Objectives: (i) To estimate changes in apoB and apoB/apoA-I, reflecting the balance between atherogenic and anti-atherogenic lipoprotein particles, by exercise training and compare with changes in LDL-C and TC/HDL-C ratio, and (ii) To compare strengths of relationships between physical fitness and various lipoprotein variables.
Design, setting, and subjects: The study was a 1-year open randomized trial comprising 219 healthy middle-aged subjects aged 40-49 years who were allocated to exercise or no exercise, dietary advice or no advice in a 2 x 2 factorial design. This study includes 188 men who completed the trial, 45 to diet, 48 to exercise, 58 to diet + exercise and 37 to control.
Interventions: Exercise; supervised endurance exercise three times a week. Diet; reduce weight, increase intake of fish and reduce total fat intake.
Main outcome measure: One-year change in apoB and apoB/apoA-I ratio.
Results: Exercisers decreased their ApoB and ApoB/ApoA-I values significantly compared to non-exercisers. LDL-C was not, but LDL-C/HDL-C was marginally but statistically significantly reduced by exercise. One-year change in ApoB and ApoB/ApoA-I correlated more strongly to 1-year changes in physical fitness than LDL-C or LDL-C/HDL-C. Adjusting for changes in LDL-C or LDL-C/HDL-C did not influence the correlation between changes in fitness and ApoB or ApoB/ApoA-I. However, adjusting for changes in ApoB or ApoB/ApoA-I wiped out the correlation between change in fitness and LDL-C or LDL-C/HDL-C. Relationships weakened when adjusting for changes in waist circumference, but Apo B or ApoB/ApoA-I still correlated significantly to changes in fitness.
Conclusion: Physical exercise reduced the atherogenic burden as experienced by the reduction in apoB or apoB/apoA-I levels, but not by LDL-C in healthy middle-aged men. Possibly, regular physical activity might increase the LDL-C particle size, thereby making LDL less atherogenic. Monitoring of apolipoproteins rather than the cholesterol moiety of lipoproteins might improve the assessment of lipoprotein changes after exercise training.