Introduction: Oxidized LDL (ox-LDL) is associated with lifestyle diseases such as cardiovascular diseases, metabolic syndrome, and type 2 diabetes. The present study investigated the association between ox-LDL and overweight/obesity and how cardiorespiratory or muscle fitness affects this association.
Methods: Healthy young (mean age = 25.1 yr, range = 18–48 yr) men (n = 831) were divided into normal-weight (n = 486), overweight (n = 269), and obese (n = 76) groups according to their body mass index (BMI). The participants underwent physical fitness tests (maximal oxygen uptake with bicycle ergometer and muscle fitness index using series of muscle endurance tests), a general health examination including determination of lipid profile, and a detailed questionnaire. Subjects were further divided into six subgroups according to BMI (normal vs overweight) and physical fitness (fitness tertiles: unfit, average, fit). Age and smoking were used in the statistical analysis as covariates.
Results: In overweight and obese participants, the concentrations of ox-LDL (14%/32%) and the ratio of ox-LDL/HDL cholesterol (32%/68%) were higher compared with subjects with normal weight (P < 0.005, in all). In BMI and cardiovascular fitness subgroups, ox-LDL (23%, P < 0.0001) and the ox-LDL/HDL cholesterol ratio (45%, P < 0.0001) were higher in the overweight/unfit subgroup when compared with the normal-weight/unfit subgroup, whereas no differences were observed between the overweight/fit and normal-weight/fit subjects. Among the BMI and muscle fitness subgroups, ox-LDL (24%, P < 0.0001) and the ox-LDL/HDL cholesterol ratio (51%, P < 0.0001) were higher in the overweight/unfit group compared with the normal-weight/unfit group.
Conclusions: Overweight and obesity are associated with ox-LDL lipids and serum conventional lipids. However, both good cardiorespiratory fitness and muscular fitness seem to protect overweight subjects from the atherogenic lipid profile.