Metabolic Signalling
In a squad that is developing as strongly as ours, we are faced with a good problem. The athlete starts to look towards their hard work in training to get the improvements they desire.
This sends the athlete into a tricky place however. One where they start to see each session as a performance that is chasing numbers and outputs.
What pace did I hold? What power did I do? Did I hit a PB?
But the body doesn't really see training like that. The body sees two things when you train … stress and disturbance.
When we train, things start changing inside the muscle cell. We use energy. ATP demand increases. Calcium repeatedly moves through the cell as the muscle contracts. Oxygen demand changes. Metabolic by-products increase.
The muscle cell senses these changes and that is where metabolic signalling begins and is the main topic of this article.
*One quick word before you read on. I am a coach talking about physiological processes and how we can think about them in relation to training. I’m not a scientist trying to confuse you with words. The goal is a balance between both methods of messaging.
A metabolic signal is not a message from the brain.
It is a biochemical change inside the cell that tells the body something has happened and that it may need to adapt.
Different types of training can create different signals.
AMPK is strongly linked to energy stress.
In very simple terms:
"We are using energy quickly. We need to become better at producing it."
CaMK responds to the repeated calcium movement associated with muscle contraction.
Its message is:
"We are contracting repeatedly. We need to become better equipped for this work."
p38 MAPK is activated by the cellular stress associated with exercise.
Its message is roughly:
"This environment is stressful. We need to adapt."
These signals can interact with pathways involving PGC-1α, an important regulator of mitochondrial adaptation.
The process actually looks like this:
Training → cellular disturbance → metabolic signal → adaptation
The important point is this:
The session is not the adaptation.
The session creates the signal.
The body then does the work of adapting to that signal in the hours and days that follow.
Athletes need to stop seeing every training session as a performance.
A steady aerobic ride is not a failed session because the power was low.
An interval session is not automatically better because you did more watts than last week.
A long run does not need to destroy you to be effective.
The question should be:
What signal are we trying to create?
As coaches, our job is to prescribe enough of the correct training stress to create the signal we want.
Then recover.
Then repeat it.
Training is not about proving how fit you are every day.
Training is about repeatedly giving the body the right biological message and allowing it to adapt.
Long Course Triathlete Desired Signals
Become extremely efficient, resistant to fatigue and able to keep producing energy for a very long time.
The dominant word is durability.
The cell needs to repeatedly experience:
Energy demand + repeated contraction + prolonged metabolic disturbance.
Short Course Triathlete Desired Signals
Produce aerobic energy at a very high rate, rapidly change energy demand and tolerate repeated severe disturbances.
The dominant process is energy production rate.
One Final Important Point
Each energy pathway isn’t a completely separate signal we prescribe.
AMPK, CaMK and p38 overlap and talk to each other. We're manipulating the cellular environment, not pressing an AMPK button on Tuesday and a p38 button on Thursday.