How do you measure physical fitness? The majority measure it according to how the body looks, how it performs during workouts, how much weights it can lift, how fast it can run, how much fat percentage it holds, etc.
The real measure of fitness, however, is largely ignored by most people. The answer lies in the state of your heart. Knowing your heart rate during your workouts, when you’re not exercising, and when you’re resting or sleeping, can lead you to optimal wellness.
It can also give you the peace of mind that your heart is a strong as the rest of you. Your heart rate will vary according to age, type of workout, your level of conditioning, health issues, medications, exercise goals, and environment or weather.
“A healthy heart will immediately start dropping its rate once exercise has stopped, whereas an unhealthy heart or an unconditioned body will cause your heart rate to remain high after exercise has stopped.
“This could be a sign of a serious health issue, it could mean your exercise intensity was too high, or it could mean a case of deconditioning,” says personal trainer, exercise therapist and author of It’s All Heart, Bobby Whisnand.
Heart rate measurement is simple and can be done manually by counting your pulse. Generally, Mayo Clinic says a normal resting heart rate for adults ranges from 60 to 100 beats a minute.
A lower heart rate at rest implies more efficient heart function and better cardiovascular fitness. For example, a well-trained athlete might have a normal resting heart rate closer to 40 beats a minute.
Lately, research has revealed that knowing your heart rate alone is not a good indicator of heart health. To dig a little deeper, you also have to measure your heart rate variability (HRV), which can enable you to see how you handle stress.
While heart rate focuses on the average beats per minute, HRV measures the specific changes in time (or variability) between each successive heartbeat. The time between beats is measured in milliseconds (ms) and is called an “R-R interval” or “inter-beat interval” (IBI).
Previously, HRV could only be measured at the doctor’s office with an electrocardiogram (ECG) test, which measures the electrical activity of the heartbeat. With each beat, an electrical impulse (or “wave”) travels through the heart. This wave causes the muscle to squeeze and pump blood from the heart.
But, with the availability of multiple wearables and smartphone apps, these devices can now do the work for you.
According to an overview of research conducted by the HeartMath Institute in the United States, the importance of HRV was noted as far back as 1965, when it was found that foetal distress was preceded by reductions in HRV before any changes occurred in heart rate.
Later, studies revealed that reduced HRV was shown to predict autonomic neuropathy in diabetic patients before the onset of symptoms. Reduced HRV was also found to be a higher risk factor of death from heart attacks, compared to other known risk factors.
It has been shown that HRV declines with age and that age-adjusted values should be used in the context of risk prediction. Age-adjusted HRV that is low has been confirmed as a strong, independent predictor of future health problems in both healthy people and in patients with known coronary artery disease.
Generally, a low HRV (or less variability in the heart beats) indicates that the body is under mental, physical, emotional or physiological stress. Higher HRV (or greater variability between heart beats) usually means that the body has a strong ability to tolerate stress or is strongly recovering from prior accumulated stress.
It is also associated with improved body system functioning and better athletic performance. At rest, a high HRV is generally favourable, while in an active state, a lower HRV is favourable.
The study, Short-Term Heart Rate Variability – Influence of Gender and Age in Healthy Subjects, by Voss A et al. (2015) published in the Plos One peer-reviewed journal, shows that males typically have lower HRV than females in the same age range.
This indicates that males exhibit stronger sympathetic (fight-or-flight stress response) tendencies over parasympathetic (rest-and-digest), than comparable females. Yes, women do have healthier hearts!
Can you improve your HRV? It depends. If you have no underlying medical conditions, then yes. Otherwise, speak to your doctor first.
Regular exercise (aim for 30 minutes of moderate aerobic activity a day), combined with breathing techniques, can help increase your HRV. Deep and controlled breathing taps into the parasympathetic nervous system, helping you calm down and lower your pulse.
Do not compare your HRV to others as there are many factors such as age, health, gender and fitness level to account for. Compare yourself against people within similar demographics. Knowing the numbers and where you stand can motivate you to make lifestyle changes and healthier choices.