Recommended Levels of Physical Activity and Health- Related Quality of Life Among Overweight and Obese Adults in the United States, 2005

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1 Journal of Physical Activity and Health, 2009, 6, Human Kinetics, Inc. Recommended Levels of Physical Activity and Health- Related Quality of Life Among Overweight and Obese Adults in the United States, 2005 Gregory W. Heath and David W. Brown Background: Since overweight (25 BMI < 30) and obesity (BMI 30 Kg/m 2 ) are associated with poor health-related quality of life (HRQOL) and regular physical activity is associated with higher levels of HRQOL, the authors examined the relationship between physical activity and HRQOL among overweight and obese adults (age 18 years) residing in the United States. Methods: Using the 2005 BRFSS survey, they examined the independent relationship between recommended physical activity and measures of HRQOL developed by the Centers for Disease Control and Prevention among 283,562 adults age 18 years or older with overweight or obesity. Measures of physical activity, height, weight, and HRQOL were self-reported. Multivariable logistic regression was used to obtain odds ratios and 95% confidence intervals adjusted for age, race/ethnicity, sex, education, smoking status, chronic disease, and body-mass index. Results: The proportion of adults with overweight and obesity who attained recommended levels of physical activity had higher levels of HRQOL than physically inactive adults for all age, racial/ethnic, and sex groups. After multivariable adjustment, overweight and obese adults who met the recommended level of physical activity had higher levels of HRQOL than physically inactive adults across all age strata. Conclusions: These results highlight the HRQOL role that physical activity can have among overweight and obese persons despite their excess body weight. Keywords: health promotion, risk-factor surveillance, energy balance, exercise Heath is with the Depts of Health and Human Performance and Medicine, University of Tennessee at Chattanooga, Chattanooga, TN. Brown is with the World Health Organization, Geneva, Switzerland. Overweight and obesity affect more than 130 million US adults, or approximately 3 in 5 adults. 1 The prevalence of overweight, defined as 25 kg/m 2 bodymass index (BMI) < 30 kg/m 2, and obesity, defined as a BMI 30 kg/m 2, has increased significantly over the past 3 decades. 2 The increase in the prevalence of overweight and obesity is troubling given the observed concurrent increases in the prevalence of type 2 diabetes mellitus and hypertension, known risk factors for coronary heart disease. 3 In addition, the prevalence of physical inactivity, an independent risk factor for coronary heart disease, has remained virtually unchanged over the same time period, with over a quarter of US adults being physically inactive and another quarter not achieving recommended levels of physical activity. 4 Physical activity is one of several lifestyle strategies known to effectively prevent and treat overweight and obesity. 5,6 Health-related quality of life (HRQOL) has developed into an important indicator of an individual s or group s perceived physical and/or mental health and has become an essential measure used to understand the health status of a population. 7 Previous studies have demonstrated that adults who are overweight or obese have lower HRQOL than their normal-weight counterparts. 8 In addition, persons who engage in regular physical activity have been shown to have better HRQOL than their inactive counterparts. 9 A recent report that examined HRQOL, BMI, and physical activity among a sample of US adults found that low HRQOL was inversely related to physical activity participation. 10 Furthermore, the authors found that this relationship was not affected by BMI status and concluded that adults should be encouraged to engage in physical activity regardless of their weight status. 10 Current guidelines 11 recommend that adults obtain at least 30 minutes (continuous or intermittent) of moderate-intensity physical activity on 5 or more days per week, or at least 20 minutes of vigorous physical activity on 3 or more days per week. We recently reported that adults who participate in recommended levels of physical activity have higher levels of HRQOL. 12 In light of these findings and the apparent independent 403

