A recent pilot study published in PeerJ found that morning mood and heart rate variability are inversely related to training intensity in amateur road cyclists.
In the study, five recreational road cyclists were followed for a 6-week period. During that time, heart rate variability, morning mood, training power, and rate of perceived exertion were measured regularly and compared. Overall, higher training power during an exercise session led to lower heart rate variability and worse mood the following morning. Heart rate variability, or fluctuations in the time between heartbeats, is essentially an indicator of your body’s resilience. Lower heart rate variability is often considered an indicator for potential health issues.
In addition to the link between exercise intensity, mood, and heart rate variability, a separate relationship was found between mood and heart rate variability — higher heart rate variability was related to more positive moods. These relationships could help athletes determine their ideal training loads and prevent overtraining. While increasing training loads are necessary for improvement, too much training could lead to worse results.
Overtraining is a relatively common problem that can be caused by too much exercise in combination with insufficient rest between sessions. Symptoms of overtraining can include soreness, fatigue, loss of appetite, irritability, overuse injuries, worsening performance, sleep problems, decreased immune response, decreased motivation, and more. If any of these symptoms are present, an extended period of rest with minimal intense exercise is necessary for recovery. Scheduled rest days can also help prevent overtraining and prevent injury. Although exercise is one of the healthiest activities for heart health and overall wellbeing, too much exercise can have a negative impact on health and mood.