All subjects will receive DGB-01 during the study. Approximately one-half of the subjects during the first period and the other half during the second period.

Approximately one-half of the subjects will initially receive DGB-01. The other half of the subjects will receive casein. Investigators and subjects are blinded to the product the subject is receiving. Subjects will be asked to consume one pouch of their assigned study product twice daily for four weeks.

Subsequently, all subjects will undergo a supplement-free washout period of at least four weeks duration. Following the washout period, the subjects who originally received DGB-01 will receive casein and the subjects who originally received casein will receive DGB-01. Subjects will be asked to consume one pouch of their assigned study product twice daily for four weeks.

Time to complete the 40km time trial for subjects with DGB-01 intervention in period 1 (minimum 4 weeks of supplementation) versus the time for time trial completion of these subjects with casein in period 2 (minimum of 4 weeks of supplementation); Between the two periods with supplementation, there will be a washout period of a minimum 4 weeks; Results of time trial for subjects with DGB-01 intervention in period 2 (minimum 4 weeks of supplementation) versus the time trial completion of these subjects with casein in period 1 (minimum 4 weeks supplementation).

• A) Plasma samples will be obtained before and during the final minute of each time trial. These samples will be stored at -80oC for no longer than 14 days to prevent sample deterioration.
• B) All samples will be analyzed for glutathione (GSH), oxidized glutathione (GSSG), cysteine (CySH), cystine (CySS), and cysteine-glutathione disulfide (CySSG) using high-performance liquid chromatography (Clinical Biomarkers Laboratory, Emory University, Atlanta, GA). Total glutathione (TGSH) will be calculated as GSH + 2•GSSG + CySSG. Total cysteine (TCyS) will be calculated as CySH + 2•CySS + CySSG.