Sessions: Alactic Capacity
Teaching The Body To Manage More Hard Work
High intensity endurance, or what we will call Alactic Capacity, is the ability to exert repeated hard efforts in a session or a comp. This means more tries on a hard crux move, more power toward the end of a bouldering day, or consistent performance across a whole competition.
Although you may not be familiar with the term Alactic Capacity, it is simply the ability to do lots of work in your high-intensity zone. It’s the difference between being able to do 15 attempts at hard boulders in a session and the ability to do 20 attempts. Alactic capacity then naturally leads toward greater output because you are increasing the amount of stimulus your body sustains over time.
Think of it this way: you can improve your capacity somewhat easily, and once your capacity is up, you can improve utilization. If you don’t address capacity first, utilization is harder to come by.
We have power and capacity qualities in each energy system. My favorite way of describing this currently is to imagine a large battery. The utilization or power output of the battery might always be 9V, yet if you double the size of the battery (in our terminology, doubling that battery’s capacity), we can do 9V of work for longer and longer durations. If we want to increase the voltage, that would be training the energy systems utilization or power output instead.
For the purposes of today, we are going to talk about capacity building as the primary adaptation.
In the aerobic system, capacity is lots of pitches per day, while utilization is the effort you can put into single pitches.
In the lactic or glycolytic system, capacity is how many times you can go into the deep pump in a day, where utilization is how hard you can climb with that pump.
In the alactic or ATP system, the output component is correlated specifically with how strong or powerful you are. Capacity, though, is a tougher nut to crack.
This is the ability to repeat high-output bursts with minimal drop-off. Since most of us don’t spend much time developing repeated high-effort capacity, this is highly trainable in many athletes. Through training, you can significantly increase the storage of fuel (phosphocreatine) and the enzymes required to use it.
Physiological Adaptations
When you train alactic endurance, three specific physiological changes occur:
Increased Fuel Storage: Training increases resting levels of ATP (Adenosine Triphosphate) and PCr (Phosphocreatine) in the muscles. This allows you to maintain max effort for a few seconds longer in many situations, maybe going from 6 to 8 seconds up to 9 to 10 seconds at a maximum level.
Enzyme Efficiency: We increase the activity of Creatine Kinase, the enzyme responsible for breaking down PCr to create energy. This allows for faster energy release.
Neural Efficiency: Your nervous system becomes better at recruiting high-threshold motor units rapidly and relaxing them quickly (inter-muscular coordination), which saves energy.
The “Secret” Ingredient: The Aerobic System
This is the most misunderstood part of alactic endurance. The Alactic system does not recharge itself. It relies entirely on the Aerobic system to replenish phosphocreatine stores during rest intervals.
If you have a weak aerobic system, you cannot recover as quickly between explosive bursts.
Therefore, improving alactic endurance often requires improving aerobic capacity (specifically cardiac output) so your body can “pay back” the oxygen debt and resynthesize PCr faster.
We can do this through lower-intensity steady-state methods, such as easy climbing or easy weight circuits. In our gym, though, we have developed a series of alactic intervals that address both the intensity and the recovery needs to improve this system.
