Can we summarize the load of a session in one variable?

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Can we summarize the load of a session in one variable?

As we have discussed in the blog of last week, it is important to quantify the load of different kind of actions to get a comprehensive picture of the load on the players. Some of the actions that you want to monitor are the high-speed actions and the short explosive actions. These can be captured with the distances covered in different speed zones and with accelerations and/or decelerations. But would it also be possible to capture the load of a session with one variable? In this blog we will try to find an answer to this question.

Since it is known that running with a constant speed requires less energy than accelerated running, the idea came to make an estimation of the energy cost of a session by integrating accelerated running into a new variable: Metabolic Power. Even though most scientists liked the idea of the new variable, the scientific results were less promising. It was found that the variable could not measure the actual energy cost during team-sport specific activities (i.e. there were underestimations of the energy cost during accelerated running, whereas there was an overestimation during running at a constant speed).

Based on these results, it is advised to not use Metabolic Power for overall training load monitoring. Since this variable does not measure the actual energy cost of a session and does not contain specific information about the type of activities performed, it cannot help you determine what kind of exercises you need to do during training. Sprint distance and accelerations/decelerations are more suitable to do this. Furthermore, this variable shouldn’t be used for nutritional guidelines either. As the actual energy cost is unknown, it cannot inform you about how much protein and carbohydrates the players need to take after a session or match.

Does this mean that the variable is useless? No, the estimated energy cost of the Metabolic Power variable still partly accounts for the extra energy needed during accelerated running. This in contrast to distances covered in different speed zones, which do not take into account that accelerated running is energetically more demanding. Therefore, power might be a better indicator of the overall intensity of a session than distances covered in the different speed zones. However, more tests need to be done to confirm this.

So what is JOHAN’s view on Metabolic Power? Based on the fact that the variable does not measure the actual energy cost, we have not included the variables in our variable list (for now). However, as an overall indication(!) of the intensity of a session, it might be an interesting parameter. Therefore, we are currently testing an adapted power parameter (i.e. power = speed x acceleration) in our Advanced Match Report to check if it is an indicator of the decay of intensity during a match.

Conclusion

Accelerated running places higher loads on the players than running at a constant speed. This, in turn, leads to a likely underestimation of the load if one only takes the distances covered in the different speed zones into account. Therefore, sports scientists have developed a new parameter to account for these differences: Metabolic Power. Even though most scientists liked the idea of the new parameter, the results were less promising. Results indicated that this measure does not measure the actual energy costs of players in sports like football and field hockey. Therefore, it is advised to not use this variable for overall training load monitoring and nutritional guidelines. However, it might be a better indicator of the overall intensity of a session than the distances covered in different speed zones.