Identifying Training Load Variables for Elite Youth Soccer Through a Conceptual Framework, the latest study published by the Mapei Sport Research Centre in February in the International Journal of Sports Physiology and Performance answers this question. Ermanno Rampinini, Chief Operating Officer and Head of the Human Performance Lab at the Varese-based centre, together with Darragh Connolly from the Sport Science and R&D Department at Juventus Football Club in Turin and colleagues Sean Stolp and Aaron J. Coutts from the University of Technology in Sydney, analysed two seasons of training for 145 elite footballers in the Under-15 and Under-19 categories.
The researchers used GPS and motion sensors to record distances covered, sprints, accelerations and decelerations. They supplemented this data with physiological indicators such as heart rate and the players’ subjective perception of effort.
The analysis showed that a footballer’s workload cannot be described by a single indicator. In reality, it depends on four main dimensions:
- the total volume of work, such as distance covered;
- the amount of high-speed running and sprinting;
- the number of accelerations and decelerations, which represent significant biomechanical stress;
- the physiological response, measured by heart rate.
According to the authors, these four categories of data best represent the physical stress experienced by athletes during training and matches.
Another interesting finding concerns age: although the load dimensions remain similar between Under-15s and Under-19s, the relative importance of the variables changes as players develop.
In summary, to best manage the training of young talents and their growth, it is not enough to look at a single number. Movement data and physiological responses need to be combined to obtain a complete picture of the athletes’ fatigue.