Journal of Epidemiology and Community Health 1992; 46: 114-119

Physical activity at 36 years: patterns and childhoodpredictors in a longitudinal study

D J L Kuh, C Cooper

AbstractObjective-The aim was to describe the

sex and socioeconomic differences inpatterns of physical activity at work and inleisure time of men and women aged 36years, and to investigate factors inchildhood and adolescence which predicthigh rates of participation in sports andrecreational activities in later life.Design-Data collected in childhood,

adolescence, and at 36 years on members ofa national prospective birth cohort studywere used.Setting-The population sample was

resident in England, Scotland, and Wales.Subjects-A stratified sample of about

3500 men and women was studied regularlyfrom birth until 43 years.Measurements and main results-More

men than women reported high rates ofsports and recreational activities, garden-ing, and do-it-yourself. In contrast womenreported higher rates of bicycling andwalking. Higher levels of education wereassociated with frequent participation insports. Individuals often engaged in onetype of activity without necessarilyengaging in other types. Those who weremost active in sport had been above averageat sports in school, more outgoing socially inadolescence, had fewer health problems inchildhood, were better educated, and hadmore mothers with a secondary educationthan those who were less active.Conclusions-Studies that examine the

relationship between physical activity andchronic disease should consider a broadrange of pursuits rather than extrapolatingfrom only one area of physical activity, andin their explanations should take accountof the possible role of childhood charac-teristics. The findings suggest theimportance of developing skills and habitsin childhood as well as of encouraginghealthier exercise habits in adults who mayhave had few opportunities or lowmotivation previously.

The importance of physical activity for individualhealth and wellbeing has been recognised for 2000years. ' 2 The lack of physical fitness in the Britishpopulation has been seen as a problem throughoutthis century and the need for physical training wasstressed by a number of major public healthreports.>5 The promotion of physical activity inthe general population gathered momentum withthe passing of the Physical Training andRecreation Act in 19376 which increased

government financial support to local authoritiesfor the development of public sports andrecreational activities. The setting up of theadvisory Sports Council in 1965 (which becamethe independent Sports Council in 1972) was anindication that sport and physical recreation wereconsidered to be self justified and did not need thesupport of a drive to national fitness.7

Physical activity "is not a single entity; there aremany kinds of activity which vary in intensity,frequency and duration, and which have variableeffects on body systems".8 Physical capacitiesmay be broadly divided into muscle strength andstamina. These two attributes are distinct, anddifferently trained. Muscle strength depends oncontractile proteins within muscle cells, andchanges in strength throughout life are thought tobe mediated through muscle cell hypertrophyrather than increased cell number. Stamina(endurance capacity, aerobic capacity, maximaloxygen uptake) is required for rhythmic exercisesuch as walking, swimming, or cycling. Inaddition to muscle strength, stamina requires agood capacity for oxygen delivery in the cardio-vascular system, and a good capacity for workuptake in muscle cells.

Epidemiological research has attempted toassociate inactivity with several diseases, mostnotably ischaemic heart disease and osteoporosis.While vigorous exercise, requiring high endur-ance capacity, appears to be associated with lowcoronary risk,9-4 muscle loading activity seemsmore important to the maintenance of skeletalintegrity in later life.'5The generation of preventive strategies

incorporating exercise for these public healthproblems requires greater knowledge of the kindsof activity currently undertaken by members ofthe general population, and an understanding ofits determininants. Such information is scarce.We have therefore examined activity patterns inwork and leisure in a national sample of over 3300men and women aged 36 years who are membersof the 1946 national birth cohort study. Thelongitudinal nature of these data enables us toinvestigate childhood influences on adult activitypatterns.

MethodsThe MRC National Survey of Health andDevelopment is a social class stratified sample ofthe single legitimate births that occurred in theweek 3-9 March 1946 in England, Wales, andScotland. There were 10 follow up contacts ininfancy and childhood and nine contacts so far inadult life, up to the age of 43 years. Losses haveoccurred at population appropriate rates through

MRC National Surveyof Health andDevelopment,University CollegeLondon and theMiddlesex HospitalMedical School,Department ofCommunity Medicine,66-72 Gower St,London WClE 6EA,United KingdomD L KuhDepartment of HealthSciences Research,Section of ClinicalEpidemiology, MayoClinic, Rochester,Minnesota, USAC Cooper

Correspondence to:Diana Kuh

Accepted for publicationMay 1991

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death and emigration, and at the last contact 89%Oofthe resident target population were interviewedand measured. Summaries of the survey are givenby Atkins et al'6 and Wadsworth.'7 Adjustmentsfor sample stratification have been made wherenecessary.

