BrJ Sports Med 1996;30:94-101 Associations between health behaviours and health related fitness Roy J Shephard, C Bouchard Abstract Objective-To examine relations between health behaviours and health related fitness. Methods-Subjects were a convenience sample of 350 healthy adults (172 men, 178 women). Covariance analysis adjusted data for significant influences of age and socioeconomic status. Obesity was as- sessed by anthropometry and body density. Cardiovascular fitness was assessed and various metabolic measurements were made. Questionnaires on physical activity and health related behaviours were completed. Results-Cigarette abstinence was asso- ciated with a small abdominal circum- ference (men) and a low trunk/extremity skinfold ratio (women). Obesity indices (body mass index, total skinfolds, percent fat, and abdominal circumference) were negatively associated with perceived fitness. Leisure activity and exercise frequency were also negatively linked to some obesity indices. Blood glucose, cholesterol, HDL-cholesterol, and trig- lycerides were favourably influenced by perceived activity, exercise frequency, and perceived fitness, but not by exercise intensity. Abstinence from coffee was as- sociated with a low cholesterol/HDL ratio (men only). Principal component, dis- criminant, and multiple logistic re- gression analyses showed only weak clustering of habitual physical activity with other positive health behaviours. Conclusions-Although multiphasic health promotion programmes are economical, favourable interactions between individual programme elements seem likely to be quite limited. (BrJ Sports Med 1996;30:94-101) School of Physical and Health Education, University of Toronto, 320 Huron Street, Toronto, Ontario, Canada M5S lAl R J Shephard, professor Physical Activity Sciences Laboratory, Laval University, Ste Foy, Quebec, Canada C Bouchard, director Correspondence to: Professor Shephard Accepted for publication 5 July 1995 Key terms: health related fitness; metabolic fitness; obesity; physical activity Several reports have suggested that there is an association between regular exercise or attained physical fitness and other favourable health behaviours. l Such an association could indicate interactions between the various types of health promotion, pointing to the thera- peutic value of multifaceted lifestyle pro- grammes rather than simple exercise classes as a means of enhancing industrial or community health. Nevertheless, the evidence for a clustering of habitual physical activity with other positive health behaviours is not particu- larly strong,27 and it is difficult to rule out a mutual dependence of exercise and other health behaviours upon extrinsic variables such as the age or socioeconomic status of the subject.8-" In this report we therefore consider the extent of associations between health behav- iours and indices of health related fitness (obesity, metabolic health, and cardiovascular fitness) in a substantial sample of Quebecois adults after covariance adjustment of data for the influences of age and a composite index of socioeconomic status. Principal component analyses examine the clustering of reported health behaviours after such covariance adjust- ment, and the specific impact of reported leisure activities upon the consumption of alcohol, coffee, tea, and cigarettes is tested by discriminant analysis and multiple logistic regression analysis. Methods SUBJECTS AND EXPERIMENTAL PLAN A convenience sample of clinically healthy but relatively sedentary volunteers (172 men and 178 women) were recruited in accordance with a protocol approved by the Laval University Committee on Human Experimentation. A radio announcement indicated an opportunity to participate in a study that would provide measurements of fitness and body compo- sition, and would explore the relations of these variables to current lifestyle. Respondents came from an area of some 80 km around Quebec City; it is likely that they had an above average interest in health, and application of the Blishen scale showed that their median socioeconomic status was somewhat greater than that of the overall Canadian population. A preliminary clinical examination excluded those with any chronic disease. Ages ranged from 14 to 68 years [mean(SD) 38-8(15-6) years, men; 39 4(15-0) years, women]. The average height [1.74(0.06) m, men; 1-61(006) m, women] corresponded closely with norms for middle aged Canadian adults.9 However, the body mass [74.9(11-6) kg, men; 59 7(8-3) kg, women] was a little below these same Canadian norms.'2 Measurements of obesity included the body mass index, skinfold thicknesses and their ratios, hydrostatic estimates of percentage body fat, and abdominal circumference. Metabolic measures included resting blood glucose, total cholesterol, high density lipo- protein (HDL), cholesterol, and triglycerides. 94 on January 27, 2021 by guest. Protected by copyright. http://bjsm.bmj.com/ Br J Sports Med: first published as 10.1136/bjsm.30.2.94 on 1 June 1996. Downloaded from
