Bioenergetics and Training For Specific Adaptation
Here is a piece I've written which details the four ATP generating energy systems, how and when these energy pathways are used, linking this up with how they fit into human movement and physiology, and finally how to use this knowledge to train specific performance goals.
Cellular Respiration and ATP
Most of us are familiar with calories and that these are units of measuring the potential energy we get from proteins, carbohydrates, fats and alcohols. While these do end up giving us the energy and building blocks to live and grow, if they are used for energy they are first broken down into a chemical called adenosine triphosphate (ATP), which is an adenosine molecule with three phosphate groups attached. Whatever energy is needed and generated by our body to be used chemically, mechanically, thermally or electrically, this is achieved by an enzyme splitting one of the phosphate groups off of the ATP molecule, which yields energy. This then becomes ADP (adenosine diphosphate; ATP with just two phosphate groups remain), which can continue to be broken down to AMP (adenosine monophosphate, a single phosphate group), and so on. Whether from the broken down nutrients from food or the storage forms of nutrients, the forming and reforming of ATP is the goal of our energy systems.
In a lot of ways this may seem simple and in a lot of ways this may seem complicated. Putting it simply, our nutrients (proteins, fats, etc.) are broken down until they are either building blocks or ATP, and then the phosphate groups are stripped off one at a time for energy as needed. The important thing to know about all of this as an athlete, a trainer, coach, or other medical/exercise practitioner, is that there are four ways that our body turns large nutrients into ATP, with each of the four taking a different amount of time to refill our ATP potential energy stores, but each one also has a different capacity/endurance. One system restores ATP for use very quickly, but the energy that it makes can generally only yield 4-12 seconds or so of activity, while the opposite end of the spectrum can be quite slow to generate the energy we need but has an incredible endurance if we are not demanding highly intense amounts of energy use for long periods of time (aka this is the energy system that keeps us breathing and alive, whenever we are not actually in moments of intense exercise).
And what does this all end up meaning? If you want to train to be a sprinter...you need to emphasize training of the right energy system. If you want to be an endurance cyclist, it will require the development of a different energy system than a sprinter. Each different goal in sport and life when it comes to movement will require a different mode of training if you want to improve physical performance. As the fundamental unit of energy for the human body, anything we need to use energy for (as listed above as for mechanical, thermal, chemical, or electrical needs and actions) uses ATP, but I will be chiefly approaching the use of ATP for exercise and other movement. ATP is used in the contraction and release of our muscle fibers and so for proper training methods to optimize energy systems for any given action, so in this text it is muscular ATP needs that are being addressed most directly.
In this text I will describe each of the four energy systems, how they chemically work in our bodies to (re)generate ATP, how they function during bouts of exercise in different intensities and durations, as well as other topics such as how supplementation and stresses on the body can alter the ability of these systems to work at peak potential. Through this I will cover how to appropriately train for your particular sport or activity with a better chance of optimum performance and improvement.
Most people have heard of the terms aerobic and anaerobic before, often being taken to mean light cardio work and then high intensity exercise, respectively. The word aerobic means with oxygen, the word anaerobic means without oxygen. Two of the four energy systems are anaerobic and only last a short while because they can be done without oxygen (so they generate lots of waste without disposing of it at the same time), while two are aerobic and offer energy over much longer periods of time and with much higher efficiently (albeit at a slower rate). It must be noted that all four of your energy systems are always going at any given moment, but the degrees at which any given energy system is providing the majority of energy being expended varies depending on how intense your activity is (from sitting in a chair to sprinting a 100 meters, with a lot of room in between) and for how long it lasts.
The four energy systems are the creatine phosphate system, fast glycolytic system, slow glycolytic system, and beta oxidative system. This list goes from the fastest ATP generating system while having the lowest overall output (runs out the quickest), to the slowest but most enduring system. The first two are anaerobic and second two are our aerobic systems. During our periods of lower intensity movement and energy demands it is the last two systems that supply the majority of our energy needs because they are most efficient. While slower to process they generate by far the most energy. Below we see two tables, one which compares the energy output of each system, as well as about how long they last. Also note, oxidation is a process which can turn several types of nutrients into ATP, and they have been separated into two systems in one of the graphs below as they do have some differences in time and yield.
As stated before, each of the energy systems is always contributing some portion of the (re)generation of our ATP stores in our muscles and throughout the body, even after they have ‘fatigued’ and are not longer the main source of energy supply. When at rest or low intensity activity it is our aerobic systems that are most responsible. At high(er) intensity levels the anaerobic systems dominate, until they fatigue. If you are lifting heavy weights in a gym that are really challenging you, you are probably resorting to your creatine phosphate system, and as it quickly fatigues it mingles with the next fastest system until it phases out, and so on until the body can lower its intensity or rest to refill the anaerobic systems, or the body simply fails to continue to perform at such high intensities and it slows down until it can get enough oxygen for the aerobic systems to cover its energy expenditures.
