired accuracy in downward movements. Actimetry data suggest that these effects are direction-specific and linked to the training, as no significant impact was observed in the less trained movement direction (UP).
Reference: (1) Fitts PM (1954) J Exp Psychol