What Is High Intensity Fitness?

Exploring Intensity

What Is High Intensity Fitness?

What is high intensity fitness? At Cardio High we choose to focus on high heart rate because there are hundreds of scientific studies that focus on heart rate to measure high intensity fitness. There are also quite a few good heart rate devices that allow users to see the results of their workout during and after the session.

In our gym we display each client’s heart rate on a tv monitor, so they can judge their own effort with a glance up at the monitor. Different companies break down the various heart rate zones by measuring heart rate as a percentage of a person’s maximum heart rate. As people age their maximum heart rate drops by about one beat per year. The basic formula for determining your max heart rate is to take 220 and subtract your age. A 40-year-old will likely have a max heart rate of 180 beats per minute. The measure of intensity is a percentage of that number. 

Zone 1 is anything below 60% of max heart. For most people this is doing a gentle warm up or light walking. 

Zone 2 is 60-70% of max heart rate. For most people simple movements like squats, lunges or a light jog will have them hitting Zone 2. People generally do not feel out of breath in Zone 2.

Zone 3 is 70-80% of max heart rate. For most people a medium-paced jog or more challenging movements like a complete set of pushups will help them hit Zone 3. Breathing in Zone 3 is heavy but comfortable. Most people can comfortably maintain Zone 3 for long periods of time. 

Zone 4 is 80-90% of max heart rate. Anything above 80% of max heart rate is considered high intensity exercise. Most people will hit Zone 4 when they are jogging, cycling or swimming at a fast pace. Breathing becomes heavy and challenging in Zone 4. Most people can carry on a conversation in Zone 4, but it becomes more difficult as they approach 90%.

Zone 5 is 90-100% of max heart rate. Most people will hit Zone 5 when they do activities like running a 5K at fast speed or playing sports like squash or soccer. It’s very difficult to speak when in Zone 5, and the breathing can feel uncomfortable for those who are not used to the feeling. It is challenging to maintain training in Zone for long periods of time (more than 20 minutes). 

Some gyms focus on heart rate training and reward clients for time training above 80%, but this will often reward those who are out of shape and punish those who have efficient cardiovascular systems.

If someone is out of shape, they may be able to hit 90% of max heart rate by simply walking rapidly. An athlete who is in peak physical condition will find it challenging to hit 90% max heart rate. They will often have to move at a high rate of speed for up to a minute or two before they even hit 90%.

As people train consistently at high intensity levels two major changes occur in their cardiovascular performance. It becomes harder to reach 80+% of max heart rate, and their recovery to resting heart rate will improve. Experiment: run up two flights of stairs and see how long it takes you to catch your breath. It will much longer for someone who is out of shape than for someone who has been training. 

Why does this happen? We will get to that question with the help of Doctor S. in our next mini chapter. But basically, the body changes to allow it process oxygen much more efficiently, so the body gets more out of each breath and each heart beat, thus needing fewer heart beats per minute to power the machine at similar levels of exertion. 

There are other measures of intensity that are harder to measure. One of the best is VO2 Max which provides a measure of how much oxygen the body can process while at peak performance. It requires wearing a contraption over the nose and mouth and a hook up to a machine which makes it impractical to use during a fitness session or certainly while playing a sport. 

Some people focus on calories burned per hour of exercise, and that can be useful for comparing one workout to the next, but it does not give a person the ability to measure intensity on a minute-by-minute basis during a workout. 

-Mark G.

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