Aerobic training is related to an increase in blood oxidation markers. The purpose of the present study was to investigate the antioxidant capacity of Lippia citriodora extracts (PLX(®) ) on plasma and blood cell oxidative status of university students beginning a 21 days aerobic training routine (3 days/week). Using a double-blind design, 15 male athletes (21 ± 2.1 years) were assigned to a group consuming 1.8 g/day of the plant extract (PLX(®) -group) or a placebo (PLB-group). Two blood extractions were performed at day 0 and 21, from which lymphocytes, erythrocytes and plasma were isolated. Several circulating parameters, antioxidant enzyme activities and oxidative stress markers were measured. The PLX(®) -group displayed an increased HDL-cholesterol, a modest decrease in erythrocyte number and an increased circulating urea. Activation of glutathione (GSH)-reductase was observed in erythrocytes and lymphocytes of PLX(®) -group, accompanied by lower levels of oxidative stress markers, such as malondialdehyde and protein carbonyls in plasma. The antioxidant action exerted by PLX(®) on GSH-reductase seems to be post-translational and mainly due to verbascoside, a phenylpropanoid that represents 10% (w/w) of extract content. In conclusion, PLX(®) shows antioxidant properties that could play an important role in modulating GSH-reductase activity in lymphocytes and erythrocytes and protecting plasma from exercise oxidative damage.

Intense exercise is directly related to muscular damage and oxidative stress due to excessive reactive oxygen species (ROS) in both, plasma and white blood cells. Nevertheless, exercise-derived ROS are essential to regulate cellular adaptation to exercise. Studies on antioxidant supplements have provided controversial results. The purpose of this study was to determine the effect of moderate antioxidant supplementation (lemon verbena extract) in healthy male volunteers that followed a 90-min running eccentric exercise protocol for 21 days. Antioxidant enzymes activities and oxidative stress markers were measured in neutrophils. Besides, inflammatory cytokines and muscular damage were determined in whole blood and serum samples, respectively. Intense running exercise for 21 days induced antioxidant response in neutrophils of trained male through the increase of the antioxidant enzymes catalase, glutathione peroxidase and glutathione reductase. Supplementation with moderate levels of an antioxidant lemon verbena extract did not block this cellular adaptive response and also reduced exercise-induced oxidative damage of proteins and lipids in neutrophils and decreased myeloperoxidase activity. Moreover, lemon verbena supplementation maintained or decreased the level of serum transaminases activity indicating a protection of muscular tissue. Exercise induced a decrease of interleukin-6 and interleukin-1β levels after 21 days measured in basal conditions, which was not inhibited by antioxidant supplementation. Therefore, moderate antioxidant supplementation with lemon verbena extract protects neutrophils against oxidative damage, decreases the signs of muscular damage in chronic running exercise without blocking the cellular adaptation to exercise.

Background:Exhaustive exercise causes muscle damage accompanied by oxidative stress and inflammation leading to muscle fatigue and muscle soreness. Lemon verbena leaves, commonly used as tea and refreshing beverage, demonstrated antioxidant and anti-inflammatory properties. The aim of this study was to investigate the effects of a proprietary lemon verbena extract (Recoverben®) on muscle strength and recovery after exhaustive exercise in comparison to a placebo product.

Methods:The study was performed as a randomized, placebo-controlled, double-blind study with parallel design. Forty-four healthy males and females, which were 22-50 years old and active in sports, were randomized to 400 mg lemon verbena extract once daily or placebo. The 15 days intervention was divided into 10 days supplementation prior to the exhaustive exercise day (intensive jump-protocol), one day during the test and four days after. Muscle strength (MVC), muscle damage (CK), oxidative stress (GPx), inflammation (IL6) and volunteer-reported muscle soreness intensity were assessed pre and post exercise.

Results:Participants in the lemon verbena group benefited from less muscle damage as well as faster and full recovery. Compared to placebo, lemon verbena extract receiving participants had significantly less exercise-related loss of muscle strength ( = 0.0311) over all timepoints, improved glutathione peroxidase activity by trend ( = 0.0681) and less movement induced pain ( = 0.0788) by trend. Creatine kinase and IL-6 didn't show significant discrimmination between groups.

Conclusion:Lemon verbena extract (Recoverben®) has been shown to be a safe and well-tolerated natural sports ingredient, by reducing muscle damage after exhaustive exercise.

Trial registration:The trial was registered in the clinical trials registry (clinical trial.gov NCT02923102). Registered 28 September 2016.