Correlation between Compound Hop Index and Single Leg Vertical Hop Test Performance in Contact Sports: A Cross-sectional Study
Amrinder Singh, M. Dipshika, Monika Sharma, Abhinav SatheAbstract
Background:
Anterior cruciate ligament (ACL) injuries are relatively common in contact sports, in order to reduce the risk of ACL injuries in athletes, single leg hop tests has been used to measure functional performance. However, in clinical practice and field screening, practitioners frequently obtain multiple hop-test outcomes (single hop, triple hop, timed hops) which must be interpreted together; this multiplicity of measures can make decision-making complex and can lead to inconsistent interpretation of an athlete’s unilateral functional status. A composite metric such as the Compound Hop Index (CHI) aims to summarise the battery into a single, clinically interpretable score that reduces the risk of over-or under-estimating limb function. This consolidation is particularly relevant for hockey and football athletes, who perform repeated unilateral acceleration, deceleration and directional changes and therefore require an assessment that captures combined horizontal hop performance.
Aim:
The study aimed to present an effective method to reduce the hop-test battery data to a single score, namely, the CHI and to evaluate the correlation between CHI and single-leg vertical hop test (SLV-HT), thereby comparing the CHI between hockey and football athletes. Specifically, the study seeks (1) to determine whether CHI correlates with vertical asymmetry assessed using SLV-HT LSI, and (2) to compare CHI values between hockey and football athletes separately for male and female players, recognising sex-specific biomechanical and neuromuscular differences that may affect hop performance. The rationale for comparing hockey and football is that although both are contact sports, their movement demands differ (e.g. prolonged gliding vs. sprint–stop–cut mechanics), and these differences may influence hop-test performance and symmetry patterns.
Materials and Methods:
A convenience sample of 64 healthy, trained university-level (18–25 years old) hockey and football athletes participated in the study. They performed 3 trials of single leg hop test (SLHT), triple hop test (THT), 6-m timed hop test (6MT-HT) and SLV-HT on both sides with 5-minute rest between each test. Distance they hopped in SLHT, THT along with the height they jumped in SLV-HT and time to cover 6MT-HT was recorded; normalized distances (to height) and limb symmetry index (LSI) were calculated. The relationship between the tests was assessed using the Pearson correlation and sport comparisons were made using sex-stratified independent-samples
Results:
Pearson correlation findings suggested a weak correlation between CHI and SLV-HT in male (
Conclusion:
The study concluded that the CHI provides a consolidated measure of horizontal hop performance and limb symmetry that can assist clinicians and sports practitioners in contact sports. While the correlation between CHI and SLV-HT was weak and not statistically significant in this sample, sport- and sex-specific differences emerged: football male athletes tended to show higher CHI (trend), whereas hockey female athletes showed higher CHI compared to football female athletes (statistically significant). Athletes with lower CHI values may require further neuromuscular assessment and targeted strengthening to reduce potential knee injury risk. Overall, CHI is a promising composite metric for summarizing multitest hop batteries but requires further validation in longitudinal and larger samples before being used as a standalone predictor of injury.