Table 1. Study characteristics of the included articles.
Author Study region Included age groups
[mean age]		 Type of sports Net sample size[athletic sample, if this is subgroup] Kind of athletes Method of data
collection		 Statistical method
Aerenhouts et al. 2008 Belgium 12-18 Track and field 60
(51.7% male)		 Competitive athletes Questionnaire, 7 day food record Bivariate analyses
Aleixandre et al. 2005 unspecified 13-19
[15.67]		 unspecified 1,378
(43.7% male)
[NN; NN% male]		 unspecified unspecified Linear modeling
Assanelli et al. 1991 North Italy 17-19 unspecified 696
(100% male)
[330; 100% male]		 Members of sports teams Questionnaire Logistic regression analyses
Bachner-Melman et al. 2006aa unspecified 18.9 Dancing, gymnastics, acrobatic, artistic (synchronized) swimming 458
(0% male)
[111; 0% male]		 unspecified Questionnaire ANCOVA
Baumert et al. 1998 Georgia, USA Grades 9-12 unspecified 4,036
(58% male)		 Students who have participated in organized sports, outside of gym class Questionnaire Multiple linear regression
Beals 2002 USA 14-17
[15.8]		 Volleyball 23
(0% male)		 Nationally ranked athletes Questionnaire, anthropometric measurements, 3 day food records, blood analyses Univariate analyses
Bergen-Cico & Short 1992 New York State, USA 11-16
[13.9]		 Cross-country 44
(0% male)		 unspecified Questionnaire, anthropometric measurements, 3 day food records, 24 hour activity record Univariate analyses
Berning et al. 1991 California, USA 14-18 Swimming 43
(51.2% male)		 National athletes Dietary food records Bivariate analyses
Castrucci et al. 2004 USA 13-19 unspecified 16,357
(45.7% male)
[10,015; NN% male]		 Data for participation in organized sports were measured Questionnaire Logistic regression analyses
Cavadini et al. 2000 Switzerland 9-19 unspecified 3,540
(49.8% male)
[NN; NN% male]		 Non-athletic was defined as engaging in sports less than once a week Questionnaire, in subgroup: 3 day dietary record & interview with dietician Bivariate analyses
Crissey & Crissey Honea 2006 USA 12-21 Cheerleading/dance team, softball/baseball, basketball, field hockey, football, ice hockey, soccer, swimming, tennis, track and field, volleyball, wrestling, other sports 7,214
(0% male)		 Students participating in school Questionnaire Logistic regression analyses
Croll et al. 2006 Minnesota, USA 11-18
[14.9]		 Weight-related sports, power team sports 2,553
(52.9% male)
[1,715; 57.5%]		 Hours of physical activity were considered Questionnaire, anthropometric measurements Bivariate Analyses
Cupisti et al. 2002 Italy 14-18
[16.1]		 Gymnastics, tennis, fencing 119
(0% male)
[60; 0% male]		 Elite national-level athletes Anthropometric measurements and 3-day food recalls; non-standardized questionnaires ANOVA
Davis et al. 1997 Lousiana, USA [15.8] unspecified 1,200
(100% male)
[990; 100% male]		 High school athletes Questionnaire Logistic regression analyses
Dlin et al. 1991 Israel 14-18 Strength-, endurance-, mixed-, skill- and non-competitive sports 2,447
(100% male)
[822; 100% male]		 Athletes undergoing routine testing at the Department of Sport Medicine at Wingate Institute Questionnaire Bivariate analyses
Donato et al. 1994 Italy 17-19 unspecified 696
(100% male)
[330; 100% male]		 Adolescents being in sports teams Questionnaire Logistic regression analyses
Donato et al. 1997 Italy Grades 9 - 13 unspecified 1,462
(NN% male)
[425; NN% male]		 Sporting activity was defined as being engaged in out-of-school programs Questionnaire Logistic regression analyses
DuRant et al. 1995 USA Grades 9 - 12 Strength training 12,267
(48.8% male)
[8,245; NN% male]		 Strength training was measured Questionnaire Logistic regression analyses
Elliot et al. 2007 USA rades 9 - 12 unspecified 7,544
(0% male)
[3,847; 0% male]		 Participating in team sport Questionnaire Logistic regression analyses
Escobedo et al. 1993 USA Grades 9 - 12 unspecified 11,248
(NN% male)
[4,568; NN% male]		 Subjects participating in junior sports team during last 12 months Questionnaire Logistic regression analyses
Ewing 1998 USA 14-21 unspecified 1,458
(53.3% male)
