Table 2.

Study characteristics.

Study	Participant Information	Instrumentation	Design	Risk of bias assessment	Main findings
Barkoukis et al., 2015	309 adolescent Greek athletes, aged between 14 and 18 years old (M age = 16.64 years). This included 178 males and 131 females.	Questionnaires to assess beliefs about sporting success, current and past PEDs usage, attitudes, norms, situational temptation, and social desirability.	Cross-sectional	Low	Those who believed that deception strategies (i.e., cheating) were needed to be successful in sport were also more susceptible to doping. Athletes who possessed favorable doping attitudes and who felt others approved of them doping were more likely to take PEDs.
Barkoukis et al., 2015	650 athletes from Greece, who were aged between 14 and 20 years old (M age = 16.09 years). Gender not reported.	Questionnaires to assess doping intentions, attitudes, norms, and beliefs about NS use.	Cross-sectional	Low	NS users, who did not take PEDs, reported stronger intentions to dope, more favorable doping attitudes and beliefs, compared to non-supplement users.
Blank et al., 2015	883 parents of junior athletes.	Questionnaires to assess knowledge of PED, side effects of PEDs, and doping attitudes.	Cross-sectional	Low	Male parents reported greater knowledge of PEDs and their side effects than female parents. There were no significant gender differences in attitudes toward doping.
Blank et al., 2016	1,265 junior athletes from Australia, aged between 14 and 19 years. Mean age or gender not reported.	Questionnaires to assess doping susceptibility, well-being, goal orientation, confidence of success, performance motivation, depressive mood, anxiety, and locus of control.	Cross-sectional	Low	Low self-esteem, fear of failure, ego orientation, and a depressive mood were associated with the athletes who were the most susceptible to doping.
Blashill et al., 2017	6,248 14 to 18 year olds from the United states.	Questions to measure ethnicity, sexual orientation, and AAS use.	Cross-sectional	Low	Sexual minority boys were more likely to take AAS than heterosexuals. These differences were more pronounced among Black and Hispanic males.
Bloodworth et al., 2012	403 athletes aged between 12 and 21 years of age who were classified as being talented. 67% of the athletes were aged between 16 and 19 years.	Questions relating to the beliefs about the necessity of PEDs, body satisfaction and modification, and willingness of competitors to use PEDs.	Cross-sectional	High	Older athletes (17 to 20 years) with more than 5 years' experience agreed that PEDs were necessary in their sport. Of these, males (18%) displayed more favorable attitudes toward PEDs than females (10%). In turn, those who felt that taking PEDs was necessary in their sport were more likely to possess favorable attitudes toward using PEDs. Although many athletes reported that they would not take a magic (and undetectable PED; <10%) PED, 72.6% believed that others would use a magic PED if it were un-harmful, and 40% believed others would use a PED if it shortened one's life.
Chan et al., 2015a	410 elite or sub-elite athletes from Australia (M age = 17.7; male = 55.4%).	Behavioral regulation, self-regulation, and doping avoidance in relation to the theory of planned behavior.	Cross-sectional	Low	Athletes with an autonomous motivation for sport had an autonomous motivation for avoiding doping (i.e., doping was against personal values), and an attitude of doping avoidance. Alternatively, athletes with a controlled motivation had a controlled motivation for doping avoidance (e.g., wanting to avoid ban or gaining a poor reputation).
Chan et al., 2015b	410 elite or sub-elite athletes from Australia (M age = 17.7; male = 55.4%).	Trait self-control, doping attitudes, doping intentions, adherence to doping avoidant behaviors, and prevention of unintended doping behaviors. Participants also took part in a Lollipop decision-making task.	Cross-sectional	Low	Self-control was negatively associated with doping attitudes and intentions to use PEDs. Self-control was also associated with adherence and intention to avoid doping behaviors and a refusal to eat the unfamiliar lollipop presented in the decision-making task. Athletes with less self-control were more likely to have a favorable doping attitude and a stronger intention to dope, but reduced adherence to doping avoidance behaviors.
