Don Schollander's world and Olympic record of 4:12.2 in the 1964 Olympics for the 400 meter freestyle would have placed him third in the 1976 games, in the women's race! Johnny Weissmuller's time for the 100 yard freestyle was 51 seconds. Today, it is swum in 41 seconds. Improved conditioning techniques and stroke mechanics have benefitted today's swimmers. Formal and highly organized age group swimming has given more children the opportunity to train, in addition to enhancing the process of natural selection. Research into the effects of swim training has generated more efficient turns, starts, and stroke mechanics based on biomechanical principles. Aerobic and anaerobic testing, muscle biopsy, and advanced strength measuring devices have identified the need for specificity in training sessions, which are based upon stroke and event. Coaches can no longer rely on the combination of talent and hard work to guarantee success but must prescribe individualized training programs based upon sound physiological principles.