A more realistic understanding of neuro-muscular load: how Empoli Primavera uses the mechanical analysis.


Eduardo is Fitness Coach at Empoli Primavera. He shared his experience on how he used gpexe to profile his U19 players and to monitor their performance, with a particular focus on neuro-muscular load.

Eduardo, starting this season you have new information available to describe the performance, concerning the neuro-muscular load. What is your impression at this point of the season?

The use of the mechanical approach opens up new possibilities for better understanding the activity of athletes on the pitch, specifically when referring to maximum-intensity actions. The criterion for defining these actions may appear complicated at first glance… but, once you understand the concepts, it is pretty simple. I have found several advantages compared to traditional monitoring.
The first feature I appreciated was the opportunity to create an individual acceleration profile for each athlete, thanks to the generation of the “in-situ” ASP profile. Starting from the data collected during matches and training sessions, I can describe the acceleration capabilities of each player as I’d do through a sprint test… but without the need to perform a maximal test! Players and coaches do not appreciate these test sessions, especially when extreme effort is required. Even the fitness coaches don’t go crazy about them: it’s tricky to be sure that the player is genuinely expressing his best! Thanks to the “in-situ” ASP profile I can overcome these limits and get the same information from the daily activity. If the number of training sessions taken into account is high enough (we are currently considering one month of sessions), I am pretty sure I’ll find a profile which is very representative of the maximum acceleration capabilities of each player.

ASP acceleration speed profile empoli fc primavera u 19 athlete
Profiling could also be used as a periodic evaluation of the athletes: this perspective is really interesting. Particularly with young players, I consider it a useful tool to check whether specific interventions (for example, I want to improve initial acceleration through strength work) have produced concrete effects in the game context. This is a completely new possibility, we don’t have any references yet, but I want to explore this approach’s potential.

What about the neuro-muscular load?

The notion of how to evaluate the most muscle-demanding actions has changed quite a bit. Previously I always referred only to accelerations and decelerations, which were counted on the basis of a fixed threshold (in my case ±2.5 m/s²), the same for all players. Now, every player is evaluated compared to his potential. This changes things a lot! We have several advantages by using the ASP as a threshold: the first, as I mentioned before, is that we can measure intense efforts on the basis of a subjective limit. The second one is that we can identify both intense actions performed starting from low speed and those performed starting from medium-high speeds. Mainly these latter actions were often “lost” by using acceleration alone. Now, thanks to the mechanical approach, we measure all the work done close to the maximum profile of the individual player. To me, this is a great plus to a more accurate estimate of the load accumulated at high intensities.

Which parameters do you use?

Overall, I use two main metrics: the number of actions performed near the profile and the corresponding amount of work. The first one gives me an idea of the number of times the athlete has reached a maximum peak. The second is very useful to determine an overall volume of work done at high intensities.

Can you go into more detail?

The system provides the bursts to define the maximum actions (close to the profile) from an acceleration point of view. And the same goes for the counting of actions with a high eccentric load which are called brakes. At the end of the training session (or game), I get the total number of actions. Then, for both kinds of actions, I can go into further details related to the starting speed (which characterises certain players and certain roles) and the distance of exposure close to the profile. This way, I can highlight all drills and players with peculiar characteristics.

I can do something similar for the work done close to the profile, which is called high external work. It is positive for concentric activity and negative for decelerations. This mechanical work is quantified in J/kg and can be further divided into the portion performed at low speeds, where there is a prevalence of force, in the portion performed at intermediate speeds, where there is a prevalence of power, and – obviously – in the portion carried out at high speed. I will tell more about our practical approach and share some data from our training week and matches.

Interview with Eduardo Pizzarelli, Fitness Coach at Empoli Calcio Primavera

We will soon publish the second part of this article to go into detail with training and match data and a more practical approach to mechanical analysis.

Additional references:

C. Osgnach, “How easy is to stumble over acceleration and deceleration?
C. Osgnach, “The limits of acceleration

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