Corbin et al., 1994	1,690 US high-school athletes aged 13 to 17 years.	Questions to assess previous use of AAS, attitudes, and peer influence.	Cross-sectional	Low	2.4% of males and 1.1% of females reported using AAS. Males reported being able to obtain AAS more easily than females. 10% reported they would use AAS if they were guaranteed an Olympic medal.
Dodge and Clarke, 2015	244 students from the US, aged between 12 and 18 years (M age = 15.8 years), which comprised of 118 males, 121 females, 5 people who did not report gender.	Questionnaires to assess willingness to use AAS, behavioral intentions, amount of communication, and past substance use.	Cross-sectional	Low	Students engaged in little communication about AAS with their parents, although conversations about the positive impact of AAS on performance was associated with an increased willingness to use newly developed PEDs.
Dodge and Jaccard, 2006	Approximately 15,000 (exact number not provided) US males and females age 12 to 18 years.	Study created questions to assess steroid, supplement, physical activity, demographics, and substance use (e.g., binge drinking, use of drugs, and injection drugs).	Cross-sectional	Low	Males (2.7%) were more likely than females (0.4%) to use AAS, and these differences were greatest for those who played high-school sports. There was a positive relationship between legal dietary supplements and AAS use.
Dodge and Jaccard, 2008	241 adolescent athletes (M age = 15.8 years) from the US (154 males, 81 males, and 6 participants who did not report their gender).	Questionnaires to assess intentions, attitudes, social norms, substance use, and beliefs about doping.	Cross-sectional	Low	2.5% of the sample reported taking a PED. Attitudes and norms favoring abstinence from PEDs were the strongest predictors of intentions to take PEDs and legal supplements.
Dunn and White, 2011	22,830 Australian students aged between 12 and 17 years of age (M age = 14.5 years). 53% of the sample were females.	Questions to assess life time use of steroids, other illegal substances, and demographic variables.	Cross-sectional	Low	2.4% of the sample reported using AAS. The 12–15 years olds reported using AAS more than 16–17 year olds. Independent of age, factors associated with an increased use of AAS were being male, speaking a non-English language at home, not being at school the previous day, and rating one's educational ability as being below average. AAS use was also associated with using illegal substances.
DuRant et al., 1995	12,272 US high-school students aged 14 to 18 years old.	Study created questions to assess frequency of anabolic steroids, cigarettes, and other illegal drugs.	Cross-sectional	Low	Males (4.08%) were more likely than females to use anabolic steroids (1.2%). 16–18 year olds were more likely to take AAS than 15-year-olds. There were differences in relation to where athletes lived (i.e., higher prevalence of ASS use in south, than Northeast or West of US). Among males, there was a positive association between those who used had injected drugs, other illegal drugs, alcohol and AAS. Those who had participated in strength training were more likely to use AAS. ASS was not associated with level of performance. Among females, other drug use, followed by injected drugs were the strongest predictors of AAS.
Elkins et al., 2017	38,414 adolescents, aged between 14 and 18 years. 51% female.	Questions to assess demographics, AAS usage, and other drugs.	Cross-sectional	Low	2.6% of the sample reported using AAS within the year prior to the assessment. AAS were more common among male, older, and ethnic minority pupils.
Elliot et al., 2007	7,447 US female students aged between 14 and 18 years old.	AAS usage.	Cross-sectional	Low	5.3% of female students reported using AAS. Caucasian females were more likely to use AAS than Hispanic or African-American students. 14 and 15 year olds were more likely to report AAS than 18 year olds. AAS engaged in health harming behaviors such as drink driving, having more sexual partners, not wearing a seatbelt, being a passenger with a drink driver, or carrying a gun more than non AAS users. Athletes were less likely to use ASS than non-athletes.