[675; 58.7% male]		 Subjects participating in high school sports Questionnaire Logistic regression analyses
Ferrand et al. 2005 France [Synchronized swimmers: 15.4;Other athletes: 16.5;Non-athletes: 16.3] Synchronized swimming, basketball, handball, volleyball, soccer 132
(0% male)
[82; 0% male]		 Subgroup of national athletes Questionnaire; anthropometric measurements Multivariate analyses, regression analyses
Forman et al. 1995 Chicago and Northwest Indiana, USA 13-19 Cross country, football, soccer, basketball, gymnastics, hockey, swimming, wrestling, baseball, tennis, track 1,117
(100% male)		 High school students participating at least in one interscholastic sport Questionnaire Bivariate analyses
French et al. 1994 USA Grades 7 - 10 “Leisure sports” (swimming, skating, golfing, sailing, canoeing, running), “conditioning sports” (running, sit-ups, weight lifting), and “atypical sports” (aerobics, gymnastics, dance, softball) 1494
(47.4% male)
[NN; NN% male]		 unspecified Questionnaire Principal component analyses
Grossbard et al. 2007b West Coast of the USA [18.4] unspecified 1,360
(40% male)
[335; NN% male]		 Intramural athletes among first-year college students Questionnaire Linear models
Haase & Prapavessis 2001 New Zealand [Group 1: 18.21;
Group 2: 18.73;
Group 3: 18.97]		 Group 1: aerobics and diving;
Group 2: lightweight rowing;
Group 3: soccer		 251
(0% male)
[198; 0% male]		 National or international competitors Questionnaires ANOVA
Hoffmann 2006 USA Grades 10 - 12 Softball, football, basketball, baseball, swimming, other individual and team sports 9,893
(45.4% male)
[NN; NN% male]		 Subjects participating in sport as an extracurricular activity Questionnaire Multilevel regression analyses
Irving et al. 2002 Minnesota, USA 11-18
[14.9]		 unspecified 4,746
(50.2% male)
[NN; NN% male]		 Hours of physical activity were considered Questionnaire Logistic regression analyses
Jerry-Szpak & Brown 1994 USA [15] Football, field hockey, track and field, gymnastics 75
(44% male)		 Subjects spent at least 20 hours a week participating in organized sports Repeated questionnaires and interviews with coaches Bivariate analyses
Jonnalagadda et al. 2004c USA [15.5] Figure skating 49
(46.9% male)
[26; 0% male]		 Elite figure skaters Questionnaires, body measurements Bivariate analyses
Karvonen et al. 1995 Finland 16 & 18 unspecified T1: 3,667;
T2: 3,175;
T3: 2,936
(100% male)		 Leisure time physical activity organized by sport clubs Questionnaire Bivariate analyses
Kiningham & Gorenflo 2001 Michigan, USA [16] Wrestling 2,532
(NN% male)		 High school competing athletes Questionnaire Bivariate analyses
Kokkevi et al. 2008 Bulgaria, Croatia, Cyprus, Greece, Slovak Republic, UK [16] unspecified unspecified Students doing exercise on almost every day Questionnaire Logistic regression analyses
Lindholm et al. 1995 Sweden Athletes: 13-16 [14.8]Non-athletes: 14-15 [14.8] Gymnastics 44
(0% male)
[22; 0% male)		 Elite athletes Anthropometric measurements, food recording Bivariate analyses
Lorente et al. 2004 France [18.3] Individual and team sports 816
(46.2% male)
[621; NN% male]		 Formal and informal sporting practice was measured Questionnaire Logistic regression analyses
Mays & Thompson 2009 USA Grades 9 - 12 unspecified 13,956
(NN% male)
[NN; NN% male]		 Sport participation was measured Questionnaire Logistic regression analyses
Mays et al. 2010a USA [14.4(males: 14.5, females: 14.3)] unspecified 8,721
(43.7% male)
[NN; NN% male]		 Sport involvement was measured Questionnaire Growth models
Mays et al. 2010b Georgia, USA “≤14 years - ≥ 17 years” (Mays et al. 2010, p. 236) Individual and team sports 378
(75.9% male)		 Students engaging in school-based sports Questionnaire Regression analyses
McHale et al. 2005 Worcester, MA, USA Seventh-grade students (91% were 12 or 13 years old) Football, baseball, softball, basketball, soccer, other team sport 423
(51% male)
[271; 62% male]		 Students taking part in an organized sport during the previous year Interview & questionnaire Multivariate Analysis of Variance (MANOVA)
Melia et al. 1996 Canada 11-18 unspecified 16,169
