The mistake most athletes make is behaving physiologically like specialists when nature designed them to be generalists. That’s what you’re built for, on an ancestral level and on a molecular one. The way to injury-free, indefatigable, lifelong performance is to respect your whole biochemistry.
The Energy System Continuum
The first thing to understand is that these systems don’t switch on and off in sequence. They’re all running at the same time, with contribution shifting based on how hard and how long you’re working.
The ATP-PCr system handles the first 10 seconds of maximal effort. It burns through the phosphocreatine to rebuild adenosine triphosphate (ATP) almost immediately – no oxygen is necessary. This is the energy needed to complete a tug, sprint, or launch. It’s fast, but it runs out quickly.
The glycolytic system takes over from here and fuels efforts of approximately 30 to 120 seconds. It breaks down carbohydrates in the absence of oxygen to maintain high levels of ATP production. Hydrogen ions, on the other hand, are produced as a by-product, resulting in the burning feeling that finally causes you to slow down or stop. To train this system, you must become accustomed to buffer this discomfort and postpone it.
The oxidative mechanism is responsible for everything longer. It uses oxygen to break down both fats and carbohydrates, and while it can’t keep up with the other two, it can support performance for hours. It also eliminates the metabolic waste of the other systems.
During a sustained maximal effort, the aerobic system contributes around 50% of total energy supply by approximately the 75-second mark. There’s not much time until the all-out push. The distinction between “aerobic” and “anaerobic” sports is much vaguer than most training camps would suggest.
Building The Aerobic Base
Many strength and power athletes neglect their aerobic base altogether. Aerobic work not only makes up the majority of your training volume even as you’re going max-effort in the gym or on the field, it also supports most of those high-output efforts. 90+% of sport is metabolically aerobic and the better your aerobic system, the faster and more completely you recover between speed, skill, or strength efforts.
This work isn’t completed in one or two sweat sessions, though. When you’re structuring a full week that incorporates both high-intensity sprint work and lower-intensity recovery sessions, the question of aerobic vs anaerobic exercise ratios becomes practical and worth getting right. Build this foundation and you’ll see the impact in speed, power, and recovery time.
Training The ATP-PCr System
In order to increase your explosive power, it is essential that your phosphocreatine is fully replenished between sets. This requires you to take rest periods of 2 to 5 minutes between efforts that last under 10 seconds. However, most people tend to shorten their rest periods because they feel like they are not being productive by just standing around.
Unfortunately, short rests will automatically switch your ATP-PCr workout to a glycolytic one. If you want to achieve maximal output, such as during a 40-yard dash, a snatch, or a standing vertical jump, your rest time needs to be appropriate for the exercise. Professional track sprinters and Olympic lifters already apply this concept, while many field sport athletes still do not.
Training The Glycolytic System
This workout may not feel the best, but that’s on purpose: If you want to build your ability to buffer lactate and hammer out high-effort work for thirty seconds to two minutes (see: CrossFit Open WOD), you need to spend time doing exactly that.
Hit a set of intervals in the range of 30-90 seconds at near-maximal effort, and take just enough rest between reps to hit the same pace again (usually 1:00-2:00). Recovery runs, light erging, light cycling, or even fast walking are good choices here because it keeps the heart and lungs elevated without putting more work on the muscles.
Structuring It Without Burning Out
Attempting to maximize all three at once is a perfect way to get overstressed and/or injured. Block periodization is likely a better idea – e.g. spend 3-6 weeks really focusing on one of the systems, and then when the other two are worked on, it’s often at a reduced volume. Then switch the priority.
E.g. a soccer player may spend the preseason phase with a block of aerobic work including long low-intensity runs and some glycolytic interval work, and when they transition to block the power phase, they’ll still do some aerobic work but at a reduced volume, and same when they do specific endurance work. This ensures the aerobic system takes a backseat for a bit and doesn’t get in the way of CNS recovery since it recovers faster than the glycolytic and alactic systems.
Putting It Together
Many athletic deficiencies are due to an insufficiently trained energy system rather than the absence of skills specific to a sport. If an explosive athlete struggles in the third period, build up their aerobic base. If an endurance athlete has problems accelerating, focus on glycolytic and ATP-PCr training. If you train physiology, performance will improve.
Thanks for stopping by!
Magda
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