The Health Benefits of Muscular Fitness for Children and Adolescents: A Systematic Review and Meta-Analysis

BackgroundPhysical fitness during childhood and adolescence has been identified as an important determinant of current and future health status. While research has traditionally focused on the association between cardio-respiratory fitness and health outcomes, the association between muscular fitness (MF) and health status has recently received increased attention.ObjectiveThe aim of this systematic review and meta-analysis was to evaluate the potential physiological and psychological benefits associated with MF among children and adolescents.MethodsA systematic search of six electronic databases (PubMed, SPORTDiscus, Scopus, EMBASE, PsycINFO and OVID MEDLINE) was performed on the 20th May, 2013. Cross-sectional, longitudinal and experimental studies that quantitatively examined the association between MF and potential health benefits among children and adolescents were included. The search yielded 110 eligible studies, encompassing six health outcomes (i.e., adiposity, bone health, cardiovascular disease [CVD] and metabolic risk factors, musculoskeletal pain, psychological health and cognitive ability). The percentage of studies reporting statistically significant associations between MF and the outcome of interest was used to determine the strength of the evidence for an association and additional coding was conducted to account for risk of bias. Meta-analyses were also performed to determine the pooled effect size if there were at least three studies providing standardised coefficients.ResultsStrong evidence was found for an inverse association between MF and total and central adiposity, and CVD and metabolic risk factors. The pooled effect size for the relationship between MF and adiposity was r = −0.25 (95 % CI −0.41 to −0.08). Strong evidence was also found for a positive association between MF and bone health and self-esteem. The pooled effect size for the relationship between MF and perceived sports competence was r = 0.39 (95 % CI 0.34–0.45). The evidence for an association between MF and musculoskeletal pain and cognitive ability was inconsistent/uncertain. Where evidence of an association was found, the associations were generally low to moderate.ConclusionThe findings of this review highlight the importance of developing MF in youth for a number of health-related benefits.

[1]  J. Whitehead,et al.  A Study of Children’s Physical Self-Perceptions Using an Adapted Physical Self-Perception Profile Questionnaire , 1995 .

[2]  I. Ara,et al.  Adiposity, Physical Activity, and Physical Fitness Among Children From Aragón, Spain , 2007, Obesity.

[3]  L. Straker,et al.  Fitness, motor competence, and body composition are weakly associated with adolescent back pain. , 2009, The Journal of orthopaedic and sports physical therapy.

[4]  W. Goodman,et al.  Changes in vertebral bone density in black girls and white girls during childhood and puberty. , 1991, The New England journal of medicine.

[5]  C. Mbada,et al.  Isometric endurance of the back extensors in school-aged adolescents with and without low back pain. , 2009, Journal of back and musculoskeletal rehabilitation.

[6]  U. Kujala,et al.  Leisure time physical activity in the young. Correlation with low-back pain, spinal mobility and trunk muscle strength in 15-year-old school children. , 1993, International journal of sports medicine.

[7]  D. Lubans,et al.  Muscular fitness, body composition and physical self-perception in adolescents. , 2011, Journal of science and medicine in sport.

[8]  S. Henauw,et al.  Muscular fitness, fatness and inflammatory biomarkers in adolescents , 2014, Pediatric obesity.

[9]  T. Lohman,et al.  Relationship of somatotype and body composition to physical performance in 7- to 12-year-old boys. , 1977, Research quarterly.

[10]  S. Biddle,et al.  Physical activity and mental health in children and adolescents: a review of reviews , 2011, British Journal of Sports Medicine.

[11]  J. Eisenmann,et al.  Associations of physical activity and fitness with adipocytokines in adolescents: the AFINOS Study. , 2012, Nutrition, metabolism, and cardiovascular diseases : NMCD.

[12]  A. Claessens,et al.  Association between bone, body composition and strength in premenarcheal girls and postmenopausal women , 2004, Annals of human biology.

[13]  M. Sjöström,et al.  Physical fitness levels among European adolescents: the HELENA study , 2009, British Journal of Sports Medicine.

[14]  E. Jansson,et al.  Adolescent determinants of cardiovascular risk factors in adult men and women , 2001, Scandinavian journal of public health.

