Louise M Burke1,2, Avish P Sharma1,3, Ida A Heikura1,2, Sara F Forbes1, Melissa Holloway1, Alannah K A McKay1,4,5, Julia L Bone1,2, Jill J Leckey2, Marijke Welvaert1,6, Megan L Ross1,2. 1. Australian Institute of Sport, Canberra, Australia. 2. Mary MacKillop Institute for Health Research, Australian Catholic University, Melbourne, Australia. 3. Griffith Sports Physiology and Performance, School of Allied Health Sciences, Griffith University, Gold Coast, Australia. 4. School of Human Sciences (Exercise and Sport Science), The University of Western Australia, Crawley, WA, Australia. 5. Western Australian Institute of Sport, Mt Claremont, WA, Australia. 6. University of Canberra Research Institute for Sport and Exercise, Canberra, Australia.
Abstract
INTRODUCTION: We repeated our study of intensified training on a ketogenic low-carbohydrate (CHO), high-fat diet (LCHF) in world-class endurance athletes, with further investigation of a "carryover" effect on performance after restoring CHO availability in comparison to high or periodised CHO diets. METHODS: After Baseline testing (10,000 m IAAF-sanctioned race, aerobic capacity and submaximal walking economy) elite male and female race walkers undertook 25 d supervised training and repeat testing (Adapt) on energy-matched diets: High CHO availability (8.6 g∙kg-1∙d-1 CHO, 2.1 g∙kg-1∙d-1 protein; 1.2 g∙kg-1∙d-1 fat) including CHO before/during/after workouts (HCHO, n = 8): similar macronutrient intake periodised within/between days to manipulate low and high CHO availability at various workouts (PCHO, n = 8); and LCHF (<50 g∙d-1 CHO; 78% energy as fat; 2.1 g∙kg-1∙d-1 protein; n = 10). After Adapt, all athletes resumed HCHO for 2.5 wk before a cohort (n = 19) completed a 20 km race. RESULTS: All groups increased VO2peak (ml∙kg-1∙min-1) at Adapt (p = 0.02, 95%CI: [0.35-2.74]). LCHF markedly increased whole-body fat oxidation (from 0.6 g∙min-1 to 1.3 g∙min-1), but also the oxygen cost of walking at race-relevant velocities. Differences in 10,000 m performance were clear and meaningful: HCHO improved by 4.8% or 134 s (95% CI: [207 to 62 s]; p < 0.001), with a trend for a faster time (2.2%, 61 s [-18 to +144 s]; p = 0.09) in PCHO. LCHF were slower by 2.3%, -86 s ([-18 to -144 s]; p < 0.001), with no evidence of superior "rebound" performance over 20 km after 2.5 wk of HCHO restoration and taper. CONCLUSION: Our previous findings of impaired exercise economy and performance of sustained high-intensity race walking following keto-adaptation in elite competitors were repeated. Furthermore, there was no detectable benefit from undertaking an LCHF intervention as a periodised strategy before a 2.5-wk race preparation/taper with high CHO availability. TRIAL REGISTRATION: Australia New Zealand Clinical Trial Registry: ACTRN12619000794101.
INTRODUCTION: We repeated our study of intensified training on a ketogenic low-carbohydrate (CHO), high-fat diet (LCHF) in world-class endurance athletes, with further investigation of a "carryover" effect on performance after restoring CHO availability in comparison to high or periodised CHO diets. METHODS: After Baseline testing (10,000 m IAAF-sanctioned race, aerobic capacity and submaximal walking economy) elite male and female race walkers undertook 25 d supervised training and repeat testing (Adapt) on energy-matched diets: High CHO availability (8.6 g∙kg-1∙d-1 CHO, 2.1 g∙kg-1∙d-1 protein; 1.2 g∙kg-1∙d-1 fat) including CHO before/during/after workouts (HCHO, n = 8): similar macronutrient intake periodised within/between days to manipulate low and high CHO availability at various workouts (PCHO, n = 8); and LCHF (<50 g∙d-1 CHO; 78% energy as fat; 2.1 g∙kg-1∙d-1 protein; n = 10). After Adapt, all athletes resumed HCHO for 2.5 wk before a cohort (n = 19) completed a 20 km race. RESULTS: All groups increased VO2peak (ml∙kg-1∙min-1) at Adapt (p = 0.02, 95%CI: [0.35-2.74]). LCHF markedly increased whole-body fat oxidation (from 0.6 g∙min-1 to 1.3 g∙min-1), but also the oxygen cost of walking at race-relevant velocities. Differences in 10,000 m performance were clear and meaningful: HCHO improved by 4.8% or 134 s (95% CI: [207 to 62 s]; p < 0.001), with a trend for a faster time (2.2%, 61 s [-18 to +144 s]; p = 0.09) in PCHO. LCHF were slower by 2.3%, -86 s ([-18 to -144 s]; p < 0.001), with no evidence of superior "rebound" performance over 20 km after 2.5 wk of HCHO restoration and taper. CONCLUSION: Our previous findings of impaired exercise economy and performance of sustained high-intensity race walking following keto-adaptation in elite competitors were repeated. Furthermore, there was no detectable benefit from undertaking an LCHF intervention as a periodised strategy before a 2.5-wk race preparation/taper with high CHO availability. TRIAL REGISTRATION: Australia New Zealand Clinical Trial Registry: ACTRN12619000794101.
Authors: Louise M Burke; Avish P Sharma; Ida A Heikura; Sara F Forbes; Melissa Holloway; Alannah K A McKay; Julia L Bone; Jill J Leckey; Marijke Welvaert; Megan L Ross Journal: PLoS One Date: 2020-06-26 Impact factor: 3.240
Authors: David J Dearlove; Adrian Soto Mota; David Hauton; Katherine Pinnick; Rhys Evans; Jack Miller; Roman Fischer; James S O Mccullagh; Leanne Hodson; Kieran Clarke; Pete J Cox Journal: Physiol Rep Date: 2022-05
Authors: Rieneke Terink; Renger F Witkamp; Maria T E Hopman; Els Siebelink; Huub F J Savelkoul; Marco Mensink Journal: Nutrients Date: 2021-01-06 Impact factor: 5.717
Authors: Jamie Whitfield; Louise M Burke; Alannah K A McKay; Ida A Heikura; Rebecca Hall; Nikita Fensham; Avish P Sharma Journal: Med Sci Sports Exerc Date: 2021-04-01