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Research Quarterly for Exercise and Sport Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/urqe20
The Validity of Objective Physical Activity Monitoring in Older Individuals a
a
Richard A. Washburn , Carol A. Janney & Julie R. Fenster
a
a
New England Research Institute , 9 Galen Street, Watertown , MA , 02172 , USA Published online: 08 Feb 2013.
To cite this article: Richard A. Washburn , Carol A. Janney & Julie R. Fenster (1990) The Validity of Objective Physical Activity Monitoring in Older Individuals, Research Quarterly for Exercise and Sport, 61:1, 114-117, DOI: 10.1080/02701367.1990.10607489 To link to this article: http://dx.doi.org/10.1080/02701367.1990.10607489
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http:// www.tandfonline.com/page/terms-and-conditions
WASHBURN. IANNIlY. AND FBJllS11lR
RESEARCH NOTB
RESEARCH QUARTBRLY FOR EXBRCISB AND SPORT 1990, VOL. 61, No.1. pp. 114-117
The Validity of Objective Physical Activity Monitoring in Older Individuals
Downloaded by [University of Sydney] at 17:03 03 May 2015
RICHARD A. WASHBURN, CAROL A. JANNEY, JULffi R. FENSTER New England Research Institute
Key words: physical activity assessment. activity monitors.
elderly PhysiCal activity has been identified as a potentially modifiable behavioral risk factor relating to health and quality of life among older individuals (Heckler, 1985). Recent evidence from the Alameda County Study (Kaplan. Seeman. Cohen, Knudsen, & Guralnik, 1987) suggests that having little leisure-time physical activity is associated with an increased mortality risk independent of age, socioeconomic status, self-reportedhealth status. and behavioral risk factors suchas smoking,relative weight.and alcoholconsumptionin a 17-yearfollow-up ofindividualsaged60-94 yearsatbaseline. To further evaluate the relationship between physical activityand health among individualsover age 65, valid and reliable measures of activity specific for this age group need to be developed.Unlike other potential health-relatedfactors suchas bloodpressure. serumcholesterol,cigarettesmoking. or Type A behavior. there are currently no standardized protocols or laboratory tests for the assessment of physical activity(LaPorte, Montoye, & Caspersen. 1985; Montoye & Taylor,1984).Physicalactivityquestionnaires, thoughwidely used in epidemiologic research. may not be appropriate for use with older individuals. Questionnairesmay not be sensitive enough to detect small, yet important. differences in the levelof physicalactivity in a group where the generallevel of activity is likely to be low. Therefore. it is important to investigate the effectiveness of objective measures of physical activity among older individuals. The measurement of body movement using electronic motion sensors may serve as an objective measure of daily physical activity (LaPorte et al., 1979; Wong. Webster.
Montoye, & Washburn. 1981).One of these motion sensors. the Caltrac Personal Activity Computer. has receivedrecent attention as an objective physical activity monitor among youngersubjectsinbothlaboratoryandfieldsettings(Klesges & Klesges, 1987; Klesges, Klesges, Swenson, & Pheley, 1985; Montoye et al.• 1983; Washburn & LaPorte, 1988). However.weare unawareof anyreportsregardingthevalidity of the Caltrac as a measureof daily physical activity in older individuals. It was the purpose of the current investigation to assess the validityof theCaltracas a measureof dailyactivity in individualsage 65 andover by comparingCaltracreadings withphysicalactivityassessedby activitydiaries.In addition, we sought to assess differences in the association of the Caltrac and activity diary records by gender, age, and body size.