Transcript
BrJ Sports Med 1996;30:94-101
Associations between health behaviours and healthrelated fitness
Roy J Shephard, C Bouchard
AbstractObjective-To examine relations betweenhealth behaviours and health relatedfitness.Methods-Subjects were a conveniencesample of 350 healthy adults (172 men, 178women). Covariance analysis adjusteddata for significant influences of age andsocioeconomic status. Obesity was as-sessed by anthropometry and body density.Cardiovascular fitness was assessed andvarious metabolic measurements weremade. Questionnaires on physical activityand health related behaviours werecompleted.Results-Cigarette abstinence was asso-ciated with a small abdominal circum-ference (men) and a low trunk/extremityskinfold ratio (women). Obesity indices(body mass index, total skinfolds, percentfat, and abdominal circumference) werenegatively associated with perceivedfitness. Leisure activity and exercisefrequency were also negatively linked tosome obesity indices. Blood glucose,cholesterol, HDL-cholesterol, and trig-lycerides were favourably influenced byperceived activity, exercise frequency,and perceived fitness, but not by exerciseintensity. Abstinence from coffee was as-sociated with a low cholesterol/HDL ratio(men only). Principal component, dis-criminant, and multiple logistic re-gression analyses showed only weakclustering of habitual physical activitywith other positive health behaviours.Conclusions-Although multiphasic healthpromotion programmes are economical,favourable interactions between individualprogramme elements seem likely to bequite limited.(BrJ Sports Med 1996;30:94-101)
School ofPhysical andHealth Education,University ofToronto,320 Huron Street,Toronto, Ontario,Canada M5S lAlR J Shephard, professorPhysical ActivitySciences Laboratory,Laval University, SteFoy, Quebec, CanadaC Bouchard, directorCorrespondence to:Professor ShephardAccepted for publication5 July 1995
Key terms: health related fitness; metabolic fitness;obesity; physical activity
Several reports have suggested that there is anassociation between regular exercise or
attained physical fitness and other favourablehealth behaviours. l Such an association couldindicate interactions between the various typesof health promotion, pointing to the thera-peutic value of multifaceted lifestyle pro-grammes rather than simple exercise classes as
a means of enhancing industrial or communityhealth. Nevertheless, the evidence for a
clustering of habitual physical activity with
other positive health behaviours is not particu-larly strong,27 and it is difficult to rule out amutual dependence of exercise and otherhealth behaviours upon extrinsic variables suchas the age or socioeconomic status of thesubject.8-"
In this report we therefore consider theextent of associations between health behav-iours and indices of health related fitness(obesity, metabolic health, and cardiovascularfitness) in a substantial sample of Quebecoisadults after covariance adjustment of data forthe influences of age and a composite index ofsocioeconomic status. Principal componentanalyses examine the clustering of reportedhealth behaviours after such covariance adjust-ment, and the specific impact of reportedleisure activities upon the consumption ofalcohol, coffee, tea, and cigarettes is tested bydiscriminant analysis and multiple logisticregression analysis.
MethodsSUBJECTS AND EXPERIMENTAL PLANA convenience sample of clinically healthy butrelatively sedentary volunteers (172 men and178 women) were recruited in accordance witha protocol approved by the Laval UniversityCommittee on Human Experimentation. Aradio announcement indicated an opportunityto participate in a study that would providemeasurements of fitness and body compo-sition, and would explore the relations of thesevariables to current lifestyle. Respondentscame from an area of some 80 km aroundQuebec City; it is likely that they had an aboveaverage interest in health, and application ofthe Blishen scale showed that their mediansocioeconomic status was somewhat greaterthan that of the overall Canadian population.A preliminary clinical examination excluded
those with any chronic disease. Ages rangedfrom 14 to 68 years [mean(SD) 38-8(15-6)years, men; 39 4(15-0) years, women]. Theaverage height [1.74(0.06) m, men; 1-61(006)m, women] corresponded closely with normsfor middle aged Canadian adults.9 However,the body mass [74.9(11-6) kg, men; 59 7(8-3)kg, women] was a little below these sameCanadian norms.'2Measurements of obesity included the body
mass index, skinfold thicknesses and theirratios, hydrostatic estimates of percentagebody fat, and abdominal circumference.Metabolic measures included resting bloodglucose, total cholesterol, high density lipo-protein (HDL), cholesterol, and triglycerides.
