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Physical Activity

Television Viewing Time and Measured Cardiorespiratory Fitness in Adult Women Larry A. Tucker, PhD; Peter J. Arens, MS; James D. LeCheminant, PhD; Bruce W. Bailey, PhD

Abstract Purpose. This study assessed the relationship between television viewing time and measured cardiorespiratory fitness and the influence o f various potential confounders. Design. Cross-sectional. Setting. Intermountain West. Subjects. The sample was composed o f302 nonsmoking women aged 40.2 ± 3 .0 years, with ~ 9 0 % Caucasian and 82% married. Measures. T V viewing was assessed by using a questionnaire, and cardiorespiratory fitness was measured by using a graded, maximum treadmill test. Physical activity (PA) was evaluated by using accelerometers fo r 7 days, and body fa t percentage (BF% ) was measured by using the Bod Pod. Analysis. Analysis of variance and partial correlation. Results. V 0 2max of Frequent (> 3 h/d) T V viewers (32.6 ± 6.4 m L/kg/m in) was significantly loiver than that o f both Moderate (1 -2 h/d) (36.2 ± 7.2 m L /kg /m in ) or Infrequent (< 1 h/d) (36.5 ± 6.5 m L/kg/m in) viewers (F= 8.0, p = .0004). The Infrequent and Moderate groups did not differ in V 02max. Age, education, body mass index, and season o f assessment had no influence on the relationship when controlled statistically. Adjusting fo r PA (F= 4.2, p = .0157) and BF% (F= 5.0, p = .0071) weakened the relationship by 59% and 58 %, respectively, but the relationships remained significant. After controllingfo r both PA and BF% simultaneously (F= 2.9, p = .0572), the relationship was weakened by 81 % and was only borderline significant. Conclusion. Female Frequent T V viewers have significantly lower cardiorespiratory fitness levels than Moderate or Infrequent viewers. This association appears to be largely a function o f differences in levels o f PA and BF%. (Am J Health Promot 2015;29[5]:285-290.)

Key Words: Media, Physical Activity, Screen Time, Obesity, Sedentary Lifestyle, Prevention Research. Manuscript format: research; Research purpose: relationship testing; Study design: cross-sectional; Outcome measure: biometric, morbidity; Setting: community; Health focus: physical activity; Strategy: education, skill building/behavior change; Target population age: adults; Target population circumstances: education/income level, geographic location

Larry A. Tucker, PhD; Peter J. Arens, MS; James D. LeCheminant, PhD; and Bruce W. Bailey, PhD, are with the Department o f Exercise Sciences, Brigham Young University, Provo, Utah. Send re p rin t requests to Larry A. Tucker, PhD, D e p artm en t o f Exercise Sciences, B righam Young University, 106 SFH, Provo, UT 84602; tucker@ byu.edu. This m anuscript was submitted November publication February 24, 2014.

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2013; revisions were requested January 3, 2014; the m anuscript was accepted fo r

Copyright © 2 0 1 5 by American Journal o f Health Promotion, Inc. 0 8 9 0 -1 1 7 1 /1 5 /$ 5 .0 0 + 0 DOI: 1 0 .4 2 78/ajhp. 131107-QUAN-565

American Journal of Health Promotion

PURPOSE It is widely accepted that TV viewing is a sedentary activity and increases risk of disease and all-cause mortality.1-3 It is also known that there exists a negative association between TV watching and physical activity (PA).4,5 Given the positive relationship be­ tween cardiorespiratory fitness and PA,1’ one would also expect cardiore­ spiratory fitness levels to decrease as television viewing time increases. However, only a few studies have examined the television and fitness association, and a number of these have focused on components other than cardiorespiratory fitness.'-10 In 1986, Tucker' studied high-school males and found that infrequent TV viewers scored significantly better on a composite fitness index than frequent viewers. In 1990, Armstrong et al.8 measured various components of fit­ ness and found a weak and inconsis­ tent negative relationship between the two variables in children. Others9 have found no significant relationship be­ tween TV viewing and fitness in chil­ dren, leaving one to question the true connection between these variables. In adults, only one study has directly examined the relationship between TV watching and cardiorespiratory fit­ ness.10 Using a step test to measure cardiorespiratory fitness in almost 9000 adults, Tucker10 found that frequent viewers (>4 hours of TV per day) were .37 times as likely to be physically fit as infrequent viewers (less than 1 hour of TV per day). The apparent lack of research involving TV viewing and cardiorespiratory fitness in adults war­ rants further study. The purpose of this study was to assess the relationship between TV viewing and cardiorespiratory fitness by

