Table 5.
Measures used to determine early specialization.
| References | Specialization determined by | Young age measured | Age used for young | Measure of intensity |
|---|---|---|---|---|
| Beese et al. (2015) | Single vs. multi-sport | No | None | No |
| Bell et al. (2016) | Sport Specialization Scale/ Single vs. multi-sport | No | None | No |
| Bell et al. (2018b) | Sport Specialization Scale | No | None | No |
| Bell et al. (2018a) | Sport Specialization Scale | No | None | No |
| Black et al. (2019) | Full history | Yes | Before 12 | No |
| Bridge and Toms (2013) | Single vs. multi-sport | Yes | 6–12 | No |
| Brooks et al. (2018) | Sport Specialization Scale | No | None | No |
| Buckley et al. (2017) | Single Item “Did you quit other sports to focus on one sport?” | No | None | No |
| Buhrow et al. (2017) | Single item “At what age did you specialize in year-round training in one sport?” | Yes | 14 | No |
| DePhillipo et al. (2018) | Case report | Yes | 11 | Yes |
| DiCesare et al. (2019) | Single vs. multi-sport | No | None | No |
| DiStefano et al. (2018) | Sport Specialization Scale | Yes | Did not Specify | No |
| Ferguson and Stern (2014) | Case report | No | None | Yes |
| Ford et al. (2012) | Full history | Yes | 6–12 | No |
| Gallant et al. (2017) | Full history | Yes | 6–11 | No |
| Ginsburg et al. (2014) | Full History | Yes | Before 12 | No |
| Hall et al. (2015) | Full history | No | None | No |
| Hill (1993) | Single Item “did you specialize during highschool?” | No | None | No |
| Ferguson and Stern (2014) | Sport Specialization Scale | Yes | Did not specify | No |
| Jayanthi et al. (2018) | Sport Specialization Scale | No | None | No |
| Larson et al. (2019) | Full History | Yes | Before 12 | Yes |
| Martin et al. (2017) | Single item “Did you specialize before college?” | Yes | Did not specify | No |
| McDonald et al. (2019) | Single item “What age did you specialize?” | Yes | Before 12 | No |
| McFadden et al. (2016) | Sport Specialization Scale | Yes | Before 12 | No |
| McGuine et al. (2017) | Sport specialization Scale | No | None | No |
| McLeod et al. (2019) | Sport Specialization Scale | No | None | No |
| Mendes et al. (2018) | Full history | Yes | Before 12 | No |
| Miller et al. (2017) | Sport Specialization Scale | No | None | No |
| Moseid et al. (2019) | Single item “At what age did you decide to focus on your sport?” | Yes | Before 12 | No |
| Noble and Chapman (2018) | Did not specify | Yes (sport specific) | 19–23 | No |
| Padaki et al. (2017a) | 3 item importance scale | Yes | Did not specify | No |
| Padaki et al. (2017b) | Self-assignment | No | None | No |
| Pantuosco-Hensch (2010) | Full history | Yes | Before 12 | No |
| Pasulka et al. (2017) | Sport Specialization Scale | No | None | No |
| Patel and Jayanthi (2018) | Qualitative interview | No | None | No |
| Post et al. (2017c) | Sport Specialization Scale | No | None | No |
| Post et al. (2017b) | Sport Specialization Scale | No | None | No |
| Post et al. (2017a) | Sport specialization Scale | No | None | No |
| Rugg et al. (2018) | Single vs. multi sport | No | None | No |
| Russell (2014) | Single item “did you specialize as a youth?” | Yes | Before Adolescence | No |
| Russell and Limle (2013) | Single item “did you specialize as a youth?” | Yes | Before 15 | No |
| Russell and Molina (2018) | Single item “Are you a specializer or not?” | No | None | No |
| Santos et al. (2015) | Full History | Yes | Did not specify | No |
| Santos et al. (2017) | Full history | Yes | Before 12 | No |
| Storm et al. (2012) | Qualitative Interview | Yes | Before 12 | No |
| Strachan et al. (2009) | Hours per week | No | None | No |
| Swindell et al. (2019) | Did not specify | Yes | Before 12 | Did not specify |
| Wilhelm et al. (2017) | Single item “Did you specialize before high school, yes or no?” | Yes | Before high school | No |