Methods Forty-fiveindividuals,23 men and 22 women,meanage (± SO) 72.9± 5.3 years(range65-85 yes). height 167.0± 11.0 em, and weight 74.0 ± 16.8kg participatedin this studyafter providing written informed consent. These subjects were from a random sample of healthy, noninstitutionalized individuals over age 65 selected from a household listing for the town of Amherst, Massachusetts. All testing was completed between March and October 1987. Potential subjects were contacted by telephoneto determine their willingness to participate. Volunteers were then scheduled for a home visit. During the home visit. height
RBsBARCH QuARTBRLY FOR EXBRCSIl AND SPORT,
114
VOL. 61. No.1
Downloaded by [University of Sydney] at 17:03 03 May 2015
WASHBURN, JANNBY, AND FBNS'I1lR
Results and Discussion
(carpenter's rule) and weight (Norelco digital scale, model HS7) were measured, and the use of the Caltrac and the activity diary were explained. Physical activity was monitored over 3 consecutive weekdays using a Caltrac Personal Activity Computer (Hemokinetics Inc., Madison, Wisconsin). Details regarding the development and construction of the Caltrac have been published elsewhere (Wong et al., 1981).The Caltrac is small and lightweight(9.5 em x 7.0 em x 1.25 em, weight = 75 g) and is designed to measure accelerationvia a piezoelectricbender element. A numerical score (Kilocalories) is provided by a liquid crystal display. The totalkilocaloriescore is a functionof the basal metabolic rate of the subject which is calculated by a computer chip programmedwith the subject's age, height, weight, and gender, plus additional caloric expenditure as a result of body movement. Our purpose was to assess the validity of the Caltraconlyas a movementsensor;thereforeweprogrammed identical values for age, height, weight, and gender for all subjects.The Caltracmonitorsused in the study wereoff-theshelf modelsavailable to the public. Subjectswere instructed to wear the Caltrac on a belt over the nondominanthip and to record Caltrac readings and the time both in the morningand on retiring for the evening in a record form provided. The meanCaltracreadings (counts/hr)over the 3 days of observation were used in the analysis. Duringeach hourof observationsubjectswere instructed to record the amount of time spent in nine categories of physicalactivityranginginintensityfromlow(1yingdown)to high (heavy sport and recreation). With the relatively small samplesize (N =45) therewereinsufficientnumbersofentries in several of the nine categories. Therefore,we collapsed the nine categories to 3: 1) sitting and lying down, 2) standing includingstanding performing light work, 3) walking, sport, and recreation. The mean percent time spent in each activity category over the 3 days was used in the analysis.
Subject characteristics are presented in Table 1. There were no significantdifferencesbetween men and womenfor age, body mass index, monitor time, Caltrac readings,or the percent time spent sitting or lying down. Men reported a significantly higher percent time engaged in walking and sport and recreation, whereas women reported significantly more time spent standingand standing doing light work.The total percenttimeinTable 1does notequal 100%.Thisis most likelybecauseof both failureto accuratelyrecordeach hour's activityand thefact that, with some individuals,the diary and Caltrac monitoring were not exactly concurrent. The small mean percent time unaccounted for by the diary record (5% for men,4% for women)representsa fairlycompleteactivity record. We are aware of the potential weakness of using a diary record as a criterion measureof physicalactivityin any sample, particularly with older individuals. However, given the alternatives, such as direct observation or physiologic measuressuch as heart rate or blood lipids,we felt that a diary record, where activity categories were listed, was an acceptable criterion measure. With the age-associated decline in levels of physical activity (Montoye, 1975)it would be expected that the mean Caltrac readings from our sample (mean age approximately 73 yes) wouldbe lowerthan thosefroma youngersample.We found the mean Caltrac readings of the present study (99.7 counts/hr)were significantlylower than Caltrac readingswe have observed in a sample of 98 college freshman (113.6 counts/hr), 1(141) =4.34, P < .0001). We also expected that readingsfromtheCaltrae,whichisa movementsensor,would be negativelyrelated to theamountof timespentin nonmovement activities (i.e., lying and sitting down) and positively related to the amount of time spent in movement activities such as walking and sport and recreation. To examine these
