The purpose of the present investigation was to compare the content of 8 weeks of training in young endurance-trained male and female runners and study the potential impact of this training content on performance. Fourteen men and 11 women performed two criterion exercises until exhaustion on an outdoor track before and after the 8-week training period. The first test was a graded exercise to determine maximal aerobic velocity (Mav), the velocity at the lactate concentration threshold (v-Tlac), and the velocity at delta 50 (v[delta]50: the velocity halfway between Mav and v-Tlac). The second test was a constant run at v[delta]50 to determine the time to exhaustion at this velocity (tlimv[delta]50). Training logs were used to monitor the self-directed training sessions. The results showed that the women had a lower training volume but trained at higher exercise velocities than the men. However, they presented similar values as the men for expected temporary performance capacity and did not improve their performance (Mav and tlimv[delta]50) over the 8-week period. After the training period, only v-Tlac (absolute and relative values) was slightly but significantly increased by training. These results could be due to the fact that both men and women did not train more than 10% of the total distance run at exercise velocities equal to or higher than their Mav and did not increase their training load during the 8-week training period. We suggest that changes in training content during the season, such as severe (long-duration or high-intensity) training sessions, may have improved their performance capacity. (Contains 1 figure and 4 tables.)