Association between sedentary behavior and normal-range lactate dehydrogenase activity.

OBJECTIVES: Recent research demonstrates that lactate dehydrogenase (LDH) activity within the normal range may serve as a mediator in the (positive) relationship between physical activity and cardiovascular disease risk. Emerging work supports deleterious associations between sedentary behavior and health, independent of physical activity. Thus, this study evaluated if sedentary behavior was associated with normal-range LDH activity, independent of physical activity.

METHODS: Data from the 2003-2006 NHANES were used (N = 2,087 adults; 40-79 yrs). LDH activity levels were estimated from a blood sample using LX20 and LDH reagent; participants were included if they had LDH activity levels within the normal range (105-333 IU/L). Physical activity and sedentary behavior were assessed via accelerometry.

RESULTS: Sedentary behavior was inversely associated with normal-range LDH activity when physical activity was excluded from the model (OR = 0.89; 95% CI: 0.83-0.97, P = 0.009 for LDH activity quartile 4 vs. 1). However, sedentary behavior was no longer associated with normal-range LDH activity after controlling for physical activity and other covariates (OR = 1.00, P = 0.49 for LDH activity quartile 2 vs. 1; OR = 1.00, P = 0.72 for LDH quartile 3 vs. 1; and OR = 0.99, P = 0.36 for LDH quartile 4 vs. 1).

CONCLUSION: Unlike physical activity, sedentary behavior is not independently associated with normal-range LDH activity.