Quantification of training and competition loads in endurance sports: A key to recovery-stress balance and performance

Training is the systematic application of stress (predominantly in the form of exercise) and recovery to enhance physiological capacity, refine motor patterns, reduce injury/illness risk, and ultimately improve performance. Coaches and trainers generally consider that the outcome of the training process depends on the type and amount of the stimulus, and understanding this cause-and-effect relationship between training dose and response is crucial to prescribe exercise training accordingly (Lambert & Mujika, 2013a). To analyse and establish causal relationships between the training performed by an athlete and the resultant physiological and performance adaptations, it is necessary to quantify precisely and reliably the training load undertaken by the athlete. Indeed, it is difficult to assess a competitive performance without first considering the prior training of an athlete (Mujika, 2013). For this reason, several sport scientists have underlined the importance of proper training quantification in relation to both individual athlete adaptation and scientific research (Foster, Florhaug, et al., 2001; Hopkins, 1991; Pollock, 1973).