In the most vigorous activities our body uses up its stores of ATP in each muscle, or other activity related cell, quickly and its first reserve system to refill it’s energy stores is the creatine phosphate system. This is a very simple one for one reaction where our now partially expended adenosine diphosphate takes a phosphate group from the molecule creatine phosphate (an enzyme is often used for these processes to separate a portion of a molecule off for some biological process, in this case creatine kinase, though we will not go into the detail to describe most of the other enzymes for the other energy systems, which are far more complex), resulting in one ATP and one creatine (the enzyme is always unchanged after a reaction, it is just a facilitating molecule). This process, as well as the next (fast glycolysis) happens in the cytoplasm (or sarcoplasm in muscles fibers) of each cell, which is the ‘watery’ open space of your cells. This can be analogous to maybe the middle of your living room floor.
Here we can see an ATP molecule, with the right sections being
adenosine, and the three phosphate groups being visible on the left.
The chemical equation for this would be: ADP + Creatine Phosphate ---> ATP + Creatine. With each reaction a single ATP is created, which is not a lot of energy but as only one reaction is required it is very quick, so at the first few moments of an intense exercise (only 4-12 seconds!) it provides a burst of energy. Towards the end of these few seconds fast glycolysis starts to merge with creatine phosphate as the chief ATP re-supplier.
The next energy system that quickly gets recruited is glycolysis, which can either be done in a short cut route to supply energy, but doesn’t supply much, or can go a much slower aerobic route but will generate more than 15 times as much ATP. At certain intensities, however, we are just simply not able to supply an adequate stream of oxygen, raw energy materials and waste disposal to keep up aerobic energy pathways to supply our needs, so the fast glycolysis is used to ‘bide our time’ until we can switch back to the slower but more efficient aerobic energy systems. Both forms of glycolysis start the same way, with glucose (a simple sugar) that was floating in the blood or the cell, or a storage form of glucose known as glycogen (which is two glucose connected to each other) either in the cell or the liver (which is where our body stores its largest amount of reserve sugars, usually equivalent to ~100 grams of sugar or 4 hours of low-intensity daytime non-exercise) starting a several step process to turn each glucose into pyruvate, and other materials as well that can be used later with oxygen is available that will yield energy.
When oxygen is available, pyruvate goes on into the kreb cycle and onwards in slow glycolysis as described in the next section. When there isn’t enough oxygen, however, the body goes through this process and converts the pyruvate into lactate, which is is shuttled off from the cell into the blood and into the liver, which will convert the lactate back into glucose or glycogen for storage or it will be distributed back out to the cells for fast glycolysis again (or an aerobic energy system if oxygen has become adequately available). This lactate to glucose and back process is called the cori cycle (pictured below). Lactate can also be converted back into pyruvate and be used aerobically when oxygen does become available. As we will see in the image at the end of this section, fast glycolysis is a much more elaborate process than the phosphagen (creatine phosphate) system, but yields 2 ATP instead of 1 (if oxygen becomes present it will also be responsible for more ATP production because of other materials it creates, specifically 2 NADH that will create around 5-6 ATP, which will be described later) and instead of lasting 4-12 seconds it can last up to around two minutes.
Fast glycolysis is the energy process that is often believed responsible for the muscular burn some people experience during exercise, which is thought to be from the ‘lactic acid’ that is pumped into the blood, however this was a misconception in a fashion as lactate is not the acid, it is the H+ (hydrogen ion) which is a side effect of the fast glycolytic process that is an acid, but was named and referred to incorrectly. This is still not completely known, however, as ongoing research is coming to suggest that even these hydrogen ions both may not come from this process and may not be responsible for any kind of muscle fatigue or burning before or after a workout, but perhaps even a way to delay fatigue further. There are as yet no solid conclusions on the matter, but suffice it to be that lactate and this mythological ‘lactic acid’ is if anything, hydrogen ions.
When the intensity is low enough or has become low enough to not need the fast turnover rates of anaerobic systems (or at least the anaerobic systems have met their capacity and fatigued so can no longer be the prime energy producer) and is no longer based in a non-sufficiently oxygen supplied environment, slow glycolysis takes over as the primary energy source with anaerobic being inadequate but with still too high an intensity for energy supply dominance from oxidation. Slow glycolysis starts with the same steps as fast glycolysis, but when it reaches the pyruvate step it is then further transformed into acetyl coenzyme A instead of into lactate and then instead of the cori cycle, it enters a much more complicated process called the kreb cycle. Once the kreb cycle is complete it moves on to the electron transport chain, the two of which we will now detail.
The kreb cycle is a fairly complex process (shown in simplified form in the diagram above) which involves numerous enzymes and agents which results in 2 ATP being produced, as well as Co2 waste products that will be exhaled, but the real goal of the kreb cycle is to manufacture the ‘reducing agents’ FADH2 and NADH which will donate their hydrogen atoms into what is called the electron transport chain. This whole process takes place in the mitochondria of each cell (though there is some degrees of it that happen elsewhere, but this doesn’t really pertain to our topic here), which is generally known as the ‘powerhouse’ of the cell, and the electron transport chain is why.