2 404 Heath and Brown health-promoting effects of regular physical activity seen even among overweight and obese adults, we hypothesized that the HRQOL of overweight and obese adults who were meeting recommended levels of physical activity would be higher than that of overweight and obese adults who were either insufficiently active or inactive. Using data from the Behavioral Risk Factor Surveillance System (BRFSS), we examined relationships between physical activity and HRQOL among a sample of US adults. Methods The BRFSS is a state-based surveillance system that collects data on many of the behaviors and conditions that place adults (age 18 years) at risk for chronic disease. Trained interviewers collect data on a monthly basis using an independent probability sample of households with telephones among the noninstitutionalized US population. In 2005, complete survey data were collected from 328,025 persons. The median BRFSS CASRO response rate, which assumes that the unresolved numbers contain the same percentage of eligible households as the records whose eligibility or ineligibility are determined, across all 50 states, the District of Columbia, and territories was 51% (min 35%, max 67%). A detailed description of the survey design and random-sampling procedures is available elsewhere. 13 The BRFSS has been approved as exempt research by the Centers for Disease Control and Prevention s institutional review board. For this analysis, data were available for 283,562 persons age 18 years or older with complete information for study variables. Compared with those excluded from the analysis due to incomplete data, persons included in the analysis were slightly younger (45 vs 47 years) and slightly more likely to be men (50% vs 45%), white, and non-hispanic (71% vs 62%) and have more than a high school education (60% vs 46%). BMI was calculated based on self-reported height and weight, where respondents were asked to report their height in inches (without shoes) and their weight in pounds. All such responses were converted to metric equivalents before BMI was calculated. Respondents were asked 6 questions about their participation in moderate or vigorous physical activity during a usual week. Regarding moderate physical activity, they were asked Now, thinking about the moderate physical activities you do in a usual week, do you do moderate activities for at least 10 minutes at a time, such as brisk walking, bicycling, vacuuming, gardening, or any other activity that causes small increases in breathing or heart rate? For vigorous physical activity, they were asked Now, thinking about the vigorous physical activities you do in a usual week, do you do vigorous activities for at least 10 minutes at a time, such as running, aerobics, heavy yard work, or any other activity that causes large increases in breathing or heart rate? For each type of activity, respondents indicated the number of days per week and the total time per day they participated in the activity for at least 10 minutes at a time. Current guidelines 11 recommend that adults obtain at least 30 minutes of moderate-intensity physical activity on most, preferably all, days of the week or at least 20 minutes of vigorous physical activity on 3 or more days per week. The recommendation that people be moderately active most days of the week is typically defined in the scientific literature as 5 or more days. Consistent with these guidelines, we defined 3 mutually exclusive and exhaustive groups: adults who engaged in no physical activity (ie, inactive), adults who engaged in physical activity that was less than the recommended level of moderate or vigorous physical activity but greater than none (ie, insufficient), and adults who engaged in recommended levels of moderate or vigorous physical activity. Respondents were asked the following questions related to HRQOL: Now thinking about your mental health, which includes stress, depression, and problems with emotions, for how many days during the past 30 days was your mental health not good? and Now thinking about your physical health, which includes physical illness and injury, for how many days during the past 30 days was your physical health not good? Respondents were not asked for specific underlying reasons of any reported unhealthy days. These questions and their construct validity are described elsewhere. 7,14 We calculated overall unhealthy days as the sum of physically and mentally unhealthy days, not to exceed 30 days. We defined a dichotomous HRQOL variable as <14 or 14 unhealthy physical days, unhealthy mental days, and unhealthy days (mental or physical). A total of 14 unhealthy days is a meaningful cut point for those reporting substantially impaired HRQOL and corresponds to the upper 10% to 15% of the distribution for each healthy-days measure in the BRFSS. Respondents were also asked, Would you say in general your health is excellent, very good, good, fair, or poor? Based on the response to this question, we defined a dichotomous variable for fair or poor self-rated health status. Prevalences of the 4 HRQOL variables were agestandardized to the 2000 US standard population. 15 We used logistic regression to examine the independent relationship between the relative odds of each HRQOL variable and physical activity level adjusted for age (continuous), sex, race/ethnicity (white, non-hispanic; black, non-hispanic; other, non-hispanic; Hispanic), education (<high school, high school, >high school), smoking status (smoker, nonsmoker), employment status (employed, unemployed), and presence of selfreported arthritis, diabetes, and cardiovascular disease. Models were stratified by BMI (<25.0, 25.0 to 29.9, 30.0 kg/m 2 ). Parameter estimates were obtained by maximum likelihood techniques, and 95% CIs were based on the standard error (SE) of the model coefficients. We used SUDAAN 8.0 (Research Triangle

