Electronic Thesis and Dissertation Repository


Master of Science




John M. Kowalchuk


The purpose of this study was to determine the effects of a high carbohydrate (HCHO) and low carbohydrate (LCHO) diet on the adjustment of pulmonary oxygen (O2) uptake ( ) and muscle deoxygenation ([HHb]) during transitions to heavy intensity exercise. Young, healthy, male subjects aged (24+/-3) underwent a 4 day LCHO followed immediately by a 4 day HCHO diet, with each diet preceded by a glycogen depletion protocol. This protocol was designed to alter PDH activity. Subjects completed 3 step transitions to a work rate corresponding to 35% of the difference between their lactate threshold and peak for each condition. On day 3 of the diets gas exchange measurements were collected using mass spectrometry and [HHb] measures were recorded using near-infrared spectroscopy (NIRS). On day 4 of the diets muscle biopsies were taken from the vastus lateralis muscle of the quadriceps muscle group at steady-state baseline exercise (20 W) and at 15 s and 360 s during the transition to heavy exercise. These biopsies were frozen for later analysis. It was found that the dietary manipulation had a significant effect (p0.05) [HHb]. This study posits that PDH plays a crucial role in the adjustment of oxidative metabolism to exercise.