Faigenbaum et al., 1998	965 US athletes (466 males, 499 females), aged between 9 and 13 years (M age = 11.4 years).	Questions to assess AAS usage, attitudes, and perceptions toward AAS.	Cross-sectional	Low	2.6% of males and 2.8% of females abused AAS. 58% of users compared to 31% of non-users reported that AAS made their muscles bigger. Users (31%) and non-users (11%) thought that AAS improved performance. Users (23%) knew someone their own age who was taking AAS, whereas only 9% of non-users did. 54% of users compared to 91% of non-users felt AAS were bad for them. 38% of users and 4% of non-users were asked to take AAS.
Giraldi et al., 2015	423 soccer players from Italy who were aged under 15 years (53%) or between 16-18 years old (47%), although the exact age of the 15 and under soccer players was not reported. 94.3% of the sample were male.	Questionnaires regarding attitudes and opinions regarding sports participation, reasons for winning, using PEDS enhance performance, opinions about self-image, in addition to views, knowledge, and behavior regarding doping, NS, and medical appointments for athletes.	Cross-sectional	High	50% of the sample was unaware of the health-related side effects that PEDs can cause. 6.5% of the males, but none of the females considered doping to enhance their performance.
Goldberg et al., 1991	192 high-school varsity American football teams from the US.	Study created questions to use of AAS and supplements, in addition to beliefs, opinions, and attitudes toward AAS.	Longitudinal (2 weeks between assessments).	High	Negative education programs did not increase athletes' beliefs of adverse effects of AAS, whereas those who received a balanced education program (i.e., positive and negative effects of AAS) were more aware of the adverse effects of AAS.
Hoffman et al., 2008	3,248 students from the 12 states in the US, aged between 13 and 18 years old. Sample comprised of 1,559 males and 1,689 females. Mean age not provided.	Questions relating to demographics, NS use, AAS use, attitudes and beliefs toward AAS, and main sources of education.	Cross-sectional	Low	1.2% of the sample abused AAS (2.4% of males and 0.8% of females). NS use was associated with the consumption of AAS, and this association was stronger among the male participants, who also reported using more NS. In particular, males who used supplements for increased strength or body mass, were the nutritional users who were most likely to use AS. Among males and females, supplements designed to reduce body mass or body fat were associated with students using AAS. The use of AAS was higher among 18 year olds than 13 year olds. AAS was significantly higher among 14 to 18-year-old males than females, with 6% of 17-18-year-old males abusing AAS. Teachers and parents were the main source of information regarding supplements and AAS, although parents were less important by the time the students were 17 to 18 years old. As parents became less important, older students relied more on friends, coaches, trainers, and the internet, with older males reporting strength and conditioners as being more important than females.
Irving et al., 2002	4,746 middle and high-school athletes from the US.	Study created questions to assess AAS use, demographics, psychological constructs, and behaviors.	Cross-sectional	Low	AAS was more common in males than females. Non-Caucasians and middle school students (in comparison with high-school students) were more likely to use AAS. AAS among males was linked to depressed mood, less knowledge of health and poor attitude to health, sports where weight and shape were important, disordered eating, and substance use. The pattern for females was less consistent than males, although the results were similar.
Jampel et al., 2016	6,000 US males aged between 14 and 18 years old (M age = 16).	Questions to assess ASS use, weight, height, sports participation, weight change attempts, and asthma history.	Cross-sectional	Low	Males who perceived that they were under weight or over weight were more at risk of using AAS throughout their lifetime.
Judge et al., 2012	98 track and field athletes from the United States, who were aged between 12 and 19 years old (M age for males = 15.2 years, M age for females = 15.8 years). Sample comprised of 46 males and 52 females.	Questionnaire to assess attitudes, subjective (including both injunctive and descriptive) norms, perceived behavioral control, moral convictions, history of doping, and doping intentions.	Cross-sectional	Low	There were no gender differences in regards to doping intentions. The use of PEDs was predicted by attitude strength, injunctive norms, and moral conviction.
