# 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.

## Key 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.