Table 1 sample Characteristics Men (n- 23) M±SD
Variable
Age (yrs) Body Mass Index (kg/m 2) Monitor Time (min/day) Caltrac (Countslhr) Percentage Time Sitting and Lying Down Percentage Time Walking & Sport & Recreation Percentage Time Standing & Standing Performing Light Work
72.9 25.9 844.9 99.7 53.9 14.4
± 3.9 ± 4.3 ± 60.4 ± 7.9 ± 14.9 ± 9.1
26.8 ± 12.6
Note. *ps .05 RBsI!AROi QuAR11IRLY FOR
ExERasa
U5
AND SPatT,
VOL. 61, No.1
Women (n - 22) M± SO
72.9 27.1 822.1 99.7 50.5 9.9
± 6.5 ± 6.1 ± 93.5 ± 7.5 ± 10.7 ± 4.5*
34.7 ± 12.8*
Downloaded by [University of Sydney] at 17:03 03 May 2015
WASHBURN. JANNBY. AND FBNS11IR
associations Spearman rank order correlations were calculated between Caltrae readings and the three activity diary variables. Caltrae readings were positively related to the percent time engaged in walking and sport and recreation (r = .28, p < .05) and percent time standing (r = .28, p < .05). There was a nonsignificanttrend (r =-.20) toward a negative relationshipbetweenCaItraereadings andpercenttimesitting andlyingdown.Althoughthesecorrelationsarenot high,they are in the expecteddirection. Other investigators,using more 'sophisticatedcriterionmeasuresof physicalactivityin groups of younger subjects, have reported stronger associationsbetween physical activity and Caltrac readings. For example, Klesges et al. (1985) reported correlations between Caltrae readingsand 1 hr of observed behavior in a gymnasiumin 50 youngadults(age 21.5 yrs) ranging from-.43 for sittingto .82 for running. In a recent report, Klesges and Klesges (1987) showed correlations of .54 between Caltrac readings and physicalactivity assessed by all-day personal observation in 30 children aged 24 to 48 months. The magnitude of the correlationcoefficientsbetween theCaltracandactivitydiary variables shown in the current study are similar to that reported by LaPorte et al. (1984) between another objective physicalactivity monitor (LSI) and the Paffenbargeractivity questionnaire (r =.23) in women, mean age 61 years. To identify factors that may influence the validityof the Caltrac,wecomputedSpearmancorrelationsbetweenCaltrac readingsand activity diary variablesby gender,age (65-74 & 75-85 yrs), and body mass index (above and below the median, 25.6 kg/m2) . These correlations are presented in Table2. The associationbetween Caltrac readings and activity diary variables tend to be higher in men than women and weresimilarin age and body massindex categoriesfor sitting and lying down and walking, sport, and recreation. In their study of children aged ~8 months, Klesges and Klesges (1987) reported higher associations of Caltrae and observed
activity for older children ~ vs. 32.5 months), females and overweight ~ vs. 75th percentile of body mass index); however, none of these differenceswere statisticallysignificant We haveno explanationfor the generallylowerassociations between the Caltrae and activity diary variablesseen in womenas comparedto menin thecurrentstudy.We speculate that perhaosthe men maintainedmore accurate diary records andtheseprovidea moreaccuratecriterionmeasure.We have no data, however, to support this contention. The association of the CaItrae and a self-reporteddiary assessment of physical activity shown in our data and the observationof a lowermeandailyCaltracreadinginourolder, comparedwithour younger,populationprovidesevidencefor the validityof the CaItraefor the assessmentof dailyphysical activityin healthyolder individuals. The results presentedin this report represent preliminary analyses of an ongoing projectdesignedtoassess thereliabilityand validityof objectivephysicalactivitymonitoringin individualsoverage 65. It is possible that with a larger sample, where more precise categories of daily activity can be derived from the activity diaries than was possible in the present study, stronger associations between the Caltrac and physical activity will be found. In additional studiesuse of a combinationof criterion measuressuchas heartrate,diary,andphysiologicalmeasures may yield additional valuable information regarding the validity of the Caltrae monitor. Although objective physical activity monitors such as the CaItrae may provide valid assessmentsof dailyactivityinolder individuals,the logistics associated with their use, the subject cooperation required, the relatively short time frame during which physical activitycan be assessed,andthepotentialalterationofactivity behavior may make the use of objective physical activity monitors practical only for smaller scale studies in specific populations.
