With the advent of COVID-19 and the dangers of going to the gym and risking possible exposure, we’ve had to get creative to stay in shape without equipment or access to a gym. One of the best-recommended exercises has always been cardio, but no one really explains why or what that means. To understand what it takes to get the most out of any cardio workout, there is some key information that is great to know about the human body and the processes it goes through. 

What exactly is cardio?

Cardio is commonly mistaken for running. While running is a great form of cardio, cardio is not just running. Cardio is short for cardiovascular exercise, and any exercise that elevates your heart rate is considered cardio. Cardio does a few things to the body while doing the exercises:

  • Increases the cardiac output of the body
    • Your body is training itself to increase the pumping capacity of fuel and oxygen to your muscles
  • Increases muscle blood flow
    • Blood vessels dilate in muscles increasing local blood flow
  • Redirects blood from organs, such as the liver, kidney, and gut, to working muscles
    • This lowers the amount of blood those organs get, redirecting the same blood to working and active muscles in the body

These reactions to cardiovascular activity help the body use what we know as calories. To further understand how this reaction works, we must explore what a calorie is first and how it interacts with oxygen.

What is a calorie, and what does it have to do with cardio?

The numbers and math of calories may seem frightening. However, the common misconception that calorie counting is the only way to lose weight is misguided in its attempt to give people good health advice. A calorie is not an actual compound or even a substance. A calorie is a measurement of the amount of heat an item gives off when burned. A caloric value is measured by the heat given off when burned in a special apparatus by scientists. With this knowledge, we can tie the relation between caloric consumption to oxygenation in the body. Without proper oxygenation in the body, there is no fuel to help burn a calorie in the human body. Cardio is usually an aerobic exercise, which is an exercise that requires the person to breathe to maintain oxygen levels in the body. As you condition your body with cardio, you will increase the cardiac output, therefore burning calories while conditioning your heart to be able to sustain an elevated output potential.

What are the best forms of cardio?

Now that we understand what cardio is and how it works, we need to discuss the most effective forms of cardio available for people.

  1. The best starting cardio is steady state cardio. Steady state cardio is great for people who have roughly 30-60 minutes of free time and discipline to be able to do any of the following activities:
    • Jogging/Walking
    • Swimming
    • Cycling
    • Dancing
    • Running (Intermediate level)
    • Jump rope (High level)

These exercises are all able to be tailored to the individual. You want to have an elevated heart rate during the entire time of the exercise. It is ideal to be around 70% or 80% of your maximum heart rate. A good way to estimate your maximum heart rate is to subtract your age from the number 220. You could use the following formulas as well:

  • (220 – age) x .7 = Estimated 70% maximum heart rate
  • (220 – age) x .75 = Estimated 75% maximum heart rate

If you don’t own a device that measures your heart rate, you can just gauge whether or not you’re in the target heart rate by trying to speak during your workout. You should find it slightly difficult to talk and breathe, but it should not be impossible. You can do daily steady state, but do keep in mind that certain activities like running and jump rope are high impact and will take a toll on the body without ample rest. It is usually recommended to do daily light impact steady-state cardio or 3-5 times a week of high impact steady-state cardio.

RestSteady state cardio for 20 minutesRestSteady state cardio for 20 minutesRestSteady state cardio for 20 minutesRest
RestSteady state cardio for 25 minutesRestSteady state cardio for 25 minutesRestSteady state cardio for 20 minutesRest
RestSteady state cardio for 30 minutesRestSteady state cardio for 30 minutesRestSteady state cardio for 30 minutesRest
RestSteady state cardio for 30 minutesRestSteady state cardio for 30 minutesRestSteady state cardio for 30 minutesRest

The best form of cardio for people who either don’t have a lot of time or want a better workout while having experience is called HIIT (High Intensity Interval Training). HIIT is essentially a circuit workout where you have incredibly high bursts of intensity and power for very short amounts of time with cool downs in between.

A good way to think about HIIT is intervals and ratios. The big difference between HIIT and traditional steady-state cardio is the workout being an anaerobic exercise, which means it is an exercise that breaks down glucose in the body without oxygen. Calories are burning during the workout and, most notably, after the workout since the body is deprived of the necessary oxygen levels. The post-workout consumption of oxygen is elevated, which causes excess post-exercise oxygen consumption (EPOC) in order for the body to maintain its normal metabolic function. During the time of high activity, the target heart rate will be around 80-90% of the maximum heart rate for a short amount of time. The formula for finding out the maximum heart rate at these levels is similar to the ones before for steady state.

(220 – age) x .8 = Estimated 80% maximum heart rate

(220 – age) x .9 = Estimated 90% maximum heart rate

The intervals starting out should be a 1:3 ratio for a very new HIIT beginner. If you’re interested in trying HIIT, you need to understand that this is usually a very high-impact and high-intensity workout routine. The routine also requires proper management of diet to supplement your energy levels as you’ll need a proper diet to sustain the rigorous training. Improper diet and sleep can lead to injuries. A 1:3 ratio is one second of activity having 3 seconds of rest. This scales with minutes as well. A circuit of HIIT lasts anywhere from 10 to 30 minutes, depending on intensity and experience. A good workout might look like the following diagram.

Here are a few of the workouts you can do for HIIT:

  • Shadow Boxing
    • Sprinting intervals
      • Sprint during the active time and jog or walk during rest intervals
    • Swimming
    • Cycling
    • Calisthenics (Push-ups, Sit-ups, Burpees, etc.)
Day 1Day2Day 3Day 4Day 5Day 6Day 7
RestHIIT 1: 3 ratio 10 minutesRestHIIT 1: 3 ratio 10 minutesRestSteady-state cardio 30 minutesRest
Steady-state Cardio 30 minutesRestHIIT 1: 3 ratio 15 minutesRestHIIT 1: 3 ratio 15 minutesRestSteady-state cardio 30 minutes
RestSteady-state Cardio 30 minutesRestHIIT 1:2 ratio 12 minutesRestHIIT 1:2 ratio 12 minutesRest
Steady State Cardio 35 minutesRestSteady State Cardio 35 minutesRestHIIT 1:2 ratio 15 minutesRestHIIT 1:2 ratio 20 minutes

Intervals can be as followed for 1:3:

  • 10 seconds of activity for 30 seconds of rest
  • 20 seconds of activity for 60 seconds of rest

Intervals can be as followed for 1:2:

  • 10 seconds of activity for 20 seconds of rest
  • 20 seconds of activity for 40 seconds of rest

Remember that working out should be fun, and these examples can be tailored to your personal needs and goals. The goal of working out should be at a level of slight discomfort unless you’re doing HIIT. When you exercise for extended periods of time, your intensity should be low enough that you make it to your time. Whenever you’re exercising for a steady state, focus on making it to the desired time. Whenever you’re exercising on HIIT, try to have your activity intervals be intense and make good use of your rest intervals. After a while, your body will adjust to the workouts, so inevitably, you will have to change your routine when you start to adapt.

Most importantly, please consult with your doctor before beginning any new exercise.