1. USATF. Youth—age divisions. 2022. http://legacy.usatf.org/groups/Youth/ageDivisions.asp. Accessed 13 Jan 2022.
2. Hulteen RM, Smith JJ, Morgan PJ, Barnett LM, Hallal PC, Colyvas K, et al. Global participation in sport and leisure-time physical activities: a systematic review and meta-analysis. Prev Med. 2017;95:14–25.
3. Fakhouri THI, Hughes JP, Burt VL. Physical activity in U. S. Youth aged 12-15 years, 2012. NCHS Data Brief. 2014;141:1–8.
4. The National Federation of State High School Associations. 2018–19 high school athletics participation survey—NFHS. https://www.nfhs.org/media/1020406/2018-19-participation-survey.pdf. Accessed 21 Nov 2021.
5. Solomon ML, Briskin SM, Sabatina N, Steinhoff JE. The pediatric endurance athlete. Curr Sports Med Rep. 2017;16(6):428–34.