We aimed to compare self-reported adherence to the physical activity recommendation with accelerometry in older adults and to identify determinants of misperception. The sample included 138 adults age 65–75 yr old participating in the Longitudinal Aging Study Amsterdam. Participants completed a lifestyle questionnaire and wore an accelerometer for one week. More than half (56.8%) of the participants reported to adhere to the physical activity recommendation (in 5-min bouts), however, based on accelerometry, this percentage was only 24.6%. Of those who reported to adhere, 65.3% did not do so based on accelerometry. The misperceivers were older (p < .009), more often female (p = .007), had a poorer walking performance (p = .02), reported a lower social support (p = .04), and tended to have a lower self-efficacy (p = .09) compared with those who correctly perceived their adherence to the recommendation. These results suggest that misperception of adherence to the physical activity recommendation is highly prevalent among specific subgroups of older adults.
Marjolein Visser, Robert J. Brychta, Kong Y. Chen, and Annemarie Koster
Maciej S. Buchowski, Leena Choi, Karen M. Majchrzak, Sari Acra, Charles E. Matthews, and Kong Y. Chen
Environmental factors including seasonal changes are important to guide physical activity (PA) programs to achieve or sustain weight loss. The goal was to determine seasonal variability in the amount and patterns of free-living PA in women.
PA was measured in 57 healthy women from metropolitan Nashville, TN, and surrounding counties (age: 20 to 54 years, body mass index: 17 to 48 kg/m2) using an accelerometer for 7 consecutive days during 3 seasons within 1 year. PA counts and energy expenditure (EE) were measured in a whole-room indirect calorimeter and used to model accelerometer output and to calculate daily EE and intensity of PA expressed as metabolic equivalents (METs).
PA was lower in winter than in summer (131 ± 45 vs. 144 ± 54 × 103 counts/d; P = .025) and in spring/fall (143 ± 48 × 103 counts/d; P = .027). On weekends, PA was lower in winter than in summer by 22,652 counts/d (P = .008). In winter, women spent more time in sedentary activities than in summer (difference 35 min/d; P = .007) and less time in light activities (difference −29 min/d, P = .018) and moderate or vigorous activities (difference −6 min/d, P = .051).
Women living in the southeastern United States had lower PA levels in winter compared with summer and spring/fall, and the magnitude of this effect was greater on weekends than weekdays.
Robert J. Brychta, Vaka Rögnvaldsdóttir, Sigríður L. Guðmundsdóttir, Rúna Stefánsdóttir, Soffia M. Hrafnkelsdóttir, Sunna Gestsdóttir, Sigurbjörn A. Arngrímsson, Kong Y. Chen, and Erlingur Jóhannsson
Introduction: Sleep is often quantified using self-report or actigraphy. Self-report is practical and less technically challenging, but prone to bias. We sought to determine whether these methods have comparable sensitivity to measure longitudinal changes in adolescent bedtimes. Methods: We measured one week of free-living sleep with wrist actigraphy and usual bedtime on school nights and non-school nights with self-report questionnaire in 144 students at 15 y and 17 y. Results: Self-reported and actigraphy-measured bedtimes were correlated with one another at 15 y and 17 y (p < .001), but reported bedtime was consistently earlier (>30 minutes, p < .001) and with wide inter-method confidence intervals (> ±106 minutes). Mean inter-method discrepancy did not differ on school nights at 15 y and 17 y but was greater at 17 y on non-school nights (p = .002). Inter-method discrepancy at 15 y was not correlated to that at 17 y. Mean change in self-reported school night bedtime from 15 y to 17 y did not differ from that by actigraphy, but self-reported bedtime changed less on non-school nights (p = .002). Two-year changes in self-reported bedtime did not correlate with changes measured by actigraphy. Conclusions: Although methods were correlated, consistently earlier self-reported bedtime suggests report-bias. More varied non-school night bedtimes challenge the accuracy of self-report and actigraphy, reducing sensitivity to change. On school nights, the methods did not differ in group-level sensitivity to changes in bedtime. However, lack of correlation between bedtime changes by each method suggests sensitivity to individual-level change was different. Methodological differences in sensitivity to individual- and group-level change should be considered in longitudinal studies of adolescent sleep patterns.
Dane R. Van Domelen, Paolo Caserotti, Robert J. Brychta, Tamara B. Harris, Kushang V. Patel, Kong Y. Chen, Nanna Ýr Arnardóttir, Gudny Eirikdottir, Lenore J. Launer, Vilmundur Gudnason, Thórarinn Sveinsson, Erlingur Jóhannsson, and Annemarie Koster
Accelerometers have emerged as a useful tool for measuring free-living physical activity in epidemiological studies. Validity of activity estimates depends on the assumption that measurements are equivalent for males and females while performing activities of the same intensity. The primary purpose of this study was to compare accelerometer count values in males and females undergoing a standardized 6-minute walk test.
The study population was older adults (78.6 ± 4.1 years) from the AGES-Reykjavik Study (N = 319). Participants performed a 6-minute walk test at a self-selected fast pace while wearing an ActiGraph GT3X at the hip. Vertical axis counts·s−1 was the primary outcome. Covariates included walking speed, height, weight, BMI, waist circumference, femur length, and step length.
On average, males walked 7.2% faster than females (1.31 vs. 1.22 m·s−1, P < .001) and had 32.3% greater vertical axis counts·s−1 (54.6 vs. 39.4 counts·s−1, P < .001). Accounting for walking speed reduced the sex difference to 19.2% and accounting for step length further reduced the difference to 13.4% (P < .001).
Vertical axis counts·s−1 were disproportionally greater in males even after adjustment for walking speed. This difference could confound free-living activity estimates.
Jennifer Zink, David A. Berrigan, Miranda M. Broadney, Faizah Shareef, Alexia Papachristopoulou, Sheila M. Brady, Shanna B. Bernstein, Robert J. Brychta, Jacob D. Hattenbach, Ira L. Tigner Jr., Amber B. Courville, Bart E. Drinkard, Kevin P. Smith, Douglas R. Rosing, Pamela L. Wolters, Kong Y. Chen, Jack A. Yanovski, and Britni R. Belcher
Purpose: Sedentary time relates to higher anxiety and more negative affect in children. This study assessed whether interrupting sitting over 3 hours is sufficient to influence state anxiety, positive affect, or negative affect, and tested weight status as a moderator. Methods: Analyses were the second (preplanned) purpose of a larger study. Children (N = 61; age: mean [SD] = 9.5 [1.3]; 43% healthy weight) completed 2 experimental conditions: continuous sitting for 3 hours and sitting for 3 hours interrupted with walking for 3 minutes in every 30 minutes. State anxiety, positive affect, and negative affect were reported at pretest and posttest. Multilevel models for repeated measures assessed whether experimental condition predicted posttest scores. Results: Experimental condition was unrelated to posttest state anxiety or positive affect. Weight status moderated how experimental condition influenced posttest negative affect (P = .003). Negative affect was lower in the children of healthy weight after interrupted sitting (vs continuous sitting; β = −0.8; 95% confidence interval, −1.5 to 0.0, P = .05), but it was higher in the children with overweight/obesity after interrupted sitting (vs continuous sitting; β = 0.6; 95% confidence interval, 0.0 to 1.2, P = .06). Conclusions: Interrupting sitting acutely reduced negative affect in children of healthy weight, but not in children with overweight. Further research is needed to better understand the potential emotional benefits of sitting interruptions in youth.