This study compares the 10/5 repeated jumps test (RJT) with drop jumps from 30 cm and 40 cm for assessing reactive strength index (RSI), a measure of an athlete’s ability to utilise the fast stretch-shortening cycle. Thirty male athletes from a range of sports completed three trials of each jump protocol on a force platform. RSI, jump height (JH) and ground contact time (GCT) were recorded and compared between tests.

The 10/5 RJT demonstrated excellent reliability for RSI, jump height and ground contact time, with acceptable variability. Drop jumps also showed good-to-excellent reliability, although variability was slightly greater. While there were no significant differences in overall RSI between the repeated jump and drop jump protocols, significant differences were found in ground contact time and jump height, indicating that athletes used different jumping strategies to achieve similar RSI scores.

Despite similar RSI values, only around 30% common variance was found between the 10/5 RJT and drop jump assessments. The authors therefore conclude that reactive strength is task-dependent and that the two testing methods should not be used interchangeably when monitoring athletes over time.

From a practical perspective, the 10/5 RJT may be particularly useful for practitioners with limited time or resources because it avoids the need for a drop box and the difficulties associated with standardising actual fall height. However, coaches should consistently use the same testing protocol when longitudinally monitoring changes in an athlete’s RSI.