Abstract
Blood-brain barrier permeability to L-lactate was studied in 18 patients with the double indicator technique. Venous outflow curves were obtained during normo- and hypercapnia and were analyzed by means of a model that takes tracer backflux and capillary heterogeneity of transit times into account. The average unidirectional extraction of L-lactate was 15%; the transport from the blood to the brain (PS1) was 0.081 ml g-1 min-1 and the transport from the brain to the blood (PS2) was on the same order of magnitude. In hypercapnia, arterial pH decreased from 7.39 to 7.26 and PS1 to L-lactate increased significantly by 110%. PS2 also increased although a statistically significant difference compared to the resting state was not reached. It is concluded that L-lactate is easily taken up by the human brain, and that the mechanism by which it crosses the blood-brain barrier is equilibrative. Furthermore, the brain permeability to lactate is enhanced by hypercapnia and the mechanism is believed to act through the decrease in pH.
https://www.ncbi.nlm.nih.gov/pubmed/2050746/
Kinetic analysis of the human blood-brain barrier transport of lactate and its influence by hypercapnia.
Effect of Low-Carbohydrate-Ketogenic Diet on Metabolic and Hormonal Responses to Graded Exercise in Men
“Summary:
The following information was written by Atkins professionals.
This study evaluated the effect a ketogenic diet had on the exercise capacity of eight healthy men. Subjects were placed in either a mixed diet group or a ketogenic group. The ketogenic diet consisted of 50% of calories derived from fat, 45% from protein and 5% from carbohydrate. After three days on the diet, subjects performed an exercise test in which they worked out at varying intensities. In comparison to subjects on the mixed diet, those on the ketogenic diet displayed increased maximal oxygen consumption (the amount of oxygen taken in by the lungs per minute, which is an excellent predictor of overall fitness). Moreover, the ketogenic subjects showed a decreased respiratory exchange ratio, meaning more fat was burned for energy. Finally, the ketogenic group showed a shift in the lactate threshold toward higher exercise loads. When the amount of lactate in the blood reaches a certain level at a certain intensity, performance is impaired; this point occurred after a longer duration of time at a higher intensity level of exercise. Blood lactic acid levels before and after exercise as well as blood pH were also lower. The ketogenic diet also lowered insulin concentration. The authors concluded that a short-term ketogenic diet does not impair, but in fact increases, aerobic exercise capacity, as indicated by an elevated maximal oxygen consumption and elevated lactate threshold.”
https://www.atkins.com/how-it-works/lib ... ise-in-men
The following information was written by Atkins professionals.
This study evaluated the effect a ketogenic diet had on the exercise capacity of eight healthy men. Subjects were placed in either a mixed diet group or a ketogenic group. The ketogenic diet consisted of 50% of calories derived from fat, 45% from protein and 5% from carbohydrate. After three days on the diet, subjects performed an exercise test in which they worked out at varying intensities. In comparison to subjects on the mixed diet, those on the ketogenic diet displayed increased maximal oxygen consumption (the amount of oxygen taken in by the lungs per minute, which is an excellent predictor of overall fitness). Moreover, the ketogenic subjects showed a decreased respiratory exchange ratio, meaning more fat was burned for energy. Finally, the ketogenic group showed a shift in the lactate threshold toward higher exercise loads. When the amount of lactate in the blood reaches a certain level at a certain intensity, performance is impaired; this point occurred after a longer duration of time at a higher intensity level of exercise. Blood lactic acid levels before and after exercise as well as blood pH were also lower. The ketogenic diet also lowered insulin concentration. The authors concluded that a short-term ketogenic diet does not impair, but in fact increases, aerobic exercise capacity, as indicated by an elevated maximal oxygen consumption and elevated lactate threshold.”
https://www.atkins.com/how-it-works/lib ... ise-in-men
Debbie