This study reports the results of a 20-year (2005-2024) follow-up study of two 2-time Olympic and 6-time world champion rowing athletes. To provide a comprehensive picture of adaptations in physiological and performance characteristics to long-term training, we monitored the athletes' physiological and performance data annually through five 4-year developmental phases. Maximal oxygen uptake (V̇O2max), maximal minute power (MMP), and power output corresponding to anaerobic threshold (PAT) were derived from a ramp-wise exercise test on a rowing ergometer. Additionally, average power output sustained during all-out tests over 2000-m and 6000-m on a rowing ergometer was also obtained. V̇O2max peaked at age 22 for Athlete A and at age 25 for Athlete B (at ~7 L·min-1), before stabilizing and then gradually declining to a range of 6.2-6.5 L·min-1 for both athletes. MMP stabilized in both rowers at values between 550 and 575 W and displayed minimal fluctuations over the final two phases of the study. Additionally, MMP closely resembled the corresponding average power output sustained during the 2000-m all-out tests on a rowing ergometer. Average power output during 2000-m and 6000-m all-out tests showed steady improvements over the monitored phases of the study, with highest power output crew averages for both 2000-m (532 W; 5 min 48 s) and 6000-m (463 W; 18 min 4 s) tests recorded during the last 4-year phase of the assessment. Improvements in rowing ergometer performance over 2000-m and 6000-m appear to be largely independent of the multi-year changes in V̇O2max. Long-term rowing training resulted in continuous improvements in MMP and PAT throughout the monitored phases, which more closely mimicked improvements in rowing ergometer performance.