The mitochondria is a double membrane structure, with the kreb cycle taking place inside the center membrane space (called the matrix) and uses the opposing hydrogen concentration between the two membranes to create energy with the electron transport chain. Specifically, when the NADH and FADH2 are generated from glycolysis and the kreb cycle, their hydrogen is removed and donated, pushed through what you can think of as a pump from the matrix to the intermembrane space. There are few hydrogen molecules in the matrix, but through this process there are lots in the intermembrane space. In any given space or body anything that is in high concentration wants to flow to a lower concentration, and so there is turnstile like structure (pictured in the top left of the diagram below) that allows the high concentration hydrogen in the intermembrane space to filter back inside. As they push their way in through this turnstile structure, it acts like a windmill and the mechanical energy that this turning generates is used to attach a phosphate group to an ADP to reform an ATP. The hydrogen atoms are linked up in two’s with an oxygen to make H20 (water), which is then exhaled (this is the main reason why your breath is moist!). This is why oxygen is required for aerobic energy systems, to remove the hydrogen from the matrix of the mitochondria.
PLEASE VIEW LAST SECTION OF THIS ARTICLE FOR PICTURE (the forum code will not allow 5 in one post).
This may seem like such a long process to get ATP but as long as there is a presence of oxygen and the other components of the reaction, it is relatively easy and efficient on the body, yielding about 36 ATP per glucose! This is 18 times more than glycolysis without oxygen! It also produces very little waste products, namely CO2 and H2O which can easily be expelled via exhalation.
Beta oxidation is in large part the same process as slow glycolysis, but instead of starting with glycogen or glucose, triglycerides (the common blood circulated form of fat) are broken down into their constituent three fatty acid chains and the glycerol that binds them (an alcohol), and from there these fatty acid chains are broken down into acetyl coenzyme a, which from there enters the kreb cycle and the electron transport chain. The difference is, while slow glycolysis yields about 36 ATP, each triglyceride yields around 463 ATP! This degree of efficiency is why we live aerobically from our carbohydrates and fats unless we are exerting ourselves enough to need more rapid energy supply from one of the anaerobic energy systems. It should be noted that protein can be oxidized as well, but as protein is a lot less efficient to metabolize for energy, it is usually kept for use as a structural component, only making up some 8% or so of materials to fulfill energy needs.
Also, something many athletes may have wondered about, the period between slow glycolysis dominance and beta oxidation is often referred to as the second wind, as our body desperately wants to minimize its energy expenditure, especially from its precious fat stores, and seeks to spare them and mentally tries to deter us from continuing such exertion without a situation where we are running for our lives or such similarly important activities. This is because while oxidation of fats is by far the more efficient energy system, working at high intensities while burning through our fat stores cuts into our caloric reserves at a severely faster rate than during periods of fasting such as while we sleep. To our evolutionary brain this means we are cutting into important starvation prevention reserves and so tries to get us to slow down unless we are, as said, running for our lives. Evolutionarily none of our ancient ancestors in hunting and gathering times would have ‘exercised’ because this would only mean a greater chance of starvation, and as our biological period of more available food is only about 200 years old (0.0001% of our time as humans) this hasn’t changed our feelings on exercising at times! As our body and mind passes this grueling period we get a new steady stream of energy from the highly efficient process of oxidation, especially fat oxidation, and the body accepts that it’s happening and we have our second wind.
You might ask, as I’m sure many have before, what actually stops each energy system from continuing and what would happen if they did anyway? Over time when performance intensity raises, as we have described before, aerobic energy systems can no longer make energy fast enough to deal with energy needs, even though by oxidizing fat in particular twice as much energy per unit mass is generated (remember nutrition, fats are about 9 calories per gram compared to carbohydrates approximate 4!). Over time as the intensity level is maintained the anaerobic energy pathways reach their capacity and aerobic energy systems take over once more, with a decrease in performance to match whatever energy output the aerobic system can muster.
The big reason aerobic systems are dependent on oxygen is to take the waste hydrogen away from the mitochondria and the cells in general, bound in water, among other waste products. The hydrogen is acidic and would alter the pH of the system, inhibiting enzymes and other components from carrying out reactions. This is a functionally similar reason to why we have storage glycogen in the liver instead of large amounts of glucose stored in each cell for it’s quick use, as too much glucose stored in a cell eventually crystallizes the cell like it were filled with cement. The cell simply cannot cope with a buildup of H+, or at least this is the pervading theory, but as mentioned previously ongoing research suggests a different mechanism is our cause. With the anaerobic energy systems the culprit is simply a faster use of substrate materials (such as creatine phosphate) than can be regenerated. As fast as the anaerobic systems are at generating new ATP it can only keep up with so much. Aerobic systems do also require materials like glucose or triglycerides to function, we just simply often have many hours or even weeks supplies of them on hand, compared to moments in an anaerobic environment.
