Conceptual Frameworks and Assessment of Readiness to Train in Endurance Exercise: A Systematic Review

Readiness to train has emerged as a construct to guide daily training prescription and recovery management in endurance athletes. However, its conceptual basis, assessment, and methodological quality and validity remain inconsistently defined. This systematic review aimed to (1) identify how readiness is defined in endurance exercise and (2) categorize tools used to assess it. As a secondary aim, the review evaluated the methodological approach of the studies employing these tools.

Following PRISMA guidelines, PubMed, Scopus, and Web of Science were explored. Eligible studies included endurance athletes aged 18-65 years, evaluating readiness before or after training or competition. Two reviewers independently screened, extracted data, and assessed quality using the revised Cochrane Risk of Bias tool. Fourteen studies were included.

Readiness definitions were inconsistent and frequently overlapped with related constructs such as recovery and fatigue. Ten studies used self-reported tools (fatigue, sleep, stress, and soreness). Nine studies assessed objective tools, including heart rate (HR) variability, resting HR, countermovement jump, and submaximal tests. HR variability-based approaches and individualized feedback were used to track autonomic recovery and guide training prescription, while on-field indices (eg, HR-running speed, HR-running power, countermovement jump) provided neuromuscular insights, although they can also be influenced by cardiovascular and metabolic factors. Overall, there was considerable heterogeneity in tools and their combinations, highlighting the lack of standardized approaches to assess readiness to train. Seven studies combined subjective and objective measures, suggesting a more comprehensive monitoring strategy. However, many of these tools were primarily used to assess related constructs (eg, fatigue, recovery, and training adaptation) rather than directly predict performance; consequently, their ability to predict performance outcomes remained limited or was not even assessed.

This review highlights substantial conceptual ambiguity, methodological limitations, and heterogeneity in readiness assessment. A multidimensional framework conceptualizing readiness as a dynamic psychophysiological state influenced by stress, recovery, and contextual factors may support more structured and meaningful monitoring in endurance athletes.