Handball playing volume and knee injury risk in youth handball: the influence of sex

Objectives

To investigate if sex modifies the association between change in weekly handball volume and knee injury risk in youth handball players.

Design

Prospective cohort study.

Methods

679 players aged 14-18 reported weekly on any new handball-related knee injury and handball volume (training and competition hours) over 31 weeks through the SMS, phone and medical examination system. Weekly handball volume was categorized based on changes relative to the exponentially weighted moving average of handball volume the preceding four weeks: (1) less than 20% increase or decrease (reference group), (2) 20% and 60% increase and (3) increase greater than 60%. Players indicated their sex as a part of their baseline survey, identifying as either a female player or male player.

Results

Female players who increased their weekly handball volume by over 60 % had a knee injury risk of 31.2 % (95% confidence interval: 21.6–40.8 %) the following week compared to female players who increased their handball volume below 20 %, which was higher than that in male players whose risk was 10.5 % (95 % confidence interval: 2.1–18.8 %) corresponding to a risk difference of 20.6 %-points (95 % confidence interval: 6.5–34.6 %-points).

Conclusions

Female handball players aged 14–18 years were more susceptible to a handball-related knee injury following weeks with large increases in handball volume compared with age-identical males, suggesting a previously unexplored association between sex-related differences in load tolerance and knee injury risk that warrant further investigation. The provided cut points for increases in handball volume should be interpreted and used with caution.