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.
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