Kindlundh et al., 1999	2,742 Sdish students, comprising of 1,592 16 to 17 year olds, and 1,150 18 to 19 year olds.	Questions about PEDs, behavioral activities, and lifestyle.	Cross-sectional	Low	Those involved in strength training, tobacco use, large alcohol intake, living alone, and playing truant at least once per week were linked to the participants consuming PEDs. Some illegal substances (e.g., cannabis oil, LSD, opioids, and amphetamine) were positively associated with AAS use.
Laure et al., 2004	1,459 males and female high-school athletes from France.	4-page questionnaire pack to assess drug use, beliefs about doping (including psychological factors).	Cross-sectional	Low	4% of athletes reported using PEDs, which were generally supplied by friends or health professionals. PEDs users perceived that PEDs posed less of a health threat than non-users. Those who used PEDs were less anxious and more confident than non-users, but also perceived that they were not happy or healthy.
Laure and Binsinger, 2007	3,564 students aged 11-12 years old from France started the study and 2,199 of these completed the second assessment 4 years later.	PED use, sports participation, self-esteem, and trait anxiety.	Longitudinal (assessments every 6 months for 4 years).	Low	1.2% reported taking PEDs as an 11 or 12-year-old, which rose to 3% by the time the students were 14 or 15 years old and there was also an increase in the frequency of use. PED use increased with training hours and level of competition, and was higher among males than females. Some PED users are also more anxious and report lower self-esteem than non-users.
Lazuras et al., 2015	650 Greek athletes, aged 14 to 20 years old (M age = 16.09 years). 68.3% were males.	Questionnaires regarding social desirability, achievement goals, motivation regulation, sportspersonship, social cognitive variables (e.g., attitudes, norms, and self-efficacy), and anticipated regret.	Cross-sectional	Low	4.2% reported they committed a doping violation. The model assessed variables that accounted for 57.2% of doping intentions variance. Social cognitive factors and anticipated regret directly influenced intentions to dope. Indeed, anticipated regret predicted doping intentions over and above the other variables. Current or past use of PEDs did not predict future doping intentions.
Lucidi et al., 2004	952 Italian students aged between 14 to 20 years old (M age = 16.48 years). 50.1% of the sample were males.	Questionnaire pack that contained three sections: (1) sporting activities over last 3 months, (2) use of NS and PEDs, and (3) behavioral intentions, attitudes, subjective norms, and perceived behavioral control.	Cross-sectional	Low	3.1% of the sampled reported using a PED. Those who participated in competitive sport or recreational sport were more likely to use PEDs than sedentary people. Males used more PEDs than females, across all PED types (e.g., AAS, growth hormones, and stimulants etc.). Attitudes were the strongest predictor of intentions to use PEDs, followed by subjective norms (medium), moral disengagement, and then perceived behavioral control (small). Past use of ergogenic aids predicted intentions to use PEDs.
Lucidi et al., 2008	1,232 Italian high-school students assigned to psychometric condition (variables assessed 3 weeks apart; 51% females, M age = 17 years) or longitudinal condition (n = 762; 51% females, M age = 16.8 years).	Study created questionnaire to assess psychological factors (e.g., behavioral intentions, attitudes, subjective norms, and perceived behavioral control, and doping-specific self-regulatory efficacy) that predict doping on two separate occasions, either 2 weeks or 3 months apart. Those in the longitudinal group also reported the PEDs consumed within 3 months after completing the Time 1 assessments, at Time 2.	Longitudinal (3 months between assessments)	Low	Males portrayed more favorable attitudes toward doping, greater approval from others, more eager to justify using PEDs, and possessed stronger intentions to use PEDs than females. Females expressed a stronger capacity to overcome personal or interpersonal pressure to use PEDs. 2.1% of the longitudinal group reported using a PED in the previous 3 months and more males reported doping during this time, than females. Intentions to take PEDs were linked to attitudes, others' approval, doping, and the belief that PEDs were morally justified. Participants who reported a stronger moral disengagement or intentions to use PEDs at Time 1, were more likely to dope in the intervening 3 months. Being able to resist pressure from others and stronger perceptions of self-control were negatively associated with PED use. The prevalence of PEDs correlated significantly and positively with nutritional supplementation.
