What is Heart Rate Variability?

Heart rate variability (HRV) is the variation in time intervals between successive heartbeats. It is regulated by the autonomic nervous system, which controls the body’s response to stress and other environmental stimuli. When the body is under stress, the sympathetic nervous system (SNS) is activated, causing an increase in heart rate. In contrast, the parasympathetic nervous system (PNS) has the opposite effect, slowing the heart rate down.

Regular exercise is a form of stress on the body, and the appropriate amount of stress varies depending on the individual’s fitness level, age, and overall health. HRV can provide insights into how the autonomic nervous system responds to exercise stress and whether the body is adapting to or becoming overwhelmed by it.
During exercise, the sympathetic nervous system is typically activated, resulting in an increase in heart rate and a decrease in HRV. However, as the body becomes more efficient at handling exercise stress, the parasympathetic nervous system becomes more dominant, increasing HRV.

HRV and Cardio

Research has suggested that HRV can guide submaximal aerobic cardiovascular conditioning, particularly for endurance athletes. To regulate submaximal aerobic cardiovascular conditioning using HRV, an individual can measure their HRV and use it to guide the intensity and duration of their exercise. Typically, the higher the HRV, the more recovered an individual’s body is and the more intense and longer they can exercise. Conversely, if an individual’s HRV is low, they may need to decrease the intensity or duration of their exercise to avoid overtraining and injury.
To measure HRV, an individual can use a heart rate monitor compatible with HRV analysis software or a smartphone app. The individual can then measure their HRV at the same time each day, preferably in the morning before any physical activity or caffeine intake, and record the results.

Based on the HRV measurements, the individual can adjust the intensity and duration of their submaximal aerobic cardiovascular conditioning. For example, if the HRV measurement is high, they could increase the intensity and duration of their workout. In contrast, if the HRV measurement is low, they could decrease the intensity or duration of their workout.
It is important to note that HRV is just one tool for regulating exercise intensity. Other factors, such as sleep quality, stress levels, and overall fitness level, should also be considered when designing a workout program. Additionally, individuals with pre-existing health conditions or taking medications should consult a healthcare professional before using HRV to regulate their exercise program.

By measuring HRV before and after exercise, trainers and healthcare professionals can assess an individual’s ability to handle the exercise stress and determine the appropriate amount of exercise for them. This can help prevent overtraining and injury while maximizing the benefits of exercise.