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Cardiovascular fitness was assessed fromresting heart rate, physical working capacity ata heart rate of 150 beatsmin-' (PWC150), andsystolic and diastolic blood pressures.
Subjects also completed recently validatedquestionnaires relating to education, occu-pation, habitual physical activity, and otherhealth behaviours.'3
MEASURES OF HEALTH RELATED FITNESS
ObesityThe height and body mass were determined bystadiometer and clinical scales, respectively,with the subjects wearing only shorts and at-shirt.
Skinfolds (biceps, triceps, subscapular, ab-dominal, suprailiac, and medial calf) weremeasured on the left side of the body, usingHarpenden calipers. Estimates were made oftotal subcutaneous fat'4 15 and the ratio ofcentral to peripheral skinfold measurements.'6Total body fat was determined by underwaterweighing,'7 18 using the mean of six validmeasurements.Abdominal circumference measurements
followed the recommendations of the AirlieConference of 1988. "The subject stood erect,with the abdomen relaxed, the arms at thesides, and the feet together. The observer facedthe subject and placed an inelastic tape in ahorizontal plane at the narrowest part of thetorso. The reading was taken at the end of anormal expiration, taking care that the tape didnot compress the skin.
Metabolic fitnessPlasma glucose was determined enzymatically. '
Cholesterol and triglyceride concentrations inplasma and in lipoprotein fractions weredetermined by an enzymatic method (RA-1000analyer, Technicon), using specimens of ante-cubital venous blood collected after a 12 hovernight fast. Very low density lipoproteinswere isolated by ultracentrifugation.20 TheHDL fraction was estimated after the lowdensity lipoprotein had been precipitated usingheparin and manganese chloride.
CardiovascularfitnessMeasurements were made at 8 am, with thesubjects fasting. Two heart rate determinationsand two sphygmomanometer readings ofbloodpressure22 were made in a supine position, after10 and 12 min of rest respectively. The PWC150per kg of body mass was determined with aMonark ergometer, using a progressive testprotocol. Three individually adjusted loadingsof 6 min duration were each separated by 1 minrecovery intervals for a total exercise time of 18
23min.
QUESTIONNAIRE DATA
Socioeconomic statusQuestionnaires evaluated (1) attained edu-cation (results collapsed to three level scale:1 = secondary school not completed or less,2 = university not completed, 3 = universityqualification); (2) profession (collapsed tothree level scale; 1 = office supervisor, sales-person, skilled, semiskilled or unskilled worker,
other; 2 = semiprofessional, technician, ownerof small business or manager; 3 = professional,administrator, owner of factory or largecompany); and (3) total family revenue(average dollar value of $64 500 per year con-verted to three level scale). A nine grade socio-economic status categorisation was derived byadding:
Education (1, 2, or 3) + Occupation (1, 2, or3) + Family income (1, 2, or 3).
Habitual physical activity"Demanding" physical activity was evaluatedon a three level scale. Workplace walking(sitting, standing, or walking) and lifting or themanipulation of heavy objects ("heavy hand-ling") were each evaluated on a four level scale,ranging from 1 = "rarely/never" to 4 = "all thetime".
Perceived leisure activity was compared withage matched peers on a five level scale, rangingfrom 5 = "much more active" to 1 = "muchless active". The typical frequency of partici-pation in physical activity sufficient to provokesweating and a rapid heart beat ("exercisefrequency") and the typical intensity of partici-pation in sport or leisure activity ("exerciseintensity") were each rated on a three levelscale (1 = "rarely/never" to 3 = "at least threetimes per week", and 1 = "light" to3 = "intense", respectively). Perceived fitnessrelative to age matched peers, and changes infitness status over the past 10 years were eachrated on a five level scale (1 = "very bad" to5 = "very good" and 1 = "much worsened" to5 = "much improved", respectively).
