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.
Marquis Hawkins, Anne B. Newman, Magdalena Madero, Kushang V. Patel, Michael G. Shlipak, Jennifer Cooper, Kirsten L. Johansen, Sankar D. Navaneethan, Ronald I. Shorr, Eleanor M. Simonsick and Linda F Fried
Physical activity (PA) may play a role in preserving kidney health. The purpose of this study was to determine if PA and sedentary behavior are associated with incident chronic kidney disease (CKD) and change in kidney function in older adults.
The Health, Aging, and Body Composition study is a prospective cohort of 3075 well-functioning older adults. PA and television watching was measured by self-report, and serum cystatin C was used to estimate glomerular filtration rate (eGFR). CKD was defined as an eGFR <60 ml/min/1.73m2. Rapid kidney function decline was defined as an annual loss in eGFR of >3ml/min/1.73m2. Discrete survival analysis was used to determine if baseline PA and television watching were related to 10-year cumulative incidence of CKD and rapid decline in kidney function.
Individuals who reported watching television >3 hours/day had a higher risk of incident CKD (HR 1.34; 95% CI, 1.09-1.65) and experiencing a rapid decline in kidney function (HR 1.26; 95% CI, 1.05-1.52) compared with individuals who watched television <2 hours/day. PA was not related to either outcome.
High levels of television watching are associated with declining kidney function; the mechanisms that underlie this association need further study.