 |
| Basic relationship between intensity and duration of exercise (1). |
Just as a car will not drive without fuel, our bodies will not perform without it. Thus, getting in shape requires working out and the right nutrition for fueling our energy production, and the meaning of 'right' nutrition is dependent upon the intensity and duration of the exercise in which you will be engaging. Put simply, this is because our bodies use different energy systems for different types of exercise. That said - take a few minutes to learn the basics! I promise in this post I have made complex concepts very simple for you to understand, and you WILL save yourself a very large amount of time, money, and frustration both now and in the long haul by simply investing a few minutes now. Understand how things work and you'll be able to make solid choices for yourself, regardless of the situation. It will just "make sense." For your body to perform work and function on any level, it
 |
| Energy metabolism (1). |
needs fuel (food) which goes through a chemical process to provide you with energy. ATP is a molecule that serves as a primary source of energy to be used during exercise, among other things. Your body processes nutrients and provides you with energy by generating this ATP in three different ways. It is NOT a one-rule-for-all gig and the energy systems used are very dependent upon the types & subsequent demands of exercises performed! In the most basic sense, the intensity and duration of whatever type of exercise you’re performing will determine which energy supply system/process(es) your body will use. So, it’s important to understand your nutrition requirements as they relate to YOU specifically - in other words, what you need more and/or less of and when, to compliment the energy system your body will use (and thus how much you will "get" out of your workouts) depending on the level of intensity + duration of whatever exercise(s) you specifically are performing. This is critical if you are to see the results you set out to achieve. My guess is if you are working your ___ off at the gym or elsewhere, you want it to pay off and you don't want to work against yourself or get in your own way. ;)
Here are the basics regarding the three energy systems.
You generate ATP(energy) in three ways:
1. ATP-PC system
2. Glycolysis
3. Oxidative/aerobic system
THE ATP-PC SYSTEM:
HELPFUL HINT: THIS IS YOUR 'IMMEDIATE' ENERGY SYSTEM
Just as quick background knowledge, this is an anaerobic system, and:
ATP = adenosine triphosphate
PC = phosphocreatine (notice the a word hidden in there?... phosphocreatine. ;) For those who may
not be aware, this is the system that deals with creatine and in turn, using creatine
supplementation.)
HOW IT WORKS:
ATP is used as energy. This happens when it splits off a phosphate group which is used as free energy. Once it is used, what's left over is ADP and one inorganic phosphate molecule called Pi. Don't let the long names intimidate you. It's really simple! The relationship can be thought of like this:
ATP <----> ADP + Pi + energy release
As you'd expect, something that is used up, is...well...used up! Makes sense. :) But wait! What happens when we still need more energy, and from this system? Well...what happens is this used up ATP has to be replenished before it can provide you with energy again. This is when PC comes into play. PC is another high energy molecule, and when combined with that left over ADP and Pi...boom! You have an ATP molecule for energy again. :) And that's the whole cycle and system, simplified. (Great, but who cares? You do. Particularly when strength training. Next, let's cover "who" cares and when to care about this system....)
WHEN IT IS USED:
Think of this as your short term, high-intensity energy system. What does that mean in the simplest form? WEIGHT TRAINING requiring maximum muscular output (maximum effort). This energy system is the simplest and fastest-delivering of the energy systems, which is why it is activated right away at the onset of your activity, and thus I will repeat...it is an essential means of energy production for high-weight/low rep strength training (weight lifting), explosive exercise (plyometrics), and other high-intensity/short-duration exercises that require quick, full effort bursts of power. It is also the system that deals with creatine. Creatine is very important to understand, and especially so in considering the benefits and drawbacks of potentially using creatine supplementation to enhance performance and energy production. So to fully understand how all of this works together, be sure to see this post about creatine/creatine supplementation. That post is very complimentary and important to understanding this one.
HELPFUL HINT: THIS IS YOUR 'IMMEDIATE' ENERGY SYSTEM
Just as quick background knowledge, this is an anaerobic system, and:
ATP = adenosine triphosphate
PC = phosphocreatine (notice the a word hidden in there?... phosphocreatine. ;) For those who may
not be aware, this is the system that deals with creatine and in turn, using creatine
supplementation.)
