PROFICIENT YEARS AT SPORTS Therefore, in some instances, younger boxers are able to supplant their older rivals, not because of superior boxing ability, but because the titleholder is no longer able to meet the weight requirement. This situa- tion may account in part for the fact that the pugilists in the heavier weight classifications are found to be slightly older than are the boxers in the lighter weight classifications. For the heavyweight champion- ships, the mean chronological age was 29.79; for the bantamweight championship, the mean was 24.83 years. AMATEUR TENNIS PLAYERS Figure 4 presents the chronological ages at which 317 national ama- teur tennis championships were either won or retained in France, Eng- land, and the United States.* The 317 tennis championships include outdoor and indoor, singles and doubles. The year of maximum success at tennis was age 27. The irregularity in the appearance of the age curve at ages 21 to 24 is probably due to chance factors. The writer can think of no logical reason why a spurt should occur at age 21 with a decline of ability from ages 22 to 24 inclusive. Ages 24 & 25. «kad it hh. it. rat ah. aa Fanaa 10 15 20 «25 30 35 40 lo 15 2 2 30 3 40 45 50 Ficure 5. Chronological ages of pro- Ficure 6. Chronological ages of pro- fessional ice hockey players. A 5-year fessional football players. A 2-year cross-sectional study involving 823 cross-sectional study involving 485 player-years. player-years. PROFESSIONAL ICE HOCKEY PLAYERS For studying the ages of professional ice hockey players, the writer tabulated the ages of the players whose names appeared in five annual *The birth dates of the United States tennis players were supplied by Mr. Edward B. Moss, Executive Secretary of the United States Tennis Association. Birth dates of the French champions were obtained from Mr. P. Gillou, Federation Francaise de Lawn Tennis. The birth dates of the English champions were supplied by Mr. H. A. Sabelli, The Lawn Tennis Association, London, England.