[15]  R M Malina,et al.  Health-related fitness and academic achievement in middle school students. , 2012, The Journal of sports medicine and physical fitness.

[16]  G. Cardon,et al.  Physical Fitness, Physical Activity, and Self-Reported Back and Neck Pain in Elementary Schoolchildren , 2004 .

[17]  J Suni,et al.  Predictive validity of health-related fitness in youth: a systematic review , 2009, British Journal of Sports Medicine.

[18]  Germán Vicente-Rodríguez,et al.  El perfil lipídico-metabólico en los adolescentes está más influido por la condición física que por la actividad física (estudio AVENA)* , 2007 .

[19]  J. Sallis,et al.  Habitual physical activity and health-related physical fitness in fourth-grade children. , 1993, American journal of diseases of children.

[20]  J. Salminen,et al.  Spinal Mobility and Trunk Muscle Strength in 15‐Year-Old Schoolchildren With and Without Low‐Back Pain , 1992, Spine.

[21]  Jane U Edwards,et al.  Relationship of nutrition and physical activity behaviors and fitness measures to academic performance for sixth graders in a midwest city school district. , 2011, The Journal of school health.

[22]  S. Pettigrew,et al.  Eight Weeks of Resistance Training Can Significantly Alter Body Composition in Children Who Are Overweight or Obese , 2009, Journal of strength and conditioning research.

[23]  E. J. Ulloa,et al.  The Relation between Aerobic Fitness, Muscular Fitness, and Obesity in Children from Three Countries at Different Stages of the Physical Activity Transition , 2013, ISRN obesity.

[24]  A. Claessens,et al.  Tracking of fatness during childhood, adolescence and young adulthood: a 7-year follow-up study in Madeira Island, Portugal , 2012, Annals of human biology.

[25]  C. Cotman,et al.  Exercise: a behavioral intervention to enhance brain health and plasticity , 2002, Trends in Neurosciences.

[26]  O. Johnell,et al.  Bone mineral density, muscle strength and physical activity. A population-based study of 332 subjects aged 15-42 years. , 1997, Acta orthopaedica Scandinavica.

[27]  J. Prochaska,et al.  A review of correlates of physical activity of children and adolescents. , 2000, Medicine and science in sports and exercise.

[28]  D. J. van der Valk,et al.  How accurately can sitting and the intensity of walking and cycling be classified using an accelerometer on the waist for the purpose of the “Global recommendations on physical activity for health”? , 2015 .

[29]  M. Sjöström,et al.  Neuromuscular training and the risk of leg injuries in female floorball players: cluster randomised controlled study , 2008, BMJ : British Medical Journal.

[30]  K. M. Chan,et al.  Determinants of axial and peripheral bone mass in Chinese adolescents , 1998, Archives of disease in childhood.

[31]  F. Rasmussen,et al.  Muscular strength in male adolescents and premature death: cohort study of one million participants , 2012, BMJ : British Medical Journal.

[32]  Tim S Olds,et al.  Secular Trends in the Performance of Children and Adolescents (1980–2000) , 2003, Sports medicine.

[33]  L. Sidossis,et al.  Body mass index, calcium intake, and physical activity affect calcaneal ultrasound in healthy Greek males in an age-dependent and parameter-specific manner , 2004, Journal of Bone and Mineral Metabolism.

[34]  O. Bar-or,et al.  Growth, Maturation and Physical Activity , 1992 .

[35]  T. G. Reeve,et al.  Age, Sex, and Body Composition as Predictors of Children's Performance on Basic Motor Abilities and Health-Related Fitness Items , 1983, Perceptual and motor skills.

[36]  Andersen Lb.  Changes in physical activity are reflected in changes in fitness during late adolescence. A 2-year follow-up study. , 1994 .

[37]  Marcela González-Gross,et al.  [Lipid and metabolic profiles in adolescents are affected more by physical fitness than physical activity (AVENA study)]. , 2007, Revista espanola de cardiologia.

[38]  A. Claessens,et al.  Secular trends in anthropometric characteristics, physical fitness, physical activity, and biological maturation in Flemish adolescents between 1969 and 2005 , 2007, American journal of human biology : the official journal of the Human Biology Council.