HOW IT WORKS:
ATP is used as energy. This happens when it splits off a phosphate group which is used as free energy. Once it is used, what's left over is ADP and one inorganic phosphate molecule called Pi. Don't let the long names intimidate you. It's really simple! The relationship can be thought of like this:
ATP <----> ADP + Pi + energy release
As you'd expect, something that is used up, is...well...used up! Makes sense. :) But wait! What happens when we still need more energy, and from this system? Well...what happens is this used up ATP has to be replenished before it can provide you with energy again. This is when PC comes into play. PC is another high energy molecule, and when combined with that left over ADP and Pi...boom! You have an ATP molecule for energy again. :) And that's the whole cycle and system, simplified. (Great, but who cares? You do. Particularly when strength training. Next, let's cover "who" cares and when to care about this system....)
WHEN IT IS USED:
Think of this as your short term, high-intensity energy system. What does that mean in the simplest form? WEIGHT TRAINING requiring maximum muscular output (maximum effort). This energy system is the simplest and fastest-delivering of the energy systems, which is why it is activated right away at the onset of your activity, and thus I will repeat...it is an essential means of energy production for high-weight/low rep strength training (weight lifting), explosive exercise (plyometrics), and other high-intensity/short-duration exercises that require quick, full effort bursts of power. It is also the system that deals with creatine. Creatine is very important to understand, and especially so in considering the benefits and drawbacks of potentially using creatine supplementation to enhance performance and energy production. So to fully understand how all of this works together, be sure to see this post about creatine/creatine supplementation. That post is very complimentary and important to understanding this one.
THE GLYCOLYSIS SYSTEM:
HELPFUL HINT: THIS IS YOUR 'SHORT-TERM' ENERGY SYSTEM
Just as quick background knowledge:
Aerobic = in the presence of oxygen
Anaerobic = in the absence of oxygen
HOW IT WORKS:
The glycolysis system isn't all that tricky to understand, but sometimes people get confused because this system itself can occur aerobically OR anaerobically. Let's quickly and briefly "uncomplicate" it. The glycolysis system as a whole produces ATP as energy for your body through the chemical breakdown of glucose or glycogen to pyruvic acid OR lactic acid.
WHETHER GLYCOLYSIS HAPPENS AEROBICALLY (WITH OXYGEN) OR ANAEROBICALLY (WITHOUT OXYGEN) THE PROCESS IS EXACTLY THE SAME. :) THE ONLY THING THAT CHANGES IN AEROBIC VS. ANAEROBIC GLYCOLYSIS IS THE END PRODUCT!... Aerobic glycolysis produces pyruvic acid. Anaerobic glycolysis produces lactic acid. Simple!
WHEN IT IS USED:
This system can provide you with a significantly greater amount of energy than the ATP-PC system (for reasons I left out for the sake of simplicity.) However, although it lasts longer than the "immediate" ATP-PC system, glycolysis too is limited to only about 30 - 50 seconds of exercise duration. But! It is a very common - if not to say THE most common - system used in most general fitness workouts, because most fitness workouts embrace a typical range of 8 - 12 reps, which falls within this 30 - 50 second time range.
THE OXIDATIVE/AEROBIC SYSTEM:
HELPFUL HINT: THIS IS YOUR 'LONG-TERM' ENERGY SYSTEM
HOW IT WORKS:
This is by far the most complicated system to understand! But I will hopefully make it easy for you to understand. :) I will leave out much of the detail that you probably don't need to learn for the purposes of just developing a basic understanding of how these systems work for your body. The oxidative/aerobic system generates ATP for energy by using SUBSTRATES (see above 'background knowledge' on substrates) with the aid of oxygen. This system uses the substrates: CARBS AND FATS.
The Oxidative System works through three component systems, which happen one after the other:
1. Aerobic glycolysis (yep - the one we already mentioned. Aerobic glycolysis is really a component
process of the Oxidative system; it uses oxygen. So it makes sense!)
2. The Krebs Cycle
3. The ETC (electron transport chain)
Here's the BASIC chain of events:
Aerobic glycolysis (which we already covered) occurs. It results in the production of pyruvic acid.
Just as quick background knowledge:
This system is also referred to as "oxidative phosphorylation." But who really cares about complicated and ridiculously long names for systems. I am just throwing in that term in case you ever see it referenced somewhere. :)
Substrates = the three main substrates are proteins, carbohydrates, and lipids (fats)
Acetyl CoA = an IMPORTANT molecule in METABOLISM. Stands for "acetyl coenzyme A."
