Establishment of an exercise-induced oxidative stress model for testing dietary herbal interventions, such as Rooibos

Background: Many experimental animal and in vitro models have been developed to conduct oxidative stress-based research, but to date few reliable human models are available. Generating oxidative stress in a predictable and controllable fashion without risk of causing harm is important. This study aimed to standardise an exercise model to induce oxidative stress in a repeatable and controllable manner to be used for the assessment of dietary herbals. Methods: To use this as a well-accepted research model, control of main factors impacting oxidative stress such as age, gender, physical activity, dietary intake, medication and general health is necessary. The study design included a randomised cross over, placebo-controlled trial with the induction of oxidative stress achieved by including sprints to failure. To assess the model, rooibos herbal tea was included as one of the interventions, while markers of safety and oxidative stress were measured on various occasions during the trial period. Results and Conclusion: The exercise regime, reliably and repeatably induced oxidative stress evidenced by increased levels of oxidative damage markers, i.e. oxidised glutathione (p=0.003), malondialdehyde (p=0.004) and Comet assay tail moment (p<0.05), while unconjugated bilirubin (P=0.002) and the ferric reducing antioxidant potential (P<0.001) increased over the time period, in the male study participants, irrespective of the oral intervention. Rooibos showed some modulation of the induced oxidative stress response with markers returning to baseline levels more rapidly than placebo. This model showed the exercise regime to induce oxidative stress and additionally demonstrated that the herbal intervention did not complicate the onset of oxidative stress.