Table 2 Spearman Correlations Between Diary Reported Percent Time for Three categories By Gender, Age, and Body Mass Index Sitting & Lying Down
Walking, Sport, & Recreation
-.35*
.41*
.20
.16
.36*
15
-.04 -.29 -.27
21 24
-.31
Variable
n
Males Females Age 65-74 Age 75-84 -Body Mass Index s 25.6 Body Mass Index> 25.6
23 22 30
-.35
.26
.10
.29 .33 .33
.66**
Note. Body Mass Index (kg/m2)
*ps .05 oOps .01 RilsBAROI QuAR11!RLY POll ExBRCSIl AND SPoRT. VOL
116
Standing & Standing Light Work
61. No. 1
.21 .49**
WASHBURN, JANNBY, AND FBNS11lR
References Heckler, M. M. (1985). Health promotion for the elderly. Publit:
Downloaded by [University of Sydney] at 17:03 03 May 2015
HealthReports, teo. 225-230. Kaplan, G. A., Seeman, T. E., Cohen, R. D., Knudsen, L. P., & Guralnilc,J. (1987). Mortality among the elderly in the Alameda County Study: Behavioral and demographic risk factors.American JOIUNJI ofPublU: He/llth, 77, 307- 312. Klesges,L.M.,&Klesges,R.C.(1987).Theassessmentofchildren's physical activity: A comparison of methods. Medicine and Sciencein Sport and Exercise, 19, 511-517. Klesges, R. C., Klesges, L. M., Swenson, A. N., & Pheley, A. M. (1985). A validation of two motion sensors in the prediction of child and adult physical activity levels. AmericanJOIUNJI of Epidemiology, 122,400410. LaPorte, R. E., Black-Sandler, R., Cauley, J. A, Link, M., Bayles, C., & Marks,B. (1984).Theassessmentofphysicalactivityinolder women: Analysis of the interrelationship and reliability of activity monitoring, activity surveys, and caloric intake. Journal ofGeronJology, 34, 394-397. LaPorte, R. E., Kuller, L. H., Kupfer, D. J, McPartland. R. K., Matthews, G., & Caspersen, C. 1. (1979). An objective measure of physical activity for epidemiologic research. American
JournalofEpidoniology, 109, 158-168. LaPorte, R. E., Montoye, H. J., & Caspersen, C. J. (1985). Assessment of activity in epidemiologic research: Problems and prospects. PublicHealthReports, 100, 131-145. Montoye, H. J. (1975). Physicalactivity and heIllth: An epidemiologic study of an enJire community. Englewood Cliffs NJ: Prentice-Hall.
R8sBARCH QuAR11lRLY POR
Montoye. H. J., & Taylor, H. L. (1984). Measurement of physical activity in population studies: A review. HUII'/Q1I Biology, 56, 195-216. Montoye. H. J., Washburn, R. A., Servais, S., Ertl, A., Webster, 1.G., & Nagle. F. 1. (1983). Estimation of energy expenditure by a portable accelerometer. Medicine and Science in Sport and Exercise, 15,403407. Washburn, R. A., & LaPorte. R. E. (1988). Assessment of walking behavior: Effect of speed and monitor position on two objective physical activity monitors. Research Quarterly for Exercise and Sport, 59, 83-85. Wong, T. C., Webster, J. G., Montoye, H. J., & Washburn, R. A. (1981). A portable accelerometer device for measuring human energy expenditure. lEE Transactions on Biomedical Engi-
neering, BME-28, 467471.
Authors' Note This study was supported by National Institutes of Health Grant no. 7-R29 AG06970-02, awarded to the first author.
Submitted: April 1, 1988 Revision Accepted: November 28,1988 RichardA.Washburn isasenior research scientist at theNew England Research Institute, 9 Galen Street, Watertown, MA 02172. Carol A. Janney and Julie R. Fenster are research associates withthesame institution.
F.xilRasB
117
AND SPal.T,
VOL. 61, No.1
Research Quarterly for Exercise and Sport Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/urqe20
The Validity of Objective Physical Activity Monitoring in Older Individuals a
a
Richard A. Washburn , Carol A. Janney & Julie R. Fenster
a
a
New England Research Institute , 9 Galen Street, Watertown , MA , 02172 , USA Published online: 08 Feb 2013.
