8,153
edits
Changes
From Fellrnr.com, Running tips
no edit summary
*** WB had higher VO<sub>2</sub> on the Ketogenic Diet.
** It seems that the low carbohydrate diet is as likely to harm performance as it is to improve it, at least in this study.
* Blood levels of the [[Ketones| Ketone]] 3-hydroxybutyrate (BOHB), which indicates ketogenisis, were insignificant at rest (0.04 mmol/L) on the normal diet and elevated (1.28 mmol/L) on the [[Ketogenic Diet]]. This level of resting BOHB is quite low compared with some levels seen on the ketogenic diet. After the endurance test, the high carbohydrate diet resulted in a slightly elevated blood ketone level of 0.46 mmol/L, which is below the threshold that would normally be considered ketogenic. Rather interestingly, on the ketogenic diet the athletes blood ketone levels actually rose to finish at 2.44 mmol/L. this is a little different to other reports, where led ketone levels start higher, and actually fall during endurance exercise.
* Unlike typical fat metabolism, the oxygen cost of calories was not different on the [[Ketogenic Diet]]. This is a huge deal, as the big problem with burning fat is that it requires more Oxygen to produce the same amount of energy. However Phinney provides no details of the power outputs.
* The RQ on the VO2max test dropped from 1.04 to 0.9, and on the endurance test from 0.83 to 0.72, indicating a shift in substrate metabolism. However, because Ketone metabolism can produce RQ values that vary significantly, it's not possible to estimate what fuel is being metabolized<ref name="Schutz-1980"/>. (The conversion of fat to Ketones consumes Oxygen without producing Carbon dioxide, the metabolism of Ketones has an RQ of 1.0, with the overall RQ matching that of Fat<ref name="Schutz-1980"/>.)
* The low carbohydrate test was four weeks after the high carbohydrate test, which means the athletes had an extra four weeks of training, which is hard to account for. It seems likely that the athletes should have performed better on the second test, suggesting the low carb diet offset the extra training.
* Blood glucose during the endurance test was similar after the [[Ketogenic Diet]] to before, but the rise and fall were somewhat reduced. At no point did blood glucose drop to the point of hypoglycemia. Blood glucose provided an estimated 28% of calories on the normal diet and 9% of calories on the Ketogenic Diet.
* Muscle [[Glycogen]] levels where higher before the endurance test on the normal diet than on the [[Ketogenic Diet]] (143 and 53 respectively). Both tests had similar muscle glycogen levels after the endurance tests. It is interesting to see that muscle glycogen levels were replenished somewhat on the [[Ketogenic Diet]], even though the subjects continued normal training for the four weeks.
{| class="wikitable" style="margin-left: auto; margin-right: auto; border: none;"
!
! Endurace-1
! Endurance-2
|-
| Average
| |
| 4%
| |
| -63%
| 75.5
|
| -24%
| 10%
| -38%
| |
| 2%
|
|-
| Exclude WB
| |
| 13%
| |
| -65%
| 73.8
|
| -24%
| 12%
| -41%
| |
| -1%
|