Other health behavioursThe consumption of alcohol, coffee, tea, andcigarettes were each assessed on a simpleyes = 1/no = 2 scale.'3
STATISTICAL ANALYSIS
Descriptive statistics [mean(SD), by sex] werecalculated for age, socioeconomic status,health related behaviours, and health relatedfitness. Sex-specific associations between age,socioeconomic status and health behaviourswere examined using Spearman rank ordercorrelations, fitted by the method of leastsquares. Correlations between health behav-iours and measurements of health related fit-ness were tested in similar fashion aftercovariance adjustment of the latter for theeffects of age, socioeconomic status (combinedindex), and age plus socioeconomic status.Principal component analyses (varimax ro-tation) examined the clustering of health be-haviours after covariance adjustment for ageand socioeconomic status. Discriminant analy-ses tested the associations between the con-sumption of alcohol, coffee, tea, and cigarettesand selected measures of occupational andleisure activity. A sex-specific generalisedsquared distance function of the type:
DJ(X) = (X-XJ)'COV-W(X-Xi)was fitted for each type of consumption, usingthe standard SAS program. The posterior
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probability of membership in each category ofconsumption was calculated as:
Pr(J IX) = exp[-.5 Dj(X)]/Sum exp [-.5 DK(X)],K
and the error count between predicted andactual consumption was then examined.
Muliple logistic regressions examined theassociation between each of several indices ofhabitual physical activity and alcohol, coffee,tea, and cigarette consumption. Odds ratiosand x2 tests examined the predictive value ofindividual activity indices, and those showingsignificant associations with consumptionswere included in a multiple logistic regressioncalculation. Only indices that proved signifi-cant in this final calculation were retained.
ResultsSOCIOECONOMIC DESCRIPTORS
The sample was of above average socioe-conomic status for Quebec, comprising 85professionals (56 M, 29 F), 64 semi-professionals (36 M, 28 F), and 201 non-
professionals (80 M, 121 F). The majority ofthe men (165/172) and women (165/178) hadcompleted both secondary school and juniorcollege, and many (76/172 men, 67/178women) had also completed some universityeducation. The men reported a family revenueof $63.3(24.0) K, and the women an averageof $65.6(24.5) K.Spearman correlations tested the associations
of age, education, occupation, and familyrevenue with health behaviours (table 1). In themen, aging was associated with an increasedlikelihood of regular coffee and tea drinking,decreased physical activity at work, and a
decreased intensity of physically active leisure.In the women, coffee and tea drinking showedparallel trends, but cigarette and alcoholconsumption were less likely in older subjects.The three socioeconomic indicators of table 1were combined to yield a single index of SES(table 2). Data for the men showed that a highsocioeconomic index was associated with areduced likelihood of smoking and of physicalactivity at work, and a greater frequency andintensity of leisure activity. Moreover, thesefindings were changed little when the data werecovaried to allow for the effects of age as wellas socioeconomic status (table 2). The womenshowed a positive association of the socio-economic index with exercise frequency and
intensity, and a greater likelihood of alcoholconsumption in women of high socioeconomicstatus. However, in the women, none of theseassociations remained statistically significantafter covariance adjustment for the effects ofage.
HEALTH BEHAVIOURS
Social habits and addictionsAlcohol consumption was reported by 86/5%of the men and 86-4% of the women. Coffeewas consumed regularly by 69-6% of men and74-8% of women, but tea was a less popularbeverage (41.3% of men, 42.9% of women).The percentage of smokers was substantiallyless than in the general population of Quebec(1 5 6% of men, 18-4% of women), suggestingthe recruitment of a health conscious sample.
Patterns of habitual activityRelatively few subjects had a physicallydemanding job. The handling of heavy objectsfor a half or more of the day was reported by36/172 men, and 19/178 women. Walking"most or all of the time" was noted by 39/172men and 52/178 women.Not all subjects were participating in
demanding physical activity. However, 33/97men and 24/102 women claimed to engage insuch activity at least three times per week. Thecurrent rating of fitness was good or very goodin 105/172 men, and 101/178 women; 60/162men and 43/175 women rated their involve-ment in sport or leisure activity as intense.
