Relationship Between Heart Rate Variability, Waking Salivary Cortisol, and Subjective Readiness in NCAA Division I Swimmers

Monitoring athlete training progressions serve to maximize positive training outcomes while minimizing the consequences of overtraining. Currently, autoregulative training methods aim to enhance training related outcomes through the assessment of individual athlete readiness to train. However, empirical research supporting the notion that physical and mental resources (i.e., readiness) influence experiential training outcomes is limited. PURPOSE: To explore relationships between physiological and psychological indices of readiness (Aim 1) and assess relationships between training-related well-being and readiness indices (Aim 2). METHODS: NCAA Division I swimmers (n=9) were recruited to collect data two days per week over the course of three weeks. During each day of data collection, the participants each completed four surveys; three assessing pre-practice readiness to train and one capturing post-practice training-related well-being. Readiness was measured physiologically (heart rate variability (HRV) estimated by the WHOOP 4.0 and waking salivary cortisol) and psychologically (Acute Readiness Monitoring Scale (ARMS)) while training-related well-being was measured subjectively (Feeling Scale, Athletes Subjective Performance Satisfaction, and Category Ratio-10). RESULTS: Physiological measures of readiness (HRV and cortisol) had a significant negative correlation within the population evaluated (r= -0.32, p=0.05). Moderate correlations between psychological and physiological readiness were limited, but a significant positive correlation was observed between the ARMS subscale of threat-challenge readiness and HRV (r=0.31, p=0.05). Several indices of readiness had significant correlations with training-related well-being (recalled affective valence and recalled performance satisfaction). Recalled affective valence was significantly correlated with HRV (r=0.45, p=0.01), Physical Readiness (r=0.36, p<0.001), Physical Fatigue (r=-0.18, p=0.05), Cognitive Readiness (r=0.34, p<0.001), and Threat-Challenge Readiness (r=0.43, p<0.001). Recalled performance satisfaction was significantly correlated with Physical Readiness (r=0.43, p<0.001), Cognitive Readiness (r=0.36, p>0.001), and Threat-Challenge Readiness (r=0.41, p<0.001). CONCLUSION: Within NCAA Division I swimmers, correlations between psychological and physiological measures of training-related readiness were limited. However, both HRV measured by the WHOOP 4.0 and subjective readiness evaluated by the ARMS had significant moderate correlations with multiple indictors of training-related well-being. Physiological and psychological readiness may not be interchangeable methods of monitoring athlete training, but each measure could be predictive of different training related outcomes, supporting incorporation of both domains to indicate holistic athlete training readiness.