time vs. speed
- Thread starter Izzo777
- Start date
Hmm, well in the first case you are staying below your threshold and using more slow twitch and in the second your heart rate will be higher and your body will burn a different source.
Great question....one I've pondered & explored as well. I often find myself bike riding alone with my thoughts and I've come to a few conclusions (based on thinking about it and then researching and getting the answers).
If I weigh 230 pounds and I ride my bike some 14 miles from my car, to the site and back again....wouldn't it figure that the amount of energy expended would be constant regardless of rate? I figure the amount of energy required to move a certain weight a certain distance would be a fairly fixed thing....but it's not, at least not when it comes to our human bodies.
By wearing a heart-rate monitor with a calorie counter I've been able to dabble with this notion. Bear in mind, the calorie-counter is entirely based on measuring heart-rate and contrasting it against an algorhythm programmed into the unit...but still, it gives some info. From my rides I've been able to figure our bodies are more efficient (burning less calories) when we exercise at a modest/mild rate. By contrast, when I ride with a faster rider and attempt to keep-up, I maintain a higher heart-rate and my projected caloric burn is much higher for the same given trip. So there's one aspect of it.
The other aspect is, what's happening in our bodies? Well...a lot of commonly understood theory suggest that we burn more actual fat at a lower/steady exertion rate. Let's cover some of what I call "Fuel Theory"
Your body has basically 3 forms of stored energy:
Creatine-Phosphate/ATP
Glycogen
Fat
The common mistake is to think that your body only burns a single one of these at any given time. No. We don't have an exclusive fuel-selector switch...at all times we source a combination from all three of these!!!
Fat is pretty much your reserve, popular thoery suggest you don't even begin to tap into your fat reserves until your blood-sugar level starts to drop (after approx. 20 minutes of exercise). Even at that, fat is metabolized and burned very slowly...think of it as wood.
Glycogen is more explosive, think of it as gasoline. You only have so much stored in your muscle and this is what you're mostly using with moderate/heavy exercise.
Creatine-Phospate/ATP is your dynamite...it burns anarobically (without oxygen), gives you a nasty lactate burning and is mostly firing when you're at top form.
To answer your question....LISS (Low Intensity Steady State) exercise is more prone to focusing on burning fat as a fuel. As your intensity increases the body will source more explosive fuel to meet your demands, so more glycogen is used. BUT YOU STILL KEEP BURNING FAT and even burn fat at a faster rate.....but you start dialing in a greater proportion of glycogen as your needs & demand rise with intensity.
It's a commonly misunderstood notion that pushing yourself to a higher level will switch to glycogen and use less fat...but that's inaccurate; your still burning just as much or more fat, just also adding glycogen!
Now....here's the thing: when you exercise at a low/med intensity you will burn calories...but once you stop exercising you entirely return to your normal resting metabolism and there is no prolonged benefits (EPOC).
The benefits of exercising at a higher intensity is that you burn calories as you exercise AND for an extended period afterwards! This is the acclaimed benefits of HIIT (High Intensity Interval Training).
Bottom line: mix it up, do what you feel comfortable and just maintain an overall healthy direction.
Bikeswimlaugh - good response...all of that was what I was alluding too but you did a great job expanding!
Hey, sounds like youve been learning quite vigourously, just a few things i wanted to reply on.
Just like a car. Same distance, but if you rev harder you use more fuel.
Isnt this a very small amount though? I dont think ive ever heard it mentioned here before but what about the cellular adaptions from lowmid intensity. Increased oxidative enzymes, capillarisation, myoglobin etc - all contribute to the benefits related to non HIIT.
Just like a car. Same distance, but if you rev harder you use more fuel.
This is plain wrong. You dont think fat is a reserve do you? i think you mentioned somewhere that its always being used.
Glucose can also be used without oxygen. I think its a bit irrevelent with ATP/PC because the ATP is already made. Only lasts a few seconds after maximal intensity. Is hardly responsible for "lactate burning".
Isnt this a very small amount though? I dont think ive ever heard it mentioned here before but what about the cellular adaptions from lowmid intensity. Increased oxidative enzymes, capillarisation, myoglobin etc - all contribute to the benefits related to non HIIT.