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using robust methodologies. To date, the one study that focused on TV and cardiorespiratory fitness in adults used a step test to measure cardiorespiratory fitness, a questionnaire to assess PA, and skinfold calipers to estimate body fat percentage.10 Although these mea­ surement methods were likely the best for assessment of nearly 9000 individ­ uals at the time, they lack the validity and precision of a graded, maximal treadmill test11 to measure maximum aerobic capacity, accelerometers to evaluate PA, and plethysmography (Bod Pod; Life Measurements, Con­ cord, California) to measure body composition. Furthermore, the meth­ ods proposed in this study were more objective than those used previously in either adults or children. Hence, the goal of the present study was to clarify the relationship between TV and fit­ ness, especially in adult women.

commenced, participants were in­ formed of all risks and benefits of the study via the consent form. Addition­ ally, all participants completed a PA readiness questionnaire to determine if there were any complications or risks that could affect the participant during testing. Participants were then administered a questionnaire that assessed demo­ graphics and television-viewing behav­ ior. After filling out the questionnaire, subjects were educated regarding how to properly wear the accelerometer for the next 7 days. Following this instruc­ tion, body fat percentage was estimated by using the Bod Pod and the ap­ pointment was completed. After 1 week, participants returned the accel­ erometer and participated in the max­ imal graded exercise test. After review of the data, participants were sent a $25 gift certificate, individual test results, and a letter of appreciation.

METHODS

Measures

Design

Television Viewing. A questionnaire was used to assess TV-viewing behavior and other demographic characteristics in­ cluding age and education. The spe­ cific question used to catalog TV watching was “How many hours do you spend watching TV and videos per day or week?” Possible responses were: (1) .95) and low standard error of the estimate ( 0.05). BF% indicates body fat percentage; and PA, physical activity. t Infrequent viewing included women who watched less than 1 hour of TV per day; Moderate viewing included those who watched 1 to 2 hours per day; and Frequent viewing included those who watched 3 hours or more of television per day.

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T a b le 3 D ifferences in th e Potential C onfo u n din g V ariab les A cross the Televisio n-V iew ing C ategories T e le v is io n -V ie w in g C a t e g o r y !

V a r ia b le

Age (y) Activity (counts)t Body fat percentage (%) Body mass index

In fr e q u e n t V ie w in g (n = 1 1 1 ) M ean SD 4 0 .6 2864§ 3 0 .3 § 2 3 .2

3 .2 967 7 .2 3 .5

M o d e r a te V ie w in g (n = 1 2 3 )

F r e q u e n t V ie w in g (n = 6 8 )

M ean

SD

M ean

SD

F

P

3 9 .8 2772§ 31.1 §,ll 2 3 .9

3 .0 792 6 .6 3 .2

4 0 .5 2485II 3 3 .0 II 2 4 .0

2 .8 624 7 .0 3.1

2 .3 4 .6 3.1 1 .6

0 .0 9 8 2 0 .0 1 1 2 0 .0 4 4 7 0 .1 9 8 4

’ Means on the same row with the same symbol are not significantly different (p > 0.05). t For the television-viewing categories, Infrequent viewing included women who watched less than 1 hour of TV per day; Moderate viewing included those who watched 1 to 2 hours per day; and Frequent viewing included those who watched 3 hours or more of television per day. Average activity counts measured objectively with accelerometers, divided by 1000.