HEALTH RELATED FITNESS
ObesityThe body mass index (BMI) averaged 24 9(3 7)kg/M2 in the men and 23 0(3 4) kg/M2 in thewomen. The hydrostatic estimate of body fatwas 21-1(8.0)% in the men and 29-9(9-1)% inthe women. The sum of the six skinfoldreadings was 103-8(43-0) mm in the men and145-8(53-0) mm in the women. The ratio oftrunk to peripheral skinfolds showed the antici-pated gender difference, averaging 1-76(0-49) inthe men and 0-93(0 27) in the women.
Respective values for abdominal circumferenceswere 0-90(0 11) and 0-84(0 11) m.
Association between these variables andhealth behaviours (after adjustment for theeffects of age, socioeconomic status, and ageplus socioeconomic status) is summarised in
Table 1 Spearman correlation matrices showing association between age, various indices ofsocioeconomic status andhealth behaviours (172 men 178 women)
High scores indicate avoidance of alcohol, coffee, tea, and smoking, high fitness or physical activity, extended education, highstatus occupation, and high family income. All correlation coefficients must attain values of 0-15, 0-19, and 0-25 or greater toreach respective probability levels of P < 0-05, 0-01, and 0 001. Given multiple comparisons, values of r < 0-25 should be regardedas trends only.
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Table 2 Spearman coefficients ofcorrelation betweenhealth behaviours and new indicator ofsocioeconomic statuswithout (SES) and with (AS) covariance adjustmentforage ofsubject (172 men, 178 women). For note on scoringand statistical significance, see table 1
tables 3 and 4. Avoidance of coffee and teaconsumption was apparently negatively asso-
ciated with various indices of obesity in bothmen and women, but this effect was no longerstatistically significant after allowing for theeffects of age and socioeconomic status. Absti-nence from cigarettes was associated with a
lesser abdominal circumference in men, and a
lesser trunk/extremity skinfold ratio in women.Walking at work was associated with a lowerbody mass index and abdominal circumferencein women only. In men, heavy handling was
positively associated with the trunk/extremityskinfold ratio. Perceived physical activity was
associated with lower skinfold totals in bothmen and women, and the frequency of exercisewas also associated negatively with the abdomi-nal circumference (in men only). Finally,perceived fitness showed relatively strongnegative associations with obesity in bothsexes.
MetabolicfitnessResting blood glucose levels were normal[5 0O(0 96) mM, men; 4 83(2 30) mM,women]. Total cholesterol [5-01(096) mM,men; 5 18(1 07) mM, women] and HDL chol-esterol [1d15(0-28) m1M, men; 1.43(0.33),women] were higher (or lower, HDL choles-terol) than desirable, but were very typical ofadult Canadians. Triglyceride readings[1'46(0-76) mM in the men, 1-30(0-64) in thewomen] were also unremarkable.
Associations between health behaviours andthese indices of metabolic health are sum-
marised in tables 5 and 6. Avoidance of coffeeand tea consumption tended to be negativelyassociated with serum cholesterol and trig-lyceride concentrations, but (with the excep-tion of cholesterol/HDL cholesterol in themen) such associations were no longer statisti-cally significant after covariance adjustment forthe effects of age and socioeconomic status.Perceived leisure activity had a negativeassociation with blood glucose and cholesterol/HDL cholesterol ratio in men only. Exercisefrequency was negatively associated with bloodglocuse in men, and was positively associatedwith HDL cholesterol in women. Perceivedfitness also had a positive association withHDL cholesterol and a negative associationwith triglyceride concentrations in men, butnot in women.
CardiovascularfitnessThe resting heart rate was relatively slow[58 0(9 6) beats-min-, men; 62 7(7 6)beats min-1, women) but the PWC150 was
Table 3 Spearman coefficients ofpartial correlation between health behaviours and measures of obesity in men (n = 172),calculated after adjustment ofobesity measuresfor effects ofage (A), socioeconomic status (SES), and age plus SES (AS).For note on units and statistical significance, see table 1
Variable BMI % Fat Sum ofskinfolds Trunklextr ratio Abd circ
BMI, body mass index; extr, extremity; Abd circ, abdominal circumference.