Lucidi et al., 2013	1,975 Italian high-school students, aged between 13 and 18 years old (M age = 16.3 years).	Questionnaires assessed moral disengagement, attitudes toward doping, self-regulatory efficacy to resist social pressure, social norms relating to doping approval, doping intentions, and motivational orientation at Time 1, and use of PEDs and supplements at Time 2 (3 months later).	Longitudinal (3 months between assessments).	Low	Athletes used different ways of justifying doping use. They denied the effects of PEDs or displaced responsibility. Moral disengagement was also associated with doping intentions and PEDs abuse.
Madigan et al., 2016	129 male athletes from the United Kingdom, aged between 16 and 19 years old (M age = 17.3 years).	Questionnaire to measure perfectionism and attitudes toward doping.	Cross-sectional	Low	Parental pressure was positively associated with favorable attitudes toward doping. The authors reported a negative relationship between perfectionism strivings and positive doping attitudes. after controlling for all overlapping variables.
Mallia et al., 2013	3,400 Italian high-school students (50.9% males, M age = 16.5 years, SD = 1.6).	Participants completed a 5-point scale to assess doping attitudes and reported previous use of doping in the 3 months prior to data collection.	Cross-section	Low	Males, older adolescents within the sample, and athletes reported using PEDs than their counterparts (e.g., females, younger adolescents, and those not involved in sport). Further, males, older participants, and athletes were more likely to report a favorable attitude toward the use of PEDs.
Mallia et al., 2016	Study 2 contained 414 adolescent athletes (M age = 16.69 years), and Study 3 contained 749 team athletes (M age participated in Study 3) from Germany, Greece, and Italy.	Interviews and Questionnaires to assess self-regulatory efficacy in teams, team collective efficacy, and moral disengagement in relation to doping.	Cross-sectional	Low	Self-regulatory efficacy in team contexts was negatively associated with intentions to dope during the next season, whereas as team moral disengagement was positively associated with intentions to dope during the next season.
Melia et al., 1996	16,169 students from Canada aged 11 to 18.	Questions relating to PED usage and attitudes toward PEDs.	Cross-sectional	Low	2.8% used AAS in the year prior to the survey, with 29.4% of these athletes injecting AAS. Of these, 29.2% shared needles. AAS was used mainly used to alter body composition rather than enhancing performance, whereas other PEDs were used to enhance sports performance.
Miller et al., 2002	16 175 US students who were aged between 14 and 19 years.	AAS usage.	Cross-sectional	Low	There were no significant gender differences. Those with parents with poorer educational achievements took more AAS. AAS users took more risks in other areas of their life such as with alcohol and in their sexual behaviors, and scored higher on suicidal risk. Girls who used AAS scored higher on suicide risk than males. Male and female users reported similar scores on alcohol and substance abuse. Female athletes were less likely to use AAS than non-athlete females.
Moston et al., 2015	312 athletes (aged between 12 and 17 years old) who were either elite or non-athletes.	Questionnaires assessed moral functioning and participants reported perceived incidence of doping violations.	Cross-sectional	Low	Participants estimated that 28.4% of athletes doped, with those in athletics, weightlifting, and cycling thought to commit the most doping offences. Elite athletes perceived that 11.26% of their competitors doped. 12 to 13 year olds and 16-17 years old estimated a higher level of doping violations that the 14 to 15 year olds. There were no gender differences.
Naylor et al., 2001	1,515 high-school students from the US (grades 912).	Questions relating to drug use and knowledge of rules.	Cross-sectional	Low	There were no differences between athletes and non-athletes in AAS use. 32% of athletes were unaware of anti-doping rules regarding the use of recreational drugs during the season.