t

associated with a risk reduction of 13% for all-cause mortality. Furthermore, according to Kodama et ah,30 for each 1 MET increase in V 0 2max, risk of coronary heart or cardiovascular dis­ ease events tends to fall by 15%. Given these differences in risk, Frequent television watchers may experience greater cardiovascular disease and overall mortality than Infrequent viewers because of their significantly lower fitness levels. This study is unique in that it directly compared objectively mea­ sured cardiorespiratory fitness to the am ount of time watching television in adult subjects. Most of the research regarding the current relationship has been conducted in children. The findings of these studies involving children have shown only weak or no relationship between cardiorespiratory fitness and television viewing.8,31,32 For example, in 1998, Armstrong et al.8 found a weak and inconsistent rela­ tionship between television viewing and cardiorespiratory fitness, mea­ sured by using a 1-mile run/walk test. Also in 1998, Katzmarzyk et al.31 revealed a weak relationship between television viewing time and cardiore­ spiratory fitness in children, measured by a submaximal cycle ergometer test. A 2010 prospective study of children conducted by Mota et al.32 showed that baseline television viewing predicted cardiorespiratory fitness during a 2year period. In 2011, Aires et al.33 found that television viewing was weakly and negatively associated with cardiorespiratory fitness in children, using a 20-meter shuttle run test.

American Journal of Health Promotion

In adults, only one study conducted in 1990 by Tucker10 has directly inves­ tigated the TV/fitness relationship. Findings of the current study are consistent with the results of the previous investigation, which included nearly 9000 adults. The 1990 investi­ gation showed that Frequent television viewers were .37 times as likely to be physically fit as Infrequent television viewers.10 However, fitness was mea­ sured by using a step test, whereas in the current study, fitness was measured by using a maximal graded treadmill test. Furthermore, PA was self-reported in the previous study, while accelerometry was used to objectively assess PA in the present study. Finally, skinfold calipers were used in the previous study to estimate body fat percentage. In the current study, air displacement plethysmography (Bod Pod) was used to estimate body fat percentage. There are multiple explanations for the findings of the present study. It is possible that Frequent television view­ ers seek activities that require little physical exertion, such as watching TV, leading to lower cardiorespiratory fit­ ness. It is also possible that those with lower cardiorespiratory fitness levels choose sedentary activities such as television viewing, because higher in­ tensity activities are viewed as less enjoyable or as more difficult. Lastly, it is possible that Frequent TV viewing does not lead to lower levels of fitness, and poor fitness does not lead to more TV watching. Instead, the relationship may be a result of other factors, third variables. This possibility was examined carefully in the present study and none of the potential confounding variables

by themselves had a meaningful effect on the TV/fitness relationship. How­ ever, when both PA and body fat percentage were controlled statistically, the relationship was no longer signifi­ cant. A few limitations of the current study warrant mention. First, the cross-sec­ tional design of the study does not allow conclusions about temporality or cause and effect. Additionally, the 302 subjects were female, middle-aged, nonsmokers, and mostly white, nonHispanic. This limits any generaliza­ tions to similarly characterized popu­ lations. The strengths of the current study include the previously m entioned ob­ jective measures of cardiorespiratory fitness, PA, and body fat percentage. Furthermore, as most research regard­ ing cardiorespiratory fitness and tele­ vision viewing has been conducted in children, the current study used adults. Finally, the current investigation had excellent statistical power (.88), in­ creasing the likelihood that a real association between TV viewing and cardiorespiratory fitness would be re­ vealed, if it existed. C O N C L U S IO N S

In conclusion, Frequent television viewing (>3 hours of TV per day) was strongly associated with lower levels of cardiorespiratory fitness in adult mid­ dle-aged women. W ren age, education, BMI, PA, body fat percentage, or season of assessment, were controlled individually, the relationship remained significant. However, when both PA and body fat percentage were con-

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trolled simultaneously, the relationship was nullified. Hence, differences in cardiorespiratory fitness across televi­ sion viewing groups appear to be largely a function of differences in PA and body fat percentage. Because low levels of cardiorespiratory fitness are predictive of increased morbidity and mortality, Frequent television watchers may be at increased risk as well. Future research should consider using either a prospective design or a randomized controlled trial to determine the effect of television viewing on cardiorespira­ tory fitness levels over time in adults.

