TY - JOUR
T1 - Crisis of confidence averted
T2 - Impairment of exercise economy and performance in elite race walkers by ketogenic low carbohydrate, high fat (LCHF) diet is reproducible
AU - Burke, Louise M.
AU - Sharma, Avish P.
AU - Heikura, Ida A.
AU - Forbes, Sara F.
AU - Holloway, Melissa
AU - McKay, Alannah K. A.
AU - Bone, Julia L.
AU - Leckey, Jill J.
AU - Welvaert, Marijke
AU - Ross, Megan L.
N1 - Funding Information:
This study was funded by a Program Grant from the Australian Catholic University Research Funds to Professor Louise Burke (ACURF, 2017000034).
Publisher Copyright:
© 2020 Burke et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
PY - 2020/6/4
Y1 - 2020/6/4
N2 - 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 VO 2peak (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.
AB - 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 VO 2peak (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.
UR - http://www.scopus.com/inward/record.url?scp=85086008611&partnerID=8YFLogxK
U2 - 10.1371/journal.pone.0234027
DO - 10.1371/journal.pone.0234027
M3 - Article
SN - 1932-6203
VL - 15
SP - 1
EP - 31
JO - PLoS One
JF - PLoS One
IS - 6
M1 - 0235592
ER -