Differences in speed, trunk range of motion, and cycle kinematics between Para-Nordic sit-skiing classes across...

In sit-skiing, propulsion is generated by the upper-extremities and trunk. We examined if terrain incline and class affected the speed, trunk range of motion, and cycle kinematics of sit-skiers during competitive distance events. Thirty-six elite Para-Nordic sit-skiers were equipped with integrated IMU- and GNSS-sensors at the 2022 and 2023 World Championships, and five individual races were analysed at each event. Relationships between speed, trunk range of motion, cycle length and cycle rate and "incline" and "class" were modelled using mixed-effects models. The classes showed similar adaptations to changing incline, with decreased speed and cycle length and relatively constant range of motion and cycle rate. Compared to the LW12 class, the LW10.5 class had a lower speed (p = 0.004), trunk range of motion (p = 0.005) and cycle length (p = 0.049) at the 2022 event and lower range of motion (p = 0.017) and higher cycle rate (p = 0.020) at the 2023 event. There were considerable overlaps between the classes in all variables, which highlights that despite a relatively large number of measurements, this study was likely statistically underpowered for the between-class comparisons. Overall, this study suggests that while some differences exist between the LW12 and LW10.5 classes, between-class differences may be smaller than the differences between individual athletes.