Don’t Assume Fitness Watches Tell Whole Health Story
I’ve been noticing a lot of people tracking their fitness with Fitbits, Apple Watches, WHOOP bands and other wrist-worn exercise monitors. While these devices are great to help people make a quantifiable measurement of activity level, do they actually measure what is most important to sustaining health and what is actually being measured?
I do believe these devices are beneficial and fun. They count your steps per day, report how long you’ve been standing, how much exercise you have accomplished and even create reward systems to help you maintain motivation to move more. They even can track your sleeping patterns. All of this information is useful.
One concern I do have is the excessive monitoring of heart rate during exercise and putting too much value on the reported calories burned in an exercise session. But first, let’s take a look at how we can use this information to benefit us the most.
First, we need to figure out your Max Heart Rate. Max Heart Rate is a number associated with the number of beats your heart makes within 1 minute and is found by taking 220-Age. So if you are 60 years old, your max heart rate formula would be 220-60=160 bpm. The 160 relates to (heart) beats per minute (bpm). How do we use this information? We can now start to define the intensity of a workout by tracking our heart rate throughout a workout. Moderate Intensity, as defined by the Center of Disease Control, is 64 to 76 percent of your Max Heart Rate, and Vigorous Intensity is 77 to 93 percent Max Heart Rate.
Let’s stay with the 60 year old example. If that person’s max heart rate is 160 bpm, then moderate intensity would be between 102-122 bpm and vigorous intensity would be 123-149 bpm. The American College of Sports Medicine has a general recommendation of at least five days per week of exercise at moderate intensity, at least three days per week of exercise at vigorous intensity and three to five days per week of a combination of both moderate and vigorous exercise.
These recommendations should be goals. If you are not used to exercise, then just getting in one or two days a week of moderate intensity will be a great starting point from which to build. After consistency of moderate intensity, then add a day or two of vigorous exercise. At bare bones minimum, we should all be getting about 150 minutes per week of exercise with moderate intensity.
Now let’s dive into the infamous calories. Everyone seems to be crazy about calories. “Calories in and calories out. I burned 50 calories here. I can only eat this many calories, because I only burned this many calories today.” All of these I believe to be semi-truths when it relates to health and wellness. So do we actually know what a calorie is or represents? A calorie is a measurement that describes how much energy it takes to increase the temperature of 1 gram of water by 1 degree Celsius. Does that help you connect with your health and wellness? Probably not. It seems pretty miscellaneous if you ask me. So how does your Apple Watch measure this parameter? It combines your age, height, weight, gender, heart rate and duration of exercise into an algorithm to calculate the number you see after you workout. In a general sense, it is telling you how hard you worked out. Does it correlate to calories actually burned because of the workout? I would suggest there are missing pieces to this modality.
There are two missing pieces:
1) The calories it takes you to just sustain your daily functions. This is called your basal metabolic rate (BMR). The energy it takes to make your heart beat, digest food, repair the body’s tissue, all brain functions and literally everything else it takes for you to live in this world at a resting state all take energy. You can increase your BMR by increasing your muscle mass, because your muscles are like fat burning factories that constantly need energy to sustain themselves.
2) All the calories that are burned to recover from exercise. This process is called Excess Postexercise Oxygen Consumption (EPOC). We described exercise intensity via the use of heart rate in a workout. The greater the intensity and the longer duration of the intensity will increase the time that it will take to recover from the workout. All of which takes energy: decreasing heart rate, decreasing the body’s temperature, repairing damaged muscles and removing all the metabolic waste that was produced during the workout (feeling the burn) all require energy after you exercise.
What I am suggesting is heart rate is a good way to measure your intensity, but it should be used in moderation. Find your Max Heart Rate and determine the intensity at which you want to focus for your workout. Use your device to gauge your effort and then truly define that by a feeling. Moderate Intensity can be sustained for long periods of time. Vigorous intensity is more like sprinting or used in high intensity interval training. When it comes to calories, we can’t measure all the calories that we burn, nor is it realistic to measure calories in and calories out. The calories that are represented shouldn’t be compared to food but rather your effort with a given amount of time. Increase your BMR by exercising more or moving more in general. This will help build muscle mass that will help you become a fat-burning machine.