Injury patterns in highly specialized youth athletes: a comparison of 2 pathways to sport

Key points

1. 01Both types of highly specialized athletes (exclusive and evolved) had similar overuse injury rates - around 59% and 54% respectively - with no statistically significant difference between them
2. 02Low-moderately specialized athletes had a lower overuse injury rate of 45.3%, significantly less than either highly specialized group
3. 03Among highly specialized athletes, playing an individual sport was associated with 1.95 times greater odds of an overuse injury compared to playing a team sport
4. 04Exclusive highly specialized athletes began intensive training earlier (age 8.23 years) than evolved highly specialized athletes (age 9.62 years)
5. 05The commonly used 3-question specialization scale misclassifies exclusive highly specialized athletes as only moderately specialized, underscoring the need for a revised tool

How it was conducted

Design

Retrospective cross-sectional chart review

Setting

Single tertiary care pediatric sports medicine clinic, January 2015 to April 2019

Participants

1171 patients aged 12 to 17.83 years (59.8% female) presenting with a sport-related injury and completing a sports participation survey

Groups

Exclusive highly specialized (n=169, only ever played 1 sport, trained >8 months/year), evolved highly specialized (n=247, quit other sports to focus on 1 sport, trained >8 months/year), low-moderately specialized (n=755)

Primary outcome

Distribution of injury types: acute, overuse, and serious overuse (overuse requiring >1 month rest)

Analysis

Chi-square tests, multivariable logistic regression controlling for age, sex, sport type, starting age of specialization, and months of rest per year

What they found

• Overuse injuries: exclusive highly specialized 59.2% (100/169), evolved highly specialized 53.9% (133/247), low-moderately specialized 45.3% (342/755)
• No significant difference in overuse injury proportion between exclusive and evolved highly specialized groups (P=0.28-0.29)
• Both highly specialized groups had significantly more overuse injuries than the low-moderately specialized group: exclusive vs low-moderate P=0.001, evolved vs low-moderate P=0.02
• Serious overuse injuries as a proportion of all overuse injuries: exclusive 10.0% (10/100), evolved 10.5% (14/133), low-moderate 9.4% (32/342) - no significant differences (P=0.70 to 0.90)
• Multivariable model (all 3 groups): exclusive highly specialized OR=1.56 (95% CI 1.10, 2.21) and evolved highly specialized OR=1.36 (95% CI 1.01, 1.82) for overuse vs acute injury compared to low-moderately specialized
• Within highly specialized athletes: individual sport vs team sport OR=1.95 (95% CI 1.17, 3.24) for overuse injury (P=0.01); validation model OR=1.86 (95% CI 1.15, 3.00)
• Female sex associated with greater overuse injury proportion across all 3 groups: OR=1.75 (95% CI 1.38, 2.23)
• Individual-sport athletes rested fewer months per year than team-sport athletes (0.50 vs 1.19 months, P<0.0001)
• Exclusive highly specialized athletes started intensive training at mean age 8.23 years vs 9.62 years for evolved highly specialized (P<0.0001)
• Proportion of exclusive highly specialized athletes in individual sports was 71.4% vs 55.3% in the evolved group (P=0.0009)

Limitations

• Single tertiary care clinic sample, which over-represents overuse injuries relative to urgent care or emergency settings, limiting generalizability
• No uninjured control group - injuries were expressed as proportions of injured athletes rather than of the full athlete population, so true incidence rates cannot be calculated
• Recall bias inherent in self-reported questionnaire data on sports participation history
• The analysis did not capture when evolved highly specialized athletes quit other sports, which could affect overuse injury risk in that group

Why it matters

For patients

Youth athletes who have always played a single sport are just as likely to experience overuse injuries as those who switched from multiple sports to one, suggesting the number of sports previously played matters less than the current intensity and sport type.

For clinicians

Clinicians should screen for exclusive high specialization separately from evolved high specialization, as the standard 3-question tool misclassifies these athletes; both groups warrant overuse injury counseling, and individual-sport athletes need particular attention.

For readers

This is the first study to distinguish between two subtypes of highly specialized youth athletes, showing sport type (individual vs team) is a stronger predictor of overuse injury than the path taken to specialization.