[39]  J. Etnier.  Psychology of Physical Activity: Determinants, Well-being, and Interventions , 2001 .

[40]  S. Pocock,et al.  Strengthening the reporting of observational studies in epidemiology (STROBE) statement: guidelines for reporting observational studies , 2007, BMJ : British Medical Journal.

[41]  L. Micheli,et al.  Strength training recommendations for the young athlete. , 2008, Physical medicine and rehabilitation clinics of North America.

[42]  C. Snow,et al.  Lean body mass and leg power best predict bone mineral density in adolescent girls. , 1999, Medicine and science in sports and exercise.

[43]  T. Jones,et al.  Exercise training normalizes vascular dysfunction and improves central adiposity in obese adolescents. , 2004, Journal of the American College of Cardiology.

[44]  Xiaofen D. Keating,et al.  Percentile Values for Muscular Strength Field Tests in Children Aged 6 to 17 Years: Influence of Weight Status , 2009, Journal of strength and conditioning research.

[45]  R. Lorentzon,et al.  The relation between bone mineral density, insulin-like growth factor I, lipoprotein (a), body composition, and muscle strength in adolescent males. , 1999, The Journal of clinical endocrinology and metabolism.

[46]  T. Hewett,et al.  Integrative Training for Children and Adolescents: Techniques and Practices for Reducing Sports-Related Injuries and Enhancing Athletic Performance , 2011, The Physician and sportsmedicine.

[47]  Philip J. Morgan,et al.  Fundamental Movement Skills in Children and Adolescents , 2010, Sports medicine.

[48]  G E Hedberg,et al.  Determinants of Self‐Reported Neck‐Shoulder and Low Back Symptoms in a General Population , 1998, Spine.

[49]  Relations of Body Fatness and Cardiovascular Fitness to Lipid Profile in Black and White Adolescents , 2005, Pediatric Research.

[50]  A. Must,et al.  Predicting Maintenance or Achievement of Healthy Weight in Children: The Impact of Changes in Physical Fitness , 2012, Obesity.

[51]  L. Abenhaim,et al.  Risk factors for the development of low back pain in adolescence. , 2001, American journal of epidemiology.

[52]  Jean Adams.  Trends in physical activity and inactivity amongst US 14–18 year olds by gender, school grade and race, 1993–2003: evidence from the youth risk behavior survey , 2006, BMC public health.

[53]  S. Brage,et al.  Muscle strength in youth and cardiovascular risk in young adulthood (the European Youth Heart Study) , 2013, British Journal of Sports Medicine.

[54]  W..  Construct Validity of Physical Self-Description Questionnaire Responses : Relations to External Criteria , 2007 .

[55]  M. Sjöström,et al.  Associations of muscular and cardiorespiratory fitness with total and central body fat in adolescents: The HELENA Study , 2009, British Journal of Sports Medicine.

[56]  J D Dawson,et al.  Increases in physical fitness during childhood improve cardiovascular health during adolescence: the Muscatine Study. , 2002, International journal of sports medicine.

[57]  M. Torode,et al.  Muscular strength and cardiorespiratory fitness is associated with higher insulin sensitivity in children and adolescents. , 2006, International journal of pediatric obesity : IJPO : an official journal of the International Association for the Study of Obesity.

[58]  L. Murray,et al.  Children with low muscle strength are at an increased risk of fracture with exposure to exercise. , 2011, Journal of musculoskeletal & neuronal interactions.

[59]  R. Lorentzon,et al.  Relationships between physical activity and physical capacity in adolescent females and bone mass in adulthood , 2006, Scandinavian journal of medicine & science in sports.

[60]  Frederic Gottrand,et al.  Muscular and cardiorespiratory fitness are independently associated with metabolic risk in adolescents: the HELENA study , 2011, Pediatric diabetes.

[61]  G. Beunen,et al.  Muscular Strength Development in Children and Adolescents , 2000 .

[62]  J. Annesi,et al.  Preliminary Effects of the Youth Fit For Life Protocol on Body Mass Index in Mexican American Children in YMCA Before- and After-School Care Programs , 2009 .

[63]  J. Kampert,et al.  Muscular Fitness and All-Cause Mortality: Prospective Observations , 2004 .

