The aim of this study was twofold: 1) to determine the rate of performance improvement among France’s top 10 athletes in middle- and long-distance events (e.g., 800 m, 1500 m and 5000 m) by analyzing their personal best performances per season over several years; and 2) to develop an index of the optimal performance improvement rate for use by elite coaches and athletes in assessing athletes’ progression, predicting potential performances, and possibly detecting high-potential athletes. METHODS: The top 10 athletes in the Fédération Française d’Athlétisme (FFA) rankings of the 800-m, 1500-m and 5000-m events for each sex were assessed for their history of race times before achieving their best race time (BRT). For each athlete, the difference between the current BRT and last season’s BRT was defined as the 1-season improvement rate (1-SIR), whereas the average improvement rate in the last and preceding seasons was the multiseason improvement rate (M-SIR). RESULTS: Sex differences were observed in the 5000 m only for M-SIR (%) (P<0.05), and significantly higher rates of improvement were observed for 1-SIR (min) and M-SIR mostly for the 5000 m as opposed to the 800 m and 1500 m. CONCLUSIONS: Prediction using this index may be used to detect talents (those who have the potential for high level performances and/or the potential to break national records) and to follow and optimize training strategy and competitions.