Social Science & Medicine 56 (2003) 363–374

Gender differences in physical activity in older children andadolescents: the central role of organized sport

Runar Vilhjalmsson*, Gudrun Kristjansdottir

Faculty of Nursing, University of Iceland, Eiriksgotu 34, Eirbergi, IS-101 Reykjavik, Iceland

Abstract

Previous studies have generally had limited success in accounting for gender differences in leisure time physical

activity. Based on a representative national survey of 3270 Icelandic 6th, 8th and 10th grade students, the study found

that girls’ lower enrollment in organized sport clubs fully accounts for gender differences in frequency of overall

physical activity, and largely accounts for gender differences in frequency of strenuous activity, and weekly hours of

overall and strenuous activity (enrollment hypothesis). Furthermore, girls’ higher sport club withdrawal rate accounted

for a small but significant part of the gender difference in weekly hours of overall activity and frequency of strenuous

activity (withdrawal hypothesis). No evidence was found to suggest that different activity levels of boys and girls

enrolled in the clubs affected gender differences in levels of overall or strenuous physical activity (activity differential

hypothesis). Other independent variables, i.e., perceived importance of sport achievement, sport and exercise related

instruction, physical education experiences, and social modeling, did not significantly affect observed gender differences

beyond the sport club variables. The meaning of the results, and their implications for gender disparities, health

promotion, and future research are discussed. r 2002 Elsevier Science Ltd. All rights reserved.

Keywords: Sport participation; Physical activity; Exercise; Gender; Iceland

Introduction

Sport and exercise is a vast enterprise involving major

social institutions and large numbers of participants,

workers and consumers. Its wide ranging implications

have resulted in numerous studies suggesting that active

involvement in sport and exercise has beneficial effects

relating to psychological well-being (Biddle, 1993;

Vilhjalmsson & Thorlindsson, 1992), self esteem and

sense of control (Gill, 1986; Gilroy, 1989; Gruber, 1986),

physical fitness (Dotson & Ross, 1985; Hagberg, 1990;

Tell & Vellar, 1988; Thorland & Gilliam, 1985), lowered

risk of negative health behaviors, such as smoking and

alcohol use (Escobedo, Marcus, Holtzman, & Giovino,

1993; Hastad, Segrave, Pangrasi, & Peterson, 1984;

Thorlindsson & Vilhjalmsson, 1991), and longevity

(Paffenbarger, Hyde, Wing, & Hsieh, 1986).

Despite the reported benefits of sport and exercise,

scientists and educators repeatedly report that many

young people are physically inactive (Armstrong, Bald-

ing, Gentle, & Kirby, 1990; Heath, Pratt, Warren, &

Kann, 1994), although the reasons for their inactivity

are not well understood (Biddle & Armstrong, 1992;

Coakley & White, 1992). One of the most persistent

findings in the literature concerns the disadvantaged

status of girls (Armstrong et al., 1990; Fuchs et al., 1988;

Guinn, Vincent, Semper, & Jorgensen, 2000; Tell &

Vellar, 1988). Their lower activity levels, especially in

late childhood and adolescence, extend across numerous

sports and forms of physical involvement (Faucette

et al., 1995; Sallis, Zakarian, Hovell, & Hofstetter 1996;

Vilhjalmsson & Thorlindsson, 1992). However, gender

differences are greatest in strenuous sports and activity

forms (Fuchs et al., 1988; Ross & Gilbert, 1985).

Socialization and attitudes

Most investigators of gender differences in physical

activity have focused on socialization into sport or

*Corresponding author. Tel.: +354-525-4960; fax: +354-

525-4963.

E-mail address: runarv@hi.is (R. Vilhjalmsson).

0277-9536/02/$ - see front matter r 2002 Elsevier Science Ltd. All rights reserved.

PII: S 0 2 7 7 - 9 5 3 6 ( 0 2 ) 0 0 0 4 2 - 4

exercise involving family, school, or peer group (e.g.,

Andersen & Wold, 1992; Greendorfer & Lewko, 1978;

Sallis, Patterson, Buono, Atkins, & Nader, 1988a). Some

have suggested that significant other’s physical activity is

a major form of influence, either through role modeling

(children’s emulation and adoption of others’ behavior),

or direct encouragement or practical assistance to

engage in physical activity given by physically active

others (Moore et al., 1991; Sallis et al., 1988a; Sallis,

Patterson, McKenzie, & Nader, 1988b). The relative

importance of socialization agents is not clearFsome

researchers suggest that fathers are most important

(Greendorfer & Lewko, 1978; Moore et al., 1991), others

suggest mothers (Sallis et al., 1988a), and still others

identify peers as most important (Andersen & Wold,

1992). As for other agents of socialization into sport and

exercise, the literature suggests that teachers and siblings

have limited influence (Greendorfer & Lewko, 1978;

Sallis et al., 1988a).

