Background A limited number of long-term prospective studies have investigated health problems in competitive cross-country skiers. Moreover, limited information exists regarding differences in the prevalence and severity of health problems between senior and development female and male cross-country skiers.

Objective To compare the prevalence and severity of health problems between senior and development female and male national team cross-country skiers.

Design Comparative, prospective, observational cohort study.

Setting Senior and development national cross-country ski teams.

Participants Eighteen (9 women, 9 men) senior and 22 (9 women, 13 men) development national team skiers.

Intervention Skiers self-reported their health problems weekly for 17 weeks throughout the 2019/2020 competitive cross-country ski season using the Oslo Sports Trauma Research Center Questionnaire on Health Problems (OSTRC-H2).

Main Outcome Measurements We calculated weekly prevalence and severity measures for illnesses, acute and overuse injuries, substantial health problems (i.e., health problems leading to moderate or severe reductions in training volume or sports performance, or a complete inability to participate) and all health problems combined.

Results Weekly response rate to the OSTRC-H2 was 90% (SD 7%). Average weekly prevalence of substantial (~12%) and all (~25%) health problems were similar between senior and development team skiers. However, illness prevalence was lower in senior vs. development skiers (8%, 95% CI [3%, 13%] vs. 13%, 95% CI [9%, 17%], respectively; p = .026) and injuries were higher (12%, 95% CI [9%, 15%] vs. 5%, 95% CI [3%, 7%]; p < .001). There were no differences in severity measures (all p > .05).

Conclusions Health problems were relatively common among the skiers, with one quarter affected by at least one problem at any given time. While the prevalence of all health problems was similar, illnesses were less prevalent in the senior compared to the development team skiers and injuries were more prevalent.