In 1982 when cohort members were 36 yearsold, information on the frequency and duration ofa range of active leisure pursuits in the precedingmonth was collected by trained nurse interviewersduring a home visit. The questionnaire was basedon the Minnesota leisure time physical activityquestionnaire.'8 From this information threemain areas of active leisure pursuits were defined:sports and recreational activities, cycling andwalking, and heavy gardening and do-it-yourself(DIY) activities. The questionnaire schedule alsoincluded questions on the amount of sitting,walking, and heavy lifting during the workingday. They were based on the questions used byShapiro et al, adapted to include survey memberswho were not in paid work.19For each area people were classified according

to the criteria in table I, either into a most activegroup, a less active group, or an inactive group.This simple classification system was choseninstead of estimating units of energy expended invarious activities from reported duration timesusing standard intensity codes.'8 There was awide variation in reported duration of particularactivities and, we suspected, a wide variation inintensity. The use ofenergy units (kcal, kJ) wouldhave given a false sense of accuracy, and data onphysical activity at work could not have beenderived in a similar manner.

Survey members were asked how many times inthe last month they had done anything at work, inthe home, or during their spare time that hadmade them out of breath. Their responses[grouped into five or more (8%), one to four

Table I Criteria used to classify physical activityType of physical activity Most active Less active InactivePhysical activity during the Either Not classified in At least half the dayworking day (i) over half the the most active sitting down

day spent or inactivewalking groupsor(ii) frequentlylifts and carriesheavy things

Sports and recreational Five of more 1-4 times in No reported activity inactivities: times in the previous month previous monthList of 27 activities (eg, previous monthbadminton, swimming,yoga, exercises such as pressups at home, dancing,football, jogging, etc)

Cycling and walking Either Either Does not normally ride(i) normally (i) normally or walk and no reportsrides or walks to rides or walks of riding or walking inwork for at least for less than j leisure time in previousj hour (round hour monthtrip) oror (ii) 1-11 rides or(ii) 12 rides or walks of 1 hourwalks of I hour in leisure time inin leisure time in previous monthprevious month

(10%,10), or no reports (82%) ofbeing out of breath]were used as an indirect check ofthe validity oftheactivity levels in terms of strenuous activity.

Ninety per cent of the interviews wereconducted between April and September.Seasonal influences on the frequency of activeleisure pursuits were investigated.Own adult social class (at 36 years) and father's

social class when the cohort member was fouryears old were assigned according to theclassification used in the 1970 census.20 Thehighest qualification achieved by cohort membersby age 26 years was classified on the Burnhamscale,2' and was grouped into five levels: noqualifications, less than "O" level, "O" level andequivalents, "A" level and equivalents, anddegree level and equivalents. The classification ofparental education not only distinguished parentswhose education had stopped at primary,secondary, or tertiary level but also took accountof those who had not attended secondary schoolbut who went back in later years for furthereducation.

In 1959, when cohort members were 13 yearsold, teachers were asked to rate cohort members'ability in sports as above average, below average,or average compared with their age peers.At 15 years teachers assessed children's energy

levels as extremely energetic and never tired,normally energetic, or always tired and washedout. The survey children's questionnaire at age 13years included the Pintner aspects of personalityinventory2223 which provided the extrovert-introvert scale used in these analyses. The scaleprovides a score from 0 (introvert) to 15(extrovert) and a high score reflects a high degreeof sociability. For example, extroverts were thosewho said they made friends easily, preferredfriends to books, found it easy to start speaking toa new pupil, and liked asking questions in class.

Serious illness in childhood (up to 15 years) wasdefined as any condition which necessitatedhospital admission of a minimum of 28 days, or

school absence of three consecutive weeks. At themedical examination when cohort members were

13 years old a doctor identified those who hadphysical disabilities that were likely to interferewith participation in school activities. Forsimplification in the multivariate analyses thesetwo measures were collapsed into a singledichotomous variable.