For both aerobic and anaerobic systems, both ultimately can hit a wall in situations where the energy demand brought on by activity is greater and more urgent than their energy production rates can meet, as well as their total capacity. Passing out and more severe situations such as anaphylactic shock can occur when there is so little metabolic components to maintain the brain and vital organs, though this is rarely a present occurrence (but it is not unheard of at all) in sports. This is regardless, however, why a quick source of calories such as simple sugar with electrolytes should always be available for athletes and active people at all times, regardless of degree of health and fitness.
While ATP is used as the fuel for every cell throughout our bodies, different organs and types of cells use it in different ways, and use different combinations of energy systems at different times. In particular our bodies are made up of several types of muscles, and the ones that make us move are called skeletal muscle. These types of muscles are even of several types, which can roughly be called fast and slow twitch fibers. Fast twitch naturally use more anaerobic energy systems, being faster and stronger but fatigue more easily, while slow twitch fibers are naturally more aerobic and aren’t as powerful but have much greater endurance. Both muscles use all types of ATP regenerating systems, but the proportions they are equipped for are fundamentally different, and to a large degree the amounts of fast and slow twitch fibers each of our bodies have, or at least proportions thereof, appears to be largely genetic and is not subject to large amounts of change, though we can still enhance each type of muscle to work better in it’s non-dominant energy system. This genetic element is a big part of what makes some people naturally fit for one sport and not another; because their muscle type ratios and capacity for each energy system is higher in one area than another.
It is not all down to genetics, however, where our energy and work capacities are or where they can go. There is still a considerable amount of improvement that can be made in the enzyme and substrate storage and efficiency, waste disposal, neurological connection and activation, and numerous other variables that may impact each energy system differently. To a degree it must be stressed that working your body heavily in one direction (aerobic or anaerobic) can negatively affect the gains in the other side, at least after a certain level of improvement as each individual cell adapts to the conditions it’s actually experiencing. This means that if your muscles are usually under quick bouts of highly intense action it will try to be as efficient and effective as possible in that environment. If the cell is needed for long term work, it will work to be aerobically efficient. If it experiences both it must try to master both, so having to work towards both will not become as efficient at either as it would if it specialized, regardless of its natural genetic predispositions. At first a couch potato will certainly make gains on all sides, but an elite athlete will need to specialize or will lose out on one system to some degree, which is a big part of why marathon runners aren’t sprinters, and sprinters aren’t marathon runners.
These points being said, it must also be pointed out that the benefits that can be made are not equal in all energy systems and all sports, at least not how one might think. The creatine phosphate system can only be improved a slight amount, perhaps from 4-8 seconds to 6-12 seconds at the highest levels of capacity and the fast glycolytic system is not going to get a better endurance cap than a few minutes of high intensity exertion. This is while the aerobic system can be brought to an unbelievable degree of endurance capacity where a body can work under substantial loads or work for many hours without failure, as long as oxygen flow and nutrients continue to be supplied. This doesn’t mean sprinters, fighters and other athletes that partake in short bouts of highly intensive activity cannot see profound improvements, but understanding how these energy systems actually function can lead them to performance gains through training in ways that may seem counter-intuitive, especially with the potential effect of training for anaerobic or aerobic energy pathways diminishing the other’s capacity.
What I am getting at with this line of thought is that many of the worlds most intensive and high speed sports, albeit not all, can benefit greatly from aerobic training as opposed to just anaerobic. Remember, all four energy systems are always going at any given time, even while we’re sleeping your ADP is stealing phosphate from creatine molecules, the ratio is just heavily dominated by aerobic energy systems. This means that even if your sport is a highly anaerobically dominated activity, you still may be getting as much as 20-40% of your ATP from aerobic energy systems, especially if there are short rests between rounds, exchanges of blows, sprints, or whatever intense action is calling up such anaerobic power. Aerobic systems are also a large mechanism for clearing out the waste products caused by anaerobic metabolism. Anaerobic pathways generate lots of fast power, but generate lots of waste. Aerobic energy systems will help rejuvenate both aerobic and anaerobic capacity during periods of rest or lower intensity. Needless to say, aerobic training should not be eschewed for only pushing anaerobic development. The fact is anaerobic improvements can only be so substantial, aerobic energy systems are more important than most athletes think, and the training for aerobic training has profound benefits for heart and overall health that cannot be ignored. The more developed your aerobic system is, the longer you can actually go or the harder you can work before your aerobic system cannot generate ATP fast enough and the anaerobic must start it’s countdown to exhaustion. This alone can win or lose a match for you or let you get away from that dangerous animal (assuming you were faster than it in the first place!).
