Background Prospective, cross-country ski injury incidence data is scarce.

Objective To describe injury type and incidence sustained by elite cross-country skiers in north-eastern America. We hypothesized that lower extremity injury incidence would be higher than other body regions. A secondary aim was to determine any factors that correlate with new injury.

Design A prospective, longitudinal study that included: demographics (ski and injury history); Movement Competency Screening (MCS); hamstring length measurement; core muscle endurance testing (trunk flexor to extensor ratio). Athletes then completed 12 consecutive, monthly electronic surveys about training, racing, and injury status.

Setting Collegiate and professional ski team practices.

Patients (or Participants) A convenience sample of 71 cross-country skiers (age 18–27 years, 35 men); 41 participants (18 men) completed the study.

Independent variables MCS score; hamstring length; ratio of trunk flexor to extensor endurance; injury history; training activities and hours; training lost to injury.

Main Outcome Measurements New injury reports.

Results Mean injury incidence was 3.81 new injuries per participant, per 1,000 hours of training. Injury incidences for lower extremity (2.13), and overuse/non-traumatic (2.76) injuries were significantly greater than trunk (0.22), upper extremity (0.46), or acute/traumatic (1.05) injuries (p<0.05). Off-season injury incidence (5.25) was higher than during ski season (2.27), but not significantly (p=0.07). New injury positively correlated with past injury (p=0.04) and also increased as monthly running time increased but not significantly (p=0.08). New injury did not correlate with: MCS score; hamstring length, or; core ratio (p>0.05). Past injuries were a significant predictor of new injuries, when accounting for training time, running time and MCS score (p<0.05).

Conclusions This year long, prospective report of injury type and incidence in competitive cross-country skiers demonstrated that lower extremity and overuse/non-traumatic injuries had the highest incidence rates. Previously injured skiers are at greater risk of further injury.