Physiologic alterations and predictors of performance in a 160-km ultramarathon

To describe physiologic alterations in runners competing in a 160-km endurance event and to evaluate the utility of weight and blood pressure measurements in the assessment of runner performance.

Prospective cohort study.

One hundred sixty-km ultramarathon.

Ninety-one of the 101 participants in the 2010 Tahoe Rim 100 Mile Endurance Run.

Brachial blood pressure, heart rate, and weight were assessed before competition, at 80 km, and at 160 km.

Alterations in brachial blood pressure, heart rate, and weight were assessed in finishers. Weight loss, brachial blood pressure, pulse pressure, and heart rate at 80 km were assessed in all participants for their ability to predict failure to finish the race.

Participants who finished 160 km (57%) experienced their fastest heart rates (P < 0.05), lowest systolic pressures (P < 0.05), highest diastolic pressures (P < 0.05), narrowest pulse pressures (P < 0.05), and lowest weights (P < 0.05) at 80 km. High rates of finishing were seen in those who lost >5% of their prerace weight (87%). Categorical weight loss (<3%, 3%-5%, and >5%) was not associated with the ability to finish (P > 0.05) or finishing time (P > 0.05), whereas the presence of a narrow pulse pressure was associated with a high likelihood (likelihood ratio = 9.84; P = 0.002) of failure to finish.

Greater intracompetition weight loss is not associated with impaired performance but rather may be an aspect of superior performance. Narrow pulse pressure was associated with a high likelihood of failure to finish.