## 2 Methods and Materials
### Data Analysis  
Marker trajectories were smoothed with a 6 Hz fourth-order low-pass Butterworth filter and kinematic data processed using Visual 3 DTM software (C-Motion Inc., Rockville, MD, USA). A power spectrum density calculation was conducted and 99% of the power was contained in the first 6 Hz, and, therefore, a 6 Hz cutoff frequency was chosen. All kinematic variables were quantified within the loading and landing phases of the unilateral 180\({}^{\circ}\) jump. The loading phase was defined as the instant the knee commenced flexion (following a stationary single-leg stance) until the instant of maximum knee flexion of the same leg. The landing phase was defined as the instant the landing foot made contact with the ground (determined from kinematic data when the metatarsal markers stopped their downward trajectory) until maximum knee flexion was attained. Individual segment pose and segment coordinate systems (SCS) for each participant was generated with Visual 3 DTM from the static calibration trial using a multi-anatomical landmark optimized method [32] and utilizing the markers as follows: The pelvis was defined using the X-Y plane passing through the ASIS and PSIS, the origin of the SCS at the midpoint between the 2 ASIS markers, which allowed the segment X axis to be determined by the vector between the origin and the right ASIS marker. The SCS Z axis was determined by the axis perpendicular to the X-Y plane in the vertical direction, and, lastly, the SCS Y axis calculated as the cross product of the X and Z axes. All remaining segments were defined using the principle of creating a frontal plane using medial and lateral proximal and distal markers and then determining the SCS Z (vertical) axis as the unit vector directed from the distal segment end to the proximal segment end. The SCS Y axis was then perpendicular to the frontal plane and Z axis, and, finally, the X axis determined by the application of the right-hand rule. The origin of each SCS was located at the proximal end for each segment. Knee joint angles were calculated according to the International Society of Biomechanics recommendations as the shank segment relative to the thigh segment resolved into the proximal segment SCS, using the Cardan sequence XYZ, where movement in the X plane denotes flexion (\(-\))/extension (\(+\)), Y plane abduction (\(-\))/adduction (\(+\)), and Z plane axial internal (\(+\))/external (\(-\)) rotation [33]. Knee alignment in the Y plane was defined as zero when the long axes of the thigh and shank were aligned. Axial rotation of the thigh segment (Z plane) was calculated relative to the pelvis segment [33]. For both adduction/abduction and axial rotation, the non-dominant leg was multiplied by negative one to allow comparison between limbs. Pelvis motion was assessed in terms of flexion/extension, adduction/abduction, and axial rotation, which was computed as the angle of the pelvic segment relative to the fixed laboratory/global coordinate system (GCS) using Cardan sequence XYZ and the right-hand thumb rule [33]. Given the dynamic nature of the activity and magnitude of axial rotation involved in this activity, the sequence XYZ was selected instead of ZYX as described by [PERSON] [34]. All variables were averaged across the five trials per leg for each participant; these means were then used to calculate group means. The continuous relative phase (CRP) was calculated as a representative measure of inter-segmental coordination between the thorax and pelvis segmental rotations about the vertical (z) axis. To calculate the CRP between two segments, the phase-angle (\(\mathcal{D}\)) from the phase-plane portraits of each segment were calculated. Phase-portraits were constructed with angular displacement (\(\theta\)) on the horizontal (\(x\)) axis and the first derivative, angular velocity (\(\omega\)) on the vertical (\(y\)) axis.