Snowman
Level 6 Valued Member
As I've been moving through Al's Plans 103 and 104c, I've also been doing intermittent fasting on some days. For the most part, I've only fasted on days that I haven't trained, but occasionally I've trained at the end of a fasting period. Since it is alactic/aerobic training, I don't worry about blood sugar issues. This usually happens when I train at the middle/end of the day, and I'll just keep my prior food intake to a minimum, train, and then eat right afterwards. Anyways, to get to the point, I have noticed a consistent pattern emerge when training at the end of a fast.
My power output remains the same (as far as I can tell), I perceive the training as more difficult (though only slightly), and my heart rate is higher. To be more specific, my maximum HR is only about 5 bpm higher, and my minimum HR is about 10 bpm higher, meaning the gap between the two becomes smaller. I'm curious regarding peoples' thoughts on why this is, as well as any pros/cons of training this way.
My thoughts are as follows:
WHY
-I have heard that fasting stimulates the sympathetic nervous system (or that is simply 'under' stimulates the parasympathetic), which means I already have one foot in the boat of being a little uncomfortable and having a high HR thanks to my relatively spun up sympathetic system.
-At the end of a fast my glycogen levels may be a little low, and since even an A+A protocol uses glycolysis a little, my body may be 'freaking out' a little (there's probably a better way to phrase that) as I dip into my already low glycogen stores.
PROS
-I'm training my body to operate at a higher level of performance in a sub-optimal state, as well as training my mind that it's ok to feel that way.
-Since I'm already in a predominantly fat burning state and (maybe) have low glycogen stores when I start the session, I'm encouraging my body to utilize fatty acids instead of glucose when it's in an aerobic state.
-Perhaps I'm stimulating my body to produce more mitochondria as I impose physical demands on it while in a state that is not conducive to glycolysis. This might be stretching it.
CONS
-If I am over-stimulating my sympathetic nervous system, I could actually be stimulating a greater use of glycolysis, which could potentially run counter to my goals of increasing my aerobic capacity.
-It makes me sweat more and makes a not-particularly-comfortable experience marginally less comfortable.
Those are my thoughts, not all of which are founded in a solid understanding of the science. I would especially like to hear what people think about that first point on the cons list. I should note that my HR still remains below the ceiling of my MAF aerobic training zone throughout the fasted sessions.
My power output remains the same (as far as I can tell), I perceive the training as more difficult (though only slightly), and my heart rate is higher. To be more specific, my maximum HR is only about 5 bpm higher, and my minimum HR is about 10 bpm higher, meaning the gap between the two becomes smaller. I'm curious regarding peoples' thoughts on why this is, as well as any pros/cons of training this way.
My thoughts are as follows:
WHY
-I have heard that fasting stimulates the sympathetic nervous system (or that is simply 'under' stimulates the parasympathetic), which means I already have one foot in the boat of being a little uncomfortable and having a high HR thanks to my relatively spun up sympathetic system.
-At the end of a fast my glycogen levels may be a little low, and since even an A+A protocol uses glycolysis a little, my body may be 'freaking out' a little (there's probably a better way to phrase that) as I dip into my already low glycogen stores.
PROS
-I'm training my body to operate at a higher level of performance in a sub-optimal state, as well as training my mind that it's ok to feel that way.
-Since I'm already in a predominantly fat burning state and (maybe) have low glycogen stores when I start the session, I'm encouraging my body to utilize fatty acids instead of glucose when it's in an aerobic state.
-Perhaps I'm stimulating my body to produce more mitochondria as I impose physical demands on it while in a state that is not conducive to glycolysis. This might be stretching it.
CONS
-If I am over-stimulating my sympathetic nervous system, I could actually be stimulating a greater use of glycolysis, which could potentially run counter to my goals of increasing my aerobic capacity.
-It makes me sweat more and makes a not-particularly-comfortable experience marginally less comfortable.
Those are my thoughts, not all of which are founded in a solid understanding of the science. I would especially like to hear what people think about that first point on the cons list. I should note that my HR still remains below the ceiling of my MAF aerobic training zone throughout the fasted sessions.