Reactive Oxygen Species (ROS)

Reactive Oxygen Species or ROS are also called free radicals – oxygen-containing molecules with an uneven number of electrons which enables them to react easily with other molecules. ROS are typically thought of as markers of oxidative stress, which is defined as an imbalance between free radicals and antioxidants in the body. However, in exercise, these molecules can have both a positive and negative role. In lower levels, ROS promotes muscle growth and strength; however, at higher levels, ROS production is associated with muscle fatigue and dysfunction.

Exercise Can Impact ROS Levels

Scientists have known for a while that regular exercise can be a way to reduce ROS by elevating levels of antioxidants. However, exhaustive and unaccustomed exercise can boost ROS, leading to tissue damage and impaired contractility of the body’s muscles. ROS are produced as a result of both aerobic and anaerobic exercise (He, et al., 2016). Specifically, researchers believe that ROS are formed by skeletal muscles during exercise (Steinbacher and Eckl, 2015). ROS is needed for muscles to be able to exert force, but too much can cause muscle fatigue and contractile problems. Exercise types such as resistance training affect not only ROS but also the levels of hormones and oxygen in the cells.

Blood Flow Restriction Training Increases ROS Levels to Promote Muscle

Remodulation and Adaptation

Blood Flow Restriction Training or BFR is a new exercise method in clinical settings which has the goal of inducing muscle growth and strength through increased anabolic processes. In one study, ROS levels increased after an exercise session, but this was thought to contribute to muscle improvement rather than cellular damage (Centner, et al., 2018).

Another scientific research study based in Brazil found that low intensity resistance training, combined with blood flow restriction and high intensity interval training, could increase metabolic stress during exercise in order to optimize muscle adaptations (de Freitas, et al., 2017).

The primary source of ROS during exercise remains unclear. Mild and acute ROS improves muscle force, while prolonged ROS exposure tends to decrease muscle force and induce fatigue.


Reactive oxygen species or free radicals are compounds that can cause oxidative stress, which can lead to tissue damage. Muscles generate ROS as a result of regular exercise in lower levels, or in greater levels during a particularly strenuous exercise session. However, research indicates that exercise boosts ROS levels on a smaller scale that promotes muscle remodulation rather than cause oxidative damage.


Centner C, et al. (2018). “Acute effects of blood flow restriction on exercise-induced free radical production in young and healthy subjects.” Free Radic Res, 52(4): 446-454.

Cheng AJ et al. (2016). “Reactive oxygen/nitrogen species and contractile function in skeletal muscle during fatigue and recovery.” J Physiol, 594(18):5149-60.

De Freitas MC, et al. (2017). “Role of metabolic stress for enhancing muscle adaptations: Practical applications.” World J Methodol, 7(2):46-54.

He F, et al. (2016). “Redox mechanism of reactive oxygen species in exercise.” Front Physiol 7: 486.

Steinbacher P., Eckl P. (2015). “Impact of oxidative stress on exercising skeletal muscle.” Biomolecules 5, 356–377.

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