Effect of antioxidant supplementation on markers of oxidative stress and muscle damage after strength exercise Original paper

Strenuous exercise causes muscle damage and inflammation. If exercise is performed in excess without adequate periods of recovery, the body synthesizes additional toxic molecules known as reactive oxygen species (ROS), leading to oxidative stress, a biological phenomenon in which there is an imbalance of pro-oxidants (induced by muscle damage) and antioxidants.

Oxidative stress can significantly reduce immune system functioning^[1] and negatively affect exercise performance.^[2] However, various antioxidant supplements have been purported to enhance one’s ability to recover from muscle-damaging exercise by reducing inflammation and oxidative stress.

This systematic review included 7 randomized controlled trials, with a total of 178 participants, all of which investigated the effects of antioxidant supplementation regimens in an exercise training program that promoted skeletal muscle damage.

All participants were considered to be healthy in the most general sense (e.g., nonsmoker, healthy weight), and the majority engaged in regular physical activity. The studies included for review spanned a 10-year period (January 2011–January 2021). Most of the studies contained only men, only 1 study included women, and 1 other study included both men and women. Two studies used the same antioxidant supplement (melatonin), and the remaining studies each used a different antioxidant supplement, namely, pomegranate juice, taurine, blueberries, oatmeal, and coenzyme Q10.

The biochemical analyses in each study generally examined markers of muscle damage and oxidative stress. Multiple studies analyzed inflammatory enzymes (tumor necrosis factor-α, interleukin-1 β, and interleukin-10) and antioxidants (catalase and glutathione peroxidase). Some studies also examined biomarkers of immune system functioning (cell adhesion molecule, colony stimulating factor, and chemotactic cytokine) and exercise metabolism (lactate).

There were decreases in markers of muscle damage and/or oxidative stress in every study that was included in this systematic review:

• Pomegranate juice reduced markers of both acute and delayed oxidative stress.
• Taurine reduced creatine kinase, a marker of muscle damage.
• Melatonin protected against muscle damage from oxidative stress overall and also reduced muscle damage induced by high-intensity training.
• Blueberries decreased oxidation by enhancing adaptive processes (recovery) in skeletal muscle.
• Oatmeal supplementation reduced markers of muscle damage and inflammation after multiple intervals of downhill running.
• Coenzyme Q10 reduced markers of oxidative stress during training.

Antioxidants are produced inside the body and can also be taken in supplemental form. However, few research studies have been conducted on antioxidant supplementation and its effects specifically on strength training. The lack of dietary control is worthy of note because dietary antioxidant consumption can significantly influence markers of oxidative stress and thus should be addressed in future studies.