Based on the linked source; automatically prepared and checked against the original report.
Study design
Researchers conducted a single-center repeated-measures experiment in Japan from September to December 2024. Twenty-two healthy young men were tested, but eight were excluded because they lacked enough valid observations, leaving 14 participants averaging 20.7 years old. None regularly used wheelchairs or had wheelchair-sport experience. Each participant propelled the same wheelchair rugby wheelchair along a straight 5 m course, with its configuration unchanged between conditions.
Comparing fixation conditions
Participants completed trials with a rigid cervical collar and without cervical fixation, in randomized order. Video from a smartphone camera recorded propulsion at 30 frames per second, while researchers analyzed velocity and two-dimensional coordinates for the left ear, shoulder, elbow and wrist. The study’s velocity assessment was not blinded, and the investigators did not formally quantify measurement reliability. Fifteen extreme kinematic observations were excluded using investigator judgment without a prespecified quantitative cutoff.
Main findings and limits
Cervical fixation did not produce a statistically significant change in propulsion velocity. The overall non-fixation versus fixation difference was 0.030 m/s, with a 95% confidence interval from −0.002 to 0.063 m/s. Fixation was associated with greater upper-arm excursion, greater maximum elbow angle and greater elbow range of motion, alongside a smaller minimum upper-arm segment angle. The authors studied healthy participants as an initial controlled step, so the findings do not directly establish effects in athletes with tetraplegia or wheelchair rugby players.