[64]  S. Srinivasan,et al.  Childhood lipoprotein profiles and implications for adult coronary artery disease: the Bogalusa Heart Study. , 1995, The American journal of the medical sciences.

[65]  P. Freedson,et al.  Status of Field-Based Fitness Testing in Children and Youth , 2000 .

[66]  Terence Dwyer,et al.  Relation of Academic Performance to Physical Activity and Fitness in Children , 2001 .

[67]  N. Wedderkopp,et al.  Association Between Back Pain and Physical Fitness in Adolescents , 2006, Spine.

[68]  J. R. Ruiz,et al.  Bajo nivel de forma física en los adolescentes españoles. Importancia para la salud cardiovascular futura (Estudio AVENA) , 2005 .

[69]  R. Viner,et al.  Epidemiology of health and illness , 2005, BMJ : British Medical Journal.

[70]  A. Ogbera,et al.  Prevalence and gender distribution of the metabolic syndrome , 2010, Diabetology & metabolic syndrome.

[71]  H. Suominen,et al.  Weight-bearing, muscle loading and bone mineral accrual in pubertal girls--a 2-year longitudinal study. , 2007, Bone.

[72]  L. Foo,et al.  Influence of body composition, muscle strength, diet and physical activity on total body and forearm bone mass in Chinese adolescent girls , 2007, British Journal of Nutrition.

[73]  L. Straker,et al.  Association of Biopsychosocial Factors With Degree of Slump in Sitting Posture and Self-Report of Back Pain in Adolescents: A Cross-Sectional Study , 2011, Physical Therapy.

[74]  Li Jung Chen,et al.  Obesity, fitness and health in Taiwanese children and adolescents , 2006, European Journal of Clinical Nutrition.

[75]  G. Fitzmaurice,et al.  Relationship of physical fitness to prevalence and incidence of overweight among schoolchildren. , 2005, Obesity Research.

[76]  C. Hillman,et al.  Physical fitness and academic achievement in third- and fifth-grade students. , 2007, Journal of sport & exercise psychology.

[77]  A. Pienaar,et al.  RELATIONSHIP BETWEEN PHYSICAL FITNESS AND ACADEMIC PERFORMANCE IN SOUTH AFRICAN CHILDREN , 2011 .

[78]  L. Andersen,et al.  Adiposity, aerobic fitness, muscle fitness, and markers of inflammation in children. , 2013, Medicine and science in sports and exercise.

[79]  R. Wiswell,et al.  Bone mass of asian adolescents in China: influence of physical activity and smoking. , 2003, Medicine and science in sports and exercise.

[80]  M. Harreby,et al.  Epidemiological aspects and risk factors for low back pain in 38-year-old men and women: a 25-year prospective cohort study of 640 school children , 2004, European Spine Journal.

[81]  Phillip A. Bishop,et al.  The Influence of Body Size and Composition on FITNESSGRAM(r) Test Performance and the Adjustment of FITNESSGRAM(r) Test Scores for Skinfold Thickness in Youth , 2003 .

[82]  K. Grimmer-Somers,et al.  The association of physical activity and physical fitness with pre-adolescent obesity: an observational study in Metromanila, Philippines. , 2011, Journal of physical activity & health.

[83]  S. Seiler,et al.  The relationship between physical activity and physical self-esteem in adolescents: the role of physical fitness indices. , 2013, Pediatric exercise science.

[84]  J. Mota,et al.  Influence of muscle fitness test performance on metabolic risk factors among adolescent girls , 2010, Diabetology & metabolic syndrome.

[85]  J. Eisman,et al.  Peak bone mass and osteoporosis prevention , 2005, Osteoporosis International.

[86]  A. S. Singh,et al.  Motor fitness in Dutch youth: differences over a 26-year period (1980-2006). , 2010, Journal of science and medicine in sport.

[87]  D. Levy,et al.  Correlates and determinants of bone mineral content and density in healthy adolescent girls. , 1993, Canadian journal of physiology and pharmacology.

[88]  P. McGrath,et al.  The epidemiology of chronic pain in children and adolescents revisited: A systematic review , 2011, PAIN.

[89]  T. Zuiderent-Jerak,et al.  Guidelines should reflect all knowledge, not just clinical trials , 2012, British medical journal.