SO WHAT? Implications for Health Promotion Practitioners and Researchers What is already known on this topic?

Television viewing is a popular and sedentary pastime. To date, the link between TV watching and fitness has been studied in children almost exclusively and findings have been inconclusive. Only one study published in 1990 has been conducted in adults. The extent to which adults who watch TV frequently differ in measured fitness from those who view TV infrequently remains unknown. What does this article add?

In the 1990 study of TV and fitness in adults, fitness was indexed by using a step test, whereas in the present study a maximal graded treadmill test was used. Moreover, in the past, PA was measured by using a questionnaire, but accelerometers were used in the present study. Also, in the 1990 study, skinfolds were used to estimate body fat, whereas in this investi­ gation the Bod Pod was used. The present investigation used high-quality measure­ ment methods and findings were signifi­ cant and meaningful. Moreover, the present study concentrated on middleaged women, which has rarely been the focus in the past. What are the implications for health promotion practice or research?

Low aerobic capacity or cardiorespira­ tory fitness is an important predictor of increased morbidity and mortality. As television viewing time increases, cardio­ respiratory fitness levels tend to decline. Consequently, frequent television watch­ ing may not be a good choice for a healthy lifestyle.

References

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classification of energy costs of human physical activities. Med Sci Sports Exerc. 1993;25:71-80. 2. Tucker LA, Bagwell M. Relationship between serum cholesterol levels and television viewing in 11,947 employed adults. Am J Health Promat. 1992;6:437-442. 3. Grontved A, Hu FB. Television viewing and risk of type 2 diabetes, cardiovascular disease, and all-cause mortality. JAMA. 2011;305:2448-2455. 4. Fung TT, Hu FB, Yu J, et al. Leisure-time physical activity, television watching, and plasma biomarkers of obesity and cardiovascular disease risk. Am J Epidemiol. 2000;152:1171-1178. 5. Hu FB, Li TY, Colditz GA, et al. Television watching and other sedentary behaviors in relation to risk of obesity and type 2 diabetes mellitus in women. JAMA. 2003; 289:1785-1791. 6. Blair SN, Cheng Y, Holder JS. Is physical activity or physical fitness more important in defining health benefits? Med Sci Sports Exerc. 2001;33(suppl 6) :S379-S399. 7. Tucker LA. The relationship of television viewing to physical fitness and obesity. Adolescence. 1986;21:797-806. 8. Armstrong CA, Sallis JF, AlcarazJE, et al. Children’s television viewing, body fat, and physical fitness. Am J Health Promot. 1998; 12:363-368. 9. G rand A, Krause H. Siewers M, et al. Is TV viewing an index of physical activity and fitness in overweight and normal weight children? Public Health Nutr. 2001 ;4:12451251. 10. Tucker LA. Television viewing and physical fitness in adults. Res Q Exerc Sport. 1990;61: 315-320. 11. George JD, Bradshaw DI, Hyde A, et al. A maximal graded exercise test to accurately predict V02max in 18-65-year-old adults. Meas Phys Educ Exerc Sci. 2007;11:149-160. 12. Tucker LA, Tucker JM. Television viewing and obesity in 300 women: evaluation of the pathways of energy intake and physical activity. Obesity (Silver Spring). 2011; 19: 1950-1956. 13. Tucker LA, Friedman GM. Television viewing and obesity in adult males. Am J Public Health. 1989;79:516-518. 14. Tucker LA, Bagwell M. Television viewing and obesity in adult females. Am. J Public Health. 1991;81:908-911. 15. George JD. Alternative approach to maximal exercise testing and V 02 max prediction in college students. Res (J Exerc Sport. 1996;67:452-457. 16. Thompson WR, Gordon NF, Pescatello LS. ACSM’s Guidelines for Exercise Jesting and Prescription. Philadelphia, Pa: Lippincott Williams & Wilkins; 2010. 17. American College of Sports Medicine. ACSM’s Guidelines for Exercise Testing and Prescription. 7th ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 2006. 18. Liu A-L, Li Y-P, Song J, et al. Study on the validation of the computer science application’s activity monitor in assessing the physical activity among adults using doubly labeled water method [in Chinese]. Zhonghua Liu Xing Bing Xue Za Zhi. 2005;26:197-200.

