The energy demand of skeletal muscle arising from physical exercise is met via aerobic or anaerobic metabolism. During physical exercise, the oxygen flux through the muscle increases by 100-fold. This increased demand for oxygen supply causes oxidative stress and, ultimately, muscle damage.
Glutathione is a thiol-containing tripeptide that acts as a redox homeostatic buffer in our body. Glutathione exists in reduced (GSH) and oxidized form (GSSH). The reduced form is predominant inside the cell (98%). Reduced glutathione (GSH) is a potent antioxidant and protects cells from Reactive Oxygen Species (ROS). Besides having an antioxidant role, GSH is also involved in redox regulation, apoptosis, DNA repair, cell cycle regulation, energy production and detoxification of xenobiotics1.
A study reported that the plasma GSSH level increased by 50% during intense exercise, while the GSH level was reduced by 13%. The depletion of GSH and accumulation of GSSH increases oxidative muscle damage2. Excessive depletion of GSH impairs muscle repair and may cause injury.
Various studies have reported that glutathione supplementation restores GSH levels and reduces oxidative muscle damage. In an in vivo study, glutathione supplementation improved exercise-induced muscle acidification and lipid metabolism3. In an 8-week double-blind, placebo-controlled trial, the effect of glutathione supplementation was observed on muscle strength and lean mass of resistance-trained males. Glutathione supplementation was observed to increase the level of cGMP and other signalling molecules involved in muscle protein synthesis. A significant increase in lean mass was observed after 4 weeks of resistance training4. Another 6-week double-blind placebo control study investigated the effects of glutathione supplementation (250 mg, once daily) on fatigue and recovery among elite swimmers. It was observed that cortisol and cortisone levels were reduced in the interventional group compared to the placebo group. Additionally, swimmers from the glutathione group showed improved adaptation towards their training schedules5.
To conclude, glutathione supplementation could replenish the GSH levels, protect against oxidative muscle damage, and help with muscle recovery.
References
(1) Averill-Bates, D. A. The Antioxidant Glutathione. In Vitamins and Hormones; Academic Press Inc., 2023; Vol. 121, pp 109–141. https://doi.org/10.1016/bs.vh.2022.09.002.
(2) Laaksonen, D. E.; Atalay, M.; Niskanen, L.; Uusitupa, M.; Hänninen, O.; Sen, C. K. Blood Glutathione Homeostasis as a Determinant of Resting and Exercise-Induced Oxidative Stress in Young Men. Redox Report 1999, 4 (1–2), 53–59. https://doi.org/10.1179/135100099101534648.
(3) Aoi, W.; Ogaya, Y.; Takami, M.; Konishi, T.; Sauchi, Y.; Park, Y. Y.; Wada, S.; Sato, K.; Higashi, A. Glutathione Supplementation Suppresses Muscle Fatigue Induced by Prolonged Exercise via Improved Aerobic Metabolism. J Int Soc Sports Nutr 2015, 12 (1). https://doi.org/10.1186/s12970-015-0067-x.
(4) Hwang, P.; Morales Marroquín, F. E.; Gann, J.; Andre, T.; McKinley-Barnard, S.; Kim, C.; Morita, M.; Willoughby, D. S. Eight Weeks of Resistance Training in Conjunction with Glutathione and L-Citrulline Supplementation Increases Lean Mass and Has No Adverse Effects on Blood Clinical Safety Markers in Resistance-Trained Males. J Int Soc Sports Nutr 2018, 15 (1). https://doi.org/10.1186/s12970-018-0235-x.
(5) Petrov, L.; Alexandrova, A.; Kachaunov, M.; Penov, R.; Sheytanova, T.; Kolimechkov, S. Effect of Glutathione Supplementation on Swimmers’ Performance. Pedagogy of Physical Culture and Sports 2021, 25 (4), 215–224. https://doi.org/10.15561/26649837.2021.0403.
