Self-pacing during sustained, repetitive exercise.

During Exercise Fastball, 25 young French infantry soldiers walked 204 km in 6 d. A different load weight was assigned to each subject to ensure that they all worked at the same percentage of their aerobic power (Vo2max). The actual energy expended during the march was monitored by recording heart rates by ECG telemetry. The results confirmed that adjusting the load weight is a practical means of ensuring the same relative workload for subjects with different Vo2max. Furthermore, fit young soldiers will self-pace at 30-40% of Vo2max and will continue to do so for at least 6 d. The factor limiting performance for many of these subjects was the condition of their feet as a result of walking on the hard road surface.