Page 74 - 《运动与健康科学》(英文)2024年第2期

TaggedEnd196 J. Liao et al.
the strongest associations observed in low- to middle-income included adults aged 2059 years from 4 NHANES cycles
10
countries. Meanwhile, several studies that have analyzed these (20112012, 20132014, 20152016, and 20172018) who
associations jointly have suggested that the elevated disease risks had complete information on self-reported daily sitting time
associated with sedentary behavior could be offset by meeting and LTPA as well as whole body DXA-measured fat (Supple-
the physical activity guidelines. 5,6 Given the emerging evidence mentary Fig. 1). The NHANES data used are publicly avail-
and increasing trend in sedentary behavior, the World Health able. The statistical code and working dataset are available
Organization updated the guidelines on physical activity and from the corresponding author upon reasonable request.TaggedEnd
sedentary behavior in 2020 and for the first time recommended
limiting sedentary time and replacing sedentary behaviors with
TaggedH22.2. Daily sitting time and LTPATaggedEnd
11
any physical activity to increase health benefits. However, due
TaggedPSelf-reported time spent on daily sitting and weekly LTPA
to the low certainty level of the evidence, no quantitative guide-
were based on respondent-level interviews using the Global
line on sedentary behaviors could be made. To date, few studies 2,31
Physical Activity Questionnaire. Participants were asked to
have been conducted to examine the potential biological mecha-
recall, “On a typical day, how much time do you usually spend
nisms underlying the joint association of sedentary behaviors and
sitting at school, at home, getting to and from places, or with
physical activity with disease outcomes at the population level.TaggedEnd
friends, including time spent sitting at a desk, traveling in a car
TaggedPObesity is a national epidemic in the United States. In
or bus, reading, playing cards, watching television, or using a
20172018, researchers concluded that more than 40% of
computer (except for time spent sleeping)?” Responses were
U.S. adults were obese, and this was consistent between men
12 converted to hours per day and further categorized into: 0 to
and women as well as across age groups. Excess fat accumu-
lation, particularly in the abdominal region, is associated with less than 4, 4 to less than 6, 68, and 8 h/day or more, which
57
is in line with the recent studies. The total time spent on
metabolic dysregulation and increased risk of cardiometabolic
disease and premature death. 1315 Some experimental studies LTPA was calculated as minutes of moderate-intensity recrea-
tional activities plus twice the minutes of vigorous-intensity
in the lab setting have suggested that prolonged sitting and
recreational activities. According to the 2018 Physical Activity
reduced physical activity resulted in a lack of muscle contrac-
Guidelines for American adults: people without any LTPA,
tions and low energy expenditure, leading to weight gain and
obesity. 1618 Other studies have suggested that prolonged with LTPA more than 0 but less than 150 min/week, and with
LTPA 150 min/week or more in the past week were classified
sitting was consistently associated with a higher body mass
as inactive, insufficiently active, and sufficiently active,
index and waist circumference, which are markers of 32
obesity, 19,20 but inconsistently associated with body fatness respectively. TaggedEnd
and fat accumulation. 2124 Few studies have used validated
measures of body fat (i.e., dual X-ray absorptiometry (DXA)) TaggedH22.3. Measurement of body fatTaggedEnd
to investigate the impact of prolonged sitting on fat accumula-
TaggedPWhole body fat was determined by DXA scans acquired on
tion by body region, particularly at the population level. Also,
a Hologic Discovery A, using software Version APEX 3.2
the existing literature indicates that the effect of sedentary 33
(Hologic, Bedford, MA, USA). NHANES applied specific
behaviors and physical activity on health outcomes might exclusion criteria to determine the eligibility of participants
differ by sex. 25,26 Despite well-documented differences in fat for DXA examination (i.e., 60 years, pregnant or menstru-
accumulation and exercise habits by sex, 27,28 few studies have
ating women, self-reported body mass of more than 450
examined the sex-specific associations of sitting time and
pounds or height greater than 195.58 cm, and self-reported
history of radiographic contrast material (barium) use in the
physical activity with body fat accumulation.TaggedEnd
TaggedPTo address these knowledge gaps, the present study aimed
past 7 days). The software Version APEX 4.0 (Hologic) was
to investigate the independent and joint associations of daily
used to analyze the DXA examinations and provide the body
sitting time and leisure-time physical activity (LTPA) with 33
composition data. Fat percentages for total body (including
DXA-measured body fat among a nationally representative
the head, limbs, and trunk area) and trunk (only the trunk area)
were derived to measure the magnitude and distribution of
sample of U.S. adults.TaggedEnd
body fat. DXA-measured trunk fat reflects the fat accumula-
TaggedH12. MethodsTaggedEnd
tion in the central region of body (e.g., abdomen) and is a reli-
34
able and accurate surrogate of abdominal fat. TaggedEnd
TaggedH22.1. Study populationTaggedEnd
TaggedPWe obtained data from the National Health and Nutrition
TaggedH22.4. Assessment of covariatesTaggedEnd
Examination Survey (NHANES), a continuous survey using a
cross-sectional, stratified, multistage probability sampling TaggedPThe covariates included sociodemographic data (age, sex,
method to obtain a representative sample of the U.S. popula- race/ethnicity, education attainment, and family poverty ratio),
tion every 2 years since 1999. All NHANES protocols were lifestyle behaviors (smoking status, alcohol use, total energy
approved by the Ethics Review Board of the U.S. National intake, and healthy eating index-2015 (HEI-2015)), and
Center for Health Statistics, and written informed consent was chronic conditions (hypertension, hypercholesterolemia,
provided by each participant. Detailed descriptions of the history of diabetes, history of CVDs, history of cancer, and
survey have been published elsewhere. 2,29,30 The present study depression). Race/ethnicity was categorized as non-Hispanic