Decreased training volume and increased carbohydrate intake increases oxidized LDL levels

Area of Science:

• Exercise Physiology
• Nutritional Biochemistry
• Sports Science

Background:

• Marathon running involves intense training and physiological stress.
• Oxidative stress markers like oxidized LDL lipids (ox-LDL) and antioxidant potential (s-TRAP) are relevant in endurance athletes.
• The impact of probiotics and training modifications on these markers requires investigation.

Purpose of the Study:

• To investigate the effects of Lactobacillus rhamnosus GG (LGG) probiotics and training volume changes on ox-LDL, s-TRAP, and serum antioxidants in marathon runners.
• To analyze these effects during a 3-month training period, a 6-day preparation phase, and the marathon run itself.

Main Methods:

• A randomized, double-blind, placebo-controlled study involving 127 marathon runners.
• Intervention included daily Lactobacillus rhamnosus GG (LGG) or placebo for the study duration.
• Blood samples were analyzed for ox-LDL, s-TRAP, and various serum antioxidants at baseline, pre-preparation, pre-marathon, and post-marathon.

Main Results:

• LGG probiotics did not significantly affect ox-LDL, s-TRAP, or serum antioxidant levels.
• Oxidized LDL lipids (ox-LDL) increased significantly during the preparation period (reduced training, increased carbohydrate intake) in both groups.
• Serum antioxidant potential (s-TRAP) increased during the marathon run in both groups, with no changes observed before the race.

Conclusions:

• Probiotics, specifically LGG, do not appear to influence key oxidative stress markers in marathon runners under these conditions.
• A pre-marathon tapering period with reduced training and increased carbohydrate intake is associated with increased ox-LDL levels.
• Aerobic training may play a role in reducing ox-LDL concentrations, while reduced training intensity before a race can elevate them.