Multivariate analyses were undertaken usingthe stepwise logistic regression model in theBMDP statistical package and interactions in thefinal model were investigated.

ResultsPATTERNS OF PHYSICAL ACTIVITYSixty six per cent of men and 560o of womenreported participating in sports and recreationalactivities in the preceding month (ie, those in themost and less active categories in table II). Thismay overestimate average levels of activity over a

year as there were significant seasonal fluctuationsin the frequency ofreported activities, and 900,0 ofthe interviews were conducted between April andSeptember. Table III shows the most frequentlyperformed activities. Swimming was reported by24% of subjects, and "exercise like press ups at

Heavy gardening and DIY: Five or more 1-4 times in No reported activity inList of 10 heavy activities times in the previous month previous month(eg, digging earth, chopping previous monthwood, brick laying, movingheavy objects, etc)

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Table II Activity levels for men and women by type of activity (n 3322)

Activity level

Most active Less active Inactive Not knownM F M F M F M F( 0 oJK0) )({)O" ( 0 ) ( ( " ) ( ")0

Workplace activity 51 6 60 8 8-9 12 5 38 3 25-7 1-1 1-1Sports/recreational 41 2 31 2 25 1 25 1 33 1 43 5 0-6 0 2Cycling/walking 27 9 36 0 46 2 42-6 24 8 21-0 1.0 0-3Heavy gardening/DIY 29-1 11 9 35 1 31 7 35 1 56 2 0-7 0 1

home" by 17" ',. Swimming and golf were more

frequently reported by those interviewed in thesummer months. Figure 1 shows that theproportion of men and women in the most activecategory increased significantly (p<0 001) witheducational qualifications.Men were more likely than women to report

heavy gardening activities in the previous month.Cycling and walking, in contrast, were reportedmore frequently by women than men (table II).Both types of activity showed significant seasonalfluctuation. In neither area was membership ofthe most active group significantly associated witheducational qualifications. Differences in educ-ational attainment were only apparent betweenthe inactive and less active groups; compared withthose with few or no educational qualificationsbetter educated men and women were more likelyto report some cycling or walking rather thannone, and better educated women were more

likely to report some heavy gardening and DIYrather than none.

Figure 2 shows the overlap between sports,walking/cycling, and gardening/DIY in individ-uals. Only 5 " 0 of men and 3O° of women were

classified in the most active category for all three

groups; most of the subjects were in only one ofthese groups. Just under a third ofmen (32 ,) andtwo fifths of women (42" O) were in the less active

or inactive categories for all three activity types.

Table III Sports andrecreational activities inthe previous monthreported by at least one in10 men and women at 36years

60 r

401-

a-cJ

20

0

Men

Men Women(0o) (0v)

Swimming 23-3 Swimming 24-7Exercises at home 16-0 Exercises at home 18-2Golf 11-6 Dancing 15-4

Jogging 11-1 Movement to music 9-5Squash 10-9Dancing 10-0Football 9-8

Women

7,ZZZ1VAtV//AVZZZZZA I///

D A 0 V NQualifications

A 0 V N

Fifty two per cent ofmen and 61 " ofwomen inthe sample were categorised in the most physicallyactive group at work (defined as either walking forover half the day or frequently lifting and carryingheavy loads). Those in the manual social classeswere significantly more active at work than thosein the non-manual classes (see fig 3; p <0 001).Women did less lifting and carrying than men,

and were more likely to be classified as active on

the basis of walking. Women in social classes 1 and2 were more active than their male counterparts.

There was some evidence that men, but not

women, in sedentary occupations compensated bybeing more active in their leisure time: 71" ofmen who were inactive at work were classified intoat least one of the most active leisure groups

compared with 62"C, of men reporting high levelsof activity at work (p < 0 00 1).

Overall 13" 0 ofmen and 17 0, of women did not

achieve membership ofa most active group, eitherat work or in their leisure time.

EARLY PREDICTORS OF ADULT PARTICIPATION IN

SPORTS

There was evidence from this study that measuresof socioeconomic status of the family of origin andcertain childhood attributes were associated withparticipation in sporting activity of men and

women in later life (table IV). Parental educationwas a significant (p < 001) predictor of those inthe most active sports category at 36 years.