(NN%male)
[NN; NN% male]		 Involvement in competitive sports was measured Questionnaire Bivariate analyses
Melnick et al. 2001 USA [16.08 for females, 16.22 for males] unspecified 16,251
(54.8% male)
[9,363; 63.8% male]		 Students participating in sports teams at school and/or outside of school Questionnaire Logistic regression analyses
Miller et al. 2002ad USA “14 and younger to 18 and older” (Miller et al. 2002b, p. 389) unspecified 504
(71.4% male)		 Students who played on a sports team in the past year Questionnaire Regression analyses
Miller et al. 2002b USA “14 and younger to 18 and older” (Miller et al. 2002a, p. 476) unspecified 16,181
(54.6% male)
[9,685; 61.5% male]		 Students who played on a sports team in the past year Questionnaire Logistic regression analyses
Miller et al. 2005 USA 14-18 unspecified 16,183
(NN% male)
[NN; NN% male]		 Activity in sports team and strength conditioning activity were measured Questionnaire Logistic regression analyses
Moore & Werch 2005 Florida, USA [13.39] Basketball, rollerblading, skateboarding, surfing, tennis, dance, cheerleading, gymnastics, football, swimming, wrestling 981
(42.6% male)
[772; NN% male]		 Out-of-school sports and school-sponsored sports were measured Questionnaire ANOVA, logistic regression analyses
Moulton et al. 2000 USA Grades 7 - 12 unspecified 455
(42.0% male)
[210; NN% male]		 Athletic participation was measured Questionnaire ANOVA
Papaioannou et al. 2004 Greece 11, 13 & 16 unspecified 5,991
(49.2% male)
[NN; NN% male]		 Sport behavior and involvement in organized sports were measured Questionnaire Logistic regression analyses
Pate et al. 2000 Columbia, USA 9th through 12th grade students (≤16 to >16) unspecified 7,821
(59,5% male)
[6,400; 37.2% male]		 Students participating in sports teams, run by the school and/or outside of school in the past year Questionnaire Multiple logistic regression analyses
Peretti-Watel et al. 2002 France 14-19 unspecified 10,807
(47.9% male)		 Students with different intensity of sporting activity Questionnaire Multinomial logistic regression
Peretti-Watel et al. 2003 South-Eastern France 16-24
[18.3]		 Individual, team and sliding sport 458
(65.3% male)		 Elite-student-athletes Questionnaire Logistic regression analyses
Peretti-Watel et al. 2004a South-Eastern France 16-24
[18.3]		 unspecified 458
(65.3% male)		 Elite student-athletes Questionnaire Cluster analyses and logistic regression analyses
Peretti-Watel et al. 2004b South-Eastern France 16-24
[18.3]		 unspecified 458
(65.3% male)		 Elite-student-athletes Questionnaire Cluster Analysis, ANOVA
Peretti-Watel & Lorente 2004 France 18 unspecified 12,512
(29.0% male)
[NN; NN% male]		 Formal and informal sport practice were measured in hours per week Questionnaire Logistic regression analyses
Pernick et al. 2006 California, USA 13-18
[15.7]		 Track and field, cross-country running, tennis, volleyball, basketball, softball, soccer, swimming, lacrosse, field hockey 453
(0% male)		 High-school athletes Questionnaire ANCOVA
Rainey et al. 1996 South Carolina, USA Grades 9-12 unspecified 7,846
(48.6% male)
[3,960; 60.9% male]		 Different levels of activity were measured Questionnaire Linear models, logistic regression analyses
Rhea 1999 USA 13-19
[15.5]		 Volleyball, basketball, cross-country, track and field, swimming, tennis, softball 1,034
(0% male)
[571; 0% male]		 High school athletes with at least 3 years of competitive experience Questionnaire MANCOVA
Ruiz et al. 2005e Spain [Team I: 14.0; Team II: 15.0;Team III: 16.6] Soccer unspecified
(100% male)		 Athletes that trained three times per week Food diaries & questionnaire ANOVA
Sabo et al. 2002 USA [Athletes: 16.17; Non-athletes: 16.32] unspecified 8,057
(100% male)
[5,973; 100% male]		 Sport participation was measured Questionnaire Logistic regression analyses
Scott et al. 1996 Nebraska, USA Grades 7 - 12 unspecified 4,722
(45.2% male)
[3,183; 49.9% male]		 Sport participation was measured Questionnaire Bivariate analyses
Sherwood et al. 2002 Connecticut, USA Grades 7, 9 & 11 Weight-related sports 5,174
(0% male)
