Physical Activity and Insulin Resistance in 6,500 NHANES Adults: The Role of Abdominal Obesity

Table 5

Differences in mean HOMA-IR values by level of weekly guideline-based physical activity in US men and women, after adjusting for covariates applied to waist circumference groups divided into sex-specific quartiles.

Covariate	Weekly guideline-based physical activity level					F
	Sedentary-G	Low-G	Moderate-G	High-G	Very High-G
	Mean ± SE	Mean ± SE	Mean ± SE	Mean ± SE	Mean ± SE
Small waist only
Demographics	1.2 ± 0.05	1.2 ± 0.06	1.1 ± 0.06	1.2 ± 0.07	1.2 ± 0.06	0.9	0.4589
Demographics and lifestyle	1.2 ± 0.05	1.2 ± 0.06	1.1 ± 0.09	1.1 ± 0.08	1.1 ± 0.06	0.9	0.4738
Demographics, lifestyle, and waist circ.	1.2 ± 0.05	1.2 ± 0.06	1.1 ± 0.07	1.2 ± 0.07	1.2 ± 0.06	0.9	0.4985
Medium waist only
Demographics	1.8 ± 0.06	1.9 ± 0.08	1.9 ± 0.11	1.7 ± 0.08	1.8 ± 0.07	0.6	0.6776
Demographics and lifestyle	1.8 ± 0.10	1.9 ± 0.10	1.9 ± 0.11	1.7 ± 0.11	1.8 ± 0.11	0.4	0.8382
Demographics, lifestyle, and waist circ.	1.8 ± 0.09	1.8 ± 0.10	1.8 ± 0.11	1.7 ± 0.11	1.8 ± 0.11	0.4	0.8435
Large waist only
Demographics	2.9 ± 0.17	2.8 ± 0.21	2.9 ± 0.27	2.9 ± 0.42	2.7 ± 0.19	0.8	0.5234
Demographics and lifestyle	2.8 ± 0.16	2.7 ± 0.20	2.8 ± 0.26	2.8 ± 0.42	2.6 ± 0.19	1.7	0.1606
Demographics, lifestyle, and waist circ.	2.8 ± 0.16	2.7 ± 0.20	2.8 ± 0.26	2.8 ± 0.42	2.6 ± 0.20	1.3	0.2669
Abdominal obesity
Demographics	4.1^a ± 0.24	3.9^a ± 0.21	3.3^b ± 0.27	3.3^b ± 0.31	3.2^b ± 0.26	4.3	0.0039
Demographics and lifestyle	2.7^a ± 0.26	2.5^a ± 0.27	1.9^b ± 0.30	1.9^b ± 0.38	1.8^b ± 0.33	5.3	0.0011
Demographics, lifestyle, and waist circ.	3.3^a ± 0.26	3.1^a ± 0.25	2.7^b ± 0.24	2.5^b ± 0.29	2.6^b ± 0.28	3.7	0.0098

^a,bMeans on the same row with the same superscript letter were not statistically different (). Because of nesting, there were only 59 degrees of freedom in the denominator of each model. The physical activity categories were based on MET-minute guideline levels. Across the five guideline-based categories of physical activity, weighted percentages were as follows: 34% (N = 2640) reported no physical activity (Sedentary-G), 21.7% (N = 1326) reported Low-G levels (>0 and <500 MET-minutes per week), 13.7% (N = 809) reported Moderate-G levels (≥500 and <1000 MET-minutes per week), 9.3% (N = 529) reported High-G levels (≥1000 and <1500 MET-minutes per week), and 21.3% (N = 1196) reported Very High-G levels of physical activity (≥1500 MET-minutes per week). Because sample weights were applied to each participant, differences in the number of subjects in each category should be interpreted using percentages, not N. Means on the same row were adjusted for the covariates in the left column. The demographic covariates were age, sex, race, and year of assessment. The lifestyle covariates were body mass index and cigarette smoking. Waist circ. = waist circumference measured in centimeter.