Odgovor Po nov 09, 2015 07:23

Metabolic characteristics of keto-adapted ultra-endurance ru

Metabolic characteristics of keto-adapted ultra-endurance runners

, Daniel J. Freidenreich
, Catherine Saenz
, Laura J. Kunces
, Brent C. Creighton
, Jenna M. Bartley
, Patrick M. Davitt
, Colleen X. Munoz
, Jeffrey M. Anderson
, Carl M. Maresh
, Elaine C. Lee
, Mark D. Schuenke
, Giselle Aerni
, William J. Kraemer
, Stephen D. Phinney

Published Online: November 02, 2015Accepted: October 27, 2015Received in revised form: September 26, 2015Received: June 26, 2015


Many successful ultra-endurance athletes have switched from a high-carbohydrate to a low-carbohydrate diet; but they have not previously been studied to determine the extent of metabolic adaptations.

Twenty elite ultra-marathoners and ironman distance triathletes performed a maximal graded exercise test and a 180 min submaximal run at 64% VO2max on a treadmill to determine metabolic responses. One group habitually consumed a traditional high-carbohydrate (HC: n=10, %carbohydrate:protein:fat = 59:14:25) diet, and the other a low-carbohydrate (LC; n=10, 10:19:70) diet for an average of 20 mo (range 9 to 36 mo).

Peak fat oxidation was 2.3-fold higher in the LC group (1.54 ± 0.18 vs 0.67 ± 0.14 g/min; P=0.000) and it occurred at a higher percentage of VO2max (70.3 ± 6.3 vs 54.9 ± 7.8%; P=0.000). Mean fat oxidation during submaximal exercise was 59% higher in the LC group (1.21 ± 0.02 vs 0.76 ± 0.11 g/min; P=0.000) corresponding to a greater relative contribution of fat (88 ± 2 vs 56 ± 8%; P=0.000). Despite these marked differences in fuel use between LC and HC athletes, there were no significant differences in resting muscle glycogen and the level of depletion after 180 min of running (−64% from pre-exercise) and 120 min of recovery (−36% from pre-exercise).

Compared to highly-trained ultra-endurance athletes consuming a HC diet, long-term keto-adaptation results in extraordinarily high rates of fat oxidation, whereas muscle glycogen utilization and repletion patterns during and after a 3 hr run are similar.
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