A Deep Dive Into Athlete Monitoring: Background, Context and Practical Applications
Within current professional sport, the monitoring of athletes has become a cornerstone of the daily training schedule. The monitoring systems implemented by the sports science & medicine departments within clubs are dependent on its ability to reliability and accurately quantify the training dose and the individual response to the training dose of each player. This information in turn is then used to inform and assist the actions that are taken in terms of future planning of the training process to maximise player availability and performance through understanding the complex relationships between the training dose, performance outcomes, injury, and illness 17.
The ultimate/continuous aim of the training process is to progressively develop the required qualities of the sport (soccer) in order to improve performance 3. This is achieved via the balance between the application of an appropriate training dose and the time afforded to facilitate adequate recovery for sustained adaptations 8, 9.
In essence, for adaptations to occur, an overloading training dose must be applied to the individual and homeostasis must be disturbed resulting in reduced performance (fatigue) 10. If appropriate recovery is afforded, adaptations occur which are protective against further fatigue arising from a similar training dose 11-13.
In essence, the training-recovery cycle can be partly explained based on three governing theories 14:
- Selye’s general adaptation syndrome theory 10, which describes the body’s response to a stressor/stimulus.
- The stimulus-fatigue-recovery-adaptation theory 15-17, which proposes that the accumulation of fatigue is in proportion to the duration, volume and/or intensity of the stressor/stimulus.
a. Furthermore, the frequency of subsequent stressors/stimuli is also crucial in order to optimise performance outcomes, with any subsequent training occurring during the supercompensation phase 13, 18-20, if the subsequent stressors/stimuli is applied too soon – the additional fatigue may accumulate which results in a prolonged return to homeostasis and reduced performance 18, 21, 22. However, when the subsequent stressors/stimuli are applied at the appropriate time, during the supercompensation phase, performance can be enhanced 9.
- The fitness-fatigue model 14, 23, 24, which advises that training doses which minimise fatigue accumulation while also maximising adaptation will have the greatest transfer to performance outcomes.
However, to fully explain the training-recovery cycle, practitioners must also account for the multitude of additional internal psycho-physiological responses /adaptations that also occur during training which dilute the accuracy of quantifying the training response 25-27, resulting in the complex relationship between the training dose, performance outcomes, injury and illness 28, 29. Therefore, a multi-dimensional monitoring approach to evaluate the individual response to the implied training stressor has become an essential part of informing the training process.
A key component of any successful monitoring system is its ability to accurately & reliably quantify the training load (Figure 1). This is achieved through the quantification of both external load (Figure 1) and the internal load (Figure 1) of the athlete. The collection of these measures forms the foundations of a training process framework (Figure 2) 26 to inform the monitoring process. Ultimately, it is the athletes internal load that determines the stress that governs the individual response to the implied external load training stressor 26.
Figure 2: Training Load Framework 26
Even though internal load measures are associated with adaptations, it is imperative that we understand and quantify the external loads that contribute to an athlete’s internal response. Due to advancements in technology, the process of measuring external loads has become widespread across the sporting landscape 31 and is quantified depending on the context of the sport or mode of training 32.
The advantage of monitoring external loads is that it allows the practitioners to prescribe training more precisely in advance of the session being carried out based on the valid and reliable variables collected during previous sessions and the athletes prior response 33 to the external load that was prescribed. As mentioned, how external load is collected and prescribed is context specific however in invasion team sports the most commonly technologies include both local and global positioning systems, along with accelerometers, inertial measurement units, and camera-based measurements 3.
Detailing each of these systems and their variables is beyond the scope of this section however, they have been extensively researched within the literature and the reader is directed to the following 31, 34-38 for more information on this topic (Figure 3). Nonetheless, it is not necessarily how (i.e. the technology used) the external load is quantified but rather the why (i.e. what is this tool used, is it valid?, is it reliable?), and that is to inform the training process in order to achieve the desired adaptations imposed by the external load prescribed 26. As a result, these adaptations, either positive or negative, are what correspond to the internal load 25, 26.