Career performance outcomes by specialisation status and age at specialisation for elite versus sub-elite athletes
| Study | Population (N) | Outcome measure description | Specialised/ single sport/ high | Moderately specialised | Unspecialised/ multisport/ low | P value |
| Black et al 23 | Professional and collegiate ice hockey (n=91) | Percentage professional hockey specialise before age 14 | 24% | – | ||
| Percentage professional hockey specialise before age 12 | 5% | – | ||||
| Percentage NCAA D1 hockey players specialise before age 14 | 24% | – | ||||
| Percentage NCAA D1 hockey players specialise before age 12 | 12% | – | ||||
| Percentage NCAA DIII hockey players specialise before age 14 | 28% | – | ||||
| Percentage NCAA DIII hockey players specialise before age 12 | 12.5% | – | ||||
| Bridge and Toms24 | Youth athletes (n=1006) | Odds of elite sport at 16–18 if playing two sports at age 11 | REF | 1.6 (1.2, 2.2) | <0.05 | |
| Odds of elite sport at 16–18 if playing two sports at age 13 | REF | 1.4 (1.1, 2.0) | <0.05 | |||
| Odds of elite sport at 16–18 if playing two sports at age 15 | REF | 1.6 (1.2, 2.2) | <0.05 | |||
| Odds of elite sport at 16–18 if playing three sports at age 11 | REF | 2.2 (1.4, 3.4) | <0.05 | |||
| Odds of elite sport at 16–18 if playing three sports at age 13 | REF | 2.1 (1.4, 3.1) | <0.05 | |||
| Odds of elite sport at 16–18 if playing three sports at age 15 | REF | 2.1 (1.4, 3.1) | <0.05 | |||
| Odds of elite sport at 16–18 if playing four sports at age 11 | REF | 2.1 (1.2, 3.8) | <0.05 | |||
| Odds of elite sport at 16–18 if playing four sports at age 13 | REF | 3.2 (1.8, 5.8) | <0.05 | |||
| Odds of elite sport at 16–18 if playing four sports at age 15 | REF | 3.7 (2.1, 6.6) | <0.05 | |||
| Buckley et al 25 | HS and collegiate athletes; professional hockey and baseball (n=3090) | Percentage professional MLB specialised | 45.4% | – | ||
| Percentage professional USA hockey specialised | 87.5% | – | ||||
| Martin et al 35 | Div I collegiate athletes (n=1036) | Percentage collegiate athletes specialised | 41.9% | 58.1% | – | |
| Post et al 3 | Div I collegiate athletes (n=343) | Percentage D1 athletes specialised in 9th grade | 16.9% | 53.5% | 29.6% | – |
| Percentage D1 athletes specialised in 10th grade | 28.0% | 50.4% | 21.6% | – | ||
| Percentage D1 athletes specialised in 11th grade | 35.6% | 45.6% | 18.8% | – | ||
| Percentage D1 athletes specialised in 12th grade | 41.1% | 41.7% | 17.2% | – | ||
| Rugg et al 36 | NBA first round picks (n=237) | Percentage of games played | 72.8% | 78.4% | <0.001 | |
| Percentage athletes still playing | 81.1% | 94% | 0.03 |
| Study | Population (N) | Mean age at specialisation comparisons | Elite | Semi-elite comparator | Non-elite comparator | P value |
| Black et al 23 | Professional and collegiate ice hockey (n=91) | Professional hockey | 14.1 (NS) | – | ||
| NCAA D1 hockey | 14.5 (NS) | – | ||||
| NCAA DIII hockey | 14.6 (NS) | – | ||||
| Buckley et al 25 | HS and collegiate athletes; professional hockey and baseball (n=3090) | HS athletes | 12.7 (2.4) | – | ||
| Collegiate athletes | 14.8 (2.5) | – | ||||
| Professional athletes | 14.7 (2.4) | – | ||||
| Baseball professional vs collegiate vs HS | 14.9 (2.2) | 15.4 (1.9) | 12.3 (2.3) | <0.001 | ||
| Professional hockey vs collegiate | 13.4 (3.2) | 13.3 (2.9) | – | 0.65 | ||
| Coutinho et al 26 | Portuguese semi-professional volleyball (n=60) | Female (skilled vs less skilled) | 14.0 (2.1) | 13.0 (2.7) | >0.05 | |
| Male (skilled vs less skilled) | 15.0 (2.1) | 12.2 (1.7) | 0.001 | |||
| Cupples et al 27 | Professional Australian rugby (n=224) | Australian professional rugby league | 15.6 (2.4) | – | ||
| Hornig et al 34 | German professional soccer (n=102) | National team vs professional team vs elite amateur | 14.3 (9.2) | 10.9 (6.5) | 9.9 (7.2) | <0.05* |
| Güllich29 | German Olympic sport (n=166) | International medalists vs non-medalists | 14.8 (6.0) | 11.9 (5.5) | <0.01 | |
| Gullich et al 31 | German Olympic sport (n=1558) | World class vs National class | 14.4 (6.6) | 12.1 (5.5) | <0.01 | |
| Güllich and Emrich28 | German Olympic/National field hockey (n=54) | Olympic champions vs World Class vs National | 15.0 (8.7)*† | 13.3 (6.5)† | 9.4 (4.6) | 0.04*; 0.51† |
| Gullich30 | German national T&F (n=264) | Strong vs weak responders juniors (ages 13–17) | 13.0 (5.8) | 12.7 (6.2) | >0.05 | |
| Strong vs weak responders seniors (ages 19–23+) | 15.9 (7.6) | 10.9 (5.2) | <0.01 | |||
| Haugaasen et al 32 | Norwegian elite youth soccer (n=558) | Professional vs non-professional | 13.1 (1.9) | 12.1 (2.2) | <0.05 | |
| Hayman et al 33 | Elite youth UK golf (n=8) | Adolescent amateur male | 16 (NS) | – | – |
*Significance between elite and non-elite comparator.
†Significance between elite and semi-elite comparator.
HS, high school; MLB, major league baseball; NCAA, National Collegiate Athletic Association; NS, not stated.