Performance trends and cardiac biomarkers in a 30-km cross-country race, 1993-2007.

Purpose: Long-distance running events enjoy increasing popularity in all ages. Whereas the health benefits of regular moderate exercise are undisputed, the net health effects of single or repeated participation in endurance events of marathon type remain to be determined. We wanted to investigate performance trends over time and the relationship between race performance and cardiac biomarker levels among participants in a large annual 30-km cross-country race.

Methods: We analyzed a database containing age, gender, run times, and previous race participation of 124,608 runners finishing the Lidingöloppet (30 km) between 1993 and 2007. In 249 male runners age ≥ 45 yr, we also performed a thorough cardiovascular examination, including measuring the cardiac biomarkers N-terminal pro-brain natriuretic peptide (NT-proBNP) and troponin.

Results: Total participation increased 56% with the largest gains in younger female and older male runners. Mean run times rose from 164 ± 27 min in 1993 to 184 ± 33 min in 2007 (P < 0.001) in men and from 179 ± 26 to 203 ± 32 in women (P < 0.001) after a strong linear relationship (men, r = 0.98; women, r = 0.93). Increased run times were seen in the mean, top, and bottom quartiles as well as in the top and bottom 5% of all age and gender groups. In the substudy among 249 older male runners, not only higher body mass index, older age, and fewer previous race participations but also higher baseline NT-proBNP was independently associated with increased run time.

Conclusions: Whereas participation in the Lidingöloppet increased, fitness deteriorated over time in both genders and in all ages. In a subset of older male athletes, longer run times were associated with higher levels of NT-proBNP. The present findings may support the usefulness of preparticipation evaluation to ensure appropriate fitness and cardiovascular health in long-distance race participants.