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Low carbohydrate, high fat diet impairs exercise economy and negates the performance benefit from intensified training in elite race walkers

Burke, LM and Ross, ML and Garvican-Lewis, LA and Welvaert, M and Heikura, IA and Forbes, SG and Mirtschin, JG and Cato, LE and Strobel, N and Sharma, AP and Hawley, JA (2016) Low carbohydrate, high fat diet impairs exercise economy and negates the performance benefit from intensified training in elite race walkers. The Journal of Physiology, 595 (9). pp. 2785-2807. ISSN 0022-3751

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Abstract

We investigated the effects of adaptation to a ketogenic low carbohydrate (CHO), high fat diet (LCHF) during 3 weeks of intensified training on metabolism and performance of world-class endurance athletes. We controlled three isoenergetic diets in elite race walkers: high CHO availability (g kg−1 day−1: 8.6 CHO, 2.1 protein, 1.2 fat) consumed before, during and after training (HCHO, n = 9); identical macronutrient intake, periodised within or between days to alternate between low and high CHO availability (PCHO, n = 10); LCHF (< 50 g day−1 CHO; 78% energy as fat; 2.1 g kg−1 day−1 protein; LCHF, n = 10). Post-intervention, ˙V O2peak during race walking increased in all groups (P < 0.001, 90% CI: 2.55, 5.20%). LCHF was associated with markedly increased rates of whole-body fat oxidation, attaining peak rates of 1.57±0.32 gmin−1 during 2 h of walking at 80% ˙V O2peak.However, LCHFalso increased the oxygen (O2) cost of race walking at velocities relevant to real-life race performance: O2 uptake (expressed as a percentage of new ˙V O2peak) at a speed approximating 20 km race pace was reduced in HCHO and PCHO (90% CI:−7.047,−2.55 and−5.18,−0.86, respectively), but was maintained at pre-intervention levels in LCHF. HCHO and PCHO groups improved times for 10 km race walk: 6.6% (90% CI: 4.1, 9.1%) and 5.3% (3.4, 7.2%), with no improvement (−1.6% (−8.5, 5.3%)) for the LCHF group. In contrast to training with diets providing chronic or periodised high-CHO availability, and despite a significant improvement in ˙V O2peak, adaptation to the topical LCHF diet negated performance benefits in elite endurance athletes, in part due to reduced exercise economy.

Item Type: Article
Additional Information: This is the accepted version of the following article: Burke, L. M., Ross, M. L., Garvican-Lewis, L. A., Welvaert, M., Heikura, I. A., Forbes, S. G., Mirtschin, J. G., Cato, L. E., Strobel, N., Sharma, A. P. and Hawley, J. A. (2017), Low carbohydrate, high fat diet impairs exercise economy and negates the performance benefit from intensified training in elite race walkers. J Physiol, 595: 2785–2807. doi:10.1113/JP273230, which has been published in final form at http://dx.doi.org/10.1113/JP273230
Uncontrolled Keywords: 06 Biological Sciences, 11 Medical And Health Sciences
Subjects: T Technology > TX Home economics > TX341 Nutrition. Foods and food supply
Q Science > QP Physiology
R Medicine > RC Internal medicine > RC1200 Sports Medicine
Divisions: Sport & Exercise Sciences
Publisher: Wiley
Related URLs:
Date Deposited: 22 Nov 2017 13:01
Last Modified: 22 Nov 2017 13:01
DOI or Identification number: 10.1113/JP273230
URI: http://researchonline.ljmu.ac.uk/id/eprint/7588

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