What is ECG (Electrocardiogram)
An electrocardiogram (ECG or EKG) means recording of electrical activity of the heart. Small electrical impulses are created in the heart by so called pacemaker cells. These impulses spread through the heart muscle and make it contract. ECG records these signals as they travel through the heart. To the trained specialists, ECG provides large amount of information about the structure and the function of the heart.
In most cases ECG is measured from the skin surface with ECG electrodes. These electrodes detect very small electrical changes on the skin that comes from the heart as it contracts.
ECG is widely used to detect various abnormalities in heart rhythm, size of the heart chambers or possible damage to the heart muscle or it’s nervous system.
What is HRV
Your body reacts to nearly everything happening around you through your emotions, observations, thoughts and activity. Your brain guides the body by regulating heart and other organs through autonomic nervous system. This physiological variation of heart rate, controlled by autonomic nervous system, is called Heart Rate Variability (also commonly known as HRV). Measuring heart rate variation reveals wide range of information about your body and health.
Heart rate variability (HRV) is calculated based on variation of time in milliseconds between two heartbeats. HRV varies as you breathe in and out (see picture below). HRV is a relatively new method for assessing, for example, stress. What makes HRV interesting is the fact that it can reflect changes in stress while other physiological parameters, like blood pressure, are still in normal or accepted ranges. That’s why HRV is becoming increasingly popular parameter in the fields of sports and sports science, corporate health, cardiology, ergonomics, diabetes care and relaxation training therapy. HRV is also being widely used on physiological research of autonomic nervous system.
Figure 1. Heart rate variability
HRV can be utilized in different applications through different kinds of measurements. Quick assessment can be done through a short 1 to 10 minute test. These measurements include for example:
- 1 minute deep breathing test
- Real time frequency spectrum indicating sympathetic and parasympathetic nervous system activity (FFT)
- 10 minute supine/standing test
One sensitive and important measurement is called HRV deep breathing test. This unique 1 minute deep breathing test (DBT) provides instant real time information about your acute stress level. Through follow up measurements it is possible to evaluate your health more in-depth. From figures 2 and 3 you can see simple results of the 1 minute deep breathing test. These results can be utilized when analyzing your health and acute stress. Constantly poor results in DBT may be caused e.g. by high blood pressure, heart disease, obesity, diabetes, mental disorders (e.g. depression) or chronic stress overload.
Good news is that you can learn to improve your heart rate variability through practicing with biofeedback training, and training of breathing and relaxation. This kind of practice will help in getting out from the unhealthy body regulation and improving life quality in general.
If more detailed information about condition is needed, long-term HRV measurements of 1-7 days can be used. Scientific evidence has linked high heart rate variability to good health and fitness. In contrary, decreased HRV is linked to stress, fatigue or even burnout. Because of this it is important to monitor your HRV during normal everyday life. When measurement of physical activity is combined with HRV it is possible to analyze and evaluate the reason for low or high HRV. In addition it is possible to analyze the quality of sleep. Physical activity measurement allows you to see exercise, sleep and relaxation periods during the day and night. This information helps in making comprehensive analysis of your current life style and health status. As measuring of physical activity detects your body position during the sleep, it is possible to assess how calmly you have been sleeping. This way we can assess the quality of sleep. When sleeping periods are identified, also recovery can be evaluated and optimized in order to avoid overtraining, stress, fatigue or even burnout.