
 physical exercise and sports have positive effects on physical and psychological health . physical activity among adolescents
is correlated with increased cardiovascular fitness and bone strength [ 1 , 2 ] and inversely associated with insulin resistance , metabolic syndrome , and premenopausal breast cancer [ 36 ] .
the psychological effects of physical activity are associated with reduced depression and reduced risk of hopelessness and suicidality amongst adolescents [ 7 , 8 ] .
also , when exercise is based on motivational factors such as health , social participation , or stress management , it seems to decrease body dissatisfaction .
extensive exercise is related to body dissatisfaction , especially amongst women with eating pathology [ 10 , 11 ] , and physical activity often results in increased focus and awareness concerning weight and shape . perceived sociocultural pressure and body dissatisfaction are especially associated with a compelling need to exercise .
self - rated health ( srh ) is an individual 's subjective perception of his or her own health status and constitutes an essential predictive indicator for later morbidity , mortality , school - dropout , use of health care services , and social welfare [ 14 , 15 ] .
srh is constructed early in life when parental influence is strong and remains relatively stable and insensitive of transient diseases during adolescence .
poor self - rated health is positively associated with body dissatisfaction and negatively associated with exercise and school achievements [ 18 , 19 ] .
body dissatisfaction represents the discrepancy between an individual 's current and ideal body size and shape , and its prevalence increases throughout adolescence [ 2022 ] .
some studies claim that body and weight dissatisfaction represent worse health threats than obesity in itself , as they may trap adolescents in a vicious cycle of futile dieting , health compromising weight shifts , dysfunctional motivation for exercise , and thereby increased vulnerability for modern ideals of body size and shape [ 23 , 24 ] .
however , most of the previously referred studies have focused on females and on how sports might contribute to the development of eating pathology .
although sports engagement is positively related to srh , our hypothesis is that exercise might also be associated with negative health effects among adolescents in the general population .
thus , in a nonselected adolescent population , we aimed to study the distribution of self - rated health and body dissatisfaction as expressed by both drive for thinness and desire to change the body and to explore the association between these factors and sports ' type and amount in both genders .
the study was based on data from three cross - sectional surveys carried out in 2001 , 2005 , and 2009 amongst tertiary school students in frde in the county of sogn and fjordane , in norway .
three of them offered vocational training , while the remaining school offered an academic curriculum .
students completed the questionnaires without other information than a brief instruction from the teacher followed by 45 minutes to complete the questionnaire .
the 2001 , 2005 , and 2009 surveys included 837 ( 50% females ) , 776 ( 49% females ) , and 914 ( 55% females ) students , with response rates of 93 , 87 , and 90 percent , respectively .
missing responses were almost exclusively due to absence from school on the days of surveys .
students that were nonresponders on single variables were included in the analysis of remaining responded variables .
the variables of interest were equivalent in each survey and the samples included the same schools at the three different years of study .
as no other differences could be detected between the surveys and in order to increase statistical power of the study , the three study samples were combined .
in addition to self - reported information on gender , height , and weight , five other questions from the survey regarding sports activity , srh , and body dissatisfaction were included in this study .
the questions were based on the world health organization cross - national survey , health behaviour in school - aged children , which aims to increase the knowledge about lifestyle and health in adolescents .
these self - reported variables have proved reliable and valid among slightly younger age groups [ 19 , 25 ] , and also among adolescents at similar age .
do you think you are ?  with the response alternatives  very healthy ,   quite healthy ,  and  not very healthy . 
are you on a diet to lose weight ?  with corresponding responses  yes , 
 no , but i need to lose weight ,  and  no , because my weight is fine .  the categories  yes  and  no , but i need to lose weight  were combined , thus respecting the underlying drive for thinness
. the second question was  is there anything about your body you would like to change ?  with the response options  yes  and  no  .
the sample was differentiated according to amount of time spent on physical activity during a week and type of sports performed .
the latter was classified by whether the main activity was team sports , individual sports without advantage of leanness ( e.g. , horseback riding , snowboarding , tennis , and boxing ) , or individual sports with advantage of leanness ( e.g. , ballet , taekwondo , swimming , fitness , and running ) .