[90]  Elin Kolle,et al.  Low muscle fitness is associated with metabolic risk in youth. , 2009, Medicine and science in sports and exercise.

[91]  J. Strong,et al.  Association of Coronary Heart Disease Risk Factors with microscopic qualities of coronary atherosclerosis in youth. , 2000, Circulation.

[92]  D. L. Gallahue,et al.  Understanding Motor Development : Infants, Children, Adolescents, Adults , 1994 .

[93]  Ilse de Bourdeaudhuij,et al.  Physical fitness and physical activity in obese and nonobese Flemish youth. , 2003, Obesity research.

[94]  P. Bovet,et al.  International Journal of Behavioral Nutrition and Physical Activity Strong Inverse Association between Physical Fitness and Overweight in Adolescents: a Large School-based Survey , 2006 .

[95]  H. Kemper,et al.  Tracking of health and risk indicators of cardiovascular diseases from teenager to adult: Amsterdam Growth and Health Study. , 1990, Preventive medicine.

[96]  S Duval,et al.  Trim and Fill: A Simple Funnel‐Plot–Based Method of Testing and Adjusting for Publication Bias in Meta‐Analysis , 2000, Biometrics.

[97]  C. Caspersen,et al.  Physical activity, exercise, and physical fitness: definitions and distinctions for health-related research. , 1985, Public health reports.

[98]  L. Mo-Suwan,et al.  Physical fitness of obese school children in Hat Yai, southern Thailand. , 1994, The Southeast Asian journal of tropical medicine and public health.

[99]  R. Sacchetti,et al.  Physical fitness of primary school children in relation to overweight prevalence and physical activity habits , 2012, Journal of sports sciences.

[100]  C. Mbada,et al.  Relationship of Physical Activity and Back Extensor Muscles’ Endurance to the Risk of Low-back Pain in School-Aged Adolescents , 2011 .

[101]  G. Sandercock,et al.  Ten year secular declines in the cardiorespiratory fitness of affluent English children are largely independent of changes in body mass index , 2009, Archives of Disease in Childhood.

[102]  K. Newcomer,et al.  Low back pain and its relationship to back strength and physical activity in children , 1996, Acta paediatrica.

[103]  M. Müller,et al.  Relationships between physical activity, physical fitness, muscle strength and nutritional state in 5- to 11-year-old children , 2000, European Journal of Applied Physiology.

[104]  K. Kyvik,et al.  At What Age Does Low Back Pain Become a Common Problem?: A Study of 29,424 Individuals Aged 12‐41 Years , 1998, Spine.

[105]  D Colella,et al.  Physical self‐perception and motor performance in normal‐weight, overweight and obese children , 2011, Scandinavian journal of medicine & science in sports.

[106]  Matthew B. Pontifex,et al.  Aerobic fitness and cognitive development: Event-related brain potential and task performance indices of executive control in preadolescent children. , 2009, Developmental psychology.

[107]  T. Olds,et al.  Secular changes in pediatric aerobic fitness test performance: the global picture. , 2007, Medicine and sport science.

[108]  A. Faigenbaum,et al.  Correlates of Upper and Lower Body Muscular Strength in Children , 2008, Journal of strength and conditioning research.

[109]  R. Malina,et al.  Physical fitness of normal, stunted and overweight children 6–13 years in Oaxaca, Mexico , 2011, European Journal of Clinical Nutrition.

[110]  R. Rizzoli,et al.  Maximizing bone mineral mass gain during growth for the prevention of fractures in the adolescents and the elderly. , 2010, Bone.

[111]  R. Pate,et al.  Relationships between skinfold thickness and performance of health related fitness test items. , 1989, Research quarterly for exercise and sport.

[112]  C. Bouchard,et al.  Physical Activity and Health , 2006 .

[113]  R. Malina,et al.  Body mass index and individual physical fitness tests in Taiwanese youth aged 9-18 years. , 2010, International journal of pediatric obesity : IJPO : an official journal of the International Association for the Study of Obesity.

[114]  L. Andersen,et al.  Physical fitness and physical activity during adolescence as predictors of cardiovascular disease risk in young adulthood. Danish Youth and Sports Study. An eight-year follow-up study. , 2002, International journal of sports medicine.

