Introduction: Lactate dehydrogenase (LDH) has historically been used as an indicator of negative health outcomes, such as myocardial ischaemia and lung disease; however, recent evidence has suggested that LDH levels within normal limits may be inversely related to coronary heart disease. Therefore, the purpose of the current study was to examine the association between physical activity and normal-range LDH levels, and how LDH levels, in turn, are associated with the predicted risk of cardiovascular disease (CVD).
Methods: Data from the 2003-2006 National Health and Nutrition Examination Survey (NHANES) were used (N = 2087 adults aged 40-79 years; analysed in 2015). Participants were included if they had LDH levels within the normal range (105-333 IU/L). LDH values were obtained from a blood sample. Physical activity was measured using accelerometry and expressed in total minutes per day (TPA), as well as in the total activity count per day (TAC/d). Finally, the predicted 10-year risk of a first atherosclerotic cardiovascular disease (ASCVD) event was calculated using validated Pooled Cohort Equations.
Results: In a polytomous logistic regression, for a 1-standard-deviation (1SD) increase in TPA (SD 102.3 min/day), the participants were at 30% increased odds (odds ratio [OR] 1.30, 95% confidence interval [CI] 1.11-1.52, P = 0.002) of being in LDH quartile 4 (versus quartile 1). Those in LDH quartile 4 (versus quartile 1) were at 55% reduced odds (OR 0.45, 95% CI 0.20-0.99, P = 0.04) of being in ASCVD quartile 4 (versus quartile 1).
Conclusion: These findings contribute to mounting evidence of the diagnostic value of normal-range LDH levels, implicating normal-range LDH levels as a novel biomarker through which physical activity may be associated with CVD.