How Do You Get in Better Cardio Shape?

An Army soldier runs with the new K5 portable VO2 unit.
U.S. Army Capt. Zachary Schroeder, Headquarters and Headquarters Company commander, Army Public Health Center, runs with the new K5 portable VO2 unit on May 9, 2019, as part of his training to compete in the Army Ten Miler in October 2019. (Graham Snodgrass/U.S. Army photo)

If you are familiar with some common tests in exercise science, you may have heard about VO2 max. According to, it's the maximum volume of oxygen that can be utilized in one minute during maximal or exhaustive exercise. It is measured as milliliters of oxygen used in one minute per kilogram of body weight (ml/kg/min). Basically, it is the measurement of when you are breathing your hardest and your body's ability to consume oxygen.

The higher VO2 max, the better in terms of cardiovascular aerobic conditioning. A person's VO2 max is mostly genetic in regards to the size of your heart and the number of red blood cells in your body, but it also depends on how adapted you are to specific cardio events like running, swimming, biking, cross country skiing, etc.

As summer nears and more people start running again after a few months of alternate workouts, you may feel like you are out of running shape. So when people see better running times for instance, most of us say, "I got into better running shape over the past 12 weeks." A physiologist would say, "You increased your VO2 max by X%." 

There are tests to gauge an individual's VO2 max that are taken in exercise science labs where you run or bike as fast as you can and have your oxygen measured. There are also some ballpark calculators online that cover running and rowing, such as this rowing machine calculator.

For the average person, increasing your VO2 max by 15%-20% is very possible by starting some form of cardio. However, there are studies that show that even basic resistance training programs (circuits) and more advanced kettlebell workouts can improve VO2 max. But the common denominator is that you have to push yourself to near maximal levels of exertion to increase your VO2 max effectively. This study investigates how to increase VO2 max efficiently. 

As with many elements of fitness, VO2 max is all relative. The more in shape you are, the less percentage your VO2 max will improve. However, if you are untrained and have never reached your full athletic potential, walking, resistance training and interval training will help increase your VO2 max. It is very similar to the gains seen with people who do pull-ups regularly and those who do not.

A person who just did his first pull-up ever will see huge gains in the next month of training -- likely a 400%-500% increase in pull-ups. A person who can do 10 pull-ups, though, may see the same increase in performance (4-5 reps), but it is only a 40%-50% increase in performance. 

So why worry about VO2 max? Well, it is a great measure of cardiovascular health on any level of fitness. However, depending on what you do specifically, a VO2 max on a bike or treadmill may not be the best test if you do another sport like swimming or MMA. So it is not a perfect measure for higher-end athletes who are not runners or bikers.

Here are some sample workouts that will get you in better shape, which I think is a better term for most people instead of "increase your VO2 max."

Cardio Workouts: Intense Intervals, Time Related

Do high-intensity intervals 2-3 times a week.

  • 30/30: Run, bike, elliptical, row, swim, etc., as fast as you can for 30 seconds. Go at an easy pace for 30 seconds. Can you continue this cycle for 15-20 minutes? Can you build up to 30 minutes?

  • 60/60: This is the next level interval as you progress with your conditioning: one minute fast, one minute slow.

  • Tabata intervals: This interval is similar to the above but with less recovery time. You sprint for 20 seconds as fast as you can, followed by 10 seconds of very slow recovery while running, biking, elliptical, rowing, etc. Using this protocol, some even mix in high-rep calisthenics like burpees, mountain climbers and other full-body movements with kettlebells.

Cardio Workouts: Intense Distance Intervals

Doing short, fast distance intervals with matching or just less-than-matching recovery periods is another tough way to push your cardio conditioning (VO2 max).

Start with shorter distances until you can master them at your goal mile pace for several sets greater than or equal to your timed run distance:

Repeat 6-8 times.

  • Run a quarter-mile fast.

  • Rest with easy jog for the time it took to run a quarter-mile.

The goal is to complete these runs as fast as you can.

Repeat 3-4 times.

  • Run a half-mile fast.

  • Rest with an easy jog for the time it takes to run a half-mile.

The other type of running you should focus on is an easy, paced run 2-3 times a week to learn how to run at your pace for the goal distance of your test. These other runs can be intervals like those above, just at your goal mile pace or longer, or slower distances with different sections of goal paced running measured. Check out this article on goal pace running.

All of the running workouts are great for getting you into well above passing/maxing conditioning for any military timed run event. So if you build your cardio conditioning (VO2 max), using both high-speed interval training and goal pace running distances, your 1.5-, two- and three-mile timed military runs will get better.

Related articles/studies on VO2 max:

90-100% Effort Yield Best Results

Weight Training Can Increase VO2 Max in Untrained People

Stew Smith is a former Navy SEAL and fitness author certified as a Strength and Conditioning Specialist (CSCS) with the National Strength and Conditioning Association. Visit his Fitness eBook store if you're looking to start a workout program to create a healthy lifestyle. Send your fitness questions to

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