[115]  J. Heikkinen,et al.  Determinants of Bone Mass and Bone Geometry in Adolescent and Young Adult Women , 2000, Calcified Tissue International.

[116]  G. Sandercock,et al.  Ten‐year secular changes in muscular fitness in English children , 2011, Acta paediatrica.

[117]  I. Ara,et al.  Regular participation in sports is associated with enhanced physical fitness and lower fat mass in prepubertal boys , 2004, International Journal of Obesity.

[118]  G. Myer,et al.  Resistance training among young athletes: safety, efficacy and injury prevention effects , 2009, British Journal of Sports Medicine.

[119]  L. Moreno,et al.  Health‐related fitness in adolescents: underweight, and not only overweight, as an influencing factor. The AVENA study , 2009, Scandinavian journal of medicine & science in sports.

[120]  I. Ara,et al.  Enhanced bone mass and physical fitness in prepubescent footballers. , 2003, Bone.

[121]  S. Tokmakidis,et al.  Fitness levels of Greek primary schoolchildren in relationship to overweight and obesity , 2006, European Journal of Pediatrics.

[122]  Muscular fitness and clustered cardiovascular disease risk in Australian youth , 2012, European Journal of Applied Physiology.

[123]  Chia-Ing Li,et al.  Approaching healthy body mass index norms for children and adolescents from health‐related physical fitness , 2002, Obesity reviews : an official journal of the International Association for the Study of Obesity.

[124]  B. Weeks,et al.  Eight Months of Regular In‐School Jumping Improves Indices of Bone Strength in Adolescent Boys and Girls: The POWER PE Study , 2008, Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research.

[125]  L. Straker,et al.  The relationship between back muscle endurance and physical, lifestyle, and psychological factors in adolescents. , 2010, The Journal of orthopaedic and sports physical therapy.

[126]  J. Pino-Ortega,et al.  Health-related fitness in school children: compliance with physical activity recommendations and its relationship with body mass index and diet quality. , 2010, Archivos latinoamericanos de nutricion.

[127]  U. Kujala,et al.  Secular trends in muscular fitness among Finnish adolescents , 2010, Scandinavian journal of public health.

[128]  S. Trost.  Discussion paper for the development of recommendations for children's and youth's participation in health promoting physical activity , 2005 .

[129]  A. Prentice,et al.  Positive, site-specific associations between bone mineral status, fitness, and time spent at high-impact activities in 16- to 18-year-old boys. , 2005, Bone.

[130]  David F. Stodden,et al.  A Developmental Perspective on the Role of Motor Skill Competence in Physical Activity: An Emergent Relationship , 2008 .

[131]  T. Olds,et al.  Secular trends in the aerobic fitness test performance and body mass index of Korean children and adolescents (1968-2000). , 2007, International journal of sports medicine.

[132]  W. van Mechelen,et al.  Physical fitness, body fatness, and physical activity: The Amsterdam Growth and Health Study , 2000, American journal of human biology : the official journal of the Human Biology Council.

[133]  E. van Praagh,et al.  Relationship between indicators of fitness and bone density in adolescent Brazilian children. , 2008, Pediatric exercise science.

[134]  Justine J. Reel,et al.  Effects of Home- and University-Based Programs on Physical Self-Perception in Mothers and Daughters , 2004, Women & health.

[135]  L. Andersen,et al.  A 3‐year longitudinal analysis of changes in fitness, physical activity, fatness and screen time , 2009, Acta paediatrica.

[136]  C. Gonzalez-Suarez,et al.  The Association of Physical Fitness With Body Mass Index and Waist Circumference in Filipino Preadolescents , 2013, Asia-Pacific journal of public health.

[137]  M. Torode,et al.  The effect of high-intensity progressive resistance training on adiposity in children: a randomized controlled trial , 2008, International Journal of Obesity.

[138]  T. Olds,et al.  What is the Effect of Resistance Training on the Strength, Body Composition and Psychosocial Status of Overweight and Obese Children and Adolescents? A Systematic Review and Meta-Analysis , 2013, Sports Medicine.

[139]  J. Kaprio,et al.  Adolescent flexibility, endurance strength, and physical activity as predictors of adult tension neck, low back pain, and knee injury: a 25 year follow up study , 2006, British Journal of Sports Medicine.