Paternal social class showed a similar trend inboth sexes, but the relationship only attainedsignificance in women. Multiple logisticregression showed that although these variableswere highly interrelated, they each contributed a

significant independent effect. When account was

also taken of cohort members' own educationalqualifications, the effects of fathers' social classand educational level became insignificant as

those from poor family backgrounds who rose up

the educational ladder took on the same level ofsports participation as other well educated peoplefrom more favoured backgrounds.

Adolescent characteristics which were positivepredictors of high sporting activity at age 36 years

included above average ability at school games,

high energy level (table IV), and an extrovert

personality. The mean scores on the Pintnerextrovert scale for men and women in the most

active sports category were 9 1 and 8 6respectively, and were significantly higher thanthe mean scores for other men and women (8 6and 8 3) (p<0 01).

Negative predictors of high sporting activity inlater life included physical disability and, forwomen only, serious illness in childhood or

adolescence (table IV).The childhood variables (except for fathers'

social class and level of education which had

already been found to be mediated by the surveymembers' own educational qualifications) were

examined in a multiple logistic regression model.

They all retained statistically significantindependent effects on adult participation in

sports (table V).

VALIDITYThe validity of the various measures of physicalactivity adopted in this study was difficult to

D = Degree; A = "A" level; 0 = "O" level; V = Vocational; N = None

Figure 1 Percentage reporting sports activities at least five times in previous month

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estimate within the framework of the data setitself. We were able, however, to explore therelationship between the levels of variousactivities and the reported prevalence ofbreathlessness during the previous month. All ofthe leisure activities inquired about showedstatistically significant (p<0 001) associationswith this variable. Using the whole sample, thosereporting frequent heavy lifting at work were nomore likely to report having been out of breath.However, a significant association (p < 0 01) wasrevealed when the sample was restricted to thosewho were inactive or less active in leisureactivities, suggesting that the previous lack ofassociation had been due to higher activity levelsof sedentary workers in their leisure time.

Men (n = 1637)

Most active.

LI-.. Frequent liftirng andcarrying

m Walking -> half a day

Women (n = 1660)

Wome-

Mer

- Less active

LmII Inactive sitting haIf aday)..

DiscussionThis study provides data on the activity patternsof a national sample of people aged 36 years.When categorised into occupational and leisurecomponents, there was little concordance withinindividuals on the level of activity in eachcomponent. Sex, social class, and previouseducational attainment appear to have differentialbut statistically significant effects on activity inthe work place and at leisure. Several childhoodattributes, most notably ability at games,extrovert personality, serious illness, andeducational attainment, exerted independentadditional effects on sports and recreationalactivities at age 36 years.Many epidemiological studies have sought an

association between activity level and disease.Activity assessment in such studies constitutes amajor methodological problem. The four majormethods which have been evaluated are astructured questionnaire, diary recording, bodyborn instruments such as an electrocardiograph,and measurement of energy intake. Only thequestionnaire and diary methods are capable ofproviding information on the wide range ofoccupational and leisure activities whichconstitute total physical activity. They are,however, prone to bias in recall, as well as tovariation in validity. The sample adopted in ourstudy was large and representative of the 36 yearold population of this country. The response ratewas high, and careful descriptions of a wide rangeof activities which constitute total physicalactivity were sought. It thus seems unlikely thatreporting bias could explain the observedrelationships between activity and sex, socialstatus, and educational level.The validity of activity recall constitutes a

greater problem. Investigators are faced with awide array of questionnaires of varyingcomplexity, length, and time frame. Ascertain-ment of information on leisure activity in oursurvey was based upon the Minnesota leisure timephysical activity questionnaire.'8 In a recentstudy,24 this questionnaire correlated well withtreadmill estimation of oxygen uptake and bodycomposition, two traditional gold standards forphysical activity measurement. A poorrelationship was found, however, between thequestionnaire and occupational activity. Yet,occupational activity is clearly relevant to diseaseaetiology under certain circumstances, asevidenced by the recently reported associationbetween occupation in middle life and subsequentrisk of hip fracture.25 Perhaps of greater interest,most of the nine other activity questionnairesincluded in the validation study described above24performed in a similar manner. Such data supportthe notion that there are many separatedimensions of physical activity each requiringtheir own method of validation. Perhaps thelength and attention to detail ofany questionnaireare less important than the logic of its questions inthe context of the disease being studied.Our observation that those who were active at

work engaged in less leisure activity, and thatindividuals often engaged in one type of leisureactivity without necessarily becoming involved inother types, suggests that future studies shouldtake account of a broad range of pursuits rather

