[Research Review] Biomechanical Quantification Experimental Report on the Clinical Application of Heart Rate Variability (HRV) in Autonomic Nervous System Monitoring and Overtraining Prevention (Article No. 298)

Reference Journal Source: European Journal of Applied Physiology • International Research Findings Review Series

This article explores the clinical application of Heart Rate Variability (HRV) in autonomic nervous system monitoring and overtraining prevention.

Physiological Significance Reflected by HRV

HRV measures the degree of variation in the time intervals between consecutive heartbeats, regulated by the dynamic balance between the sympathetic and parasympathetic branches of the autonomic nervous system. Generally speaking, the higher the parasympathetic nervous system activity (indicating the body is in a recovery, relaxed state), the higher the HRV value; long-term accumulation of high-intensity training stress, insufficient sleep, or illness/infection are often accompanied by a decline in HRV, reflecting relatively heightened sympathetic nervous system activity and a body in a “fight-or-flight” rather than a “repair” state.

Two Response Patterns of HRV and Overtraining Syndrome (OTS)

Overtraining is not a single linear response; two common patterns exist:

• Sympathetic-type overtraining: Elevated resting heart rate, persistently declining HRV, with athletes subjectively experiencing fatigue, irritability, and poor sleep quality
• Parasympathetic-type overtraining: Commonly seen in the later stages of long-term chronic fatigue accumulation; resting heart rate tends to be abnormally low, and HRV values fluctuate with unusual stability (lacking normal diurnal variability). This pattern is less easily assessed by simply looking at “high or low HRV” and requires observation of multi-day trend lines

21-Day Training Load and HRV Changes Comparison (Illustrative)

Core Research Conclusions and Practical Recommendations

• Establish a personal baseline: The absolute HRV value varies from person to person; the key lies in the trend “relative to one’s own average over the past 7-14 days,” rather than comparing with others
• Consistency in measurement timing: It is recommended to measure consistently upon waking, in a supine resting state, avoiding confounding factors such as caffeine, food intake, and measurement posture that could introduce data noise
• Trends take priority over single-day numbers: A single-day HRV decline does not necessarily indicate overtraining; a clearly lower reading for 3 consecutive days or more compared to baseline is a more reliable warning sign
• Combine with subjective scales: HRV should be interpreted alongside Rating of Perceived Exertion (RPE) and sleep quality records; relying on a single data source can easily lead to misjudgment

Common Research Q&A (FAQ)

Q: Is it normal for HRV to fluctuate every day?

A: Yes, it is normal. HRV itself is influenced by multiple factors such as breathing, sleep, stress, and alcohol consumption. Daily fluctuations are a normal physiological phenomenon; the focus should be on the multi-day moving average trend rather than the single-day absolute value.

Q: Should training be completely stopped when HRV declines?

A: Not necessarily. You can first reduce the training intensity for the day or switch to active recovery (low-intensity aerobic exercise), and observe the HRV trend over the next 2-3 days before deciding whether a longer rest period is needed.

References and Academic Citations

1. European Journal of Applied Physiology — Research direction on heart rate variability and training load monitoring.
2. Sports Medicine — Literature related to autonomic nervous system response patterns in overtraining syndrome.

Related Reading

• Research Review: Clinical Application of Heart Rate Variability (HRV) in Autonomic Nervous System Monitoring and Overtraining Prevention: Advances in Frontier Exercise Physiology Research (Article No. 1465)
• Research Review: Biomechanical Quantification Experimental Report on the Clinical Application of Heart Rate Variability (HRV) in Autonomic Nervous System Monitoring and Overtraining Prevention (Article No. 979)
• Research Review: Biomechanical Quantification Experimental Report on the Clinical Application of Heart Rate Variability (HRV) in Autonomic Nervous System Monitoring and Overtraining Prevention (Article No. 721)
• Research Review: Biomechanical Quantification Experimental Report on the Clinical Application of Heart Rate Variability (HRV) in Autonomic Nervous System Monitoring and Overtraining Prevention (Article No. 133)