Since the cycling movement involves the flexion and extension of the hip, knee and ankle joints, normally the sagittal plane is the one that is more explored. Nevertheless, the literature already
reported a significant movement of the knee on the frontal plane and a correlation of it with pain. Therefore, this study aims to present preliminary results of the 3D movement pattern of the knees
joint and feet during progressive cycling.
Three male competitive cyclists (age: 28±7.2, more than two years of Mountain Bike training) participated in this study. For the 3D kinematic analysis, we used eighteen OptiTrack Prime 17W cameras
(240Hz) around the subjects. Thirty retro-reflective markers were fixed on the lower body (IOR Gait protocol). They performed a progressive exercise test using their own bicycles on a stationary
cycling trainer. The motion analysis assessment consists of one minute in each intensity: 70% maximal heart rate (MHR), 80% MHR and 100% MHR. We used the equation to determine the MHR (Tanaka et al.
2001) and a FT4 Polar to control it during the test. The 3D coordinates of the markers were processed in the Visual3D software (C-Motion Inc.) and were smoothed using a low pass digital Butterworth
filter (cut off frequency 8 Hz). In order to define the pedal cycle, we referred the knee joint center to the pelvis and used the maximum values of the z coordinates. In order to perform a qualitative
analysis, we plotted the left and right knee joints and feet trajectories in each plane (sagittal, frontal and transverse). The range of motion of the knee joints (flexion/extension) was also
calculated. For each subject we analyzed the symmetry between right and left limbs and the influence of the progressive intensity on it.
The knee joint centers and feet trajectories of all the subjects were in agreement with the literature (sagittal plane) and the right and left knees RoM presented similar values. A comparison between
the right and left knee joint centers revealed larger amplitude values of the left knee in all the intensities (subject 1). Furthermore, in high intensity (100%MHR) the movement pattern of the left
knee and left foot were changed (frontal and transverse), and this could be related with muscle fatigue or with a limbs dominance. The intensity did not show influence on the knees and feet movement
patterns for both sides in the subject 2. However, in the low intensity, we found smaller amplitudes values in the left knee (frontal and transverse plane). Both knees and feet movement patterns were
influenced by the high intensity (subject 3) and the movement variability was also increased, suggesting a fatigue effect.
We can conclude that different intensities can change the knees and feet plane movement patterns in diverse ways. This fact, highlight the importance to perform a 3D analysis to evaluate the cycling
symmetries and try to prevent injuries.