PMID- 28012184 OWN - NLM STAT- MEDLINE DCOM- 20180207 LR - 20220409 IS - 1469-7793 (Electronic) IS - 0022-3751 (Print) IS - 0022-3751 (Linking) VI - 595 IP - 9 DP - 2017 May 1 TI - Low carbohydrate, high fat diet impairs exercise economy and negates the performance benefit from intensified training in elite race walkers. PG - 2785-2807 LID - 10.1113/JP273230 [doi] AB - KEY POINTS: Three weeks of intensified training and mild energy deficit in elite race walkers increases peak aerobic capacity independent of dietary support. Adaptation to a ketogenic low carbohydrate, high fat (LCHF) diet markedly increases rates of whole-body fat oxidation during exercise in race walkers over a range of exercise intensities. The increased rates of fat oxidation result in reduced economy (increased oxygen demand for a given speed) at velocities that translate to real-life race performance in elite race walkers. In contrast to training with diets providing chronic or periodised high carbohydrate availability, adaptation to an LCHF diet impairs performance in elite endurance athletes despite a significant improvement in peak aerobic capacity. 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, V̇O2 peak 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 g min(-1) during 2 h of walking at approximately 80% V̇O2 peak . However, LCHF also increased the oxygen (O(2) ) cost of race walking at velocities relevant to real-life race performance: O(2) uptake (expressed as a percentage of new V̇O2 peak ) 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 V̇O2 peak , adaptation to the topical LCHF diet negated performance benefits in elite endurance athletes, in part due to reduced exercise economy. CI - (c) 2016 The Authors. The Journal of Physiology published by John Wiley & Sons Ltd on behalf of The Physiological Society. FAU - Burke, Louise M AU - Burke LM AD - Sports Nutrition, Australian Institute of Sport, Canberra, Australia, 2616. AD - Mary MacKillop Institute for Health Research, Australian Catholic University, Melbourne, Australia, 3000. FAU - Ross, Megan L AU - Ross ML AD - Sports Nutrition, Australian Institute of Sport, Canberra, Australia, 2616. AD - Mary MacKillop Institute for Health Research, Australian Catholic University, Melbourne, Australia, 3000. FAU - Garvican-Lewis, Laura A AU - Garvican-Lewis LA AD - Sports Nutrition, Australian Institute of Sport, Canberra, Australia, 2616. AD - Mary MacKillop Institute for Health Research, Australian Catholic University, Melbourne, Australia, 3000. FAU - Welvaert, Marijke AU - Welvaert M AD - University of Canberra Research Institute for Sport and Exercise, Canberra, Australia, 2617. AD - Innovation, Research and Development, Australian Institute of Sport, Canberra, Australia, 2616. FAU - Heikura, Ida A AU - Heikura IA AD - Sports Nutrition, Australian Institute of Sport, Canberra, Australia, 2616. AD - Mary MacKillop Institute for Health Research, Australian Catholic University, Melbourne, Australia, 3000. FAU - Forbes, Sara G AU - Forbes SG AD - Sports Nutrition, Australian Institute of Sport, Canberra, Australia, 2616. FAU - Mirtschin, Joanne G AU - Mirtschin JG AD - Sports Nutrition, Australian Institute of Sport, Canberra, Australia, 2616. FAU - Cato, Louise E AU - Cato LE AD - Sports Nutrition, Australian Institute of Sport, Canberra, Australia, 2616. FAU - Strobel, Nicki AU - Strobel N AD - University College Zealand, Ankerhus, Denmark. FAU - Sharma, Avish P AU - Sharma AP AD - Physiology, Australian Institute of Sport, Canberra, Australia, 2616. FAU - Hawley, John A AU - Hawley JA AD - Mary MacKillop Institute for Health Research, Australian Catholic University, Melbourne, Australia, 3000. AD - Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UK. LA - eng PT - Journal Article PT - Research Support, Non-U.S. Gov't DEP - 20170214 PL - England TA - J Physiol JT - The Journal of physiology JID - 0266262 SB - IM CIN - J Physiol. 2017 May 1;595(9):2775. PMID: 28044326 CIN - J Physiol. 2017 May 1;595(9):2777-2778. PMID: 28294339 CIN - J Physiol. 2017 May 1;595(9):2993-2994. PMID: 28452135 CIN - J Physiol. 2017 May 1;595(9):2989. PMID: 28452138 CIN - J Physiol. 2017 May 1;595(9):2991-2992. PMID: 28452139 MH - Adult MH - *Athletic Performance MH - Diet, Carbohydrate-Restricted/*adverse effects MH - Diet, High-Fat/*adverse effects MH - Humans MH - Lipid Metabolism MH - Male MH - Oxygen Consumption MH - *Physical Conditioning, Human MH - Walking/*physiology PMC - PMC5407976 OTO - NOTNLM OT - athletic performance OT - ketogenic diet OT - sports nutrition EDAT- 2016/12/25 06:00 MHDA- 2018/02/08 06:00 PMCR- 2017/02/14 CRDT- 2016/12/25 06:00 PHST- 2016/08/17 00:00 [received] PHST- 2016/11/23 00:00 [accepted] PHST- 2016/12/25 06:00 [pubmed] PHST- 2018/02/08 06:00 [medline] PHST- 2016/12/25 06:00 [entrez] PHST- 2017/02/14 00:00 [pmc-release] AID - TJP12142 [pii] AID - 10.1113/JP273230 [doi] PST - ppublish SO - J Physiol. 2017 May 1;595(9):2785-2807. doi: 10.1113/JP273230. Epub 2017 Feb 14.