# Test–retest reliability of kicking performance assessments over a 2-day interval in elite youth soccer players

## TL;DR

This study assesses the reliability of kicking performance tests in youth soccer players over two days, finding that ball speed is reliable but accuracy is not.

## Contribution

The study provides new insights into the reliability of technical assessments in elite youth soccer, identifying specific limitations in accuracy measurements.

## Key findings

- Maximum ball speed showed good reliability (ICC = 0.87) with narrow limits of agreement.
- Kicking accuracy had poor to moderate reliability (ICC = 0.00–0.66) with wide limits of agreement.
- Ellipse angle analysis showed good reliability (ICC = 0.80), suggesting potential for assessing kicking distribution.

## Abstract

Reliable assessment of kicking performance is critical for monitoring technical development in youth soccer players. This study examined the reliability of kicking performance assessments in skilled youth soccer players aged 14–18, focusing on maximum ball speed and accuracy.

Using a test-retest design, fifty-three players from a Danish Super League academy completed standardised kicking tests on two occasions separated by 2 days. Maximum ball speed was assessed during penalty-style kicks with a stationary ball, while accuracy was assessed through target-directed kicks with a rolling ball. Two-way mixed-effects intraclass correlation coefficients (ICC) and limits of agreement (LoA) were used to assess reliability.

Results indicated good reliability for maximum ball speed (ICC = 0.87; LoA = [−2.1, 2.5] m/s), consistent with previous studies. Conversely, kicking accuracy demonstrated poor to moderate reliability (ICC = 0.00–0.66; LoA = [−0.46, 0.48] m). Stratified analyses revealed the highest accuracy ICC within the U15 group. Exploratory error ellipse analyses suggested potential utility in assessing kicking distribution, showing good reliability for ellipse angle (ICC = 0.80; LoA = [−0.98, 0.92] rad), though other parameters displayed low reliability. These findings highlight the strengths and limitations of soccer technical assessments. While maximum ball speed tests are highly reliable, kicking accuracy assessments remain problematic and require methodological refinement to improve reliability. Future research should incorporate advanced analytical techniques to enhance test reliability and consistency in elite athlete evaluations.