Table 4 Spearman coefficients ofpartial correlation between health behaviours and measures of obesity in women(n = 178), caleulated after allowance for effects ofage (A), socioeconomic status (SES) and age plus socioeconomic status(AS). For note on units and statistical significance, see table 1
Variable BMI % Fat Sum ofskinfolds Trunk/extr ratio Abd circ
Table 5 Spearman coefficients ofpartial correlation between health behaviours and biochemical workers of metabolichealth in men (n = 172), calculated after allowance for effects ofage (A), socioeconomic status (SES), and age plussocioeconomic status (AS). For note on units and statistical significance, see table 1
Table 6 Spearman coefficients ofpartial correlation between health behaviours and biochemical markers of metabolichealth in women (n = 178), calculated after allowance for effects ofage (A), socioeconomic status (SES), and age plussocioeconomic status (AS). For note on units and statistical significance, see table 1
Likewise, systolic and diastolic blood pressures[120(14)/74(10) mm Hg, men; 115(15)/71(10)mm Hg, women] were in the normal range.
Associations between indicators of cardio-vascular fitness and health behaviours are sum-marised in tables 7 and 8. Resting heart ratehad strong negative associations with thevarious markers of habitual activity in bothmen and women, and these associations per-sisted after covariance adjustment of data forboth age and socioeconomic status. In men,the PWC150 was positively associated withheavy handling at work, perceived activity,fitness, and exercise intensity, but was nega-tively associated with abstinence fromcigarettes. In women, frequency of exercisehad a positive association with PWC150. Therewere few associations between blood pressuresand health behaviours. However, in women,abstinence from tea drinking was associatedwith lower systolic pressures, and abstinencefrom cigarettes with higher diastolic pressures.
CLUSTERING OF HEALTH BEHAVIOURS
After covarying data for age and socio-economic status, principal component analysisidentified four statistically significant factors(table 9). These factors accounted for similarproportions of the total variance in both menand women. Factor 1 was heavily loaded by theassessments of habitual activity, and wasnegatively correlated with the hydrostaticestimate of body fat. Factor 2 was associatedwith abstinence from alcohol, coffee, tea, andcigarettes, with low perceptions of fitness, andwith an accumulation of body fat. Body fatloaded most strongly on factor 3. Factor 4 wasassociated with cigarette addiction in the men,and with the consumption of tea in thewomen.
DISCRIMINANT ANALYSES
High misclassification rates show that none ofthe discriminant analyses gave a very preciseindication of subjects who were likely to
Table 7 Spearman coefficients ofpartial correlation between health behaviours and cardiovascular health in men(n = 172), calculated after adjustmentfor effects ofage (A), socioeconomic status (SES), and age plus socioeconomic status(AS). For note on units and statistical significance, see table 1
Variable Resting heart rate PWC,50 Systolic BP Diastolic BP
Table 8 Spearman coefficients ofpartial correlation between health behaviours and cardiovascular health in women(n = 178), calculated after adjustmentfor effects ofage (A), socioeconomic status (SES), and age plus socioeconomic status(AS). For note on units and statistical significance, see table 1
Variable Resting heart rate PWC150 Systolic BP Diastolic BP
PWCio, physical work capacity at a heart rate of 150 beats-mi'; BP, blood pressure.
