Louise M Burke
Chair of Sports Nutrition, Mary MacKillop Institute for Health Research, Australian Catholic
University, Melbourne

This presentation will provide a summary of the effects of a ketogenic diet on the performance of endurance sports in elite and high performance athletes. Results from the author’s series of studies on the Low Carbohydrate High Fat diet in world class and sub-elite endurance athletes, will be integrated into the current literature to demonstrate:
 The LCHF diet greatly increases muscle capacity for fat oxidation across a range of exercise intensities, even in athletes who are already endurance trained and have higher capacity for fat oxidation. The adaptation to greater capacity for fat oxidation happens more quickly than is popularly promoted.
 The metabolic cost of this switch in fuel metabolism is a greater requirement for oxygen to produce the same rate of ATP generation and its transfer to exercise performance (e.g. speed).
 This is associated with a reduction in performance of endurance sport conducted at intensities that are around the so-called lactate threshold, since oxygen supply rather than substrate becomes the limiting factor in performance. This work intensity underpins success in endurance sports and many ultra-endurance sports since it describes the pace that must be sustained throughout many events, or the pace of the critical pieces of the event (e.g. breakaway, uphill portions, finishing sprints). It may better suited to events that are conducted at lower-intensities for prolonged periods, particularly when there are personal
or practical challenges to supplementing carbohydrate during the race.
 New strategies that periodize carbohydrate into the training or race day nutrition strategies of keto-adapted athletes are of interest, but need to consider that keto-adaptation creates a down regulation of carbohydrate absorption and metabolism.