To cite this article: Richard A. Washburn , Carol A. Janney & Julie R. Fenster (1990) The Validity of Objective Physical Activity Monitoring in Older Individuals, Research Quarterly for Exercise and Sport, 61:1, 114-117, DOI: 10.1080/02701367.1990.10607489 To link to this article: http://dx.doi.org/10.1080/02701367.1990.10607489
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http:// www.tandfonline.com/page/terms-and-conditions
WASHBURN. IANNIlY. AND FBJllS11lR
RESEARCH NOTB
RESEARCH QUARTBRLY FOR EXBRCISB AND SPORT 1990, VOL. 61, No.1. pp. 114-117
The Validity of Objective Physical Activity Monitoring in Older Individuals
Downloaded by [University of Sydney] at 17:03 03 May 2015
RICHARD A. WASHBURN, CAROL A. JANNEY, JULffi R. FENSTER New England Research Institute
Key words: physical activity assessment. activity monitors.
elderly PhysiCal activity has been identified as a potentially modifiable behavioral risk factor relating to health and quality of life among older individuals (Heckler, 1985). Recent evidence from the Alameda County Study (Kaplan. Seeman. Cohen, Knudsen, & Guralnik, 1987) suggests that having little leisure-time physical activity is associated with an increased mortality risk independent of age, socioeconomic status, self-reportedhealth status. and behavioral risk factors suchas smoking,relative weight.and alcoholconsumptionin a 17-yearfollow-up ofindividualsaged60-94 yearsatbaseline. To further evaluate the relationship between physical activityand health among individualsover age 65, valid and reliable measures of activity specific for this age group need to be developed.Unlike other potential health-relatedfactors suchas bloodpressure. serumcholesterol,cigarettesmoking. or Type A behavior. there are currently no standardized protocols or laboratory tests for the assessment of physical activity(LaPorte, Montoye, & Caspersen. 1985; Montoye & Taylor,1984).Physicalactivityquestionnaires, thoughwidely used in epidemiologic research. may not be appropriate for use with older individuals. Questionnairesmay not be sensitive enough to detect small, yet important. differences in the levelof physicalactivity in a group where the generallevel of activity is likely to be low. Therefore. it is important to investigate the effectiveness of objective measures of physical activity among older individuals. The measurement of body movement using electronic motion sensors may serve as an objective measure of daily physical activity (LaPorte et al., 1979; Wong. Webster.
Montoye, & Washburn. 1981).One of these motion sensors. the Caltrac Personal Activity Computer. has receivedrecent attention as an objective physical activity monitor among youngersubjectsinbothlaboratoryandfieldsettings(Klesges & Klesges, 1987; Klesges, Klesges, Swenson, & Pheley, 1985; Montoye et al.• 1983; Washburn & LaPorte, 1988). However.weare unawareof anyreportsregardingthevalidity of the Caltrac as a measureof daily physical activity in older individuals. It was the purpose of the current investigation to assess the validityof theCaltracas a measureof dailyactivity in individualsage 65 andover by comparingCaltracreadings withphysicalactivityassessedby activitydiaries.In addition, we sought to assess differences in the association of the Caltrac and activity diary records by gender, age, and body size.
Methods Forty-fiveindividuals,23 men and 22 women,meanage (± SO) 72.9± 5.3 years(range65-85 yes). height 167.0± 11.0 em, and weight 74.0 ± 16.8kg participatedin this studyafter providing written informed consent. These subjects were from a random sample of healthy, noninstitutionalized individuals over age 65 selected from a household listing for the town of Amherst, Massachusetts. All testing was completed between March and October 1987. Potential subjects were contacted by telephoneto determine their willingness to participate. Volunteers were then scheduled for a home visit. During the home visit. height
RBsBARCH QuARTBRLY FOR EXBRCSIl AND SPORT,
114
VOL. 61. No.1
Downloaded by [University of Sydney] at 17:03 03 May 2015
WASHBURN, JANNBY, AND FBNS'I1lR
Results and Discussion
(carpenter's rule) and weight (Norelco digital scale, model HS7) were measured, and the use of the Caltrac and the activity diary were explained. Physical activity was monitored over 3 consecutive weekdays using a Caltrac Personal Activity Computer (Hemokinetics Inc., Madison, Wisconsin). Details regarding the development and construction of the Caltrac have been published elsewhere (Wong et al., 1981).The Caltrac is small and lightweight(9.5 em x 7.0 em x 1.25 em, weight = 75 g) and is designed to measure accelerationvia a piezoelectricbender element. A numerical score (Kilocalories) is provided by a liquid crystal display. The totalkilocaloriescore is a functionof the basal metabolic rate of the subject which is calculated by a computer chip programmedwith the subject's age, height, weight, and gender, plus additional caloric expenditure as a result of body movement. Our purpose was to assess the validity of the Caltraconlyas a movementsensor;thereforeweprogrammed identical values for age, height, weight, and gender for all subjects.The Caltracmonitorsused in the study wereoff-theshelf modelsavailable to the public. Subjectswere instructed to wear the Caltrac on a belt over the nondominanthip and to record Caltrac readings and the time both in the morningand on retiring for the evening in a record form provided. The meanCaltracreadings (counts/hr)over the 3 days of observation were used in the analysis. Duringeach hourof observationsubjectswere instructed to record the amount of time spent in nine categories of physicalactivityranginginintensityfromlow(1yingdown)to high (heavy sport and recreation). With the relatively small samplesize (N =45) therewereinsufficientnumbersofentries in several of the nine categories. Therefore,we collapsed the nine categories to 3: 1) sitting and lying down, 2) standing includingstanding performing light work, 3) walking, sport, and recreation. The mean percent time spent in each activity category over the 3 days was used in the analysis.