19. Bassett DRJr, Ainsworth BE, Swartz AM, et al. Validity of four motion sensors in measuring moderate intensity physical activity. Med Sci Sports Exerc. 2000;32(suppl 9):S471-S480. 20. Tucker LA, Peterson TR. Objectively measured intensity of physical activity and adiposity in middle-aged women. Obes Res. 2003;11:1581-1587. 21. Breneman CB, Tucker L. Dietary fibre consumption and insulin resistance—the role of body fat and physical activity. Br J Nutr. 2013;110:375-383.' 22. Nokes NR, Tucker LA. Changes in hip bone mineral density and objectively measured physical activity in middle-aged women: a 6-year prospective study. Am J Health Promot. 2012;26:341-347. 23. Maddalozzo GF, Cardinal BJ, Snow CA. Concurrent validity of the BOD POD and dual energy x-ray absorptiometry techniques for assessing body composition in young women. 1Am Diet Assoc. 2002;102: 1677-1679. 24. Ballard TP, Fafara L, Vukovich MD. Comparison of Bod Pod and DXA in female collegiate athletes. Med Sci Sports Exerc. 2004;36:731-735. 25. Tucker LA, LeCheminant JD, Bailey BW. Test-retest reliability of the Bod Pod: the effect of multiple assessments. Percept Mot Skills. 2014;118:563-570. 26. LeCheminant JD, Tucker LA, Peterson TR, Bailey BW. Differences in body fat percentage measured using dual energy xray absorptiometry and the Bod Pod in 100 women [abstract]. Med Sci Sports Exerc. 2001;33:S174. 27. Buchowski MS, Choi L, Majchrzak KM, et al. Seasonal changes in am ount and patterns of physical activity in women. J Phys Act Health. 2009;6:252-261. 28. Sewell L, Singh SJ, Williams JE, Morgan MD. Seasonal variations affect physical activity and pulmonary rehabilitation outcomes. J Cardiopulm Rehabil Prev. 2010; 30:329-333. 29. Cohen J. Statistical Power Analysis for the Behavioral Sciences. 2nd ed. Hillsdale, NJ: L Erlbaum Associates; 1988. 30. Kodama S, Saito K, Tanaka S, et al. Cardiorespiratory fitness as a quantitative predictor of all-cause mortality and cardiovascular events in healthy men and women: a meta-analysis. JAMA. 2009;301: 2024-2035. 31. Katzmarzyk PT, Malina RM, Song TMK, Bouchard C. Television viewing, physical activity, and health-related fitness of youth in the Quebec Family Study. J Adolesc Health. 1998;23:318-325. 32. Mota J, Ribeiro JC, Carvalho J, et al. Television viewing and changes in body mass index and cardiorespiratory fitness over a two-year period in schoolchildren. Pediatr Exerc Sci. 2010;22:245-253. 33. Aires L, Pratt M, Lobelo F, et al. Associations of cardiorespiratory fitness in children and adolescents with physical activity, active commuting to school, and screen time.JPhys Act Health. 2011;8(suppl 2):S198-S205.

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Television viewing time and measured cardiorespiratory fitness in adult women.

This study assessed the relationship between television viewing time and measured cardiorespiratory fitness and the influence of various potential con...
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