Sensitivity of cycling Motion Performance Indicators (MPIs) to incremented load and their relationship with performance in professional cyclists

Abstract

There is a lack of research assessing Motion Performance Indicators (MPIs), which have been recently made commercially available. Therefore, this study explored: (1) the influence of incremented exercise on MPIs and; (2) the relationships between MPIs and cycling performance at different intensities during a graded exercise test (GXT) in professional cyclists. Thirty-six professional cyclists performed GXT until exhaustion with their own bikes attached to a cycle ergometer. MPIs were collected using a real-time motion capture system based on inertial measurement units at 100 Hz of sample rate. Data were extracted from intensities of the GXT when lactate thresholds (LT1, LT2) and peak power (POpeak) were determined. Results showed that only Pelvic Angle ( p < 0.01, d > 1.15) and Pelvic Rotation ( p < 0.01, d > 1.37) were sensitive to increases in exercise intensity (i.e. greater inclination and increased rotation at greater power). Multivariate liner regression analyses showed that a reduced range of movement (ROM) for the upper legs at sub-maximum intensities (LT1 and LT2) was associated with greater power production ( r2 > 0.21), whilst a reduced ROM for the right foot was associated with greater POpeak ( r2 = 0.20). In conclusion, changes in movement patterns were limited to a greater inclination and rotation of the pelvis at maximum power without changes in other MPIs throughout the GXT. Cyclists who produced greater power presented less ROM for their upper legs at LT1 and LT2 whilst at POpeak and greater power production was moderately associated with less ROM for the right foot. Coaches may be able to use MPI to analyze for excess ROM, particularly at higher exercise intensities, as this seems to increase inefficiencies and limit power production.