Effects of Rugby Training Exposure on Knee-Jerk Reflex Magnitude: A Feasibility Study

TL;DR

This study shows that rugby training reduces knee-jerk reflexes, suggesting possible adaptations in the nervous system that could help prevent injuries in athletes.

Contribution

A novel method for quantifying patellar reflexes using a force transducer and accelerometer was developed and tested.

Findings

Reflex magnitude decreased progressively with higher rugby training levels.

Professional players showed significantly lower reflex sensitivity compared to controls.

No significant asymmetry was found between dominant and non-dominant legs.

Abstract

Background

This study aimed to quantify the patellar reflex and assess how rugby training level influences reflex magnitude, asymmetry, and sensitivity, using a novel and accessible method for patellar reflex quantification.

Methods

A novel force transducer and ankle-mounted accelerometer were used to measure raw acceleration, which was converted to lower-limb angular velocity in 64 male participants from four rugby player groups (control, amateur, semi-professional, and professional). Each participant underwent 20 reflex trials per leg. Reflex magnitude was derived from peak angular velocity. Asymmetry and sensitivity were assessed using repeated-measures ANOVA and distributional analyses.

Results

Reflex magnitude decreased progressively with increased rugby training (p<0.0001). No significant asymmetry was observed between dominant and non-dominant legs (p=0.411). Reflex sensitivity was also lower in professional players compared to controls (p<0.0001).

Conclusion

By developing a novel force transducer and accelerometer, this study presents an accessible and accurate method for reflex quantification that, with further development, may be of clinical interest. This study demonstrated a progressive diminution in patellar reflex responses with increased exposure to rugby training. This is indicative of training-dependent reflex adaptation, which may result from central and/or peripheral plasticity. Overall, a combination of factors likely causes the reflex changes observed with rugby training. However, a deeper understanding of these effects could aid injury prevention among elite athletes of both sexes across various sports and inform clinicians during medical examinations.

Figures