Patterns of Sedentary Behavior and Association with Health Risks among African American Adults
Introduction: There is growing and compelling evidence suggesting time spent in sedentary behaviors (SB) is a unique contributor to health risk that appears to be independent of time spent in moderate- and/or vigorous-intensity physical activity (PA). However, few studies have examined these associations in women and even fewer studies have included ethnic minority populations.
Purpose: The major objectives of this study were to: (1) describe patterns of objectively measured sedentary and PA behaviors and variation in these behaviors in African American (AA) adults; (2) assess the association between bouts of and breaks in SB and waist circumference risk, body mass index, and hypertension; and (3) examine AA women’s perceptions around SB and propose novel strategies to reduce these behaviors. Methods: Using a mixed-methods approach, five aims were addressed. To address major objectives and aims in Manuscript 1 and 2 (i.e. Objectives 1 & 2; Aims 1-3), sociodemographic and health-related variables were collected from 266 AA adults recruited from African Methodist Episcopal (AME) churches. Total time spent in sedentary, light-intensity, and moderate-to vigorous-intensity behaviors; time of day most sedentary and weekday vs. weekend day differences in SB; and total number of SB bouts and breaks in SB were examined by sociodemographic and health-related characteristics. Bivariate associations and logistic regression analyses tested the independent associations between bouts of and breaks in SB and obesity, hypertension, and increased waist circumference. To address Aims 4 & 5 in Manuscript 3, 32 overweight and obese AA women participated in three focus groups. Focus groups were digitally recorded, transcribed verbatim, and analyzed separately by two coders utilizing NVivo 9.
Results: Regarding Manuscript 1 and 2, most participants were obese, hypertensive, and had a substantially increased waist circumference. On average, participants spent 65% (9.5 hours/day) of waking time in SB, 33% (4.8 hours/day) in light-intensity PA, and <2% (15.0 minutes/day) in moderate-to vigorous-intensity PA. Regarding Aim 1, participants had significantly fewer minutes per day of SB in the morning compared to the afternoon and evening. No weekday and weekend day differences were observed in SB. Age, education, and weight status were positively associated with variations and patterns of SB. For Aim 2, participants on average engaged in daily SB bouts lasting 6.6 ± 2.1 minutes. All participants engaged in ≥1 daily bout of SB lasting ≥10 and ≥30 minutes, and most participants (93%) engaged in ≥1 bout lasting ≥60 minutes. After controlling for all covariates in the total sample, total SB time was inversely associated with hypertension; and total SB time was positively associated with obesity after controlling for sociodemographic variables only. Total number of SB bouts ≥10 and ≥30 minutes were positively associated with higher rates of substantially increased waist circumference after controlling for sociodemographic variables only in the total sample. Similarly, total number of SB bouts ≥10, ≥30 and ≥60 minutes were positively associated with obesity after controlling for sociodemographic variable only. Among women only, total SB time was positively associated with obesity and negatively associated with hypertension; total number of SB bouts ≥10 minutes was positively associated with obesity; whereas, total number of SB bouts ≥60 minutes was inversely associated with substantially increased waist circumference, after controlling for all covariates.
Regarding Aim 3, on average, participants took 93.2 ± 16.6 breaks from SB; each break lasted 3.3 ± 1.0 minutes and mean intensity of breaks from SB was 446.2 ± 81.2 cpm (light intensity). Total number of SB breaks was beneficially associated with obesity in women only and each additional break in SB was associated with a 5% decreased risk of obesity. Lastly, for Aims 4 and 5, focus groups indicated most women spent a majority of time at home and work engaged in SB. Culture, environmental influences, and life stressors were the most commonly cited reasons for engaging in SB. While relaxation, personal time and productive time were considered enjoyable aspects of SB, many women described disliking the health consequences associated with SB.
Conclusions: Few studies have examined the associations between total volume and patterns of SB and health risk in AAs. This dissertation presents both an objective and subjective analysis of the associations of SB and health risks in the lives of AA living in the south.