Furthermore, there is some suggestive evidence that

significant others influence boys and girls differently. In

particular, some studies report that parental physical

activity influences boys, but not girls (Sallis, Alcaraz,

McKenzie, & Hovell, 1999), although other researchers

present opposite findings (Gottlieb & Chen, 1985), or no

gender difference in parental influence (Greendorfer &

Lewko, 1978). There is also limited evidence that

teachers are more important for boys’ involvement in

sports (Greendorfer & Lewko, 1978). The idea of

differential parental or teacher influence assumes that

gender differences in physical activity are explained by

an interaction between gender and parental or teacher

involvement. In addition, studies find that boys are more

likely to have physically active friends (Andersen &

Wold, 1992; Sallis et al., 1996), and friend’s physical

activity is among the strongest correlates of one’s own

physical activity (Andersen & Wold, 1992; Vilhjalmsson

& Thorlindsson, 1998). Some studies also suggest that

schools affect boys and girls differently through physical

education (PE) classes. Thus, more girls than boys are

believed to have negative PE experiences that lower their

interest and involvement in subsequent leisure time

physical activity (Ennis, 1996). There is quantitative

evidence of more PE disliking among girls (Sallis et al.,

1996), and a qualitative study of British adolescents by

Coakley and White (1992, 1999) suggested that girls’ PE

memories were more often negative (e.g., feeling stupid

or incompetent, being negatively evaluated, not having

enough choice, using inadequate facilities), which in turn

subverted their interest in sports.

Closely related to the socialization perspective are

attitudinal explanations of gender differences. Such

explanations implicitly assume that gender roles foster

attitudinal differences that contribute to gender varia-

tions in sport and physical activity. Attitudinal

studies repeatedly report positive relationships between

masculine identities and sports (Colley, Roberts, &

Chipps, 1985; Lantz & Schroeder, 1999), and boys seem

to value competition and sports achievement more than

do girls (Finkenberg, 1991; Koivula, 1999; Whitehead,

Evans, & Lee, 1997). Boys’ greater interest in sports may

also expose them to more optional information and

instruction (e.g. in school) on sport and exercise, thereby

strengthening their predisposition and boosting their

sport and physical activity involvement.

Organized sport settings

Despite their popularity, socialization and attitudinal

explanations have generally had limited success in

accounting for the gender difference in physical activity

(Garcia et al., 1995; Trost et al., 1996; Vilhjalmsson &

Thorlindsson, 1998). An alternative perspective focuses

on organized sport as a key explanatory factor. This

perspective is rooted in the fact that a large and

increasing proportion of leisure time physical activity

in young people takes place within organized sport

settings, and that the gender difference in organized

sports involvement is much greater than the overall

gender difference in physical activity (Vilhjalmsson &

Thorlindsson, 1992, p. 642). According to this perspec-

tive, the structure and/or culture of organized sport

favors boys and men (Coakley, 1998).

Several explanations pertaining to the influence of

organized sport in the creation of gender differences in

physical activity can be proposed. According to the

enrollment hypothesis, observed gender differences in

leisure time physical activity are explained by the fact

that girls are less likely to enroll in organized sport clubs

and programs to begin with. Lower enrollment rates of

girls may be a consequence of gender biases in the

organization of the clubs or programs whereby sports

and events of greater interest to boys are emphasized

(Lenskyj, 1990, pp. 237–238), better and more accessible

training facilities or training hours for boys, more

competition opportunities for boys, or the fact that

boys and men (especially in late adolescence and early

adulthood) are more likely to be materially or financially

rewarded for their participation (see Coakley, 1998).

Another hypothesis of organized sport effectsFthe

withdrawal hypothesisFmaintains that once in the

organized programs, girls are more likely to withdraw.

Girls’ higher withdrawal rate may result from negative

program experiences, such as unreasonable demands,

fewer challenges or opportunities to train and compete,

less qualified coaches, or even psychological or physical

manipulation and abuse by them (Lenskyj, 1990;

Stewart & Taylor, 2000). Club withdrawal, in turn,

reduces subsequent physical activity levels. A third

hypothesis of organized sport effectsFthe activity

differential hypothesisFmaintains that boys and girls

who are enrolled in the organized clubs or programs are

R. Vilhjalmsson, G. Kristjansdottir / Social Science & Medicine 56 (2003) 363–374364

not equally active, resulting in more frequent and/or

vigorous participation by boys. Thus, the generally

higher physical activity levels of boys are explained by

differences in sport and exercise involvement by male

and female club and program members. Such differences

may reflect greater training skills, expectations and

demands of boys’ coaches, or, again, greater training

and competition opportunities for boys in terms of

training hours, training equipment, tournaments or

championships, etc. Essentially, the activity differential

hypothesis posits that gender differences in physical

activity are explained by an interaction of gender and

program participation in the sense of a weaker relation-

ship between club membership and physical activity

levels among girls.

Few studies have assessed the effect of organized sport

clubs and programs on the observed gender differences

in overall and strenuous physical activity. When formal

club or program explanatory variables are included, the

above mentioned explanations are only partially tested

(Sallis et al., 1996; Trost et al., 1996). The limited

evidence suggests that involvement in community sport

teams is an important variable in explaining gender

differences in strenuous physical activity (Trost et al.,

1996).

This study focused on alternative explanations of

gender differences in physical activity. In particular, the

analysis considered the contribution of organized sport

clubs to observed gender differences in overall and

strenuous physical activity, as compared to other

frequently proposed explanations. Three hypotheses

pertaining to organized club effects were tested, i.e.,

the enrollment, withdrawal, and activity differential

hypotheses. In addition, we considered the extent to

which observed gender differences may derive from

differences in the valuation of sports, exposure to sport

related instruction in school, or the influence of

significant other’s activity, either through mediation

of the gender effect or interaction with gender.

Method

Sample and procedures

The analysis is based on a nationwide Icelandic

survey, which was part of a WHO-Euro cross-national

collaborative study of health related behaviors in school

children (Aar�, Wold, Kannas, & Rimpel.a, 1986;

Fridriksson, 1989). A random sample of 3600 students

in 6th, 8th, and 10th grade was drawn based on a

complete list of Icelandic children in these grades

(schooling is obligatory for all children in Iceland

through the 10th grade). Anonymous questionnaires

were administered to respondents in the classroom.

