Introduction
SECONDARY, INSULIN RESISTANCE
CrossFit (CF) is a relatively new training program with the goal of optimizing all aspects of physical capacity and performance. Daily workouts include strength, gymnastic, and endurance exercises that engage both aerobic and anaerobic energy systems in the body [The mechanisms of BET’s potential ergogenicity remain incompletely understood. The two main roles of BET in the body are osmoregulation and methyl group donation. The latter plays an important role in homocysteine methylation to methionine, which is then converted to S-adenosylmethionine (SAM). SAM is a universal methyl group donor for many reactions in the body including gene expression and protein synthesis. In this way BET may indirectly influence several aspects of cell metabolism. BET also prevents the formation of homocysteine thiolactone by increasing homocysteine transformation. Homocysteine thiolactone promotes insulin resistance and inactivates enzymes associated with protein synthesis, which may also hamper training adaptations [Because BET is a part of one-carbon metabolism, the effects of BET supplementation may be dependent on the entire one-carbon cycle [Interestingly, previous studies used a similar small daily dose of BET (2.0–2.5 g/day), while effective doses used for clinical reasons (e.g. for lowering homocysteine concentration) tend to be higher, at 4–6 g/day. It thus seems important to establish whether higher doses of BET would produce greater improvements in physical performance than the lower doses that have often been used.To fill in the gaps in the literature, the main goal of the present study was to evaluate the effects of three weeks of BET supplementation on CF performance, on power in the Wingate anaerobic test (WAnT), and on body composition in a group of male CF practitioners. The secondary goals were to assess the effects of different doses of BET (2.5 and 5.0 g/d) and 