A fighter is a prime example of a largely anaerobic athlete, but the aerobic system is highly important in even just the few moments between intense exchanges of blows and takedowns, as well as between rounds. While a fight can potentially last moments when a knockout is achieved in round one, some matches may be up to 5 minutes or longer a round and have as many as 5 rounds. The longer a bout continues the more dependent on the aerobic system the athlete becomes and without a strong aerobic base a fighter will may easily fail to have the energy for a definitive victory when given the right opening. One can easily see where this is the case for numerous other sports and activities. On the other end, however, powerlifters, weightlifters, some Olympic throws and sprinters, as well as other athletes may not need to be as concerned about developing both ends of their energy capacity for performance purposes. Marathon runners are much the same with not often needing to consider anaerobic conditioning, generally using in excess of 98% aerobically generated energy while performing. Regardless of the athlete, your liver and your muscles only hold around 400 calories of sugar on hand for stored energy, after that it’s coming from your fat stores, which means aerobic oxidation. If you are working intensely enough to use these up before your rounds end, the efficiency of your anaerobic system cannot keep you going because it is out of materials. This is rarely the case with fat stores, at least not because of sports competition.
We now have a pretty good understanding of the energy systems individually, as well as the roles of both the aerobic and anaerobic systems in sports and general activity. Next we look at what is involved in supporting the continued endurance and performance of these systems over time and how to improve their ability to do so: aka get more energy capacity and endurance from each system.
While not as capable of improvements from training as aerobic systems, anaerobic training certainly has several variables that can increase in ability and efficiency from proper training techniques and strategy. Each energy system has it’s ability to confer ‘power,’ which would be that pathway allowing or assisting a muscle to develop the most simultaneous strength and speed (aka power) possible for any given amount of time. Powerlifters, football players, fighters, and many other sports, let alone construction work and other such tasks, may require the individual to put out maximum power. The key here is to insure training both max strength and max speed so that they meetup at the best possible junction for power production. If one trains strength but not speed, or speed but not strength, maximum power is not achieved. This is both from muscular development, neurological activation, and also the energy systems that supplies this type, intensity and duration of action.
In training for power, including for anaerobic energy production for power, one must be careful in how an exercise is executed or it won’t be in line with, and may be harmful towards, achieving your goals. An example of this would be doing olympic lifting for power, which is generally slow at several seconds per rep, when the powerful action you are trying to achieve may be throwing a punch. While building this base of strength before tuning the neurological and energy systems, among others, for your precise task is fine if done long enough before the actual point of competition or other work where maximum performance is required, it must not be confused with beneficial training that will result in increased power. Likewise, trying to improve the power output of the anaerobic energy pathways must be done in the performance setting desired. For working towards powerful legs, this might be doing squats at high speed, really trying to throw that weight into the air, but once you start going below 90% or so power output, we stop and rest for a few minutes until the body is ready to continue. If you don’t stop when ‘losing steam’ we are training towards the wrong energy system and other variable gains that may detract from power development.
Training Creatine Phosphate
This system as you now know is the most quickly fatiguing but because of its rate of energy production, can offer incredible power to your muscles. This is what is most responsible for ‘explosive force,’ where you are lifting a heavy weight on the squat rack and the first 8 reps get pushed out cleanly but there may be a sudden drop off in explosiveness or speed, which is because this highly demanding task simply asks for too much energy too quickly for the creatine phosphate system to handle, and the other systems are too slow to offer such intense and quick energy production.
Because of this combination of high power but low endurance we have a simple and easy range to train it in: high power movements over a short period of time, but trying to push this window to force the body to adapt to maintaining high energy output for longer than it can already. Even after it ‘fatigues’ so is no longer the chief energy supplier for your cells during intense activity, it doesn’t stop, it merely lags behind due to its depleted capacity, and this is where we want to train. Our body adapts to this training by improving the actual rate of energy turnover from this system through increased enzyme supply (creatine kinase as mentioned previously) and by improving its ability to store creatine phosphate, while also neurologically improving it’s coordination and control of the order and timing of muscle tissue firing to keep the high intensity up as long as possible while still being effective.
Many athletes supplement with dietary creatine powders, which have been shown to increase the energy and endurance of athletes in such activities as weight lifting and others that require short bouts of intense physical demand. Creatine does require a ‘loading’ period where it takes time for higher levels of creatine to show up in the body and create a beneficial effect, but once ‘active’ offers real benefits to performance in this energy range comparative to the overall capacity for the creatine phosphate system to improve in endurance. Do note, however, that while creatine is cheap, it is largely an unnecessary and superfluous supplement for most individuals outside of performance athletes that operate at least moderately in this particular energy demand environment, and our cells can still only store so much of it at once.