Acetyl CoA = an IMPORTANT molecule in METABOLISM. Stands for "acetyl coenzyme A."
HOW IT WORKS:
This is by far the most complicated system to understand! But I will hopefully make it easy for you to understand. :) I will leave out much of the detail that you probably don't need to learn for the purposes of just developing a basic understanding of how these systems work for your body. The oxidative/aerobic system generates ATP for energy by using SUBSTRATES (see above 'background knowledge' on substrates) with the aid of oxygen. This system uses the substrates: CARBS AND FATS.
The Oxidative System works through three component systems, which happen one after the other:
1. Aerobic glycolysis (yep - the one we already mentioned. Aerobic glycolysis is really a component
process of the Oxidative system; it uses oxygen. So it makes sense!)
2. The Krebs Cycle
3. The ETC (electron transport chain)
Here's the BASIC chain of events:
Aerobic glycolysis (which we already covered) occurs. It results in the production of pyruvic acid.
The pyruvic acid is converted into Acetyl CoA (see above 'background knowledge' on this term.) Acetyl CoA then contributes substrates (carbs/fats) for use in the second process of the oxidative system: the Krebs Cycle. The oxidation of Acetyl CoA gives you 2 units of ATP, as well as carbon dioxide and hydrogen. Hydrogen ions are released during glycolysis and during the Krebs Cycle, they combine with other enzymes, and in the third process of oxidation - the ETC - provide energy to form the ATP. THAT IS A VERY VERY SIMPLE EXPLANATION! I've left out the complicated chemical processes because you shouldn't need to give yourself a headache trying to filter through all of that. This should give you the necessary foundation of understanding. Feel free to do your own research and you'll quickly see that if you found THIS to be complicated, it is nothing compared to the whole big-long-scientific background! Trust me...I took the headache for you in making it as simple and to the point as possible. ;)
WHEN IT IS USED:
There is NO simple way to detail the justification and science behind when it is used. Just look at how complicated the basic explanation was of how it works (and that was the really short version!) You may be able to make the correlations yourself between how it works and thus when it is used in the body. But regardless, I will simply state that this system is the one used for long-term endurance exercise/training such as long-distance running, etc.
NOW let's tie it all together in a clear and visual way, and you'll be DONE with this fundamental understanding of how and from where you get your energy during exercise. (AND IN TURN, YOU CAN BEGIN TO CONSIDER HOW TO MAXIMIZE AND EXTEND YOUR ENERGY/WORKOUT.) Below is an awesome visual representation of the relationship between the INTENSITY AND DURATION OF YOUR EXERCISE ACTIVITY, and the SPECIFIC ENERGY SYSTEM OR SYSTEMS BEING USED AT THE VARIOUS POINTS WITHIN YOUR WORKOUT. To summarize the picture below, you should see that:
-As indicated by the "Immediate Energy Systems" line, very short duration exercises (eg. sprints/heavy-weight, low rep lifting) are fueled primarily by the ATP-PC energy system (thus the relevance of creatine/creatine supplements), but a small amount of energy still does come from anaerobic glycolysis and aerobic metabolism.
-As you increase the time spent on the exercising (the duration), up to about 2 minutes, the exercise is fueled from energy mainly produced through anaerobic glycolysis...some still coming from other pathways.
-After many minutes of exercise, the oxidation of GLUCOSE AND FAT becomes the main energy system. (After about 90 minutes this too becomes depleted, however...
-One can conclude that through training and increasing carbohydrate intake, you could extend the duration of your exercise before becoming fatigued and exhausted. This is why marathon runners "carb load." ;)
References:
1. Clark, Micheal, Scott Lucett, and Brian G. Sutton. NASM Essentials of Personal Fitness Training. 4th ed.
Philadelphia: Wolters Kluwer Health/Lippincott Williams & Wilkins, 2012.
2. De Feo P, Di Loreto C, Lucidi P, et al. Metabolic response to exercise. J Endocrinol Invest 2003;23:851-4.
3. Gastin PB. Energy system interaction and relative contribution during maximal exercise. Sports Med 2001;31:725
-41.
4. Glaister M. Multiple sprint work: physiological responses, mechanisms of fatigue and the influence of aerobic
fitness. Sports Med 2005;35:757-77.
5. Grassi B. Oxygen uptake kinetics: old and recent lessons from experiments on isolated muscle in situ. Eur J Appl
Physiol 2003;90(3-4):242-9.