3 Physical Activity and HRQL Among Obese Adults 405 Institute, 2001) to account for the survey s complex sampling design. Statistical inferences were based on a significance level of P (2-sided).05. Results Overall, 13% of adults were 18 to 24 years old; 18%, 25 to 34 years; 20%, 35 to 44 years; 33%, 45 to 64; and 15%, 65 years or older. Half (50%) of the sample were women, and 71% were white non-hispanic, 9% black non-hispanic, 6% other non-hispanic, and 14% Hispanic. Sixty percent of adults had more than a high school education, 86% were employed, 20% were current smokers, 26% reported arthritis, 7% reported diabetes, and 8% reported cardiovascular disease. The agestandardized prevalence of normal weight (18 BMI < 25), overweight (25 BMI < 30), and obesity (BMI 30) among adults age 18 years or older was 39%, 37% and 24%, respectfully. Less than 1% had a BMI <18 kg/ m 2 (ie, underweight). Overall, the age-standardized prevalence of 14 or more unhealthy days (mental or physical) during the previous 30-day period was 18% (SE 0.15). Table 1 displays the prevalence and adjusted relative odds of 14 or more unhealthy days (mental or physical) by respondent characteristics. After adjustment for all variables shown in the table, the odds of having 14 or more unhealthy days (mental or physical) during the previous 30 days was greater for women; persons with a high school education or less; unemployed persons; current smokers; persons reporting arthritis, diabetes, or cardiovascular disease; and overweight or obese persons (refer to the table for the appropriate referent group). Compared with physically inactive persons, persons who participated in some but insufficient amounts of physical activity and those who met physical activity recommendations were less likely to report 14 or more unhealthy days (mental or physical; Table 1). Similar relationships were observed across BMI categories. For example, overweight or obese adults who attained recommended levels of physical activity were significantly less likely to report 14 or more unhealthy days for each of the HRQOL measures than were physically inactive adults (Figures 1 to 4). There were similarly strong associations between HRQOL measures and insufficient levels of physical activity compared with inactive groups among both overweight and obese adults. In addition, similar patterns were observed for each BMI category across age groups, in both men and women, and across racial/ethnic groups (data not shown). Discussion Previous studies have shown that inactivity among adults is associated with poorer HRQOL regardless of BMI status. 10 HRQOL, an outcome measure increasing in popularity in the health sciences including exercise science, 16,17 has evolved to include aspects of life that affect perceived physical or mental health, and it is a fundamental measure used to understand a population s health status. 7 Regular physical activity has been associated with higher levels of HRQOL and is one of several strategies available to control and prevent weight gain. 6,18 In this cross-sectional analysis of data from a national sample of men and women, we observed a greater prevalence of lower levels of HRQOL among overweight and obese persons who are physically inactive than among those who were either insufficiently active or meeting recommended levels of physical activity. That is, among overweight and obese persons, the odds of 14 or more unhealthy days are greater for physically inactive adults than either adults who engage in some physical activity but below recommended levels or those who meet recommendations. In addition, we observed, as have others, 10 that the relationships between physical activity level and HRQOL are similar for normal weight, overweight, and obese persons, with inactive persons consistently reporting lower HRQOL. Conversely, our analysis identifies a dose-response pattern linking physical activity and HRQOL, where even those not meeting recommended levels of physical activity appeared to have a similar and higher HRQOL than those meeting recommendations when compared with inactive persons across all weight categories. The notion of dose-response of physical activity and HRQOL, where even lower than recommended doses of physical activity may bring about improvements in HRQOL, has been reported by Spirduso and Cronin in their systematic review. 16 The current findings contribute to a growing body of evidence demonstrating the independent benefits of physical activity, controlling for other risk factors including overweight and obesity, in promoting health and preventing chronic disease. 18,19 In light of the current epidemic of obesity in the United States, many health professionals and others recommend physical activity, along with dietary modification, as the most effective approach in losing weight among persons who are overweight or obese. 6,20 However, it has been documented among persons trying to lose weight and/or keep from gaining weight that even when they report engaging in physical activity/exercise for such purpose, the majority rarely report achieving the minimal dose of physical activity necessary to convey some health or fitness benefit, let alone a sufficient dose of activity to facilitate significant energy expenditure for weight loss or prevention of weight gain. 21,22 Our findings, along with the findings of others, in terms of physical activity demonstrate the need to promote recommended doses of physical activity regardless of weight status for the purpose of health promotion and disease prevention and not energy balance alone. 6,10 12,18,19 That the evidencebased health benefits of physical activity can be accrued and enjoyed by people across the life cycle, across diseases/conditions such as obesity, across risk factors, and

