4%; p < 0.001), maximum peak power (5.7%; p < 0.001), average mean power (5.4%; p = 0.004), and maximum mean power (4.4%;

p = 0.004) for all subjects combined. Compared to placebo, betaine ingestion significantly increased average peak power (3.4%; p = 0.026), maximum peak power (3.8%; p = 0.007), average mean power (3.3%; p = 0.034), and maximum mean power (3.5%; p = 0.011) for all subjects combined. There were no differences between the placebo and baseline trials. There were no differences across time or between conditions for any of the body BIBW2992 mw composition variables. Table 2 Combined power (watts) comparison for all subjects selleck Variable Baseline Placebo Betaine Peak Power       Average 608 ± 140 626 ± 133 647 ± 144*# Maximum 644 ± 144 656 ± 141 681 ± 145*# Mean Power       Average 560 ± 133 571 ± 126 590 ± 138*# Maximum 596 ± 138 601 ± 131 622 ± 141*# Data are mean ± SD * p < 0.05 compared to corresponding Bafilomycin A1 order baseline value # p < 0.05 compared to corresponding placebo value Figure 1

Individual cycle runs power comparison for all subjects. A: peak power; B: mean power. * p < 0.05 compared to corresponding baseline value. # p < 0.05 compared to corresponding placebo value. W = watts, BL = baseline, PL = placebo, Be = betaine. Figure 2 Individual cycle runs power comparison for males. A: peak power; B: mean power. * p < 0.05 compared to corresponding baseline value. # p < 0.05 compared to corresponding placebo value. W = watts, BL = baseline, PL = placebo, Be = betaine. Figure 3 Individual cycle runs power comparison for females. A: peak power; B: mean power. * p < 0.05 compared to corresponding baseline value. # p < 0.05 compared to corresponding placebo value. W = watts, BL = Sitaxentan baseline, PL = placebo, Be = betaine.

Discussion Our purpose was to examine the effect of one week of betaine ingestion on anaerobic power as measured with a series of four, 12 sec work bouts. We found that one week of betaine ingestion (2.5 g.d-1) improved sprint performance by 5.5 ± 0.8% compared to baseline and 3.5 ± 0.2% compared to the carbohydrate placebo. These results contrast with data from Hoffman et al. [10], who reported daily consumption of 2.5 grams of betaine mixed with a commercially available carbohydrate beverage for 15 days did not enhance peak power, mean power, rate of fatigue, or total work across two Wingate trials separated by 5 min of active rest. One likely explanation for some of the difference in the results between the studies is the nature of the sprint test. Our subjects completed more sprints (4 vs. 2) of a shorter duration (12 vs. 30 sec) that were interspersed with shorter periods of active recovery (2.5 vs. 5 min) relative to the subjects in Hoffman et al. [10]. Experimental design may also account for some of the difference between the studies. Hoffman et al. [10] used a randomized repeated measures design, whereas we used a cross-over repeated measures design.