Adaptation to a low carbohydrate high fat diet is rapid but impairs endurance exercise metabolism and performance despite enhanced glycogen availability.
Adaptation to a low carbohydrate high fat diet is rapid but impairs endurance exercise metabolism and performance despite enhanced glycogen availability.
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DOI：
10.1113/jp280221
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发表时间：
2021-03
期刊：
影响因子：
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通讯作者：
Sharma AP
中科院分区：
文献类型：
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作者：
Burke LM;Whitfield J;Heikura IA;Ross MLR;Tee N;Forbes SF;Hall R;McKay AKA;Wallett AM;Sharma AP
在精英运动员中，短暂（5 - 6天）适应低碳水化合物高脂肪饮食使运动脂肪氧化增加到先前在中等（3 - 4周）或长期（> 12个月）坚持这种饮食时观察到的速率，代谢变化在类似的时间范围内被清除。运动中脂肪利用率的增加与奥运会项目比赛速度下耗氧量增加5 - 8%有关。内源性碳水化合物（CHO）可用性的急性恢复（24小时高CHO饲料，赛前CHO）仅部分恢复了比赛热身期间的底物利用率。脂肪氧化继续升高至高于基线值，尽管低于5 - 6天的酮适应; CHO氧化仅达到先前在与比赛事件相关的运动强度下观察到的值的61%和78%。CHO可用性的急性恢复未能逆转先前与低碳水化合物高脂肪适应相关的高强度耐力表现的损害，可能是由于CHO氧化能力减弱。我们研究了短暂（5 - 6天）适应生酮低碳水化合物（CHO）、高脂肪（LCHF）饮食和类似洗脱期后运动期间的底物利用。13名世界级男子竞走运动员完成了经济测试、25公里训练和1万米比赛（基准），具有高的CHO可用性（HCHO），重复这一点（适应）5 - 6天LCHF后（n = 7; CHO：<50 g/天;蛋白质：2.2 g/kg/天; 80%脂肪）或HCHO（n = 6; CHO：9.7 g/kg/天;蛋白质：2.2 g/kg/天）饮食。在24 h HCHO和赛前CHO（2 g kg − 1）饮食后进行适应性比赛，与基线比赛相同。在LCHF适应性经济和25公里测试中，运动脂肪氧化发生了实质性（> 200%）增加，达到了1.43 g min − 1的平均速率。然而，相对（ml min − 1 kg − 1）更高（P <0.0001），在50 km和20 km的速度下分别高出1.8%和5%。在LCHF组的适应性比赛热身期间，与前一天相比，这些速度下的脂肪和CHO氧化速率分别降低和升高（P <0.001），但未恢复至基线值。两组之间的表现变化不同（P = 0.009），所有HCHO运动员在适应比赛中提高（5.7（5.6）%），而6/7 LCHF运动员较慢（2.2（3.4）%）。在HCHO饲料5 - 6天后，底物利用率恢复至基线值。总之，运动底物使用的稳健变化发生在CHO摄入极端变化的5 - 6天内。然而，适应LCHF饮食加上内源性CHO可用性的急性恢复未能恢复高强度耐力表现，CHO氧化速率保持钝化。在精英运动员中，短暂（5 - 6天）适应低碳水化合物高脂肪饮食使运动脂肪氧化增加到先前在中等（3 - 4周）或长期（> 12个月）坚持这种饮食时观察到的速率，代谢变化在类似的时间范围内被清除。运动中脂肪利用率的增加与奥运会项目比赛速度下耗氧量增加5 - 8%有关。内源性碳水化合物（CHO）可用性的急性恢复（24小时高CHO饲料，赛前CHO）仅部分恢复了比赛热身期间的底物利用率。脂肪氧化继续升高至高于基线值，尽管低于5 - 6天的酮适应; CHO氧化仅达到先前在与比赛事件相关的运动强度下观察到的值的61%和78%。CHO可用性的急性恢复未能逆转先前与低碳水化合物高脂肪适应相关的高强度耐力表现的损害，可能是由于CHO氧化能力减弱。
Brief (5–6 days) adaptation to a low carbohydrate high fat diet in elite athletes increased exercise fat oxidation to rates previously observed with medium (3–4 weeks) or chronic (>12 months) adherence to this diet, with metabolic changes being washed out in a similar time frame. Increased fat utilisation during exercise was associated with a 5–8% increase in oxygen cost at speeds related to Olympic Programme races. Acute restoration of endogenous carbohydrate (CHO) availability (24 h high CHO diet, pre‐race CHO) only partially restored substrate utilisation during a race warm‐up. Fat oxidation continued to be elevated above baseline values although it was lower than achieved by 5–6 days’ keto adaptation; CHO oxidation only reached 61% and 78% of values previously seen at exercise intensities related to race events. Acute restoration of CHO availability failed to overturn the impairment of high‐intensity endurance performance previously associated with low carbohydrate high fat adaptation, potentially due to the blunted capacity for CHO oxidation. We investigated substrate utilisation during exercise after brief (5–6 days) adaptation to a ketogenic low‐carbohydrate (CHO), high‐fat (LCHF) diet and similar washout period. Thirteen world‐class male race walkers completed economy testing, 25 km training and a 10,000 m race (Baseline), with high CHO availability (HCHO), repeating this (Adaptation) after 5–6 days’ LCHF (n = 7; CHO: <50 g day−1, protein: 2.2 g kg−1 day−1; 80% fat) or HCHO (n = 6; CHO: 9.7 g kg−1 day−1; protein: 2.2 g kg−1 day−1) diet. An Adaptation race was undertaken after 24 h HCHO and pre‐race CHO (2 g kg−1) diet, identical to the Baseline race. Substantial (>200%) increases in exercise fat oxidation occurred in the LCHF Adaptation economy and 25 km tests, reaching mean rates of ∼1.43 g min−1. However, relative (ml min−1 kg−1) was higher (P < 0.0001), by ∼8% and 5% at speeds related to 50 km and 20 km events. During Adaptation race warm‐up in the LCHF group, rates of fat and CHO oxidation at these speeds were decreased and increased, respectively (P < 0.001), compared with the previous day, but were not restored to Baseline values. Performance changes differed between groups (P = 0.009), with all HCHO athletes improving in the Adaptation race (5.7 (5.6)%), while 6/7 LCHF athletes were slower (2.2 (3.4)%). Substrate utilisation returned to Baseline values after 5–6 days of HCHO diet. In summary, robust changes in exercise substrate use occurred in 5–6 days of extreme changes in CHO intake. However, adaptation to a LCHF diet plus acute restoration of endogenous CHO availability failed to restore high‐intensity endurance performance, with CHO oxidation rates remaining blunted. Brief (5–6 days) adaptation to a low carbohydrate high fat diet in elite athletes increased exercise fat oxidation to rates previously observed with medium (3–4 weeks) or chronic (>12 months) adherence to this diet, with metabolic changes being washed out in a similar time frame. Increased fat utilisation during exercise was associated with a 5–8% increase in oxygen cost at speeds related to Olympic Programme races. Acute restoration of endogenous carbohydrate (CHO) availability (24 h high CHO diet, pre‐race CHO) only partially restored substrate utilisation during a race warm‐up. Fat oxidation continued to be elevated above baseline values although it was lower than achieved by 5–6 days’ keto adaptation; CHO oxidation only reached 61% and 78% of values previously seen at exercise intensities related to race events. Acute restoration of CHO availability failed to overturn the impairment of high‐intensity endurance performance previously associated with low carbohydrate high fat adaptation, potentially due to the blunted capacity for CHO oxidation.