For our first training method, we are targeting the energy production speed of the creatine phosphate system. As the quickest, most powerful, and fastest fatiguing system, we train for improvement in the shortest time scale. Whether you are lifting explosively, doing jump squats, sprints, striking, or other such appropriately powerful movements, you will want to go absolutely 100% (seriously maximal effort, less will not work!) for 7-10 seconds. Every single rep, step, jump, or strike needs to be maximally fast and powerful. Once this set is done, make sure to rest for 2-5 minutes until your heart rate is under 120, and do not start again until this rest is complete! If you train without adequate rest you will not be achieving improvements in power. Some active rest between sets to allow your aerobic system to be active and shuttling nutrients and waste is perfectly fine. You should only do this particular set 2-3 times as it is highly exhausting on the neurological system, and from this also be careful what exercises you do both before and after as your body may be less likely to prevent injury for a brief period (aka don’t go and play a football game after this kind of work!). This training method will serve to improve the maximum rate of ATP regeneration by the creatine phosphate system in large part by increasing the amount of enzymes present and available.
While we are working with the goal of energy system conditioning, using maximum strength training in the right ranges uses the creatine phosphate system to a very high degree and can help stimulate an overall release of beneficial hormone release alongside anaerobic power increases. I would not make this method a priority in your conditioning, but depending on your sport or activity this may be more or less fitting. Choose a series of lifts, choosing from large compound lifts (pull-up, squat, deadlift, etc) and choose a weight or resistance that will allow you to only do 1-5 reps. Now do 2-5 sets of each exercise, trying as hard as you can on the last rep that you will fail on. Make sure to have a spotter! Serious injury or death can occur from mishandling max weight lifts or just from accidents ensuing from failing to be able to complete a rep. This is very neurologically taxing and should not be done more than one to two times a week in most situations, especially alongside other exercise or training.
Next is the topic of improving the maximum energy capacity from creatine phosphate, which means taking it to its point of exhaustion and beyond at top intensity. Many of the same intense exercises or drills can still be used, but now we will working for 10-15 intense seconds with rest periods of 20-90 seconds. After finishing your sets with this exercise, rest 8-10 minutes and use this timing method again with a new activity, overall doing 2-3 series of sets with different exercises for each. Putting our bodies in a high intensity environment where we demand more energy than it can supply, and keep up this energy demand after our bodies fail to meet it, will force adaptations in the endurance of creatine phosphate metabolism.
Training Fast Glycolysis
As the endurance of the creatine phosphate system can only be extended so far, an ongoing urgent demand for energy will start a transition into fast glycolytic metabolism after just a few seconds, so still forms a pivotal role in force production, speed, and overall power. To ensure you are keeping in the right intensity range for anaerobic training, make sure that regardless of the exercises you use (hammer swings, takedowns, tackles, sprinting, intense striking, etc.) it has to be a fast movement to recruit those fast twitch fibers which is where the biggest anaerobic production is coming from.
In our first method for fast glycolysis, choose an exercise and carry it out for 20-40 seconds at maximum intensity and then rest for 1-3 minutes until your heart rate descends to 110-130. You can go through this routine 3 times and then rest for 8-15 minutes after the set is complete before doing another set, for a total of 2-4 sets (of 3 20-40 second reps) for an entire workout. Make sure not to skimp on rest times, or you are defeating your own gains in powerful energy deployment.
The other end of the anaerobic spectrum is the development of endurance. Extending the maximum amount of time, or at least the maximum amount of ‘work’ that can be done via anaerobic energy production, given that this is dependent on the intensity and the duration of your actions while using anaerobically derived energy, has obvious benefits. Again I will remind the reader that the aerobic systems have huge roles to play in assisting the anaerobic systems even when not ‘running the show,’ as well as the fact that anaerobic endurance can only be improved so much, with the extension of the threshold between aerobic and anaerobic energy dominance being perhaps the best way to extend your high intensity endurance. With that said, however, we can still get to work on your anaerobic endurance!
The key to improving endurance, be it aerobic or anaerobic, is to force the body to keep up work at a given intensity when it is at the point of failure (not actual failing of a muscle or system necessarily, but the body having to lower intensity because it just can’t produce the requested energy). With anaerobic training, the goal is to keep the body under a lactate (often referred to as lactic) heavy state for an extended period of time. The longer the body has to deal with buffering and removing anaerobic waste while continuing to supply the necessary materials to keep the whole process going (sugar storage and transportation, enzyme supply, etc.), it will improve these abilities. When you start training at anaerobic levels like this, your cells will start converting their energy production systems to fit these stresses; meaning it will start taking some of its dedicated ability for aerobic production away for reallocation.
As we are training an energy system instead of a particular skill the exercise used could be one of many, as in the anaerobic power training described above, though if you are in a particular skill set or sport you can use something that applies to that for the greatest benefit. We will actually be doing the same workout as above as well, even if you change the specific activity, but the timing is not the same and that will make all the difference. The key is duration goes up while rest times go down, so you work at high intensity again but for 90-120 seconds with a rest period of 1-2 minutes between reps, and 4-6 minutes between each series of sets. This will keep your system filled with byproducts and waste it needs to clear up, while keeping the energy demands above what the aerobic system can handle. This will force your body to adapt to this specific kind of stress demand.