Nicholls et al., 2015	11 coaches from four countries, who coached adolescent athletes in athletics, basketball, kayaking, racquetball, rowing, rugby league, or rugby union.	Semi-structured interviews.	Cross-sectional	Low	Coaches reported that attitudes toward doping among adolescents were influenced by perceptions of threat of being caught and the perceived benefits of PEDs. Additionally, those with low morality and low self-esteem were also thought to have a favorable attitude toward PEDs. Friends and family's opinions were also perceived to be important in influence doping attitudes. Age or maturation, level of participation, pressure experienced, country of residence, and ethnicity were reported as factors that influenced doping attitudes.
Nilsson, 1995	1,383 students aged between 14 and 19 years (688 males and 695 females).	Questions to assess demographics and AAS usage.	Cross-sectional	Low	5.8% of males used AAS. 10% of 15-16 year olds used AAS and half of these injected AAS as a liquid.
Pedersen and Wichstrøm, 2001	10,828 Norwegian students aged between 14 and 17 years old.	Questions to assess use of PEDs, demographics, parental control leisure time activities, and substance abuse.	Cross-sectional	Low	2.3% of males reported using PEDs, compared to 1.3% of females. Using PEDs was associated with alcohol exposure from parents and poor monitoring, in addition to using gymnasiums, using smokeless tobacco, and alcohol abuse. There was strong associated between PEDs and illegal drugs (e.g., amphetamines, MDMA, and heroin).
Rees et al., 2008	495 US high-school students aged 14 to 18 years.	Questions to assess attitudes, sensation seeking, and supplement use.	Cross-sectional.	Low	Supplement users reported a stronger intention to take PEDs than non-NS users.
Sagoe et al., 2016	1,334 Norwegian 18-year-olds (females 58.7%).	Questionnaires to measure aggression, AAS intent alcohol disorders, anxiety, and depression.	Cross-sectional	Low	Those who were more aggressive reported a stronger intent to use AAS in the future, in comparison with their less aggressive counterparts.
Schirlin et al., 2009	97 adolescents (54.6% male), aged between 11-15 years).	Reaction times on Stroop emotion task (doping, cheating, and control words). Scales on physical self-perception, physical self-worth, physical condition, sport competence, body attractiveness, and physical strength.	Experimental	Potential	Reaction times were longer after doping words than either cheating or control words, inferring that attentional resources allocated to doping are already present by the time a person reaches adolescence. Further, low self-esteem may be a risk factor for doping, as those in the low self-esteem group demonstrated larger carry-over effects (i.e., significant slowdown of response times due to difficulty in disengaging attention from another word or stimuli) than those in the high self-esteem group.
Stilger and Yesalis, 1999	873 varsity American football players from urban, suburban, and rural high schools.	Questions relating to knowledge and attitudes toward AAS, and usage, availability, reasons to use, dosage, and method of using AAS.	Cross-sectional	Low	6.3% were previous or current abusers of AAS. Ethnic minority players (e.g., Hispanic or Asians; 11.2%) were twice as likely to use AAS than Caucasian (6.5%) players. AAS use increased with playing experience and was linked to specific positions (e.g., linebackers). Other players, doctors and coaches were the most reported source for obtaining AAS. The age when players first used AAS was: <10 years, n = 10), 11–12 years (n = 10), 13–15 years (n = 24), and 16 to 18 years (n = 22). AAS were used to enhance performance, followed by improving appearance, and to keep up with other competitors. Of those who did not take AAS, health concerns, against beliefs, and cost were the main reasons.
Terney and McLain, 1990	2,113 high-school students aged between 14 and 18 years old.	Questions relating to attitudes, usage, knowledge, and availability of AAS, and how these are perceived by others.	Cross-sectional	Low	There was a higher incidence of AAS use among athletes (5.5%) in comparison with non-athletes (2.4%). Males, American footballers, and wrestlers were more likely to take AAS than females or those involved in other sports. 2% of athletes reported that their coach or another member of staff recommended the use of AAS. 9% reported that they would consider using AAS to gain a college scholarship.
vandenBerg et al., 2007	2,516 students from the US, aged 11 to 18 years of age.	Questions to assess AAS use, demographics, eating activity, weight, and related variables.	Longitudinal (5 years between assessments).	Low	1.5% of the sample abused AAS, although the numbers of students taking AAS remained stable and thus did not increase with age. Male AAS users wanted to weigh more, whereas female AAS users reported higher BMIs, were unsatisfied with their weight, had poorer knowledge nutrition, and less concern for their health.
