Training zones are designed to help athletes control the intensity of training. What we sometimes lose sight of is the bodies physiological response to intensities in different zones.
The human body is a very adaptive organism. During exercise you expose the body to a certain level of stress. After a period of training the body adapts to this stress and will be able to handle a greater workload. This should lead to improvement in performance.
Adaption to exercise is ruled by the principles of super-compensations see the figure below.
Jan Olbrecht breaks the process into 4 phases of super-compensation in his book ‘The Science of Winning: Planning, Periodizing and Optimizing Swim Training’
Fatigue phase: during this phase the athlete completes a large volume of training. Fatigue accumulates and they become tired and performance drops. Seen int the dip in the curve above in the fatigue section.
Recovery phase: is a recovery phase with low intensity work or active recovery sessions. This allows for performance to start to return to the fitness base line.
Recovery allows for several biological adaptations to take place:
normalisation of the cell environment: waste products are removed, the pH-values normalise, and the cell structures recover
recovery of neuromuscular stimulation processes: a tired muscle does not react optimally to stimuli from the nerves. This will be restored when the muscle recovers
concentration and activity of enzymes and hormones will be restored
energy sources are replenished. Glycogen and other fuel sources are restored
(see ‘The Science of Winning: Planning, Periodizing and Optimizing Swim Training’ by Jan Olbrecht for more details)
Super-compensation phase: where physical performance increases above the initial level. The athlete can now handle the same load as before but with less strain or a more intense load with the same ease
Return to baseline: if training is not carried on, the improvement in physical capacity will be progressively lost.
This is the crux of progressive overload. Over time you add stress to your body that results in adaption to a higher level of performance.
It looks simple in the figure above but in order to achieve super-compensation there are a couple of things that need to fall into place.
Creating an environment that minimises life stressors can help set you up for training success. This deserves its own post, but for now it’s important to understand that mental and external stressors can have a negative effect for super-compensation.
The body does not distinguish between training related or emotional stress from work/life. A stress, is a stress, is a stress. Therefore, minimising these external stressors is important. It may also mean adjusting training slightly in periods of high stress at work. But that’s OK.
Training requires enough volume and intensity in order to stimulate the body to induce structural and functional adaptions. If training is too hard (Intensity) or too long (Volume) you will impede super-compensation. Too much volume and intensity will blunt the super-compensation process leading to a plateau.
Recovery is vital. Without enough rest or easy workouts between intensive training sessions will prevent super-compensation and improved performance. Structure and timing of training becomes important.
The figure below highlights the timing of super-compensation and how long it may take the body to recover from bouts of exercise.
If we return to our training zones we can estimate the recovery time needed between training sessions.
So, as we can see easy training in low intensity zones allows the body to recovery quickly between training sessions. This is where we add volume.
For zone 3 work we can bounce back within 24 to 48hrs depending on the session and then for the intensive work it can take 48hrs or more to recover. If we spend too much time at medium to high intensities we run the risk of never fully reaching super-compensation.
Easy days need to be easy in Z1 and Z2.
Let’s use an example. Below you can see a sample week of training planned out the type of session, intensity and estimated recovery time.
You will notice that for hard days it can be advatagous to pair them together. Hard days hard, easy days easy.
We use low intensity sessions in between the higher intensity sessions to mazimise training adaption.
The low intensity days are crucial for your overall athletic development.
The take home message is that the Easy sessions have to be easy. This allows us to take full advantage of the long hard sessions.
The next article will look at what happens to your physiology when you train within each of the zones.