Another common training tool, which can be used for either anaerobic power or endurance, is timed circuit training. Whether doing different lifts, drills that apply to your particular skill or sport, or mixing the two, you can set up 3 or so exercises to do, and do each with intensity and speed while transitioning directly from one to the next without rest. If you are going for anaerobic power then do each for 20-30 seconds, totaling around 60-90 seconds for each set. A rest period of 1-3 minutes between each circuit, and a rest period of 8-10 minutes between each set of circuits (with a total of 2-4 sets) should be taken. For anaerobic endurance do the same process, but each set should last 1-2 minutes with 30-60 for each exercise, and 60-90 seconds of rest between circuits. When resting between sets of circuits, take 6-8 minutes before continuing.
Many other methods exist for accomplishing these training criteria, with varying degrees of accuracy and efficiency, though depending on the person being trained this may not be overwhelmingly important as with deconditioned individuals they will still be spending time under tension with high lactate levels and so will make anaerobic goals. A few such examples are Every Minute On The Minute (EMOM), where a set of a given exercise or sequence of exercises is executed at the start of a minute countdown, and whatever time is left at the end of the set before the minute is up is for rest. At the start of the next minute a new set is begun, repeating until a designated total number of sets is completed. Another is As Many Reps As Possible (AMRAP) where in a given time period, say 8-12 minutes, an individual will go through a circuit repeatedly until time runs out. These are great for anaerobic training in groups or teams for the mutual motivation as well as the competitive factor that many athletes and individuals enjoy.
We now crossover to the other side of conditioning. As has been covered pretty substantially so far, every energy system is always active to some degree, though how much of the overall energy needs is being supplied by each system and type of system varies depending on the intensity of the exercise, the duration it has been going on for so far and substrate availability. Most of the time the aerobic system is running the show because it is by far the most efficient, but it is slow so cannot cope with high intensity exercise as the primary energy supplier. There are three main types of attributes we are seeking to improve through aerobic training, which is oxygen supply, oxygen utilization, and substrate availability. Also, through training more heavily in aerobic energy systems recall that our cells being in a more aerobic friendly environment will be more likely to convert its energy production capability towards aerobic and away from anaerobic capacity.
Within oxygen supply improvement the goal is to improve cardiac output (ability to pump more blood faster with less effort; aka overall better ability to distribute oxygen), our peripheral vascular network (the veins and artery system that extend into the furthest crevices of our muscles and organs, which is like adding more roads to a city so more people can get more places faster), and the efficiency of the respiratory system. With more oxygen supply comes a greater ability for the aerobic system to supply more energy at higher speeds and higher intensities. The more oxygen, the longer you can go before having to resort to anaerobic energy systems and the better the aerobic system can support anaerobic pathways once they do take over.
Oxygen utilization includes the actual number and size of slow twitch fibers (which recall are naturally better at aerobic metabolism), the oxidative abilities of fast twitch fibers, and the amount of aerobic enzymes present. Through these we can actually increase the amount of mitochondria (the places where slow glycolysis and oxidation take place) in our muscle cells, which seriously improves our ability to increase the speed at which we can generate power. This is like building new factories, which if you have enough parts on hand really steps up production.
In the third category, we can increase the availability of substrates (aka fuel) by improving the efficiency of aerobic energy production, total substrate storage capacity, and optimizing our hormone regulation. While fat storage is something we are often trying to minimize because most of us have too much of it, slow glycolysis uses sugar and oxidation can as well, which we can get better at storing in our liver and muscle tissue.
So as you can see we have a lot more ways to improve the aerobic system than the anaerobic system, which makes sense given how many more steps and systems are involved in aerobic power generation. We will start with addressing cardiac output, which constitutes the improved size and strength of the heart, allowing us to have a higher capacity to pump oxygenated blood. We start this with a method that is broadly thought of as ‘cardio,’ now generally used for weight loss instead of conditioning, which has in increasing numbers been in decline due to the rising popularity of high intensity exercise for fat loss, though regardless of changing trends, cardiac output training is still a major pillar of conditioning. By keeping the heart and body working at a certain intensity level, which doesn’t need to be high intensity, with any levels over your general resting heart rate will lead= to improvements depending on how conditioned or de-conditioned you are. Sustaining this pressure and load on the circulatory system forces the heart to stretch and eventually grow to become larger and thereby more effective and efficient at pumping blood, sending off a larger volume with each pump, as well as lowering resting heart rates (less wear on the heart throughout your whole life!). Do note that high intensity exercise is still a beneficial training tool, it is just not to be confused for aerobic conditioning.
