Physiological adaptations and training zones

Any physical activity generates a response in the body whose objective is to respond to the physiological demands that exercise is causing. This can be an increase in respiratory or heart rate, a mobilization of energy resources,…

The training seeks to organize these physical activities over time with the objective that these acute adaptations end up generating adaptive processes that lead to improvement in performance.
That is, add acute adaptations to achieve chronic adaptations (not for life, with inactivity they are lost, to the parrot for these days/weeks).

This is the main reason why long-term planning and work is so important and especially when we are talking about resistance. And it is that this physical quality requires time and perseverance to reach the maximum potential levels that we have available genetically .
For this reason, it is not only about training and accumulating sessions, but the variables that affect performance must be assessed and organized to work together in the appropriate periods of the season.

Training zones

As coaches we usually use training zones to simplify the work with our athletes and to plan the sessions more easily.
Since the appearance of the potentiometers it is also very easy to have control over it and that the athlete has real-time certainty of the area in which they are working. Whether on the bike or with a running stryd you can perfectly follow the various programmed phases without having the typical inaccuracies heart rate, an irregular environment, wind or other variables that affect the measurement of heart rate. performance.

There is currently a fairly broad consensus regarding the number of work zones for athletes, with the 7 zones used by doctors H. Allen and A. Coggan being the most widely used.
In order not to extend myself too much, in the following table you can see a summary of these zones, related to power, heart rate, pace and subjective perception of effort.

Physiological adaptations according to the zone

Increased plasma volume

Plasma volume is the liquid portion of the blood. Its increase improves maximal oxygen consumption (VO2 max.) since it improves hemodynamics (blood circulates more efficiently) obtaining better oxygenation of the peripheral muscles for longer.

When we work in zone 5 and 4 is when there is a greater stimulation in the increase in plasma volume.

Increased mitochondrial enzymes

Mitochondria are the powerhouses of cells. Its responsibility is to transform metabolic fuels (carbohydrates, fats and proteins) into ATP, which is the smallest energy unit that allows cell work.
On the other hand, enzymes are catalysts of chemical reactions, that is, reaction accelerators.
For this reason, if the mitochondria have more enzymes, it means that they are more efficient when it comes to breaking down energy and, therefore, they are capable of generating higher work.

When we work in zone 4 and 3 is when we are making this increase in enzymes and therefore, a improvement in our performance.

Increased lactate threshold

The lactate threshold is that point of intensity below which the effort can be sustained due to a reuse of this secondary metabolite and above which leads inexorably to fatigue.

Bringing the lactate threshold closer to maximal oxygen consumption allows an athlete’s performance potential to be fully utilized.

Work in zone 4 and 3 also produce this highly desirable elevation for endurance activities, since it is a better predictor of an athlete’s performance capacity than VO2max.

Increased storage capacity of muscle glycogen, ATP and PC

ATP, PC (phosphocreatine) and muscle glycogen are the most immediate energy fuels available to the muscle cell. In high intensity exercises this is especially interesting, since the amount of energy they produce (low in absolute terms) as well as the speed of degradation (very high), it is necessary that there be a recharge by blood and liver glycogen. This, while they reach the cells and from there to the mitochondria, translates into a reduction in the intensity level. Being able to have a few extra Kj is the difference between winning in a sprint or settling for a podium finish.

Training in zone 3 and 4 stimulate the expansion of muscle glycogen storage while work in zone 7 increases the amount of energy in the form of ATP and PC.

Slow and fast muscle fiber hypertrophy, muscle fiber conversion, and increased neuromuscular power

The strength is obtained by two mechanisms: the first is the increase of the muscular section. That is, a bigger muscle can perform more force. For this reason, hypertrophy allows you to obtain more strength that, depending on the activity, will allow you to obtain superior performance. To do this, we must take into account the particularities of each activity and the weight/power ratio. Sometimes, the increase in strength does not compensate for the increase in weight necessary to obtain it, also generating a greater energy expenditure that in resistance activities can be crucial.

On the other hand, the muscle has different types of muscle fibers. The slow ones (with a great capacity for low or moderate intensity work), the fast ones (with a limited work capacity but carried out at maximum intensity) and the fast ones that, depending on the training, can carry out work on the slow fibers.

Finally, the second way to increase strength is intramuscular coordination. In other words, with the same stimulus, we simultaneously recruit more fibers and therefore, we can exert more force.

With training in zone 5 we will get the little capacity for hypertrophy that slow fibers have to be stimulated.
Training in zone 3 and 4 will allow fast adaptive fibers to develop their potential as fibers for longer duration work than brief anaerobic exercises.
And finally, zone 7 will serve to increase the volume of the fast fibers and develop the ability to improve coordination between the fibers so that together they generate more force.

Increased muscle capillarization

The capillarization of a muscle refers to the level of irrigation available to it. An extensive and well-distributed network of capillaries allows a good supply of energy and oxygen to the muscle fiber as well as a collection of waste substances and CO2 generated in energetic combustions. This has a positive effect on sports performance, as is to be expected.

The works in zone 5 are the main responsible for the increase in this capillarization.

Increased heart volume

Cardiac volume is the amount of blood pumped by the heart with each beat. This leads to improved hemodynamics and therefore optimized functioning of the cardiovascular system, which obviously results in superior performance.

Once again, the works in zone 5 are the main responsible for this increase.

Increase in VO2 max.

VO2 max. It is the ability of the body to use oxygen to break down metabolic fuels and transform them into work. Despite being a fairly genetically predetermined value it can be improved by doing interval training in zone 5.

Increased anaerobic capacity

The anaerobic capacity is often the one that allows winning races since it is the one that is used in the most confrontational moments and in the final phases of endurance competitions. Being able to sustain higher lactate levels for a longer time is what makes one athlete cross the finish line ahead of another.
Obviously, only working in zone 6 in a strenuous, unpleasant and repetitive way, allows you to improve this capacity.

Summary table

Training implications

Looking at the table above it would seem that we could discard the low intensity training in zone 1 and 2 and underestimate those in zone 6 and 7 according to the requirements of our activity. Nothing could be further from the truth.

For a harmonious development of the athlete, it is necessary to be able to work all the areas because this implies working on the different physical qualities. Therefore, zones 6 and 7, if they are worked on at the right time, are totally necessary.
On the other hand, zone 1 and 2 are equally important since the demands of training in zone 3, 4 and 5 force us to insert recovery workouts and aerobic core workouts.