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.
Perfection in motion. BS CPT - NPTI NASM
"We must not forget that even in the most perverted and cruel human being, as long as he is human, a small grain of love and compassion exists that will make him, one day, a Buddha." -Dalai Lama