Abstract

The heart rate (HR) response to ultraendurance cycling is poorly understood. This case report describes the exercise intensity of ultraendurance cycling by means of HR monitoring in a well trained male amateur cyclist performing the Ötztal Radmarathon twice en bloque in a circuit of two identical laps (distance 460 km; cumulative altitude difference 11 000 m). The overall intensity was moderate (HR_mean = 130 beats/min; HR_mean/HR_max = 0.71) corresponding to an average individual workload of 47% of Vo₂max. Almost the whole race was performed under aerobic conditions (99.6%); high intensity work was negligible (0.4%). The average speed and the HR response also declined in the course of the two laps, average speed by 17.2% (23.8 to 19.7 km/h), HR_mean by 10.1% (138 to 124 beats/min), and HR_mean/HR_max by 10.7% (0.75 to 0.67). This scale of HR decrease corresponds to comparable data gained in the field of triathlon and represents a specific cardiac feature of ultraendurance exercise in general.