Creatine Supplementation, Physical Exercise and Oxidative Stress Markers: A Review of the Mechanisms and Effectiveness

Abstract

Oxidative stress is the result of an imbalance between the generation of reactive oxygen species (ROS) and their elimination by antioxidant mechanisms. ROS degrade biogenic substances such as deoxyribonucleic acid, lipids, and proteins, which in turn may lead to oxidative tissue damage. One of the physiological conditions currently associated with enhanced oxidative stress is exercise. Although a period of intense training may cause oxidative damage to muscle fibers, regular exercise helps increase the cells' ability to reduce the ROS over-accumulation. Regular moderate-intensity exercise has been shown to increase antioxidant defense. Endogenous antioxidants cannot completely prevent oxidative damage under the physiological and pathological conditions (intense exercise and exercise at altitude). These conditions may disturb the endogenous antioxidant balance and increase oxidative stress. In this case, the use of antioxidant supplements such as creatine can have positive effects on the antioxidant system. Creatine is made up of two essential amino acids, arginine and methionine, and one non-essential amino acid, glycine. The exact action mechanism of creatine as an antioxidant is not known. However, it has been shown to increase the activity of antioxidant enzymes and the capability to eliminate ROS and reactive nitrogen species (RNS). It seems that the antioxidant effects of creatine may be due to various mechanisms such as its indirect (i.e., increased or normalized cell energy status) and direct (i.e., maintaining mitochondrial integrity) mechanisms. Creatine supplement consumption may have a synergistic effect with training, but the intensity and duration of training can play an important role in the antioxidant activity. In this study, the researchers attempted to review the literature on the effects of creatine supplementation and physical exercise on oxidative stress.

Keywords: antioxidants; creatine supplementation; exercise; reactive oxygen species.

Figure 1

Flowchart of the study selection.

Figure 2

Physiological structure of creatine. Adopted from Clarke et al. [41]. L-arginine: glycine amidinotransferase (AGAT); anidinoacetate N-methyltransferase (GAMT); phosphocreatine (PCr); cytosolic creatine kinase (Cyt. CK); electron transport chain (ETC); adenosine diphosphate (ADP); mitochondrial creatine kinase (mtCK); and adenosine triphosphate (ATP).

Figure 3

The effect of creatine on oxidative stress. Hydrogen peroxide (H₂O₂); creatine phosphate (CrP); adenosine triphosphate (ATP); and reactive oxygen species (ROS).