Your heart rate offers an objective look at exercise intensity. In general, the higher your heart rate during physical activity, the higher the exercise intensity. — http://www.mayoclinic.com
This is not true for everyone. My heart rate is often 120, and I am not panting and sweating from exerting myself. For someone without tachycardia, the heart rate tends to indicate oxygen uptake. Oxygen uptake is the only true way to measure caloric burn and can’t be measured without wearing a mask over your face, connected to a machine that will measure your oxygen uptake.
For those of us with tachycardia, our heart rate does not have the same relationship with our oxygen uptake as it does with “normal” people. However, even for those of us with tachycardia, an increased heart rate from our normal heart rate, can indicate increased exertion. It’s just that if you use a heart rate monitor to measure you calories, you are going to get inaccurate measurements. The heart rate monitor uses a formula based on the heart rate and oxygen uptake relationship of a healthy person. So while “normal” folk may be gasping for air and sweating like a pig at 120 beats per minute, it may need to get up to 180 beats per minute for us get to the same point. While a “normal” person may be burning 15 calories a minute at 180 beats per minute (completely made up number), we would only be burning 8. This is because it takes a healthy person much more oxygen uptake to achieve 180 beats per minute than someone with tachycardia. I don’t know the scientific evidence, but I have to think when my heart rate increases, my heart is working harder even if my whole body (muscles, respiration, calorie burn) isn’t. I guess I’m trying to say, I think it works harder, but not in a cardio/aerobic way.
I find something I discovered yesterday interesting. On my body, grocery shopping requires more exertion than exercising on a stationary bike! I wear my heart rate monitor when I exercise and occasionally when I run errands.
When I ride the bike, it is nonstop exertion. Right now I am only able to do 10 minutes. My average heart rate throughout the workout averages out around 139, the average maximum heart rate is about 153.
Yesterday, I went to the grocery store. I needed to grab medicine from one side of the store, and two food items from the other side. I decided to use a regular cart rather than the motor cart since I was only grabbing a few things. I strapped on the heart rate monitor, did my hair, got dressed, walked down the stairs to my car, drove to the store, walked into and around the store, stood in a checkout line for 10 minutes (DISASTER), walked out to my car, tossed a few bags in my back seat, drove home, carried groceries up the stairs, and finally put groceries away. As you can tell, not one part of my grocery trip should have required much exertion. I didn’t buy any heavy items.
My average heart rate was 130, but my maximum heart rate was 189!! That is almost a full 40 beats higher than my maximum heart rate is when I exercise and am trying to get my heart rate up a bit. The lower average heart rate was expected since about 20 minutes (33%) of the time I was measuring my heart rate was spent sitting virtually motionless.
This goes to show you just how hard standing up is on those of us with POTS (and many other illnesses) and why it is so important we exercise sitting/lying down. Sitting or lying down reduces the stress, unique to those of with POTS, standing up causes on our bodies. This allows us to build muscle without forcing our body to use up unnecessary energy battling gravity.