The energy cost of an 80 km run.

Data was collected from two men who attempted an 80 km run. Measurements of aerobic power (VO2 max) and determinations of heart rate (HR) and submaximal oxygen consumption (VO2) during treadmill running were carried out one week before the run. Throughout the 80 km run, HR was recorded by telemetry and used together with the laboratory data to estimate VO2 as a percentage of VO2 max. One subject completed the 80 km distance at 58% of VO2 max, the other subject, operating at 74% of VO2 max, was obliged to retired after 55 km. The data in this and other studies indicate that the high energy costs reported for the marathon (70-85% of VO2 max) cannot be sustained over the 80 km distance but that about 60% of VO2 max can be continued for seven hours and longer.