[140]  김 선진,et al.  운동발달의 이해 = Understanding motor development , 2003 .

[141]  D. Castelli,et al.  Chapter 3: The Relationship of Physical Fitness and Motor Competence to Physical Activity , 2007 .

[142]  R. Rosenthal.  The file drawer problem and tolerance for null results , 1979 .

[143]  Manuel J Castillo-Garzón,et al.  A Mediterranean diet is not enough for health: Physical fitness is an important additional contributor to health for the adults of tomorrow. , 2007, World review of nutrition and dietetics.

[144]  James O Hill,et al.  UNDERSTANDING AND ADDRESSING THE EPIDEMIC OF OBESITY: AN ENERGY BALANCE PERSPECTIVE , 2008 .

[145]  S. Arent,et al.  The Impact of a 12-Week Resistance Training Program on Strength, Body Composition, and Self-Concept of Hispanic Adolescents , 2010, Journal of strength and conditioning research.

[146]  J. Anderson,et al.  Ethnic and genetic differences in bone mass: a review with a hereditary vs environmental perspective. , 1989, The American journal of clinical nutrition.

[147]  M. J. Safrit,et al.  Introduction to measurement in physical education and exercise science , 1986 .

[148]  Robert M Malina,et al.  Effect of physical education and activity levels on academic achievement in children. , 2006, Medicine and science in sports and exercise.

[149]  S. Blair,et al.  Is physical activity or physical fitness more important in defining health benefits? , 2001, Medicine and science in sports and exercise.

[150]  T. Olds,et al.  Secular changes in aerobic fitness test performance of Australasian children and adolescents. , 2007, Medicine and sport science.

[151]  G. Hunter,et al.  Physical fitness, activity, and insulin dynamics in early pubertal children. , 2009, Pediatric exercise science.

[152]  J. Twisk,et al.  Associations between aerobic and muscular fitness and cardiovascular disease risk: the northern Ireland young hearts study. , 2008, Journal of physical activity & health.

[153]  T. Lohman,et al.  Relationship between body composition measures and AAHPER test performances in young boys. , 1975, Research quarterly.

[154]  Marjukka Laine,et al.  Low Back Pain in the Young A Prospective Three‐Year Follow‐up Study of Subjects With and Without Low Back Pain , 1995, Spine.

[155]  K. M. Chan,et al.  Axial and peripheral bone mineral acquisition: a 3-year longitudinal study in Chinese adolescents , 1999, European Journal of Pediatrics.

[156]  Charles H Hillman,et al.  Aerobic fitness and neurocognitive function in healthy preadolescent children. , 2005, Medicine and science in sports and exercise.

[157]  S. Blair,et al.  Combined influence of cardiorespiratory fitness and body mass index on cardiovascular disease risk factors among 8-18 year old youth: The Aerobics Center Longitudinal Study. , 2007, International journal of pediatric obesity : IJPO : an official journal of the International Association for the Study of Obesity.

[158]  K. S. Almuzaini.  Muscle function in Saudi children and adolescents: relationship to anthropometric characteristics during growth. , 2007, Pediatric exercise science.

[159]  Jeremy A. Moody,et al.  Position statement on youth resistance training: the 2014 International Consensus , 2013, British Journal of Sports Medicine.

[160]  Michael Sjöström,et al.  Field-based fitness assessment in young people: the ALPHA health-related fitness test battery for children and adolescents , 2010, British Journal of Sports Medicine.

[161]  J. J. González-Henríquez,et al.  Enhanced bone mass and physical fitness in young female handball players. , 2004, Bone.

[162]  K. Fox.  Self-esteem, self-perceptions and exercise , 2000 .

[163]  T. Coladarci,et al.  Age, Sex, and Body Mass Index in Performance of Selected Locomotor and Fitness Tasks by Children in Grades K-2 , 2002, Perceptual and motor skills.

[164]  E. Jansson,et al.  Secular trends in body dimensions and physical fitness among adolescents in Sweden from 1974 to 1995 , 2003, Scandinavian journal of medicine & science in sports.