By comparison, working at high intensity levels leads to different adaptations in the heart such as wall thickness, which will not increase stroke volume. The higher pressures of high intensity exercise forces the heart to respond with a more durable and powerful structure, instead of a more efficient one, and at the heart rates that high intensity activity uses (generally 150+ beats per minute) there simply isn’t enough time for the heart to fully fill and be stretched. The 15-20 minute durations of high intensity exercise also is inadequate to lead to these kinds of adaptations. Cardiac output training requires 60-90 minutes of exertion at around 120-150 beats per minute, with a lower range with older age The exercise chosen can essentially be any, as long as it keeps the heart in this situation for that period of time, so can be from running, cycling, hiking, sparring work, drills (just note that sports is often more dynamic and can dip above or below the desired range), jump rope, and so on. If you cannot do this long or this intense, build up to it starting at 20-30 minutes and 100-120 BPM. Any training from wherever you start will improve heart size and extend the vascular network.
The next method is actually high intensity intervals, but they have the adaptive effect of improving mitochondrial density in the heart as well as contractile strength, extending greater conditioning power and endurance through the heart. Here you will exert maximum effort in a given activity (again, these are manifold, from rowing, to cycling, to drills, etc.) for 60-120 seconds with 2-5 minutes of rest, or whatever is needed to get the heart rate back down to 120-130. This can be repeated 4-12 times per session.
Our next method improves the ability of our fast twitch fibers to utilize oxygen, leading to a greater endurance. This can be unpleasant to some and takes some willpower to push through!
It is best to use a rowing machine or spin cycle for this exercise, but hill hiking could be potentially adequate. In this method of training we set the resistance of the bike or rowing machine to its maximum, or at least the maximum we can continuously exercise with, at slow speeds for 10-20 minutes straight, doing 1-2 sets. This high resistance recruits our fast twitch fibers but going at slower speeds will allow us to keep working with them over a long period of time, instead of fatiguing in a few minutes time from high speed high intensity work. This offers us a great, if grueling, way to force oxygen utilization and endurance on our fast twitch fibers. During this exercise your heart rate should typically be around 150-160 depending on your condition. I highly recommend this method, which can be great after other workouts in brief sessions for recovery and really hits your fast twitch fibers from a whole new angle (one reason I love uphill hiking as a hobby!).
This is another of my favorite aerobic training methods, which is known as lactic threshold training. Here we will exercise right on the border of aerobic and anaerobic dominance, which will demand your aerobic system work as fast and hard as possible, which over time will force the adaptation of the aerobic system to increase its overall capacity, being able to remain the dominant power house at higher intensities, sparing your anaerobic systems. Finding where your lactic threshold is can be difficult without professional assistance with specialized measuring devices, but until you reach the level where this is necessary (higher end sports performance) using what is called the ‘talk test’ may not be highly accurate, but should be sufficient to still make these gains. The talk test is where you exercise and slowly ramp up the intensity until you find it just beginning to be difficult to have an ongoing conversation because of your need for oxygen. For many people this is 150-170 bpm, depending on age and health. Once you find this range, stay in it for 3-10 minutes at a time, dropping down to a slower rate, perhaps working at 130 bpm for 5 minutes, before getting back to your threshold and turning the timer back on for 3-10 minutes, repeating the process 2-5 times. A multitude of exercises can be used, but due to the specific exertion requirements, I find something that can be done with steady resistance and speed like a cycle or rowing machine to be best.
Lastly there is the method of high resistance intervals, which instead of doing an activity like sprints or hammer swings into a tire for anaerobic training, we do high resistance but slower speed such as sprinting up a hill, sled drags, very high resistance bikes and rowers, and so on. This combines the high intensity slow speed ‘cardio’ method listed just above, along with the more familiar high intensity intervals we are using for anaerobic training. The result is improving the oxidative abilities of our highest threshold motor units, really seeking to jam aerobic capability into the most unlikely of places. For someone with a larger amount of fast twitch fibers, this may be especially beneficial. This technique should be done at 10-12 seconds per repetition at maximum resistance, with 30 seconds of low resistance between sets (like walking back down a hill before sprinting up again), for about 15-20 total reps per workout.
Here we have come full circle from looking at the actual anatomy and chemistry of our energy systems, that not only let us run and throw and play, but breath and think, to figuring out how to improve each of their efficiency and capacity. ATP is a fundamental essence of human life as our fuel. We have seen the differences between the four energy systems and how the aerobic and anaerobic systems work differently, and alongside each other to keep you moving in different situations. When looking through these systems and picking your exercises keep in mind the specific skills, actions, movements, and environments you are wanting to improve performance in to make sure you are not defeating your own gains by going in the wrong direction.
Lastly, all the recommended times and exercises in this text are generally aimed at sports performance, but even if you are starting into this world an obese couch potato, or at least an obese marketing desk jockey like I did, it is no worry. Scale back the intensities, the exercise times, and up the rest times until you find what you can do and work from there. Make sure to consult with a physician before undertaking these techniques, as some of the intensities prescribed are honestly very dangerous for those with heart conditions, diabetes, and numerous other possible health scenarios. Training under the guidance of a properly educated personal trainer or other professional is highly advised, at least to get you going.
Algavinn, this looks very interesting but I am not able to understand it yet. :)
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