RESUMO
The assessment of heart rate variability (HRV) upon waking has been proposed as a method to evaluate mental health; however, owing to large individual differences among athletes, it is unclear whether HRV is adequate to predict mental health decline. In this study, we sought to establish this by evaluating HRV upon awakening in one athlete over 20 months. We assessed mental health once a month by calculating the depression index. In addition, self-reported training load and psychological fatigue index were assessed as psychological indices for athletes. Heart rate and HRV were each measured three days per week in both resting (supine) and standing (upright) positions. The results showed that orthostatic HRV upon waking had moderate linear relationships with the scores on the depression index and psychological fatigue index. By contrast, self-reported training load, a measure of physical stressor, was not associated with HRV. The findings suggest that the repeated assessment of HRV upon waking and mental health indicators may be useful in preventing mental health decline in athletes.