the classification of leanness and nonleanness sports was based on a study about dieting habits in adolescent elite athletes .
leanness and weight were not considered as important for performance of any of the team sports , which were consequently not further subclassified .
the group that was not performing any kind of physical activity or sports during the week was the reference for both amount and type of sports . in the analyses , self - rated health and the two measures of body image ( drive for thinness and desire to change the body ) were the dependent variables .
the groups classified by amount of exercise and qualities of sports , gender , age , and bmi were the independent variables , and these were treated as categorical .
the relationships between the independent variables and srh and the two body image variables were tested with binary logistic regression and were presented as odds ratios ( or ) with 95% confidence intervals ( cis ) . in the adjusted , full model analyses , gender , age , and categorical bmi
the results were reported in gender separate tables only if cis were not vastly overlapping . only the relation between sports type and the desire to change body was gender specific .
we also examined if the prevalence of the outcomes differed or if the gender associations with the outcomes differed across study years .
small differences with overlapping cis were observed across study years on the gender associations with the outcomes .
we did not further explore interaction effects of time , as this was not the prime focus of the study .
the 2009 study was presented for the regional committee for medical and health research ethics in health region 3 .
however , owing to its anonymous nature , it was consented and omitted from any further ethical evaluation .
most of the students perceived themselves as healthy , boys more frequently than girls . girls reported desire to change the body and weight concerns more frequently than boys .
the majority reported some kind of physical activity , but 36% of the girls and 29% of the boys devoted no more than one hour per week to physical activity .
a majority of the students spent a moderate to a great amount of time on sports .
participation in individual sports was more common among girls , while boys were more active in team sports .
tables 2to 4((a ) and ( b ) ) summarize both unadjusted and adjusted results of the logistic regression analyses of , respectively , srh , drive for thinness , and desire to change the body according to amount of time spent on physical activity and type of sports .
a strong association between srh and time spent on physical activity was revealed , as illustrated in table 2 .
girls and adolescents with deviating body size reported impaired self - rated health to a greater extent than their peers .
all weight groups reported impaired srh as compared with the slim weight group ( 10th percentile to the median group ) . 

table 3 shows that the risk of dieting or desire to lose weight was strongly gender and bmi dependent .
performing team sports was protective for dieting or desire to lose weight in the unadjusted analyses , but this association disappeared in the adjusted analyses .
surprisingly , adolescents engaged in sports with an advantage of leanness were not significantly more weight concerned than their nonsporting peers .
we performed supplementary , stratified analyses ( not shown ) and were unable to reveal any gender specific interactions on these relations .
however , weight dissatisfaction increased conspicuously even with modest overweight ( bmi from 22.8 to 26.4 ) and escalated to the extreme among adolescents with bmi > 26.5 .
tables 4((a ) and ( b ) ) illustrate that the desire to change the body was also strongly affected by bmi .
the or that girls reported desire to change body was 5.10 ( 4.086.37 ) in the full model ( not shown ) .
the gender separated tables reveal that this desire increased with age only among girls . engaging in individual sports with advantage of leanness
the mediation effects from bmi were negligible despite the fact that bmi impacted the result variables profoundly .
the differences that we found between the sports amount groups concerning weight and body dissatisfaction were accounted for by sports type .
thus , in the final models only students of both genders engaged in sports with leanness advantage and also girls engaged in team sports were more likely than others to report body dissatisfaction .
we revealed a paradoxical association between adolescent health and sports : increasing amount of sports is correlated with good self - rated health on the one hand , but engagement in individual sports with advantage of leanness and also team sports among girls are related to body dissatisfaction on the other hand .
the response rate was very high and the survey embraced all vocational and academic students in the municipality of frde .
students in tertiary school in the county of sogn and fjordane move to frde in order to study .
the population is thus representative for both rural and urban norwegian adolescents and probably adolescents in industrial countries worldwide as well .
inclusion of a vast diversity of sports activities and different measures of body image respect the nuances within the adolescent health .
however , cross - sectional studies can not explain the direction of causality and also imply the possibility of misclassification and self - report bias .
considering that most individual sports tend to have leanness as a potential advantage , only a small proportion of the students engaged in sports where leanness was not regarded as beneficial .