Subject characteristics are presented in Table 1. There were no significantdifferencesbetween men and womenfor age, body mass index, monitor time, Caltrac readings,or the percent time spent sitting or lying down. Men reported a significantly higher percent time engaged in walking and sport and recreation, whereas women reported significantly more time spent standingand standing doing light work.The total percenttimeinTable 1does notequal 100%.Thisis most likelybecauseof both failureto accuratelyrecordeach hour's activityand thefact that, with some individuals,the diary and Caltrac monitoring were not exactly concurrent. The small mean percent time unaccounted for by the diary record (5% for men,4% for women)representsa fairlycompleteactivity record. We are aware of the potential weakness of using a diary record as a criterion measureof physicalactivityin any sample, particularly with older individuals. However, given the alternatives, such as direct observation or physiologic measuressuch as heart rate or blood lipids,we felt that a diary record, where activity categories were listed, was an acceptable criterion measure. With the age-associated decline in levels of physical activity (Montoye, 1975)it would be expected that the mean Caltrac readings from our sample (mean age approximately 73 yes) wouldbe lowerthan thosefroma youngersample.We found the mean Caltrac readings of the present study (99.7 counts/hr)were significantlylower than Caltrac readingswe have observed in a sample of 98 college freshman (113.6 counts/hr), 1(141) =4.34, P < .0001). We also expected that readingsfromtheCaltrae,whichisa movementsensor,would be negativelyrelated to theamountof timespentin nonmovement activities (i.e., lying and sitting down) and positively related to the amount of time spent in movement activities such as walking and sport and recreation. To examine these
Table 1 sample Characteristics Men (n- 23) M±SD
Variable
Age (yrs) Body Mass Index (kg/m 2) Monitor Time (min/day) Caltrac (Countslhr) Percentage Time Sitting and Lying Down Percentage Time Walking & Sport & Recreation Percentage Time Standing & Standing Performing Light Work
72.9 25.9 844.9 99.7 53.9 14.4
± 3.9 ± 4.3 ± 60.4 ± 7.9 ± 14.9 ± 9.1
26.8 ± 12.6
Note. *ps .05 RBsI!AROi QuAR11IRLY FOR
ExERasa
U5
AND SPatT,
VOL. 61, No.1
Women (n - 22) M± SO
72.9 27.1 822.1 99.7 50.5 9.9
± 6.5 ± 6.1 ± 93.5 ± 7.5 ± 10.7 ± 4.5*
34.7 ± 12.8*
Downloaded by [University of Sydney] at 17:03 03 May 2015
WASHBURN. JANNBY. AND FBNS11IR
associations Spearman rank order correlations were calculated between Caltrae readings and the three activity diary variables. Caltrae readings were positively related to the percent time engaged in walking and sport and recreation (r = .28, p < .05) and percent time standing (r = .28, p < .05). There was a nonsignificanttrend (r =-.20) toward a negative relationshipbetweenCaItraereadings andpercenttimesitting andlyingdown.Althoughthesecorrelationsarenot high,they are in the expecteddirection. Other investigators,using more 'sophisticatedcriterionmeasuresof physicalactivityin groups of younger subjects, have reported stronger associationsbetween physical activity and Caltrac readings. For example, Klesges et al. (1985) reported correlations between Caltrae readingsand 1 hr of observed behavior in a gymnasiumin 50 youngadults(age 21.5 yrs) ranging from-.43 for sittingto .82 for running. In a recent report, Klesges and Klesges (1987) showed correlations of .54 between Caltrac readings and physicalactivity assessed by all-day personal observation in 30 children aged 24 to 48 months. The magnitude of the correlationcoefficientsbetween theCaltracandactivitydiary variables shown in the current study are similar to that reported by LaPorte et al. (1984) between another objective physicalactivity