КЕТОДИТЕА В ТЕЧЕНИИ 20 МЕСЯЦЕВ СЕРЬЕЗНО ПОВЫСИЛА УТИЛИЗАЦИЮ ЖИРОВ У УЛЬТРАМАРАФОНЦЕВ НО НЕ ПОВЛИЯЛО НА ТРАТУ ГЛИКОГЕНА, ОН ПО ПРЕЖНЕМУ ТРАТИЛСЯ. http://www.ncbi.nlm.nih.gov/pubmed/26892521?dopt=Abstract
ЭТО МОЖНО ТРАКТОВАТЬ КАК ТО, ЧТО В СОРЕВНОВАТЕЛЬНЫХ УСЛОВИЯХ ПОТРЕБЛЕНИЕ ЖИРОВ НЕ ИМЕЕТ СУЩЕСТВЕННОГО ЗНАЧЕНИЯ, В ВИЖУ ТОГО ЧТО РАБОТА ВЫПОЛНЯЕТСЯ НА ГЛИКОГЕНЕ
Если прочитать не только абстракт, то можно увидеть, что большая часть работы в обеих группах выполнялась как раз-таки на жирах, что в LC группе потребление жиров было на 57% выше, что саму по себе диету LC-группы (80+ грамм углеводов в день) сложно назвать кетогенной (кетогенная — меньше 30 грамм в день), что есть исследования с другими результатами и т.д. Наконец, это все применимо для длительных циклических видов спорта, напоминающих бег на дальние дистанции. В других видах спорта будут другие шаблоны потребления энергии.
At rest prior to exercise, the RER was significantly (P = 0.000) lower in the LC (0.72 ± 0.05) than the HC (0.86 ± 0.08) group, indicating a contribution from fat of 95 vs 47%, respectively. During 3 hours of exercise, RER fluctuated between 0.73 and 0.74 translating into relatively stable and higher fat oxidation rates of ~ 1.2 g/min in the LC group, whereas fat oxidation values were significantly lower in the HC group at all time points (Fig. 3A). The rate of carbohydrate oxidation in the LC group was stable during exercise and significantly (P = 0.000) lower than the HC group (Fig. 3B). The average contribution of fat during exercise in the LC and HC groups were 88% and 56%, respectively.
[…] Interestingly, in all ten LC athletes the total amount of carbohydrate oxidized during the 3 hour run as calculated from indirect calorimetry (mean ± SD; 64 ± 25 g) was lower than the total amount of glycogen disappearance (mean ± SD; 168 ± 65 g), assuming 10 kg of active tissue.
[…] Carbohydrate oxidation was significantly lower in the LC ultra-endurance runners, but unexpectedly muscle glycogen concentrations were not different between groups. It was previously reported that a 4 week ketogenic diet in elite cyclists decreased resting muscle glycogen by half and the rate of glycogen use during exercise by 4-fold [10]. Other studies have shown that a low-carbohydrate/high-fat diet decreases resting glycogen and the rate of glycogen use during submaximal exercise [15,25].
[…] The different glycogen responses could also be due to lower carbohydrate intake, which was < 10 g/day in cyclists [10] versus 86 g/day in the LC runners.
[…] The muscle glycogen responses in the LC athletes share some similarities to that of highly trained Alaskan sled dogs [26,27]. Sled dogs have an innately high endurance capacity and often perform several hours of running at submaximal intensity while consuming a high-fat/low-carbohydrate diet. Dogs running 160 km/day for 5 days showed no cumulative muscle glycogen depletion despite eating a diet consisting of only 15% carbohydrate [26].
[…] A more recent study reported that trained Alaskan sled dogs eating a 16% carb diet showed an unexpected high rate of carbohydrate oxidation during exercise that was associated with a significant increase in gluconeogenesis from glycerol and increased lactate oxidation [28]. Thus, highly trained high-fat adapted sled dogs show very different fuel utilization patterns than would be predicted based on studies done in trained humans eating a high-carbohydrate diet.
[…] A provocative finding was that LC athletes appeared to break down substantially more glycogen (> 100 g) than the total amount of carbohydrate oxidized during the 3 hour run. This was the case in all ten LC athletes. Why would athletes with high rates of acetyl CoA generation from fatty acids bother breaking down muscle glycogen if those carbons are not terminally oxidized? Although speculative, we believe that the reason may be to provide a source of glucose for the pentose phosphate pathway (PPP) and a source of pyruvate to form oxaloacetate.
[…] The enhanced ability to oxidize fat during exercise across a range of intensities is striking, as is the ability to maintain “normal” glycogen concentrations in the context of limited carbohydrate intake. Keto-adaptation provides an alternative to the supremacy of the high-carbohydrate paradigm for endurance athletes.
http://www.sciencedirect.com/science/article/pii/S0026049515003340
