Does fasting effect athletic performance?
The better question may be at what point does your brain say
"hey buddy, I cannot keep this level of performance up?
Does this have to do with fasting , low carb or glycogen sparing?
Liver glycogen is rapidly restored during post exercise feeding helping ensure the maintenance of normal blood glucose. Even when carbohydrates are not ingested after exercise, glycogen repletion can occur at slow rates (1–2 mmol/kg wet weight/h) from gluconeogenesis and the conversion of lactate to glucose.
This depletion however does not infer complete zero or empty but rather a state that your brain feels is a minimum requirement for your current stress adaption.
Approximately 90 minutes of moderate-high intensity exercise liver glycogen stores will be depleted.
Where stores are low this can occur with 25 minutes of higher intensity exercise. Heart rates above 70% of max.
Signs and Symptom of Glycogen Depletion
Decreased Strength and power. ...
Increased Rate of Perceived Exertion. ...
Feeling of “Flatness” in Muscle
Bellies. ... Increase Weight Loss (Water) overnight. ...
Lack of Recovery. ...
Decrease exercise-Performance During Longer intense Workouts.
Where glycogen has been depleted and low intensity exercise ( below 70% of max HR ) is attempted there appears to be no time frame other than physical preparedness.
In conclusion then its not the level of glycogen available that effects athletic performance but rather the adaption to the stress of performing at lower glycogen levels.
For the non athlete the above applies to general extended fasting. Adaption to the lower glycogen levels will improve performance over time and the signs and symptoms of depleted glycogen will diminish.
For those starting out looking to do extended fasts I recommend first:
1.Breakfast to satiety increasing window of no hunger to 8 hrs
2. With 1 complete have your second meal and then do 16/8. Basically eat again at breakfast.
3.When 2 is comfortably achieved push breakfast to breakfast. 23/1
4.Now you are ready for an extended 36 hour.
At 36 hour plus we start seeing the real benefits of autophagy.