4 406 Heath and Brown Table 1 Prevalence of 14 or More Unhealthy Days (Physical or Mental) by Characteristics of Adult Participants, BRFSS 2005 Prevalence of 14 unhealthy days, physical or mental a Odds ratio (95% CI) b Age, y (0.57) 1.00 (referent) (0.33) 0.79 ( ) (0.30) 0.76 ( ) (0.24) 0.66 ( ) (0.31) 0.45 ( ) Sex male 15 (0.22) 1.00 (referent) female 21 (0.20) 1.74 ( ) Race/Ethnicity white, non- Hispanic 18 (0.15) 1.00 (referent) black, non- Hispanic 20 (0.50) 0.91 ( ) other, non- Hispanic 18 (0.67) 1.05 ( ) Hispanic 20 (0.62) 1.11 ( ) Education <high school 29 (0.64) 1.64 ( ) high school 21 (0.28) 1.19 ( ) >high school 15 (0.17) 1.00 (referent) Employment status employed 13 (0.18) 1.00 (referent) unemployed 14 (0.50) 1.21 ( ) Current smoker no 16 (0.15) 1.00 (referent) yes 27 (0.39) 1.79 ( ) Diabetes no 17 (0.15) 1.00 (referent) yes 35 (0.63) 1.76 ( ) Arthritis no 14 (0.17) 1.00 (referent) yes 30 (0.29) 2.03 ( ) Cardiovascular disease no 16 (0.15) 1.00 (referent) yes 38 (0.58) 1.98 ( ) Body mass index (BMI) BMI < (0.23) 1.00 (referent) 25 BMI < (0.24) 1.12 ( ) BMI (0.32) 1.34 ( ) (continued) Table 1 (continued) Prevalence of 14 unhealthy days, physical or mental a Odds ratio (95% CI) b Physical activity level recommended 15 (0.20) 1.00 (referent) insufficient 17 (0.23) 0.69 ( ) inactive 33 (0.48) 0.67 ( ) a Data reported as weighted percent; standard error reported in parentheses. b Adjusted for all variables in the table. across abilities should be the goal of an overall public health strategy to promote physical activity. The results of this analysis are subject to some limitations. Because the analysis was cross-sectional, determining cause and effect was impossible. Although physical activity can improve HRQOL, it is possible that persons with impaired HRQOL are less likely to participate in physical activity. Data from clinical trials, however, support the notion that physical activity is associated with improvements in HRQOL 12 and perceived health status. 23 The BRFSS is a telephone-based survey. Persons of low socioeconomic status, who are more likely to be physically inactive and have poor quality of life, are also less likely to have a telephone and to be included in the BRFSS. Finally, these data are self-reported. Conceivably, some respondents participated in regular physical activity but did not perceive it sufficient to be considered moderate or vigorous, and thus we may have underestimated the prevalence of physical activity. Similarly, some respondents may have misreported their levels of physical activity to provide a socially desirable response, 24 and thus we might have overestimated the prevalence of physical activity. Although these results may suggest that persons who participate in at least some regular physical activity have better HRQOL than those who are essentially inactive, it is also possible that HRQOL may be related to unmeasured lifestyle characteristics among these overweight and obese persons. Previous research has demonstrated the clustering of health behaviors including diet, tobacco use, and physical activity Also, respondents were not asked for possible reasons of unhealthy physical days, which may provide further insight into relationships between physical activity and HRQOL. Nonetheless, these results highlight the possible benefit of regular physical activity. In summary, participation in currently recommended levels of moderate or vigorous physical activity is independently associated with higher overall levels of HRQOL and perceived health status among adults who are overweight or obese. These relationships extend across age, sex, and racial/ethnic groups. In addition, we observed higher levels of HRQOL among persons with

5 Figure 1 Age-standardized prevalence and adjusted* relative odds of 14 or more unhealthy days (physical or mental) by physical activity level and self-reported body-mass index, BRFSS *Adjusted for age (continuous), sex, race/ethnicity, education, employment, smoking, diabetes, arthritis, and cardiovascular disease. 407

6 408 Figure 2 Age-standardized prevalence and adjusted* relative odds of fair or poor self-rated health status by physical activity level and self-reported body-mass index, BRFSS *Adjusted for age (continuous), sex, race/ethnicity, education, employment, smoking, diabetes, arthritis, and cardiovascular disease.

7 Figure 3 Age-standardized prevalence and adjusted* relative odds of 14 or more unhealthy physical days by physical activity level and self-reported body-mass index, BRFSS *Adjusted for age (continuous), sex, race/ethnicity, education, employment, smoking, diabetes, arthritis, and cardiovascular disease. 409

8 410 Figure 4 Age-standardized prevalence and adjusted* relative odds of 14 or more unhealthy mental days by physical activity level and self-reported body-mass index, BRFSS *Adjusted for age (continuous), sex, race/ethnicity, education, employment, smoking, diabetes, arthritis, and cardiovascular disease.

9 Physical Activity and HRQL Among Obese Adults 411 higher levels of physical activity from no leisure-time activity to insufficient levels of activity to recommended levels of activity in most groups. Physical activity is one of several lifestyle strategies known to effectively contribute to energy balance and prevention of weight gain or contribute to individual efforts to lose weight. However, it is apparent from our analyses, as well as the work of others, that recommended levels of physical activity convey health-promoting and enhanced wellbeing independent of these energy-balance benefits. These findings suggest that recommended levels of physical activity should be promoted among persons who are either overweight or obese primarily for overall health and fitness, not simply as a method to prevent weight gain or facilitate weight loss. References 1. Ogden CL, Carroll MD, Curtin LR, McDowell MA, Tabak CJ, Flegal KM. 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