The Effects of Parabolic Arc Height and Velocity of a Target During Interception on Forward Reach Movement Mechanics

Virtual reality (VR) provides immersive, interactive environments that can be carefully controlled for shaping movement during rehabilitation. Game mechanics such as object velocity and trajectory are often manipulated to increase engagement, but their effects on motor control strategies relevant for therapy remain unclear. This study examined how ball velocity and parabolic vertex height influence interception performance and movement patterns in VR dodgeball. Twenty-one healthy adults (10 males and 11 females; mean age of 24 ± 8 years) played virtual dodgeball in two visual environments. In the first visual environment, ‘Cannon’ dodgeball, the vertex heights were 4 m and 8 m. In the second visual condition, ‘Day’ dodgeball, the velocities were set to 40 m/s and 60 m/s. The outcomes included interception success, time to intercept, and joint kinematics (ankle, knee, hip, and lumbar spine flexion angles). Both higher velocity and vertex height reduced interception success (p < 0.001* and p < 0.001* respectively), indicating increased difficulty. However, only vertex height significantly influenced joint flexion patterns during gameplay (ankle p < 0.001*, knee p < 0.001*, hip p = 0.019*, and lumbar p = 0.026*). These results suggest that while both vertex height and velocity modulates task challenge, trajectory and vertex height more effectively shape movement strategies. Tailoring the vertex height of launched virtual objects in VR games may therefore optimize therapeutic engagement and promote desired motor behaviors.