Based on informed consent, 3270 questionnaires were

filled out and returned, resulting in a response rate of

90.8% (see Kristjansdottir & Wahlberg, 1993; Vilh-

jalmsson & Thorlindsson, 1992).1

49.5% of the respondents were female. 38.1% were

from working class families and 61.9% from middle and

upper class. 49.4% were from the Reykjav!ık area, which

includes the capital city of Reykjav!ık and the surround-

ing towns of Hafnarfj .ordur, K !opavogur, Gardabær,

Seltjarnarnes and Mosfellsbær. (61% of a total popula-

tion of 275 thousand live in the Reykjavik area which is

by far the largest urban area in Iceland.)

The formal organization of youth sport in Iceland

centers on sport clubs run by private sport organizations

that are found in every community (Vilhjalmsson &

Thorlindsson, 1998). The schools generally do not

organize sporting activities beyond mandatory physical

education classes. The sport clubs play an increasing role

in the leisure time activities of Icelandic youth (Thor-

lindsson, 1987). They are financially supported by local

government contributions, a national lottery, enrollment

fees, and advertising. Soccer and team handball are the

most popular club sports, but swimming (in public

geothermal pools) and skiing (in open areas and parks)

are popular physical activities performed mostly outside

the club system (Thorlindsson, 1987). In this national

sample, 13.1% of the respondents never participated in

sport or other physical activities outside school, 18.3%

participated less than once a week, 68.7% participated

once a week or more, and 39.4% three times a week or

more. Of those who participated at all, 56.9% were

involved in club sports and 81.4% in non-club team or

individual sports and physical activities.

Measures

The level of overall leisure time physical activity was

measured by asking respondents two questions about

how often and how many hours each week they

‘‘participated in sports, gymnastics, swimming, or other

physical activities, excluding mandatory physical educa-

tion classes in school’’ (Vilhjalmsson & Thorlindsson,

1998). Although highly correlated ðr ¼ 0:62Þ; the two

questions are not interchangeable. Some individuals

tend to have infrequent but long game or practice hours,

and others frequent and brief ones. Groups of indivi-

duals may also differ on patterns of duration and

frequency. Furthermore, the literature on leisure time

1Although more than a decade has passed since the data were

collected, they are still valuable for our analysis because of good

population coverage, and the inclusion of important questions

on club membership and withdrawal that are rarely included in

studies on gender differences. In addition, when analyzing more

recent Icelandic adolescent data (Thorlindsson, Sigfusdottir,

Bernburg, & Halldorsson, 1998), we find persistent gender

differences in overall leisure time physical activity.

R. Vilhjalmsson, G. Kristjansdottir / Social Science & Medicine 56 (2003) 363–374 365

physical activity in childhood and adolescence usually

separates hours and frequency of activity (Fuchs et al.,

1988). Therefore, the two measures were analyzed

separately. In support of criterion validity, previous

adolescent studies have reported significant and sub-

stantial correlations between these measures and self-

reports of athletic ability, physical fitness, and overall

health status (Kristjansdottir & Vilhjalmsson, 2001;

Thorlindsson, Vilhjalmsson, & Valgeirsson, 1990; Vilh-

jalmsson & Thorlindsson, 1998). Other research has

found that self-report questions of habitual physical

activity in older children and adolescents have accep-

table test-retest reliability and show evidence of objec-

tively based criterion validity (Sallis & Saelens, 2000).

To assess the level of strenuous activity, respondents

were also asked two questions about how often and how

many hours each week they ‘‘engaged in sport or

physical exercise so that they sweated or got out of

breath’’ (correlation between questions=0.68). Previous

research has found that questions of this sort have high

test-retest reliability (Andersen &Wold, 1992), as well as

criterion validity, as indicated by significant associations

with self-assessed physical fitness, athletic ability, and

overall health (Kristjansdottir & Vilhjalmsson, 2001),

and objective measures of cardiovascular fitness (VO2

max) (Lindquist, Reynolds, & Goran, 1999; Tell &

Vellar, 1988). As in the case of overall physical activity,

frequency and hours of strenuous activity were analyzed

separately.

Respondents’ relationship to sport club(s) was

assessed, first, by asking them whether they were

members of a club at the present time (0=no; 1=yes).

Membership involves formal registration and payment

of dues, but does not necessarily mean active sports

involvement, although that is usually the case (91.9% of

registered club members in this sample participated to

some extent in club sports). The membership rate was

57% among boys and 44% among girls ðpp0:001Þ: Tomeasure club withdrawal, current non-members were

asked if they had previously been members of a sport

club (0=no; 1=yes). The rate of withdrawal was 34%

among girls and 29% among boys ðpp0:01Þ:In addition to the sport club measures, several

socialization and attitudinal variables used to explain

gender differences in previous research were also

included in the analysis. Respondents were asked about

the leisure time physical activity of their father, mother,

older brother, older sister, best friend, and main teacher,

using a three point frequency scale in each instance

(0=never, 1=less than once a week, 2=at least once a

week). Respondents were also asked about the impor-

tance of sports achievement (‘‘to be good at sports’’)

(0=not important, 1=somewhat important; 3=very

important), how they liked mandatory PE classes

(0=very dissatisfied to 4=very satisfied), and whether

they had received instruction in school on ‘‘the value of

sport and exercise’’ since the beginning of the school

year (0=no; 1=yes). Such instruction would typically

be provided by teachers in health educationFa separate

component of the curriculumFor by outside

agents giving a lecture and handing out materials in

school.

