Understanding HRV readiness score

HRV during rest and recovery

In rest and recovery phases, the autonomic nervous system leans towards parasympathetic dominance, often described as the “rest and digest” state. This transition fosters relaxation, digestion, and healing. A decelerated heart rate and elevated HRV mark this phase, indicating increased variability between heartbeats. HRV levels during rest vary among individuals, with higher values generally associated with younger age, superior cardiovascular fitness, and enhanced well-being. Thus, accurate readiness monitoring necessitates historical HRV data for comparison. Elevated HRV relative to your historical data denotes heightened physiological readiness.

HRV during stress

Stress activates the sympathetic nervous system, igniting the “fight or flight” response. This condition primes the body to tackle perceived threats by elevating heart rate, blood pressure, and muscle preparedness, concurrently reducing HRV to denote diminished beat-to-beat variability. Lower HRV in stressful situations signals a constrained adaptability to challenges, potentially underscoring health concerns or the need for refined stress management tactics. Reduced HRV compared to your historical norms indicates decreased physiological readiness and escalated stress levels.

Taking a new readiness measurement

For dependable HRV measurements, consistency is key. It is recommended to:

• Adopt a specific position (ideally reclined or semi-reclined) at a set time (preferably in the morning upon waking) and minimize all disturbances.
• Remain relaxed and breathe normally during the measurement, without speaking. The app will notify you upon completion.
• Verify the quality of the measurement afterward. If quality is notably low, retake the measurement (possibly after moistening the electrodes).

Measurement duration can range from 1-5 minutes, with durations over 3 minutes recommended for increased accuracy. Prior to measuring, a brief period of relaxation (at least 15-30 seconds) ensures resting conditions. Regular measurements, ideally several times per week, facilitate observation of daily physiological recovery and stress fluctuations, refining the accuracy of weekly averages. Frequent HRV assessments also elucidate how various factors—like physical activity, training, stress, and sleep—affect your HRV, potentially enhancing cardiovascular health.

Understanding the readiness score – How to interpret HRV results?

Note that resting heart rate variability is influenced by numerous personal factors. Normal range of HRV depends, for example, on gender, age, cardiorespiratory fitness, cardiovascular system health, and certain medication uses. Thus, initial resting HRV measurements alone cannot provide a dependable readiness assessment. A history of 1-2 weeks of resting HRV data is essential for a meaningful evaluation.

Be aware that while resting HRV yields reliable information about the physiological readiness, it is sensitive to many factors affecting overall bodily stress. For instance, a low readiness score in the morning could stem from various causes:

• Poor sleep quality for any reason (late nights, alcohol consumption, disturbances by small children, etc.) ^[5]
• Incomplete recovery from intense exercise ^[2]
• Insufficient recuperation from excessive work-related stress ^{[3], [4]}
• Psychosocial stress or familial issues ^[1]
• Onset of illness and inflammation ^[6]
• Any other stressors that increase sympathetic nervous system activity.

Differentiating acute and chronic fatigue

It’s vital to distinguish between acute and chronic fatigue due to their different scales and severity. Acute fatigue results from short-term stressors, like intense training or high workloads, leading to temporary stress accumulation. Given that the accumulation of stress continues only a few days or 1-2 weeks at most, with sufficient rest, one can usually restore their stress-recovery balance and regain normal readiness within days. For athletes, acute decreases in HRV post-exercise are normal, but HRV-guided training can optimize recovery and performance by adjusting training intensity based on HRV levels ^[2].

Chronic fatigue emerges from prolonged stress exposure, significantly affecting health with risks like cardiovascular disease, depression, inflammation, and metabolic disorders ^[3]. It indicates a deeper, more serious imbalance, potentially signaling over-training in athletes. Recovering from chronic fatigue requires a much longer period, emphasizing the importance of HRV monitoring to avert long-term detriment to health.

What is a good HRV while sleeping?

In general, heart rate is low and heart rate variability is high during nighttime. During sleep, the parasympathetic nervous system activity dominates, lowering heart rate, body temperature, and relaxing muscles. Our heart rate while sleeping can be 20-30% below the resting HR measured during daytime.

Higher HRV during nighttime has been linked to deeper sleep stages, while during REM sleep increased sympathetic activity may lower HRV ^[9]. If variability of heart rate is abnormally low at night, it is an indication of poor sleep quality and possible sleep disorder. ^[7]