6. Johnson NA, Stannard SR, Thompson MW. Muscle triglyceride and glycogen in endurance exercise: implications for
performance. Sports Med 2004;34:151-64.
7. McArdle WD, Fl Katch. Exercise Physiology. Energy, Nutrition, and Human Performance, 7th ed. Philadelphia:
Lippincott Williams & Wilkins, 2010: 134-69.
8. McMahon S, Jenkins D. Factors affecting the rate of phosphocreatine resynthesis following intense exercise. Sports
Med 2002;32(12):761-84.
9. Wells GD, Selvadurai H, Tein I. Bioenergetic provision of energy for muscular activity. Paediatr Respir Rev 2009;
10:83-90.
10. Howley ET, Powers SK. Exercise Physiology: Theory and Application to Fitness and Performance, 7th ed. New York:
McGraw Hill, 2009:22-46.
WHEN IT IS USED:
There is NO simple way to detail the justification and science behind when it is used. Just look at how complicated the basic explanation was of how it works (and that was the really short version!) You may be able to make the correlations yourself between how it works and thus when it is used in the body. But regardless, I will simply state that this system is the one used for long-term endurance exercise/training such as long-distance running, etc.
NOW let's tie it all together in a clear and visual way, and you'll be DONE with this fundamental understanding of how and from where you get your energy during exercise. (AND IN TURN, YOU CAN BEGIN TO CONSIDER HOW TO MAXIMIZE AND EXTEND YOUR ENERGY/WORKOUT.) Below is an awesome visual representation of the relationship between the INTENSITY AND DURATION OF YOUR EXERCISE ACTIVITY, and the SPECIFIC ENERGY SYSTEM OR SYSTEMS BEING USED AT THE VARIOUS POINTS WITHIN YOUR WORKOUT. To summarize the picture below, you should see that:
-As indicated by the "Immediate Energy Systems" line, very short duration exercises (eg. sprints/heavy-weight, low rep lifting) are fueled primarily by the ATP-PC energy system (thus the relevance of creatine/creatine supplements), but a small amount of energy still does come from anaerobic glycolysis and aerobic metabolism.
-As you increase the time spent on the exercising (the duration), up to about 2 minutes, the exercise is fueled from energy mainly produced through anaerobic glycolysis...some still coming from other pathways.
-After many minutes of exercise, the oxidation of GLUCOSE AND FAT becomes the main energy system. (After about 90 minutes this too becomes depleted, however...
-One can conclude that through training and increasing carbohydrate intake, you could extend the duration of your exercise before becoming fatigued and exhausted. This is why marathon runners "carb load." ;)
 |
| Energy during exercise (1). |
References:
1. Clark, Micheal, Scott Lucett, and Brian G. Sutton. NASM Essentials of Personal Fitness Training. 4th ed.
Philadelphia: Wolters Kluwer Health/Lippincott Williams & Wilkins, 2012.
2. De Feo P, Di Loreto C, Lucidi P, et al. Metabolic response to exercise. J Endocrinol Invest 2003;23:851-4.
3. Gastin PB. Energy system interaction and relative contribution during maximal exercise. Sports Med 2001;31:725
-41.
4. Glaister M. Multiple sprint work: physiological responses, mechanisms of fatigue and the influence of aerobic
fitness. Sports Med 2005;35:757-77.
5. Grassi B. Oxygen uptake kinetics: old and recent lessons from experiments on isolated muscle in situ. Eur J Appl
Physiol 2003;90(3-4):242-9.
6. Johnson NA, Stannard SR, Thompson MW. Muscle triglyceride and glycogen in endurance exercise: implications for
performance. Sports Med 2004;34:151-64.
7. McArdle WD, Fl Katch. Exercise Physiology. Energy, Nutrition, and Human Performance, 7th ed. Philadelphia:
Lippincott Williams & Wilkins, 2010: 134-69.
8. McMahon S, Jenkins D. Factors affecting the rate of phosphocreatine resynthesis following intense exercise. Sports
Med 2002;32(12):761-84.
9. Wells GD, Selvadurai H, Tein I. Bioenergetic provision of energy for muscular activity. Paediatr Respir Rev 2009;
10:83-90.
10. Howley ET, Powers SK. Exercise Physiology: Theory and Application to Fitness and Performance, 7th ed. New York:
McGraw Hill, 2009:22-46.
No comments:
Post a Comment