Wanjek et al., 2007	2,319 adolescents from Germany.		Cross-sectional	Low	15.1% of athletes reported using a PED in the previous year. Non-athletes, recreational athletes, and competitive athletes generally scored poorly on a tested that assessed knowledge of doping. Older athletes and those with a more favorable attitude toward taking PEDs were more like to dope. No significant differences between non-athletes, recreational athletes, and competitive athletes for AAS, but non-athletes took stimulants more than competitive or recreational level athletes.
Wichstrøm, 2006	2,924 Norwegian high-school students (aged 15–19 years).	Questions completed on AAS use, involvement in power sports, appearance and eating problems, problematic behavior, and emotional problems. All questions completed at Time 1 (baseline), Time 2 (2 years later), and Time 3 (5 years after baseline).	Longitudinal (5 years between assessments).	Low	1.9% reported using AAS at some point during the study. Male, an involved in power sports, problematic behaviors (e.g., misconduct, cannabis abuse, alcohol abuse, and sexual debut before 15th birthday) predicted AAS use at Time 3.
Woolf et al., 2014	404 male adolescent athletes, aged 14 to 19 years old (M age = 16.06 years), predominantly Caucasian.	Questionnaires to measure intentions, descriptive norms, injunctive norms, outcome expectations, and control variables.	Cross-sectional	Low	Athletes believed that AAS would benefit their performance, which was linked to intentions. Intentions to use AAS were influenced by injunctive norms. Athletes who believed that professional athletes used ASS more than their team mates. Athletes who believed that their team mates used AAS they had a stronger intention to use AAS than if they believed other professional athletes were using AAS. As such, perceptions of what team mates do may be more important than perceptions of professional athletes in predicting doping intentions.
Wroble et al., 2002	1,553 athletes aged between 10 and 14 years from the US, with 1,079 males and 474 females. The age of the participants was 10 (n = 248), 11 (n = 394), 12 (n = 484), 13 (n = 274), 14 (n = 199), or 15 (n = 32) years of age.	15 questions that measured demographics, prevalence of AAS, knowledge of side effects, attitudes, and where to obtain AAS from.	Cross-sectional	Low	0.9% of males and 0.2% of females reported taking AAS. Of these users, 27% did so for performance, 18% to improve personal appearance, and 18% for body building. 18% took AAS due to peer pressure. 90% of athletes did not feel they needed to take AAS to be successful. The most prominent sources of information were books/magazines, parents, and coaches.
Zelli et al., 2010a	1,022 Italian students (balanced sample, around 16 years of age) completed Time 1 and 864 students (M age = 16.5 years, 51% female) completed Time 2, 4 months later.	Questionnaires regarding drive for muscularity, drive for thinness, doping attitudes, and doping intentions.	Longitudinal (4 months between assessments)	Low	Drive for thinness and muscularity were positively associated with intentions to dope. Drive for muscularity (but not thinness) exerted this effect through positive doping attitudes.
Zelli et al., 2010b	1,022 Italian students (balanced sample, around 16 years of age) completed Time 1 and 864 students (M age = 16.5 years, 51% female) completed Time 2, 4 months later.	Questionnaires assessed doping attitudes, subjective norms, behavioral control, self-regulatory efficacy, moral disengagement, and prior substance use.	Longitudinal (4–5 months between assessments)	Low	47% of the variance in doping intentions was predicted by favorable attitudes toward doping, strong views that significant others would approve, a tendency to justify using PEDs, and lower confidence in one's ability to resist social pressure. Moral disengagement was associated with favorable attitudes toward doping and intentions to dope. Doping behavior remained stable over the 4 months, intentions at Time 1 predicted the use of PEDs at Time 2.