Skip to main content
Article
Metabolic characteristics of keto-adapted ultra-endurance runners
Metabolism (2016)
  • Jeff S. Volek
  • Daniel Freidenreich, Rowan University
  • 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
Abstract
Background

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.

Methods

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 months (range 9 to 36 months).

Results

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).

Conclusion

Compared to highly trained ultra-endurance athletes consuming an 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 hour run are similar.
Keywords
  • carbohydrate,
  • fat,
  • metabolism,
  • exercise,
  • glycogen
Disciplines
Publication Date
March, 2016
DOI
10.1016/j.metabol.2015.10.028
Citation Information
Jeff S. Volek, Daniel Freidenreich, Catherine Saenz, Laura J. Kunces, et al.. "Metabolic characteristics of keto-adapted ultra-endurance runners" Metabolism Vol. 65 Iss. 3 (2016) p. 100 - 110 ISSN: 0026-0495
Available at: http://works.bepress.com/daniel-freidenreich/5/
Creative Commons license
Creative Commons License
This work is licensed under a Creative Commons CC_BY-NC-ND International License.