monitor (LSI) and the Paffenbargeractivity questionnaire (r =.23) in women, mean age 61 years. To identify factors that may influence the validityof the Caltrac,wecomputedSpearmancorrelationsbetweenCaltrac readingsand activity diary variablesby gender,age (65-74 & 75-85 yrs), and body mass index (above and below the median, 25.6 kg/m2) . These correlations are presented in Table2. The associationbetween Caltrac readings and activity diary variables tend to be higher in men than women and weresimilarin age and body massindex categoriesfor sitting and lying down and walking, sport, and recreation. In their study of children aged ~8 months, Klesges and Klesges (1987) reported higher associations of Caltrae and observed
activity for older children ~ vs. 32.5 months), females and overweight ~ vs. 75th percentile of body mass index); however, none of these differenceswere statisticallysignificant We haveno explanationfor the generallylowerassociations between the Caltrae and activity diary variablesseen in womenas comparedto menin thecurrentstudy.We speculate that perhaosthe men maintainedmore accurate diary records andtheseprovidea moreaccuratecriterionmeasure.We have no data, however, to support this contention. The association of the CaItrae and a self-reporteddiary assessment of physical activity shown in our data and the observationof a lowermeandailyCaltracreadinginourolder, comparedwithour younger,populationprovidesevidencefor the validityof the CaItraefor the assessmentof dailyphysical activityin healthyolder individuals. The results presentedin this report represent preliminary analyses of an ongoing projectdesignedtoassess thereliabilityand validityof objectivephysicalactivitymonitoringin individualsoverage 65. It is possible that with a larger sample, where more precise categories of daily activity can be derived from the activity diaries than was possible in the present study, stronger associations between the Caltrac and physical activity will be found. In additional studiesuse of a combinationof criterion measuressuchas heartrate,diary,andphysiologicalmeasures may yield additional valuable information regarding the validity of the Caltrae monitor. Although objective physical activity monitors such as the CaItrae may provide valid assessmentsof dailyactivityinolder individuals,the logistics associated with their use, the subject cooperation required, the relatively short time frame during which physical activitycan be assessed,andthepotentialalterationofactivity behavior may make the use of objective physical activity monitors practical only for smaller scale studies in specific populations.
Table 2 Spearman Correlations Between Diary Reported Percent Time for Three categories By Gender, Age, and Body Mass Index Sitting & Lying Down
Walking, Sport, & Recreation
-.35*
.41*
.20
.16
.36*
15
-.04 -.29 -.27
21 24
-.31
Variable
n
Males Females Age 65-74 Age 75-84 -Body Mass Index s 25.6 Body Mass Index> 25.6
23 22 30
-.35
.26
.10
.29 .33 .33
.66**
Note. Body Mass Index (kg/m2)
*ps .05 oOps .01 RilsBAROI QuAR11!RLY POll ExBRCSIl AND SPoRT. VOL
116
Standing & Standing Light Work
61. No. 1
.21 .49**
WASHBURN, JANNBY, AND FBNS11lR
References Heckler, M. M. (1985). Health promotion for the elderly. Publit:
Downloaded by [University of Sydney] at 17:03 03 May 2015
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Authors' Note This study was supported by National Institutes of Health Grant no. 7-R29 AG06970-02, awarded to the first author.
Submitted: April 1, 1988 Revision Accepted: November 28,1988 RichardA.Washburn isasenior research scientist at theNew England Research Institute, 9 Galen Street, Watertown, MA 02172. Carol A. Janney and Julie R. Fenster are research associates withthesame institution.
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