Table 9 Principal component analysis ofhealth (20% ofboth men and women) was lower thanbehaviours and risk factors. All variables adjustedfor in most surveys of Quebec; however, as in othercovariance of age and socioeconomic statusmmotsresfQubchwvramohr
Canadian surveys, older women were less likelyVariable Factor 1 Factor 2 Factor 3 Factor 4 to report alcohol and cigarette consumptionMen than their younger peers. In both sexes, agingCumulative variance 24-9% 40-3% 5400% 65.3% was associated with an increased likelihood ofAlcohol 0-30 0-29 0-44 0-35Coffee 0-24 0-59 -0-49 0-17 the regular consumption of tea and coffee.Tea 0-10 0-59 -0-46 0-26 Physical activity at work was less common inCigarettes 0-34 0-44 0-13 -0-71Perceived activity 0-61 0-06 0-03 -0-40 the older men, possibly because of promotionPerceived fitqness 0-76 -0-11 0-22 0-24 to managerial positions. Women also reportedExercise intensity 0-72 0-06 0-32 0-17 less heavy handling, but perceived moreBody fat % -040 0-36 0-55 0-18 walking. Leisure activity showed the expectedWomen negative association with age, but perhapsCumulative variance 25-6% 41.30/o 539% 64-8% because of selective recruitment, the olderAlcohol 0-14 0-37 -0-40 -0-04Coffee 0-19 0-76 -0-19 -0-08 women perceived themselves as of aboveTea 0-09 0-51 0-41 -0-67 aeaeftesCigarettes 0-45 0-25 -0-16 0-43 average fiess.Perceived activity 0-79 -0-18 0-38 -0-00Exercise frequency 0-69 0-03 0-41 0-23 SOIE NMCST USADH LHPerceived fitness 0-72 -0-28 -0-10 -0-28 SOCIOECONOMIC STATUS AND HEALTHExercise intensity 0-57 0-21 -0-40 0-11 BEHAVIOURSBody fat % -0-31 0-46 0-51 0-45 As in larger surveys,12 24 associations of health
behaviour with education, occupational status,consume alcohol, coffee, tea, and cigarettes and family revenue tended to move in parallel(table 10). Similar conclusions of limited (table 1). Looking at the combined index ofsuccess in classification were drawn from the socioeconomic status (table 2), the data showmultiple logistic regressions (not shown). the expected negative associations with ciga-
rette consumption and occupational activityDiscussion (men only), and the expected positiveAGE AND HEALTH BEHAVIOURS associations with various measures of habitualIn keeping with earlier research,8'2 24 habitual leisure activity.physical activity was negatively associated with In men, the associations were fairly robust,age. In keeping with the recruitment of a health and were not reduced by allowance for ageconscious sample, the proportion of smokers (table 2), but in women most associations were
Table 10 Coefficients predicting presence or absence ofgiven health behaviour (see Methods)
weakened to the point of becoming statisticallyinsignificant.The implication of these preliminary
analyses is that it is important to make dueallowance for both age and socioeconomicstatus before testing associations betweenhealth behaviours and various measures ofhealth related fitness.
HEALTH BEHAVIOURS AND HEALTH REATED
FITNESS
ObesityBoth caffeineated beverages and cigarettesmoking have sometimes been used as methodsof mobilising body fat and thus of controllingobesity.25 26 However, our dataset offers nosupport for this practice. Indeed, avoidance ofcoffee and tea consumption was apparentlyassociated with a lesser prevalence of obesity,although this effect disappeared when the datawere adjusted for age or age plus socio-economic status. The association thus seemedto indicate no more than a common influenceof age upon both obesity and beverage choice.Likewise, in contrast with the thrust of muchcigarette advertising, smoking was associatedwith a greater abdominal circumference inmen, and with a "masculine" distribution ofbody fat in women. Seidell27 has also com-mented that smoking is associated with anadverse distribution of body fat, possiblybecause of hormonal disturbances induced bysmoking.The objective measures of obesity showed
some associations with perceptions of habitualphysical activity, but the strongest associationswere with perceptions of fitness. This suggeststhat in both sexes, a slim figure still has a majorinfluence upon current perceptions of personalfitness.
Metabolic healthOur data show associations between variousindices of leisure activity and a favourable lipidprofile. In the men, there was also a weakassociation between abstinence from coffeeand a favourable cholesterol/HDL cholesterolratio, probably due to a clustering of interestsin a healthy lifestyle.7
Previous investigatorse 28 29 emphasised thatoptimisation of the blood lipid profile depen-ded upon developing a critical energy expendi-ture each week (equivalent to the walking of atleast 18-20 km). However, benefit was muchless dependent on the intensity of exercise. Ourcross sectional data support this inference.
