Resting Heart Rate
The heart circulates blood to deliver oxygen throughout the body. Heart rate is the number of times the heart beats per minute (bpm) and fluctuates based on what the body needs. While the average resting heart rate is between 60-100 bpm, a lower resting heart rate means the heart does not have to work as hard and is correlated to increased cardiovascular fitness. Highly trained athletes typically have lower resting heart rates than the average person. A higher resting heart rate is linked to high blood pressure, obesity, a sedentary lifestyle, and increased stress levels.
Maximum Heart Rate and Aerobic Fitness
Maximum heart rate is the upper limit of what your heart rate can climb to during physical activity. Maximum heart rate can contribute to aerobic capacity, which is how well the body uses oxygen during exercise. Aerobic capacity is measured by VO2 max, the maximum amount of oxygen you can use during physical activity. A higher VO2 max indicates greater cardiovascular endurance. While genetics and age play a role in resting heart rate, maximum heart rate, and aerobic capacity, implementing lifestyle changes to include more exercise can improve these measures.
Heart Rate Variability and Health
Heart rate variability (HRV) is a measurement that is different from heart rate. Heart rate variability is the variation in time between heartbeats measured in milliseconds, and can be determined in a medical setting using an electrocardiogram machine or with various fitness watches. Your heart does not beat in a perfect rhythm as your body has to adapt to a changing environment. Average HRV values are age-dependent and can give us insight into our cardiovascular health and how well we respond to life stressors. Research has shown that individuals with higher HRV have greater mental health resilience, emotional regulation, and balanced cortisol, whereas lower HRV has been associated with poorer mental health. HRV is affected by resting heart rate which is another reason why a lower resting heart rate may be favorable for an individual's health. If your resting heart rate is high, there is less time between heartbeats, and therefore, HRV will be lower. If your heart rate is low, there is an opportunity for greater variation between each heartbeat, leading to a higher HRV reading.
Heart rate variability is governed by the Autonomic Nervous System (ANS) which is responsible for controlling unconscious processes such as heart rate, breathing, blood pressure, and digestion. The ANS can further be divided into the sympathetic nervous system and the parasympathetic nervous system. The sympathetic nervous system controls our “fight or flight” responses which takes precedence during moments of high stress when we need to be alert. It causes our heart to beat faster to pump more oxygen to our muscles and release adrenaline to help us react to the stressful situation at hand. The parasympathetic nervous system is also known as the “rest and digest” branch of the nervous system and takes the lead when your body is in a restful state. Identifying an individual’s average HRV can help determine the balance between the two branches of the ANS. A low HRV may indicate an overactive sympathetic nervous system and a high HRV may indicate a more active parasympathetic nervous system. A higher heart rate variability can indicate an individual manages stress well due to a healthy balance between the sympathetic and parasympathetic nervous systems. A lower heart rate variability and greater activation of the sympathetic nervous system may lead to feelings of stress, depression, and anxiety.
The Bottom Line
Many factors contribute to an individual’s resting heart rate, maximum heart rate, aerobic capacity, and heart rate variability. These metrics can help us understand the current state of our health and more importantly, the progress we make over time. Like most advice we see, strive to eat healthy, exercise, sleep, and find ways to effectively manage stress. We will never be perfect, but we can work to improve these areas of our lives.
References
Assessed and Endorsed by the MedReport Medical Review Board
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