Tag Archives: heart rate

“Heart” your heart.

Today is World Heart Day, with a focus on encouraging all of us to make heart-healthy choices to reduce cardiovascular disease risk. I thought that sharing some information about the heart, how it works, and how to keep it healthy would be an appropriate way to celebrate. This is also the topic of my Health & Fitness column in the Aiken Standard this week.

Your heart started beating months before you were born and will continue to beat every second or so…until it stops, signaling the end of your life. During your lifetime, your heart will probably beat more than two billion times, or about 100,000 times per day. (more interesting heart facts here)

The major function of the heart is to pump blood to all of your tissues through the arteries and back again through the veins. The heart has four chambers: the left and right atria that receive blood from the veins and the left and right ventricles that pump blood into the arteries. The right ventricle pumps blood to the lungs to pick up oxygen and the left ventricle pumps oxygenated blood out to the rest of the body.

The activity of your heart will vary throughout the day. At rest your heart rate is low, typically around 70 beats per minute. Some athletes have resting heart rates that are much lower, owing to their bigger, stronger hearts.

But when you are active your heart beats faster and more forcefully to eject more blood to the working muscles. During intense exercise, a young person’s heart rate can go above 200 beats per minute and the amount of blood pumped can be five times higher than at rest!

The heart is made up mostly of muscle that functions similarly to the skeletal muscles you use to move your body. But cardiac muscle is different in that it can spontaneously contract when stimulated by a specialized area of the heart called the SA node or pacemaker. And unlike skeletal muscle, the heart is remarkably fatigue-resistant, meaning that it can contract repeatedly without needing a break.

In order to beat continuously, the heart needs a steady supply of oxygen which is delivered through coronary arteries, not from the blood inside the chambers of the heart. Normally, plenty of oxygenated blood gets through. But if the coronary arteries become narrowed through atherosclerosis, the accumulation of plaque in the vessels, blood supply can be limited.

This can lead to reversible symptoms like angina pectoris (chest pain), especially during exertion. If a clot forms in the narrowed vessel, blood flow can be blocked completely causing a myocardial infarction (heart attack). Heart disease can be managed using medications, angioplasty, or bypass surgery, but the best approach is to prevent the problem from occurring in the first place.

Taking care of your heart is one of the most important things you can do for your health. Like other muscles, regular exercise can make your heart larger and stronger to pump blood more effectively. Exercise also lowers your blood pressure and can help reduce your blood cholesterol, further reducing the risk of heart disease.

A diet that is low in salt and unhealthy fats, like trans fats, can help lower blood pressure and cholesterol, slowing the process of atherosclerosis and preventing heart failure, a condition in which the heart muscle becomes weak. Maintaining a healthy body weight and controlling blood glucose are also keys to a healthy heart.

More than anything, though, your heart likes to be active. So celebrate World Heart Day by taking your heart for a walk!

 

There’s an app for that!

There are hundreds of health and fitness applications currently available for smartphones and other mobile devices. Among the most popular are health and fitness apps that allow you to track what you eat, your weight, and your activity. Some apps can measure how intense you exercise by using the GPS and accelerometer features of the phone itself or by syncing with a wearable bracelet or belt clip.

There are some concerns about the accuracy of some of these apps and potential dangers of using unregulated health evaluation tools. In general, though, these mobile applications are thought to be safe when used for health and fitness purposes, even though they have not been independently tested.

One of the most popular health and fitness apps is Instant Heart Rate by Azumio, Inc. It works by using the camera on your smartphone. When the app is opened, the flash of the camera comes on and stays lit. Placing the tip of your index finger over the camera allows the app to measure your heart rate, and after approximately 30 seconds a reading registers on the screen.

This is useful because heart rate is widely used to monitor and prescribe exercise intensity. It is traditionally measured by palpation (feeling your pulse), which can be difficult, or by wearing a chest strap monitor, which tend to be expensive.

The Azumio Instant Heart Rate app gives smartphone users an easy way to measure their heart rate. But the question remains, is it accurate? According to research presented by my students Ashton Celec and Sam LaMunion at the American College of Sports Medicine annual meeting last week, it is.

This is the topic of my Health & Fitness column in the Aiken Standard this week.

Sam and Ashton compared the heart rate measured at rest and during light, moderate, and vigorous exercise using the Instant Heart Rate app and a Polar heart rate monitor, the “gold standard” in our lab. They measured the heart rate of 40 young men and women at rest and while they walked on a treadmill at light, moderate, and vigorous intensity.

The results showed that there were no significant differences between the Instant Heart Rate app and the Polar monitor. In fact, on average the two values were between 2-3 beats per minute! This suggests that the app accurately measures heart rate. (More details in the abstract)

They did notice something interesting, though. The instructions for using the app show that you should hold the phone in one hand, and place the index finger of the other hand over the camera lens. This worked well at rest and during light exercise, but not during more vigorous walking.

It seems that arm and hand movement made making good contact between the finger and camera lens challenging. The readings were still accurate, but the measurements took much longer that the usual 30 seconds. This problem was solved when subjects held the phone in the same hand they used for the measurement.

It would be impossible to evaluate every health and fitness app available. Frequent updates and improvements could also mean that the app you download today may be different from the first version from several months ago. But it is likely that most are accurate enough for general use.

This research suggests that at least one of these apps—Azumio Instant Heart Rate—app is as accurate as equipment we use in our lab. There is a free version of the app for Apple and Android devices, so it’s worth checking out. At the very least, you can marvel at the fact that your camera can measure your heart rate!