The Influence Of Training And Match Volume On Injuries Among Japanese Youth Rugby Players

Previous research has suggested that excessive exposure to training and competition increases the risk of injuries in adult athletes. However, there has been limited investigation into the impact of training and match volumes on injuries among youth rugby union players. PURPOSE: To examine the association between training and match volumes and injuries in youth players participating in rugby union teams. METHODS: A total of 133 players aged 9-15 years from 15 rugby union teams were monitored over two seasons for weekly training and match volumes and injuries. Weekly practice, match, and total volume (VOLp, VOLm, and VOLt) were defined as the sum of exposures during the seven days leading up to an injury. Data from seven consecutive injury-free days were used as control. The weekly VOLp, VOLm, and VOLt between weeks prior to injury and weeks without injury were compared using a Mann-Whitney U test with Bonferroni adjustment in elementary (9-12 y/o) and secondary (13-15 y/o) school cohorts. Logistic regression analysis was employed to estimate the likelihood of injury with VOLp, VOLm, and VOLt and injury incidents in these cohorts. RESULTS: In elementary school players, there were 24 time-loss injuries with an incidence rate of 4.49 per 1000 Athlete-Exposures (AEs). Secondary school players experienced 96 time-loss injuries with an incidence rate of 11.56 per 1000 AEs. In comparison with weeks without injury, the weeks prior to an injury had higher weekly VOLp (Average ± SD: 3.3 ± 1.5 exposures vs 2.4 ± 1.3 exposures, Median [IQR]: 3[3.5-4] exposures vs 2[2-3] exposures, p = 0.006), VOLm (Average ± SD: 0.8 ± 0.7 exposures vs 0.5 ± 0.7 exposures, Median [IQR]: 1[0-1] exposures vs 0[0-1] exposures, p = 0.018), and VOLt (Average ± SD: 4.1 ± 1.9 exposures vs 3.0 ± 1.6 exposures, Median [IQR]: 4[3-5] exposures vs 3[2-4] exposures, p = 0.003) in elementary school players. Logistic regression indicated that weekly VOLp, VOLm, and VOLt were predictors of injury with odds ratios of 1.69 (p = 0.003), 1.63 (p = 0.04), and 1.49 (p = 0.002), respectively, among elementary school players. However, there were no significant associations between VOLp, VOLm, and VOLt and injuries among secondary school players. CONCLUSIONS: Weekly high training and match volumes were identified as risk factors for injury occurrence in preadolescent rugby union players.