[1.164; 0% male]		 Sport participation was measured Questionnaire Logistic regression analyses
Slater et al. 2003 Singapore “<15 to >35” (Slater et al. 2003, p. 323) 30 different sports 160
(53.1% male)		 Athletes competing at a national level Questionnaire ANOVA
Soric et al. 2008 Croatia Athletes: 9-13 [11]Non-athletes: 10-12 [11] Artistics, rhythmic gymnastics, ballet 54
(0% male)
[39; 0% male]		 Competitive athletes Questionnaire, anthropometric measurements ANOVA
Sundgot-Borgen 1996 Norway 13-20 Rhythmic gymnastics 24
(0% male)
[12; 0% male]		 National athletes Questionnaire, interview, clinical examination, 4 day food records Bivariate analyses
Taliaferro et al. 2010 USA Grades 9 - 12 unspecified T1: 15,273 (48.7% male)
T5: 14,028 (49.8% male)
[NN; NN% male]		 Participation in one or more sports teams during last 12 months Questionnaire Logistic regression analyses
Taub & Blinde 1992 Midwestern, USA [Athletes: 16.2Non-athletes: 15.9] Volleyball, basketball, track/cross-country, tennis, softball 212
(0% male)
[100; 0% male]		 Participation in one or more sport was measured Questionnaire Bivariate analyses
Terney & McLain 1990 Chicago, USA Grades 9 - 12 Track, swimming, soccer, basketball, tennis, volleyball, gymnastics, softball, field hockey, badminton, baseball, football,wrestling, and others 2,113
(48.7% male)
[1,436; 58.0% male]		 Sports participation was measured Questionnaire Bivariate analyses
Turrisi et al. 2007 North-Western USA [18.8] unspecified 835
(36,6% male)
[204; 52% male]		 Collegiate athletes Questionnaire Mediation analyses
Vertalino et al. 2007 Minnesota, USA [14.9] Weight-related sports 4,746
(50.2% male)		 Participation in weight-related sports was measured Questionnaire Multiple logistic regression analyses
Walsh et al. 2000 California, USA 13-19 Baseball 1,226
(100% male)		 High school athletes Questionnaire Logistic regression analyses
Wetherhill & Fromme 2007 USA [18.4] unspecified 2,138
(39.6% male)
[NN; NN% male]		 Participants spending ten or more hours per week in competitive athletics Internet-based survey Linear Modeling
Wichstrom & Pedersen 2001 Norway 14-25
[17.33]		 unspecified 8,877
(46.2% male)
[NN; NN% male]		 Participating in strength or competitive sports Questionnaire Logistic regression analyses
Ziegler et al. 1998a USA 11-16
[13.7]		 Figure skating 21
(0% male)		 Competitive athletes Anthropometric measurements, questionnaire, 3 day food records Bivariate analyses
Ziegler et al. 1998b USA [males: 16females: 14] Figure skating 34
(44.1% male) 		Nationally ranked athletes 4 day food records, questionnaire, blood analyses Bivariate analyses
Ziegler et al. 1998c USA 12-23[females: 15.9, males: 17.8] Figure skating 39
(48.7% male)		 Nationally ranked junior athletes Questionnaires, recording of food intakes, blood analyses Bivariate analyses
Ziegler, Nelson et al. 1999 USA 11-18 Figure skating 41
(51.2% male)		 Elite athletes Anthropometric measurements, blood analyses, 4 day food records Bivariate analyses
Ziegler et al. 2001 USA 12-28[overall: 17males: 18females: 16] Figure skating 161
(49.7% male)		 Elite athletes Anthropometric measurements, 3 day food records, blood analyses Multivariate regression analyses
Ziegler et al. 2002 New England, USA 14-16 Figure skating 18
(0% male)		 Competitive athletes Questionnaire, anthropometric measurements, 3 day food records, blood analyses Bivariate analyses and range tests
Ziegler et al. 2005 USA 14-23
[17.0]		 Synchronized skating 123
(0% males)		 Competitive athletes Questionnaire, anthropometric measurements, 3 day food records Bivariate analyses
only the athlete group AA was considered in this review as the mean age of the athlete group NAA was greater than 18 (mean age: 21.4) only study I was considered in this review as the mean age of the participants in study II was greater than 18 (mean age: 21.2) only female athletes were considered in this review because the male athletes had a mean age of 19.0. only steroid users were analyzed only teams I to III were considered in this review as the mean age of team IV was greater than 18 (mean age: 20.9)