Not highly active in any activity: 32-0% (men); 42-2% (women)

Figure 2 Percentage highly active in at least one type of leisure activity

0.a-w

Figure 3 Physical activity during working day according to own social class

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Table IV Early life predictors of participation in sports and rat 36 years

Men

% in mostn active group

Father's educationSecondary+ FE or higherSecondary onl,yaPrimary + FEPrimary only

Mother's educationSecondary + FE or higherSecondary on,yaPrimary + FEPrimary only

Father's social classI and IIIII non-manualIII manualIV and V

Ability at games 13 yearsAbove averageAverageBelow average

Energy level at 13 yearsExtremely energeticNormally energeticAlways tired and washed out

Physical disability at 13 yearsNoYes

Serious illness (0-15 years)NoYes

215 51-6202 45-0213 42-3792 39-6

163 40-5172 57-0227 47-6878 38-5

333 46-5274 44-5456 42-3420 37-4

326 54-0873 41-2237 34-6

91 53-81307 42-775 34-7

1331 43-577 27-3

1272 42-7333 39-9

FE Further educationa Or primary and FE or higherb Includes those who attended FE courses but did not obtain any recop***p<00(001; **p>O0J001<0-01; *p>O001<0.05

Table V Early life predictors of a high level of participation inrecreational activities at 36 years (n = 2144)

Educational qualificationsNoneVocational"O" level or equivalent"A" level or equivalentDegree level or equivalent

Extraversion

SexMaleFemale

Ability at games at 13 yearsBelow averageAverageAbove average

Energy levels at 13 yearsAlways tired and washed outNormally energeticExtremely energetic, never tired

Mother's educationPrimary onlyPrimary + FESecondary onlySecondary + FE of higher

Childhood ill healthSerious illness or physicaldisabilityNone

n Odds rat

(805) 1-00(163) 1*10(445) 1-74(537) 2-16(194) 1-67

1.l9a

(1066) 1-00(1078) 0-63

(311) 0-72(1427) 1-00(406) 1-35

(104) 0-94(1860) 1-00(144) 1-62

(1357)(330)(221)(236)

1-001-241-521-24

(477) 0-79

(1667) 1-00

FE= further educaqtion(Goodness of fitX 0-143)based on 1 SD change

***p<0-001; *p>0.01<0.05

^ecreational activities than extrapolating from a brief description ofoccupation26 27 or a short series of questions on

Women leisure time pursuits. Such methodological% in most failings may partly explain the weaker associations

n active group between exercise and disease in studies using223 48 0 questionnaire based methodology when com-197 401 pared with those using physiological measure-182 418 2848 26-7 ments of aerobic capacity.28

For health benefits to accrue physical activitymust be maintained. Lifestyles which involve

172 47-7 walking, cycling, and gardening may be easier to199 372 maintain in the long run than participation in937 28 7 sports, which tends to decrease rapidly with age.

Those who get most of their exercise from sports335 45-7 or from work tasks will have to make lifestyle282 40 9 changes as they age and retire in order to maintain465 3021 exercise levels.

The study revealed a number of ways by whichthose who took part in sports were a selected

249 418 group compared with the less active. They had79 33-5 fewer childhood health problems, had been179 21-8

assessed as outgoing socially in adolescence, weremore likely to have been above average at school

91 56 0 games, to have been well educated and have1179 318 mothers with a secondary education. Many of

these childhood factors have also been found to beassociated with various aspects of health.29-3'

1342 34-1 Cross sectional studies and adult follow up studies79 20-37920 3 should take this problem of selection into account

when examining the relationship between sports280 26 1 activities and mental or physical health.

** The importance of the level of mothers'education to participation in sports activities by

gnised qualifications their adult offspring may reflect greater exposureto opportunities for sport for mothers who went tosecondary school compared to their peers who leftafter a primary education and went earlier into the

sports and world of work. This study did not obtaininformation about the parents' participation in

(95% confidence sports activities.rio intervals) There have been few prospective studies of

early influences on adult levels of physical(0-82-1-47) activity.32 Our findings suggest the importance of(1844-2510) developing skills and habits in childhood and(1-28-218) adolescence as well as encouraging healthier

exercise habits in adults who may have had fewopportunities or low motivation previously.