Gender was dummy coded to represent girls as

compared to boys (1=girl; 0=boy). In addition to

gender, three background variablesFage, social class,

and residenceFwere used as controls in the analysis.

Age was measured in years (last birthday). Social class,

determined by the parent with the higher class status,

was a trichotomous measure based on occupational

titles (or brief description of parent’s job in the absence

of a title) (1=working class, 2=middle class, 3=upper

class). The working class included skilled and unskilled

manual workers, fishermen and farmers. The middle

class contained service occupations, such as non-

professional health service workers, elementary school

teachers, office clerks and salespeople. The upper class

comprised business-owners, executives and university-

educated specialists and professionals. Residence is a

dummy variable indicating whether the respondent lived

in the Reykjavik metropolitan area or in other

residential areas comprising mostly small fishing and

agricultural towns and villages, and farms (1=Reykja-

vik area; 0=other residential areas).

Analysis

The data analysis involves descriptive statistics,

bivariate Pearsonian, polichoric and poliserial correla-

tions (J .oreskog & S .orbom, 1995), and multivariable

OLS regression analysis of relationships with overall

and strenuous physical activity.

Based on the regression results, the unconditional

variance test proposed by Clogg, Petkova, and Cheng

(1995, p. 1309) was used to evaluate the significance of

the adjusted reduction in mean gender difference in

physical activity attributable to explanatory variables.

Results

Table 1 presents overall and strenuous activity by

grade and gender. Although statistically significant, the

gender difference in frequency of overall physical

activity is small. The difference is larger when consider-

ing duration and strenuosity of the activity. In no

instance was there a significant interaction between

gender and age, indicating that girls’ disadvantage

remained constant across grades. (An additional analy-

sis of gender differences substituting age in years for

grade produced essentially the same results as in Table 1,

with no interaction significant) (see also Garcia et al.,

1995; Thomas & Thomas, 1988, p. 225).

R. Vilhjalmsson, G. Kristjansdottir / Social Science & Medicine 56 (2003) 363–374366

Table 2 shows bivariate correlations with overall and

strenuous physical activity, and gender. Correlations

with categorical variables were computed as polichoric

or poliserial correlations. The table shows that girls were

less physically active (r ¼ �0:069 and �0.159 for

frequency and hours of overall physical activity, and

�0.153 and �0.163 for frequency and hours of

strenuous physical activity; pp0:001), less likely to be

members of a sport club (r ¼ �0:213; pp0:001), and

more likely to have withdrawn from a club (r ¼ 0:089;pp0:001). Girls reported more physical activity by kin,

especially mother (r ¼ 0:104; pp0:001) and older sister

(r ¼ 0:056; pp0:01), whereas boys reported more

physical activity by friends (r ¼ �0:052; pp0:01). Girls

valued sports achievement less than boys (r ¼ �0:176;pp0:001), and were less likely to obtain instruction in

school on the value of sport and exercise (r ¼ �0:128;pp0:001). However, contrary to previously reported

findings, girls were somewhat more satisfied with

compulsory PE classes (r ¼ 0:060; pp0:001). As for

the control variables, older respondents reported less

frequent overall and strenuous physical activity

(r ¼ �0:104; pp0:001; r ¼ �0:049; pp0:01), however,

there was no correlation between age and hours of

Table 1

Means of weekly overall and strenuous physical activity by grade and gender ðN ¼ 3270Þ

6th grade 8th grade 10th grade Interactiona

Boys Girls Diff. Boys Girls Diff. Boys Girls Diff. (p-level)

Overall physical activity

Frequency 2.66 2.44 0.22 2.42 2.26 0.16 2.19 1.92 0.27* 0.82

Hours 3.63 2.78 0.85*** 3.98 3.11 0.87*** 3.55 2.77 0.78*** 0.95

Strenuous physical activity

Frequency 2.37 1.94 0.43*** 2.33 1.83 0.50*** 2.19 1.69 0.50*** 0.89

Hours 2.63 2.05 0.58*** 2.82 2.12 0.70*** 2.76 2.19 0.57*** 0.78

aF-test (ANOVA).

*pp0:05; ***pp0:001; two-tailed t-test.

Table 2

Bivariate correlations of gender, sociodemographic controls and explanatory variables with physical activity and gender ðN ¼ 3270Þ

Overall physical activity Strenuous physical activity Gender (1=Girl)

Frequency Hours Frequency Hours

Gender (1=girl) �0.069***a �0.159***a �0.153***a �0.163***a FSociodemographic controls

Age �0.104***b �0.012b �0.049**b 0.016b �0.014a

Residence (1=Reykjavik area) �0.052**a 0.036*a �0.039*a 0.039*a 0.013c

Social class 0.060**b 0.099***b 0.059**b 0.120***b 0.023a

Relationship to sport clubs

Sport club membership (1=yes) 0.612***a 0.584***a 0.540***a 0.540***a �0.213***c

Sport club withdrawal (1=yes) �0.392***a �0.362***a �0.350***a �0.353***a 0.089***c

Other explanatory variables

Father’s physical activity 0.145***b 0.157***b 0.114***b 0.126***b 0.042*a

Mother’s physical activity 0.113***b 0.125***b 0.100***b 0.078***b 0.104***a

Brother’s physical activity 0.090***b 0.084***b 0.085***b 0.083***b 0.026a

Sister’s physical activity 0.056**b 0.065***b 0.053**b 0.035*b 0.056**a

Best friend’s physical activity 0.264***b 0.236***b 0.233***b 0.221***b �0.052**a

Main teacher’s physical activity 0.028b 0.024b 0.011b 0.011b 0.028a

Importance of sports achievement 0.164***b 0.147***b 0.175***b 0.137***b �0.176***a

Satisfaction with gym classes 0.166***b 0.101***b 0.128***b 0.088***b 0.060***a

Instruction on sport and exercise 0.186***a 0.167***a 0.111***a 0.097***a �0.128***c

aPolyserial correlation coefficientbPearson correlation coefficientcPolychoric correlation coefficient.