Cardiovascular healthThe substantial associations between thevarious indices of habitual activity and restingheart rate support the view6 7 that resting heartrate is a simple and useful indicator of cardio-vascular health. However, somewhat in con-trast to expectation, our data suggested a closerassociation with the frequency of exercise thanwith its intensity, after control for the effects ofage and socioeconomic status. Correlationswith PWC150 are of approximately the sameorder as those for resting heart rate, despite thegreater complexity of the test. The one
exception to this generalisation is the asso-ciation with exercise intensity, which in womenis seen for PWC150, but not for the heart ratedata.The weak negative association between
abstinence from cigarettes and aerobic fitnesshas been noted in some earlier studies. 30 Theunits of measurement adopted in our study(W/kg) favour light individuals, and smokingmay thus augment PWC150 by reducing bodymass.The positive association between heavy work
and aerobic performance was not observed insome previous studies.eg 3 Earlier data tendedto be confounded by the conflicting influencesof higher socioeconomic status (a reduction ofoccupational activity, but an increase of leisureactivity). However, the present data suggestthat if appropriate control is made for socio-economic status and thus differences in leisureactivity, there is an association between type ofemployment and PWC150.
CLUSTERING OF HEALTH BEHAVIOURSThe principal component analyses support theview' 7 that any clustering of positive healthhabits is quite weak. Leisure activity tends toemerge as an independent first factor. Healthbehaviours load only slightly upon this factor,although there are weak negative associationswith cigarette consumption and the percentageofbody fat. Likewise, abstinence from alcohol,coffee, tea, and cigarettes emerges as a second,orthogonal factor.
Interestingly, this factor is associated with alow perception of fitness, but it is relativelyindependent of the other measures of physicalactivity. The negative association with per-ceived fitness may reflect the fact that healthconscious individuals tend to underestimatetheir fitness, whereas those who are sedentarytend to overestimate it.32
DISCRIMINANT AND LOGISTIC ANALYSESIf leisure activity had a major association withother health behaviours, this should emergethrough the successful prediction of such be-haviours by means of discriminant or logisticfunctions, or both. Leisure activity makes stat-istically significant contributions to theprediction of alcohol, coffee, tea, and cigaretteconsumption, but with the exception ofcigarette smoking in women, the associationbetween consumptions and habitual physicalactivity is sufficiently weak as to cause a highincidence of misclassifications.
POLICY IMPLICATIONSSome of the apparent associations betweenphysical activity and health related fitnessreported by earlier investigators reflect failureto allow for covariation with age and socio-economic status. Nevertheless, after allowingfor these factors, heavy worksite activity ispositively associated with PWC150 in men, andin both sexes habitual leisure activity hasfavourable associations with various indices ofobesity, metabolic health, and cardiovascularfitness. Habitual physical activity shows onlylimited clustering with other health behaviours
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such as abstinence from alcohol, coffee, tea,and cigarettes. Economic arguments mayfavour the adoption of multiphasic healthpromotional programmes, but any positiveinteractions between individual programelements33 34 seem likely to be quite limited.
CONCLUSIONS
Health behaviours are significantly associatedwith age and socioeconomic status, so thatcovariance adjustment for both of these factorsis needed when examining the association ofsuch behaviours with markers of obesity, meta-bolic health, and cardiovascular fitness. Inmen, occupational activity has a positiveassociation with all three domains of healthrelated fitness if data have been adjusted for theeffects of age and socioeconomic status.Leisure activity shows only a limited clusteringwith other health behaviours, although variousindices of leisure activity show positive asso-ciations in all three domains of fitness in bothmen and women. The relative strength ofcorrelations further suggests that measure-ments of resting heart rate can be as effectiveas PWC150 determination when seeking asimple estimate of cardiovascular fitness.
This work was supported in part by research grants from theCanadian Fimess and Lifestyle Research Institute and theMedical Research Council of Canada (MA-10499); the studiesof one ofus (RJS) are also supported by a grant from CanadianTire Acceptance Limited. Thanks are expressed to theinvestigators and support personnel involved in the QuebecFamily Study.
1 Allen C, Brown TE, O'Hara WJ. Aerobic fitness andcoronary risk factors. In: C Allen, ed. Proceedings offirstRSG4 Fitness Symposium, with special reference to militaryforces. Downsview, Ontario: Defence and Civil Instituteof Environmental Medicine, 1978.
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