What Is Heart Rate Variability–and Do You Need to Know Yours?

What Is Heart Rate Variability–and Do You Need to Know Yours?

HEALTH / HEART DISEASE
What Is Heart Rate Variability–and Do You Need to Know Yours?
It's one of the most important measures of heart health, but it's rarely talked about. Here's what you need
Thinking about your health means minding your heart, and you're no doubt accustomed to paying attention to measures like cholesterol, blood pressure, and triglycerides. There's one more to add to that list: heart rate variability.

“Heart rate variability is the variation in the time between each heart beat,” explains John P. Higgins, MD, MBA, a sports cardiologist at McGovern Medical School at the University of Texas Health Science Center at Houston. This is different than your heart rate, which is measured by the number of times your heart beats per minute. And unlike your heart rate, which you can calculate by counting your pulse, heart rate variability is measured at the doctor's office with an electrocardiogram (ECG or EKG) test that records the electrical activity of your heart.
Variability refers to your heart beat's ability to shift throughout the day. Your heart rate is not meant to stay the same speed at all times; it changes depending on your activity and emotions. “Think about your lowest heart rate and fastest heart rate. The difference between those is a reflection of your heart rate variability,” Dr. Higgins adds.
Need more clarity? Let's think back—way back—to our caveman ancestors. They may have had resting heart rates of, say, 60 beats per minute (bpm) when they were sitting down in those caves. But as soon as they were outside and a saber-toothed tiger came roaring by, they needed to get their heart rates up–fast–in order to move their bodies and get away quickly, explains Karol Watson, MD, PhD, director of the UCLA Barbara Streisand Women's Heart Health Program. “Our bodies were made to modulate our heart rate and blood pressure from second to second, minute to minute,” she says. That modulation is governed by the autonomic nervous system, which includes both your sympathetic nervous system (SNS, or fight-or-flight response) and parasympathetic nervous system (PNS, or your chill-out system).