# The Reliability and Validity of the Leg Lateral Reach Test in Adolescent Tennis Players

## TL;DR

This study shows that the leg lateral reach test is a reliable and valid way to assess trunk rotation flexibility in adolescent tennis players.

## Contribution

The study provides evidence for the reliability and validity of the leg lateral reach test in this specific population.

## Key findings

- The leg lateral reach test showed almost perfect intra-rater and inter-rater reliability.
- The test has a fair correlation with seated rotation angles for both dominant and non-dominant sides.
- The test is a reliable screening tool for thoraco-lumbo-pelvic rotation in adolescent tennis players.

## Abstract

Regular assessment of clinical measurements of trunk rotation flexibility that are valid and reliable is necessary to minimize the risk of injury and optimize performance in tennis players who perform repetitive trunk rotation. The objectives of this study were to investigate: (1) the intra-rater, inter-rater, and test-retest reliability of the leg lateral reach test (LLRT) in tennis players; (2) the minimum detectable change in the leg lateral reach test in tennis players; and (3) the correlation between leg lateral reach and seated rotation tests in tennis players. Twenty-four adolescent tennis players were recruited for the study. To ascertain the reliability of the leg lateral reach test, two designated raters (rater 1 and rater 2) evaluated each participant with the test 5–7 days apart (session 1 and session 2). The leg lateral reach distances and the seated rotation angle from session 1 were correlated to evaluate the validity. The intra-rater and inter-rater analysis found almost perfect reliability (ICC ≥ 0.835, SEM ≤ 2.47 cm; ICC ≥ 0.881, SEM ≤ 2.02 cm, respectively). The correlation between the distance of the lateral leg reach for the dominant and non-dominant sides and the angle of seated rotation was fair (r 0.441 and 0.406, respectively). This study demonstrates the leg lateral reach test as a reliable and valid screening tool, accurately predicting the range of thoraco-lumbo-pelvic rotation in adolescent tennis players.