Daily physical activity predicts degree of insulin resistance: a cross-sectional observational study using the 2003-2004 National Health and Nutrition Examination Survey.
BACKGROUND
This study examined the independent association of objectively measured physical activity on insulin resistance while controlling for confounding variables including: cardiorespiratory fitness, adiposity, sex, age, and smoking status.


METHODS
Data were obtained from National Health and Nutrition Examination Survey 2003-2004, a cross-sectional observational study conducted by the National Center for Health Statistics of the Centers for Disease Control that uses a stratified, multistage probability design to obtain a nationally representative sample of the U.S. population. The analysis included 402 healthy U.S. adults with valid accelerometer, cardiorespiratory fitness, and fasting plasma glucose and insulin concentrations. After controlling for relevant confounding variables we performed a multiple linear regression to predict homeostatic model of insulin resistance (HOMA-IR) based on average daily minutes of moderate-to-vigorous physical activity (MVPA).


RESULTS
In our bivariate models, MVPA, cardiorespiratory fitness and body fat percentage were all significantly correlated with log HOMA-IR. In the complete model including MVPA and relevant confounding variables, there were strong and significant associations between MVPA and log HOMA-IR (β= -0.1607, P=0.004). In contrast the association between cardiorespiratory fitness and log HOMA-IR was not significant.


CONCLUSIONS
When using an objective measure of physical activity the amount of time engaged in daily physical activity was associated with lower insulin resistance, whereas higher cardiorespiratory fitness was not. These results suggest that the amount of time engaged in physical activity may be an important determinant for improving glucose metabolism.
School of Kinesiology, University of Michigan, Ann Arbor, MI, USA.
Rachael K
RK
Nelson
Jeffrey F
JF
Horowitz
Robert G
RG
Holleman
Ann M
AM
Swartz
Scott J
SJ
Strath
Andrea M
AM
Kriska
Caroline R
CR
Richardson
D000273:Adipose Tissue; D000293:Adolescent; D000328:Adult; D001823:Body Composition; D003430:Cross-Sectional Studies; D015444:Exercise; D005260:Female; D015438:Health Behavior; D006801:Humans; D007333:Insulin Resistance; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D009749:Nutrition Surveys; D010809:Physical Fitness; D012720:Severity of Illness Index; D014481:United States; D055815:Young Adult