*pp0:05; **pp0:01; ***pp0:001; two-tailed.

R. Vilhjalmsson, G. Kristjansdottir / Social Science & Medicine 56 (2003) 363–374 367

activity (these results can be explained by the fact that

older individuals has lower frequency of physical

activity, but their sessions lasted longer). Living in the

Reykjavik metropolitan area was associated with a

lower frequency of activity, but more activity hours.

Parental social class was positively correlated with all

aspect of physical activity. The explanatory variables

were also positively correlated with all aspects of

physical activity as expected, with the exception of main

teacher’s physical activity, which was uncorrelated.

Since gender differences were age- and grade-invariant

for all measures of physical activity (see Table 1), the

regression results presented in this paper are based on

the total student sample. Table 3 shows regression

results when predicting overall leisure time physical

activity. Five regression equations were estimated by

sequentially adding independent variables, starting with

gender and sociodemographic controls. Considering first

the weekly frequency of overall physical activity, Eq. (1)

shows that the gender difference is small but significant

(beta=�0.056), controlling for sociodemographic vari-

ables. The difference is eliminated when the strong

predictor of sport club membership is controlled in

Eq. (2). (Inclusion of sport club membership increases

R2 from 0.02 to 0.24). Eq. (3) adds sport club with-

drawal, which does not affect the gender difference (and

only slightly increases R2). The coefficient for with-

drawal is positive, indicating that those who withdraw

are still more physically active than those who have

never been members of clubs. Eq. (4) adds additional

socialization and attitudinal variables, which has no

effect on the gender coefficient, and only a modest effect

on R2 (an increase of 0.03). Finally, Eq. (5) includes an

interaction between gender and club membership as a

test of the activity differential hypothesis, as well as

interaction terms between gender and other’s physical

activity to test for differential socialization (modeling)

effects. No interaction term was statistically significant

and the coefficient for gender was unaffected.

As for the weekly hours of overall physical activity,

Table 3 shows that the gender difference in Eq. (1) is

now larger than before (boys exceeded girls more in total

hours than in frequency of activity). The coefficient for

gender drops by half (from �0.128 to �0.064) when

sport club membership is introduced in Eq. (2), but is

still statistically significant. A slight 3% reduction in the

gender coefficient is observed when club withdrawal is

added to the equation. Other explanatory variables,

including interactions, slightly increased the gender

coefficient when introduced in Eqs. (4)–(5).

Table 4 presents regression results for strenuous leisure

time physical activity. Looking first at the weekly

frequency of strenuous activity, an initial gender

coefficient of �0.123 is cut by 46% (to �0.066) when

sport club membership is introduced in Eq. (2). How-

ever, the gender coefficient is still statistically significant.

Adding sport club withdrawal in Eq. (3) slightly lowers

the gender coefficient. Other explanatory variables,

including interactions, had miniscule effect on the

gender coefficient when introduced in Eqs. (4) and (5).

Considering lastly weekly hours of strenuous activity,

Table 4 shows a gender coefficient of �0.131 which is

reduced by 45% (to �0.072) when sport club member-

ship is introduced. All other explanatory variables,

including interactions, only slightly affect the gender

coefficient when introduced in Eqs. (3)–(5).

It might be argued that the conclusions in Tables 3

and 4 were due to the order in which explanatory

variables were entered into the regression (club member-

ship had the advantage of being entered first). This

possibility was explored by entering attitudinal and

socialization variables into regression equations contain-

ing sociodemographic control variables. For all four

dependent variables, the coefficient for gender was only

moderately reduced and always statistically significant.2

Thus, changing the order of explanatory variables did

not alter previously reached conclusions in a major way.

Finally, we considered the significance of the adjusted

reduction in the gender effect (mean gender difference),

using the unconditional variance test proposed by Clogg

et al. (1995, p. 1309). As it turned out, club membership

significantly ðpp0:01Þ and fully accounted for the gender

difference in frequency of overall physical activity. Also,

club membership significantly ðpp0:001Þ and substan-

tially accounted for gender differences in hours of

overall and strenuous activity and frequency of stren-

uous activity. Furthermore, beyond membership, club

withdrawal accounted for a significant ðpp0:05Þ but

minor part of the gender difference in hours of overall

activity and frequency of strenuous activity (but not

other aspects of activity). Attitudinal and socialization

variables did not account significantly for gender

differences in physical activity beyond club membership

and withdrawal.

Discussion and conclusion

Previous research has explained gender differences in

physical activity in terms of sport and exercise related

attitudes, and socialization experiences (primarily social

modeling) in family, peer-group and school. This

2Adding all attitudinal and socialization variables into

equations with gender and sociodemographic control variables,

resulted in reductions in Beta for gender of 28%, 10%, 15%

and 14% when predicting frequency of overall physical activity,

hours of overall physical activity, frequency of strenuous

physical activity and hours of strenuous physical activity,

respectively. Adding only statistically significant attitudinal and

socialization variables into the equations made very little

difference in terms of the Beta reductions for gender.

