The Effects Of Beetroot Juice Supplementation On The Oxygen Cost Of Breathing In Obese Males

The purpose of this study was to measure the O2 cost of breathing during a eucapnic voluntary hyperventilation test, and whole body VO2 and ratings of perceived breathlessness during constant work rate cycling in obese males following beetroot juice (BRJ) supplementation. Six (n=6) obese males performed spirometry measures and a VO2peak test on a cycle ergometer during the initial visit. During the remaining two subsequent visits, subjects mimicked the ventilation and breathing pattern corresponding to 50%, 70%, and 90% VO2peak. After a passive recovery period, subjects cycled at a moderate intensity for 6 minutes. Subjects supplemented with either a placebo or BRJ for ten days in a randomized, cross-over design. A 10-day washout period separated the two supplementation periods. The O2 cost of breathing, whole body VO2, or ratings of perceived breathlessness were not different between BRJ and placebo conditions. Tidal volume was reduced during moderate intensity cycling during BRJ conditions when compared to placebo conditions. These findings suggest that BRJ does not lower O2 cost of breathing during eucapnic voluntary hyperventilation, nor does BRJ lower VO2 during moderate intensity cycling in young obese males.