Methods
Between April 2013 and March 2020, 1049 athletes, 6–25 years of age, underwent an injury prevention evaluation (IPE) at a tertiary-level paediatric hospital-affiliated sports injury prevention centre. We conducted analyses of a subset of existing data structured around the athletes’ responses and measurements. The institutional review board approved the current study before commencement.
A participant who completed the IPE was defined as an athlete if they partook in organised sport(s). Several hours were spent at the centre, where risk factors for sports-related injuries were measured, and a sports injury risk-reduction plan individualised to the athlete was developed. Potential risk factors are based on available medical and scientific literature and include: age, gender, sport(s) participated in, position(s) played, medical history, training regimen and nightly hours of sleep, among others. The questionnaire takes approximately 30 min to complete by the athlete and is followed by a biomechanical and sports performance evaluation performed by an athletic trainer or kinesiologist. The goal is to obtain a comprehensive profile of injury risk. Athletes under 18 years old were accompanied by a parent or legal guardian.
Sports were categorised as either contact, limited-contact, or non-contact according to the American Academy of Pediatrics (AAP) groupings, and included baseball, basketball, boxing, cheerleading, crew, cross country, cycling, dance, equestrian, field hockey, figure skating, football, golf, gymnastics, ice hockey, lacrosse, long-distance running, martial arts, rugby, ski/snowboarding, soccer, softball, springboard diving, swimming, tennis, track and field (field), track and field (running), and wrestling.16
The AAP defines sport specialisation as an athlete focusing on only one sport, usually at the exclusion of any other and often year round.1 For the study, a sport-specialised athlete was defined as one participating in a single sport or, if a multisport athlete, one practising or competing for a primary sport year round. All athletes who participated in multiple sports without year-round dedicated training for one activity were considered non-sport-specialised.
The 2021 World Anti-doping Agency (WADA) is the international standard for describing legal and banned PES in sports. Legal PES, often found over the counter, are not on WADA’s banned list.1 17 Whey protein, caffeine, creatine and nutritional supplements are the most popular legal PES found in paediatric and intercollegiate populations.7–9 The IPE questionnaire included questions on using caffeine, energy drinks, creatine and nutritional weight gain supplements, including whey powder and protein bars. These substances were considered legal PES. The IPE questionnaire also recorded answers to the question, ‘If you were offered a banned PES that guaranteed you would accomplish a major athletic accomplishment of your choice, and you would never get caught, would you take it?’18–20 For this study, an answer of yes to this question was recorded as consideration of banned PES use.
The Pew Research Center is a Washington, D.C., based, non-partisan group, providing information such as median income level to describe demographic variances within the USA. The research group set references for low-income, low-middle income, upper-middle income and high-income homes in a three-person household after adjusting for the cost of living in each state in 2016.21 Using Census Bureau statistics, each zip code recorded on the IPE was associated with a median income from 2019 data. Each athlete’s median income per zip code was assigned as low-income, lower-middle-income, upper-middle-income, or high-income.22
Athletes with no reported date of birth or incompletion of sports specialisation questions were excluded from this set of data (n=103), resulting in a final cohort of 946 athletes 6–25 years old for analysis.
Univariable comparisons in participant characteristics were conducted across sport specialisation groupings to assess for potential confounders in each model. Variables with p values<0.05 during initial unadjusted univariate analysis were included in a subsequent multivariable model, as there was reason to believe those variables may potentially confound the association between sport-specialised athletes and PES use or consideration. Multivariable logistic regression analysis was used to determine the independent association between sport-specialised athletes and the odds of reported legal PES use, as well as for the consideration of banned PES use while controlling for potential confounding characteristics referenced from univariate to create adjusted models. Subanalyses were performed to compare sport-specialised athletes and reported legal PES use and consideration of banned PES use within gender groups.
Equity, diversity and inclusion
The study recruitment included all races/ethnicities, all income levels, a diverse spectrum of athletic involvement and competitiveness, and male and female athletes. We acknowledge the generalisability of the results may not account for the LGBTQIA2S+ community, but we have since updated our questionnaire to account for this group in future analyses. Our research team comprised three females and four males from different research disciplines and stages of their careers and represented both a North American and Asian country.
Patient and public involvement
Patients and the public were not involved in the production of recruitment, question development, analysis or distribution of this research.