Evidence from two other national samplessuggests that those who frequently engage in

(0-58-070) sports and recreational activities are bettereducated33 or have non-manual occupations.34The relationship between other leisure activities,

(060-087) such as gardening and DIY, and current(114-159) socioeconomic status is inconsistent.33 Our

findings suggest that for leisure pursuits otherthan sports better educated people were more

(0-80-1 41) likely to report some activities rather than none at(124--211) all but were no more likely to report high levels of

activity; this may go some way to explainingprevious inconsistent results.

(1-02-1 50) Information has also recently become available(1 22-1 91) on the activity patterns of children and the(0-99-1-55)

elderly. In British school children,35 a majorconcern exists that maintenance of exercisethrough school games classes is not seen as a(071-0-89) priority. A population based study of elderlypeople in Nottingham36 also points towardsgenerally low levels of activity, even in thosewithout significant disabilities. The majorcomponents of activity in this study were outdoor

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walking, home activities such as cleaning,washing, and gardening, and muscle loadingactivities, such as stair climbing. Participation insport was found to be very infrequent in theelderly. Our results complement these descriptivestudies and suggest that a different activitypattern needs to be assessed during the workingyears of adult life.There is evidence to implicate physical

inactivity in the aetiology of several chronicdiseases, most notably osteoporosis and ischaemicheart disease. The design of effective publichealth strategies requires baseline information onthe wide spectrum of physical activity undertakenby men and women at different stages throughoutlife. This study provides nationally representativenormative data on the pattern of, and earlyinfluences on, physical activity of adults in earlymiddle age. Activity patterns differ between menand women, and between the workplace andleisure time. They are influenced by currentsocioeconomic status, as well as by a number ofchildhood factors. These observations provide afirm basis for future analytical investigations totest the association between inactivity and chronicdisease.

The authors would like to thank Dr Mike Wadsworth,Dr Bryan Rodgers, and Miss Susan Mann for theirhelpful comments on drafts of this paper.

1 Jones WHS. Translation of A regimen for health. In:Hippocrates. (Vol IV.) Loeb edition, 1931.

2 Green RM. A translation of Galen's Hygiene (de SanitateTuenda). Springfield, Illinois: Charles C Thomas, 1951.

3 Great Britain Parliamentary Papers. Report of the RoyalCommission on Physical Training Scotland, vol I: report andappendix Cmnd. 1507; vol II: Minutes of evidence Cmnd.1508. London: HMSO, 1903.

4 Great Britain Parliamentary Papers. Report of the Inter-departmental Committee on Physical Deterioration. Vol I:report and appendix Cmnd. 2175; Voll II: List of witnessand minutes of evidence, Cmnd. 2210; Vol III: appendixand general Index, Cmnd. 2186. London: HMSO, 1904.

5 British Medical Association. Report of the Physical EducationCommittee. London: BMA: April, 1934.

6 Great Britain Parliamentary Papers. Training and RecreationAct. Cmnd. 5364. London: HMSO, 1937.

7 McIntosh PC. Physical education in England since 1800.Revised and enlarged edition. London: G Bell and Sons,1968.

8 Bassey EJ. Benefits ofexercise in the elderly. In: Isaacs B, ed.Recent advances in geriatric medicine No 3. Edinburgh:Churchill Livingstone, 1985.

9 Paffenbarger RS, Hale WE. Work activity and coronaryheart mortality. N Eng Jf Med 1975; 292: 545-9.

10 Morris JN, Heady JA. Mortality in relation to the physicalactivity of work. Br J Ind Med 1953; 10: 245-54.

11 Paffenbarger RS, Wing AL, Hyde R. Physical activity as anindex of heart attack risk in college alumni. Am J Epidemiol1978; 108: 161-75.

12 Paffenbarger RS, Hyde RT, Wing AL, Chung-ChengHsieh. Physical activity, all-cause mortality and longevityof college alumni. N Engl J Med 1986; 314; 605-13.

13 Morris JN, Everitt MG, Pollard R, Chave SPW. Vigorousexercise in leisure-time: protection against coronary heartdisease. Lancet 1980; ii: 1207-10.