R. Vilhjalmsson, G. Kristjansdottir / Social Science & Medicine 56 (2003) 363–374368

research has had limited success in accounting for

observed differences (Garcia et al., 1995; Trost et al.,

1996; Vilhjalmsson & Thorlindsson, 1998). An alter-

native perspective focuses on organized sport as a key

explanatory factor. Within this perspective, three

hypotheses can be proposedFthe enrollment, with-

drawal, and activity differential hypotheses.

In support of the enrollment hypothesis, this study of

Icelandic school children found that girls’ lower enroll-

ment in organized sport clubs fully accounted for the

gender difference in frequency of overall physical

activity, and largely accounted for gender differences

in frequency of strenuous activity, and weekly hours of

overall and strenuous activity. Furthermore, girls’ high-

er club withdrawal rate accounted for a small but

significant part of the gender difference in weekly hours

of overall activity and frequency of strenuous activity

(withdrawal hypothesis). No evidence was found to

suggest that different activity levels among boys and

girls enrolled in the clubs affected gender differences in

levels of overall or strenuous physical activity (activity

differential hypothesis). Finally, attitudinal and sociali-

zation variables did not significantly affect observed

gender differences beyond the sport club variables. In

short, the results generally support the enrollment

hypothesis, and partially the withdrawal hypothesis.

The study has certain implications for health promo-

tion efforts aimed at reducing gender disparities in

physical activity. It suggests that such efforts address the

different ways in which organized sport clubs and

programs cater to and enroll children and youth.3 It is

true that there has been notable increase in female

Table 3

Standardized multiple regression of overall physical activity on gender, sociodemographic controls and explanatory variables

ðN ¼ 3270Þa

Frequency of overall physical activity Hours of overall physical activity

Eq. (1) Eq. (2) Eq. (3) Eq. (4) Eq. (5)b Eq. (1) Eq. (2) Eq. (3) Eq. (4) Eq. (5)b

Gender (1=girl) �0.056** 0.010 0.013 0.011 0.011 �0.128*** �0.064*** �0.062*** �0.065*** �0.065***

Sociodemographic controls

Age �0.110*** �0.059*** �0.060*** �0.024 �0.024 �0.015 0.033* 0.033* 0.062*** 0.061***

Residence (1=Reykjavik area) �0.063*** 0.011 0.005 0.006 0.006 0.007 0.011 0.074*** 0.071*** 0.071***

Social class 0.077*** 0.043** 0.042** 0.027 0.026 0.099*** 0.067*** 0.066*** 0.046** 0.046**

Relationship to sport clubs

Sport club membership (1=yes) 0.480*** 0.532*** 0.454*** 0.439*** 0.466*** 0.513*** 0.447*** 0.474***

Sport club withdrawal (1=yes) 0.076*** 0.057** 0.056** 0.070*** 0.054** 0.056**

Other explanatory variables

Father’s physical activity 0.065*** 0.067** 0.065*** 0.068**

Mother’s physical activity 0.022 0.024 0.039* 0.022

Brother’s physical activity 0.026 0.008 0.027 0.022

Sister’s physical activity 0.003 0.019 0.024 0.038

Best friend’s physical activity 0.112*** 0.117*** 0.097*** 0.099***

Main teacher’s physical activity 0.012 0.016 0.016 0.005

Importance of sports achievement 0.052*** 0.052*** 0.048** 0.046**

Satisfaction with gym classes 0.062*** 0.061*** 0.023 0.023

Instruction on sport and exercise 0.046** 0.046** 0.024 0.024**

Gender*Club membership 0.020 �0.036

Gender*Father’s phys. activity �0.002 �0.004

Gender*Mother’s phys. activity �0.003 0.024

Gender*Brother’s phys. activity 0.024 0.006

Gender*Sister’s phys. activity �0.022 �0.017

Gender*Friend’s phys. activity �0.008 �0.003

Gender*Teacher’s phys. activity �0.007 0.016

R2 0.022 0.240 0.243 0.275 0.275 00.026 0.232 0.235 0.260 0.261

aThe table presents standardized Beta weights.b In Eq. (5), variables tested for interaction with gender were centered.

*pp0:05;**pp0:01; ***pp0:001; two-tailed.

3 In addition to the sport clubs, a growing number of

independent for-profit fitness centers in Iceland offer muscular

strength and aerobic exercises of various kinds at different

levels of difficulty. The fitness centers have been successful in

catering to both genders (some only accept female customers),

in part because they do not have the ‘‘boys sports’’ image of the

sport clubs. However, the centers are unlikely to even gender

disparities in physical activity for several reasons. First, they are

restricted to the Reykjavik metropolitan area and several large

towns (for market reasons). Second, the centers are primarily

directed at adults. Third, they are expensive (because they are

not subsidized by the government like the sport clubs), and

many families and young people are not willing or able to pay

the enrollment fees.