[165]  F B Ortega,et al.  Secular trends in health-related physical fitness in Spanish adolescents: the AVENA and HELENA studies. , 2010, Journal of science and medicine in sport.

[166]  A. Tremblay,et al.  The association between low physical fitness and high body mass index or waist circumference is increasing with age in children: the ‘Québec en Forme’ Project , 2007, International Journal of Obesity.

[167]  A. Claessens,et al.  Fatness and physical fitness of girls 7 to 17 years. , 1995, Obesity research.

[168]  D. Larkin,et al.  The relationship among physical activity, motor competence and health‐related fitness in 14‐year‐old adolescents , 2009, Scandinavian journal of medicine & science in sports.

[169]  M. Sjöström,et al.  Physical fitness in childhood and adolescence: a powerful marker of health , 2008, International Journal of Obesity.

[170]  L. Moreno,et al.  Physical fitness effect on bone mass is mediated by the independent association between lean mass and bone mass through adolescence: a cross-sectional study , 2008, Journal of Bone and Mineral Metabolism.

[171]  Marcela González-Gross,et al.  [Low level of physical fitness in Spanish adolescents. Relevance for future cardiovascular health (AVENA study)]. , 2005, Revista espanola de cardiologia.

[172]  A. Ljunggren,et al.  The Significance of High Lumbar Mobility and Low Lumbar Strength for Current and Future Low Back Pain In Adolescents , 2001, Spine.

[173]  J. Eisman,et al.  Interaction of genetic and environmental influences on peak bone density , 1990, Osteoporosis International.

[174]  José Castro-Piñero,et al.  Associations of Muscular Fitness With Psychological Positive Health, Health Complaints, and Health Risk Behaviors in Spanish Children and Adolescents , 2012, Journal of strength and conditioning research.

[175]  M. Fogelholm,et al.  Physical fitness in adolescents with normal weight and overweight , 2007, Scandinavian journal of medicine & science in sports.

[176]  D. Altman,et al.  Measuring inconsistency in meta-analyses , 2003, BMJ : British Medical Journal.

[177]  J. Tobias,et al.  Association Between Bone Mass and Fractures in Children: A Prospective Cohort Study , 2006, Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research.

[178]  M. Sjöström,et al.  Objectively-measured and self-reported physical activity and fitness in relation to inflammatory markers in European adolescents: the HELENA Study. , 2012, Atherosclerosis.

[179]  D Moher,et al.  The CONSORT statement: revised recommendations for improving the quality of reports of parallel-group randomized trials. , 2001, Annals of internal medicine.

[180]  M. Sjöström,et al.  Inflammatory proteins and muscle strength in adolescents: the Avena study. , 2008, Archives of pediatrics & adolescent medicine.

[181]  Charity L. Bryan,et al.  Relationship of Body Mass Index and Fitness Levels Among Schoolchildren , 2012, Journal of strength and conditioning research.

[182]  J. Twisk,et al.  Physical inactivity is a risk factor for physical activity-related injuries in children , 2011, British Journal of Sports Medicine.

[183]  M. Goran,et al.  Effects of resistance training on insulin sensitivity in overweight Latino adolescent males. , 2006, Medicine and science in sports and exercise.

[184]  D. Nieman.  Physical Activity, Fitness, Weight Status, and Cognitive Performance in Adolescents , 2011 .

[185]  R. Pate,et al.  Correlates to Performance on Field Tests of Muscular Strength , 1992 .

[186]  A. Rhoda,et al.  Predictors of neck pain among South African youth. , 2011 .

[187]  T. Jürimäe,et al.  Physical Activity, Fitness, and Adiposity of Prepubertal Girls , 1996 .

[188]  T. Lohman,et al.  Association of somatotype and body composition to physical performance in 7-12 year-old-girls. , 1980, The Journal of sports medicine and physical fitness.

[189]  D. Molnár,et al.  Effect of fitness and physical activity on bone mass in adolescents: the HELENA Study , 2011, European Journal of Applied Physiology.

[190]  J. Schwingshandl,et al.  Effect of an individualised training programme during weight reduction on body composition: a randomised trial , 1999, Archives of disease in childhood.

[191]  G. Vicente-Rodríguez.  How does Exercise Affect Bone Development during Growth? , 2006, Sports medicine.