#### What it is and why use it

Over the years, the quantification of the physical demand required in the game of soccer has been the subject of many scientific papers considering parameters such as body temperature, heart rate, and lactic acid concentration. All methods yield similar results regarding the total energy expenditure of a match or a training session. None of them, however, correctly quantify the metabolic output in real-time, with particular reference to instances of high-intensity, which characterize the decisive moments of a match.

Lately, the opportunity is developing in order to follow and analyze the movement of athletes on the pitch, during a match with Video Match Analysis technology, and during practice thanks to GPS technology. Using these technologies we are able to know instant by instant position and speed of the player. The engineers have focused mainly on the evaluation of the running speed, creating very detailed analysis, but these analysis do not take into account one important component: the one due to acceleration and deceleration. In fact, a remarkable metabolic commitment is required not only for running at high speeds but also to accelerate to high speeds.

If you would like to also take into account acceleration, there is a problem: a lack of scientific studies dedicated to the subject, at least with regard to the energy aspects.

Professor Pietro Enrico di Prampero, who participates in the workgroup for the development of GPEXE, thanks to his research offers an original approach to the problem, starting with the 2005 ongoing study.

According to this study, it appears that acceleration on level ground is equivalent, from the point of view of energy to running uphill at a constant speed, with a slope proportional to the value of frontal acceleration. Since the energy cost of running uphill is known, we can estimate the instantaneous energy cost of acceleration, with a particular algorithm. Noting instant speed and energy cost, it is easy to calculate the power generated by the subject and as a result a set of parameters which summarize the real physical effort given.

August 10th, 2015 – Here the podcast “The calculation of metabolic power” (Prof. di Prampero interviewed by Dr Andy Franklyn-Miller).