14 Powell KE, Thompson PD, Casperson CJ, Kendrick JS.Physical activity and the incidence of coronary heartdisease. Annu Rev Public Health 1987; 8: 253-87.

15 Cooper C. Bone mass, muscle function and fracture of theproximal femur. Br Jf Hosp Med 1989; 42: 277-80.

16 Atkins E, Cherry N, Douglas JWB, Kiernan KE,Wadsworth MEJ. The 1946 British birth cohort: anaccount of the origins, progress and results of the NationalSurvey ofHealth and Development. In: Mednick SA, BaertAE, eds. Prospective longitudinal research: an empirical basisfor the primary prevention of psychosocial disorders. Oxford:Oxford University Press, 1981: 25.

17 Wadsworth MEJ. Follow-up of the first British nationalbirth cohort: findings from the MRC National Survey ofHealth and Development. Paediatr Perinat Epidemiol 1987;1: 95-117.

18 Taylor HL, Jacobs DK, Schucker B, Knudsen J, Leon AS,Debacker G. A questionnaire for the assessment of leisuretime physical activities. Jf Chron Dis 1978; 31: 741-55.

19 Shapiro S, Weinblatt E, Frank EW, Sager RV. The H.I.P.study of incidence and prognosis of coronary heart disease.J Chron Dis 1965; 18: 527-58.

20 Office of Population Censuses and Surveys. Classification ofoccupations. London: HMSO, 1970.

21 Department of Education and Science. Burnham FurtherEducation Committee grading courses 1972. London:HMSO, 1972.

22 Pinter R, Loftus JJ, Forlano G, Alster B. Aspects ofpersonality inventory: test and manual. Yonkers: WorldBook Company, 1937.

23 Pinter R, Forlano G. Four retests of a personality inventory.J Educ Psychol 1938; 29: 93-100.

24 Jacobs DR, Ainsworth BE, Hartman TJ, Leon AS. Asimultaneous evaluation of ten commonly used physicalactivity questionnaires. Med Sci Sports (in press).

25 Cooper C, Wickham C, Coggon D. Sedentary occupation inmiddle life and later risk of fracture of the proximal femur.Br J Ind Med 1990; 47: 69-70.

26 Laporte RE, Montoge HJ, Caspersen C. Assessment ofphysical activity in epidemiologic research: problems andprospects. Public Health Rep 1985; 100: 131-46.

27 Astrom J, Ahnqvist S, Beertema J, Jonsson B. Physicalactivity in women sustaining fracture of the neck of thefemur. J Bone J7oint Surg 1987; 69B: 381-3.

28 Frazer GE. Preventive cardiology. Oxford: OxfordUniversity Press, 1986.

29 Rodgers B. Behaviour and personality in childhood aspredictors of adult psychiatric disorder. J Child PsycholPsychiatry 1990; 31: 393-414.

30 Kuh D, Wadsworth MEJ. Parental height, childhoodenvironment and subsequent adult height in a nationalbirth cohort. Int J Epidemiol 1989; 18: 663-8.

31 Kieman KE, Colley JRT, Douglas JWB, Reid DD. Chroniccough in young adults in relation to smoking habits,childhood environment and chest illness. Respiration 1976;3: 236-44.

32 Dishman RK, Sallis JF, Orenstein DR. The determininantsof physical activity and exercise. Public Health Rep 1985;100: 158-71.

33 Fenner N. Leisure, exercise and work. In: Cox BD, BlaxterM, Buckle AJ, Fenner NP, Huppert FA, Whichelow M,eds. The Health and Lifestyle Survey. London: HealthPromotion Trust, 1987.

34 Office of Population Censuses and Surveys. GeneralHousehold Survey. London: HMSO, 1986.

35 Armstrong N, Balding J, Gentle P, Kirby B. Patterns ofphysical activity among 11 to 16 year old British children.BMJ 1990; 301: 203-5.

36 Dalloss HM, Morgan K, Bussey EJ, Ebrahim SBJ, TentemPH, Arie THD. Levels of customary physical activityamong the old and very old living at home. J EpidemiolCommunity Health 1988; 42: 121-7.

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/J E

pidemiol C

omm

unity Health: first published as 10.1136/jech.46.2.114 on 1 A

pril 1992. Dow

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