it should also be noted that the classification of types of sports after the main activity was rather deterministic , as many were active in both team sports and individual sports with and without leanness requirements .
the full model analyses adjusted to the interrelationship between sports measures and other possible confounders .
we used categorical bmi and thus the j - curve association with body image was respected .
home situation with respect to parental divorce , death or sickness in family , or poor economy has the potential to influence both the opportunity to participate in sports activities as well as srh and body image .
we should therefore not confuse ors with prevalence ratios , especially concerning desire to change body , but also weight concern . in line with previous studies
[ 14 , 15 ] , we confirmed that increasing amount of sports was strongly associated with positive srh .
a systematic review revealed that physical activity improved self - esteem and that especially team sport was associated with improved health outcomes .
our study is in accordance with a previous study on adolescent girls showing that the majority participated in individual sports with advantage of leanness , and body dissatisfaction was more strongly associated with bmi than with the nature of sports .
interestingly , the girls in this study , who exercised irregularly , attempted to lose weight to a greater extent than those regularly exercising
. this might be due to motivational factors , as demonstrated by a clinical study testing body image by means of digital photo distortion technique in which body image improved right after exercise . yet another study revealing a positive relationship between exercise and
improved body image found that motivational factors partly explained this relationship and that appearance and weight motivation were associated with body dissatisfaction to a greater extent than fitness and health motivation . in the same line , these previous publications indicate that the immediate alleviating effect of exercise on poor body image depends on type of motivation and personal trait .
studies linked to the self - determination theory also find that the quality of motivation both improves subjective health and is associated with sustained physical activity .
regarding body dissatisfaction and physical exercise , a meta - analysis of 57 intervention studies showed that exercise improves body image .
a previous study on norwegian adolescent elite athletes found no difference in dieting habits between the leanness and nonleanness sports athletes . in accordance with this , body dissatisfaction related to sports in our study was not expressed with weight concern .
two previous studies amongst boys showed that body dissatisfaction and weight concerns were less prevalent amongst team sports participants   and football players compared to cross - country runners .
impaired srh is an independent predictor for later health and social problems . in our study
this is in line with previous research , although the dose - response relation was not examined in earlier studies .
although the odds for reporting body concern only modestly increased with leanness sports activities , the health consequences might be considerable due to the high prevalence of body concern .
also the gender difference concerning the association between team sports and body dissatisfaction might be explained by motivational differences .
the stigmatization of oversized bodies may be accompanied by self - reproach and subjective health jeopardy , which may be more important factors explaining increased morbidity and mortality in obese populations than obesity in itself .
therefore , it seems that we need a paradigmatic shift in the way we approach the obesity epidemic in western societies . among adolescents we are
also concerned that a one - dimensional focus on overweight and obesity may precipitate eating disorders . a unifying perspective for health promotion that emphasizes building of self - esteem and body satisfaction has therefore been suggested .
physical exercise is positively related to self - reported health but has negative associations with body image for some adolescent groups . health promotion efforts should consider this paradox and promote physical activity and sports along with body acceptance .
 
 background . physical exercise has positive effects on health 
 . however , its associations with self - rated health and body image , which are important predictors for adolescents ' wellbeing and later morbidity , are complex . methods . 
 cross - sectional survey among 2527 norwegian adolescents . 
 we examined the relations between self - reported gender , body size , amount and type of exercise and measures of self - rated health , drive for thinness , and desire to change body , with binary logistic regression analyses . 
 results . 
 girls and overweight students reported to a greater extent than their peers impaired self - rated health , weight concerns , and desire to change their body . 
 increasing amount of time spent on sports was related to improved self - rated health in a dose - response manner . 
 both girls and boys who engaged in individual sports with an advantage of leanness , but only girls engaged in team sports , reported an increased desire to change the body . 
 however , weight concern was not related to amount or type of sports . conclusions . 
 physical exercise is positively related to self - reported health but has negative associations with body image for many adolescents . 
 health promotion efforts should consider this paradox and stimulate physical activity and sports along with body acceptance . 
1. Introduction
2. Method
3. Results
4. Discussion
5. Conclusion