R. Vilhjalmsson, G. Kristjansdottir / Social Science & Medicine 56 (2003) 363–374 369

enrollment in organized sport in recent years (e.g., see

Birrell & Richter, 1987; Messner, 1988). Nevertheless,

organized sport is still dominated by and oriented

toward boys and men. The vast majority of sport club

executives and board members in Iceland are men, as in

all other countries where information is available

(Bryson, 1987). Programs offered by the Icelandic clubs

heavily emphasize competitive team sports, primarily

soccer, team handball, and, to a lesser degree, basketball

(Thorlindsson, 1987). Previous studies have repeatedly

shown that boys outnumber girls in competitive, team,

and high intensity sports and exercises (e.g., football,

soccer, baseball, basketball, team handball, bicycling

and weight lifting), and girls outnumber boys in non-

competitive, individual, and medium to low intensity

sports and exercises (e.g., walking, gymnastics, aerobic

dance and other dance, roller skating, volleyball, and

swimming) (Delaney & Lee, 1995; Faucette et al., 1995;

Ross & Gilbert, 1985; Sallis et al., 1996). Studies also

find gender differences in motivations to engage in

physical activity. More girls/women than boys/men

engage in physical activity for appearance and health

and fitness related reasons, and more boys/men for the

sake of competition, demonstration of ability, and the

pursuit of victory (Finkenberg, 1991; Gill, 1988;

Koivula, 1999). Considering the kinds of sports empha-

sized by the Icelandic sport clubs, it is not surprising to

find that more boys than girls are active sport club

participants (57% versus 44%).

We believe that in order to engage more children and

youth in physical activities and reduce apparent gender

disparities, the organization of national and community

sport programs needs to be changed in a substantial way

to include more women in managerial and coaching

positions, reflect women’s as well as men’s perspectives

and interests, offer a varied assortment of sports and

exercises, and develop linkages and partnerships with

schools to enhance continuity in physical activity.4

Table 4

Standardized multiple regression of strenuous physical activity on gender, sociodemographic controls and explanatory variables

ðN ¼ 3270Þa

Frequency of strenuous physical activity Hours of strenuous physical activity

Eq. (1) Eq. (2) Eq. (3) Eq. (4) Eq. (5)b Eq. (1) Eq. (2) Eq. (3) Eq. (4) Eq. (5)b

Gender (1=girl) �0.123*** �0.066*** �0.063*** �0.062*** �0.062*** �0.131*** �0.072*** �0.070*** �0.068*** �0.068***

Sociodemographic controls

Age �0.054** �0.010 �0.011 0.025 0.024 0.012 0.057*** 0.056*** 0.084*** 0.083***

Residence (1=Reykjavik area) �0.049** 0.016 0.012 0.013 0.012 0.006 0.072 0.069*** 0.068*** 0.067***

Social class 0.073*** 0.044** 0.043** 0.030 0.030 0.121*** 0.091*** 0.091*** 0.081*** 0.082***

Relationship to sport clubs

Sport club membership (1=yes) 0.419*** 0.456*** 0.384*** 0.418*** 0.429*** 0.457*** 0.398*** 0.422***

Sport club withdrawal (1=yes) 0.055* 0.037 0.040 0.042* 0.030 0.032

Other explanatory variables

Father’s physical activity 0.041* 0.035 0.050** 0.059*

Mother’s physical activity 0.033 0.029 �0.002 �0.021

Brother’s physical activity 0.029 0.031 0.034 0.056*

Sister’s physical activity 0.011 0.013 0.000 �0.014

Best friend’s physical activity 0.101*** 0.088*** 0.102*** 0.087***

Main teacher’s physical activity �0.001 0.007 0.008 0.033

Importance of sports achievement 0.079*** 0.077*** 0.051** 0.050**

Satisfaction with gym classes 0.045** 0.045** 0.023 0.022

Instruction on sport and exercise 0.025** 0.025 0.027 0.027

Gender*Club membership �0.045 �0.032

Gender*Father’s phys. activity 0.006 �0.015

Gender*Mother’s phys. activity 0.005 0.027

Gender*Brother’s phys. activity �0.002 0.006

Gender*Sister’s phys. activity �0.002 �0.031

Gender*Friend’s phys. activity 0.018 0.020

Gender*Teacher’s phys. activity �0.011 �0.035

R2 0.023 0.190 0.192 0.219 0.220 0.032 0.206 0.207 0.226 0.228

aThe table presents standardized Beta weights.b In Eq. (5), variables tested for interaction with gender were centered.

*pp0:05; **pp0:01; ***pp0:001; two-tailed.

4Our recommendation differs from the one sometimes made

in the literature advocating gender equality in sport and exercise

by changing the ways in which boys and girls are socialized in

school, family, or peer group to foster girls’ skills and interest in

traditional competitive sports. We do not believe that girls’

physical activity preferences are a problem (any more than

boys’) and would oppose policy recommendations favoring a

R. Vilhjalmsson, G. Kristjansdottir / Social Science & Medicine 56 (2003) 363–374370

Recently, Icelandic sport clubs have taken several

steps in this direction. Some clubs now operate fitness

centers in addition to their regular competitive pro-

grams. The centers offer aerobic and muscular training

not only to club members but everyone who signs up

and pays the monthly or seasonal dues. In addition, a

number of clubs have begun to operate summer camps

for children and adolescents interested in sports or other

physical activities irrespective of club membership. Last,

but not least, sport clubs in the city of Reykjavik

instituted the so-called Sportschool at the start of the

1997–1998 school year. A partnership between sport

clubs and primary schools in Reykjavik, organized by

the Reykjavik Sport Club Association (IBR), the

Sportschool program offers school children after school

physical activity programs in the clubs or the gym

facilities of the schools 1–3 times a week, on both a

competitive and non-competitive basis and including

a variety of sports. The program intends to broadly

recruit primary school students into sport and exercise

to enhance psychosocial development, a healthy life-

style, scholastic achievement, and future sport participa-

tion (Ithr !ottabandalag Reykjav!ıkur, 1998; Vilhjalmsson

& Thorlindsson, 1998). The above changes are based on

the premise that sport and exercise activities are widely

beneficial to children and youth. They indicate a

growing conception within the still male dominated

and oriented sport clubs that reaching out and expand-

ing the benefits of sport and exercise is not only in the

interest of children and youth, but ultimately the clubs

themselves.

It is also worth noting that sports involvement does

not necessarily require aggression, dominance, elitism,

and winning. For example, Ennis and her coworkers

have developed a physical education model called

‘‘sports for peace’’, where students are enrolled in team

sports emphasizing equal participation, rotation of

positions, student mentoring, conflict resolution, con-

sensus building, and a sense of family (Ennis et al.,

1999). Interestingly, Ennis et al. report that the ‘‘sport

for peace’’ model enabled students with lower skills and

limited experience, many of whom were girls, to

successfully and meaningfully engage in team sports.

Exploration of such alternative forms of sports involve-

ment in school physical education, as well as in

organized sport settings, may help engage children and

youth in physical activities and reduce persistent gender

disparities.

This study has several strengths. It was based on a

randomly drawn national dataset, the response rate was

unusually high, and the analysis considered the con-

tribution of sport club and other explanatory variables

to observed gender differences in frequency and hours of

overall and strenuous activity within a multivariate

regression/unconditional variance framework. Never-

theless, the study leaves several theoretical and empirical

issues unresolved. First, because the study was cross-

sectional, the causal direction of observed relationships

cannot be inferred from the data. For example, it is

possible that children’s physical activity at least partly

affects their attitudes over time, as well as their parents’

and friends’ physical activity. Physically active children

may also be more likely to enroll in sport clubs.

Longitudinal research is needed to assess the direction

and size of such alternative causal paths. Second,

although our analysis supports the enrollment and

withdrawal hypotheses, precise explanations for ob-

served differentials await future research. For example,

the gender gap in enrollment could be explained by the

predominance of male coaches within sport clubs,

inconvenience of girls’ training hours, or the kinds of

sport and exercise programs offered by the clubs.

Likewise, differential withdrawal could be explained

by higher probability of negative program experiences

by girls, such as lack of training or competition

opportunities, or negative coach experiences. Also,

coaches and program directors/executives could be

queried about their goals, expectations and efforts

regarding the recruitment and involvement of boys and

girls in club activities. There are already some indica-

tions that more girls perceive barriers to exercise than

boys (e.g., time constraints, lack of equipment or

facilities) (Sallis et al., 1996), which appears to partly

account for observed gender differences (Trost et al.,

1996). Third, it should be noted that part of the gender

difference in hours of activity and frequency of

strenuous activity remained unexplained, even when all

independent variables were controlled. This may mean

that important explanatory variables were omitted. For

example, although some authors have argued that

significant other’s physical activity is the main compo-

nent of socialization into sport and exercise (Moore

et al., 1991; Sallis et al., 1988a, b), other research shows

that significant other’s encouragement and support to

engage in sport and exercise is also important in its own

right (Greendorfer, 1977; Sallis et al., 1999; Snyder &

Spreitzer, 1976). Some research suggests that boys are

more likely to experience such encouragement from

parents (Andersen & Wold, 1992), or from coaches and

peers (Sallis et al., 1996, 1999), which may account in

part for their higher level of physical activity. Finally, it

is worth noting that physical activity includes a wide

range of activities (team and individual sports, games,

play, and other recreational activities) performed in

formal and informal settings. There are indications that

different contexts of sport and exercise and even specific

(footnote continued)

particular model of physical activity (which some authors have

called the ‘‘male model’’ characterized by competition, dom-

inance, and elitism) (see Bennett, Whitaker, Smith, & Sablove,

1987; Birrell & Richter, 1987; Gilroy, 1989).

R. Vilhjalmsson, G. Kristjansdottir / Social Science & Medicine 56 (2003) 363–374 371

sports and forms of exercise are associated with different

psychological, behavioral and social variables (Butcher,

1983; Gottlieb & Chen, 1985; Spreitzer & Snyder, 1976;

Vilhjalmsson & Thorlindsson, 1992). Many of these

forms of sport and exercise are gender related (e.g.,

Faucette et al., 1995; Sallis et al., 1996) but the reasons

for the gender differences are not well understood.

In conclusion, the study found that membership in

and withdrawal from organized sport programs largely

accounts for gender differences in overall and strenuous

physical activity. Remaining gender differences may be

due to significant other encouragement and support, or

sport and exercise related beliefs. In view of the results,

efforts to further mobilize children and adolescents and

reduce gender disparities in physical activity should

consider the ways in which organized sport clubs and

programs cater to and enroll children and youth. By

reflecting girls’ and women’s as well as boys and men’s

perspectives and interests, offering a broader array of

sports and exercises, and developing linkages with the

primary school system, we believe organized sport

programs could recruit more children and adolescents

into sport and exercise, and reduce or eliminate gender

disparities. This would be an important step towards

equalizing the life chances of young people and

enhancing the health of the public.

Acknowledgements

The Icelandic part of the WHO-Euro collaborative

study was sponsored by the Ministry of Health in

Iceland and directed by Hrafn V. Fridriksson in

cooperation with Hrolfur Kjartansson and Thorolfur

Thorlindsson.

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