VO2 Max: The What, Why, and How of the Misunderstood Fitness Score

When you are eager to enhance your training, skimming through online articles is the easiest way to get the most updated information for training plans, proper nutrition, and methods for coping with injuries. Once you start your research, you will not go too long without coming across the term “VO2 max”. There are several running-related terms that are learned that may seem foreign to us initially, but are pretty straight forward once explained. VO2 max is most definitely not one of them. It is a widely popular term used to measure how fit you are aerobically and most coaches and experienced runners will emphasize its importance. You may soon find yourself ecstatic when you see your VO2 max increase as per your Garmin watch, but not have a clue as to what it means.

 What is VO2 Max?

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Specifically, VO2 max is the maximum rate of oxygen consumption measured during exercise of increasing intensity. It is measured in milliliters of oxygen used per kilogram of bodyweight. At first it may be simple to understand just by reading its definition, but when trying to apply the term to your running routine or fitness, it all gets a bit foggy. Basically it is the amount of oxygen we can use during intense exercise. In general you want to be able to utilize the most oxygen you can during any workout, because oxygen is what allows you to continue exercising at a higher intensity level, such as while running a marathon at your goal pace. 

 With proper and consistent training, VO2 max should increase. Good training practices improve several physiological factors that play a role in the oxygen transport throughout the body. Stroke volume of the heart increases, which means more blood is pumped out with each heart beat, as is the size of mitochondria and capillaries, which are the transporters of the oxygen throughout the body and to the working muscles. These improvements in oxygenation in the body lead to increases in the VO2 max value. Essentially, if you are looking to get faster and last longer during running, your goal should be to improve these physiological mechanisms.

 What is a Normal Value?

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A typical value for a sedentary adult ranges from 25 to 35 ml/kg/min, between 35 to 55 ml/kg/min for an active adult, and over 60 ml/kg/min for an elite athlete. All of these values can vary from workout to workout depending on the intensity of the training run. If you are trying out a harder than usual speed session, you may see your value drop, but as you continue performing that training run, it will eventually assist in increasing your VO2 max. Usually long distance runners such as marathoners will have a lower VO2 max than short distance runners. This is because the VO2 max testing, as well as the training to improve it, is done at a distance and speed that is much closer to a 5K intensity.

Improving VO2 Max

Beginner runners have it the easiest when it comes to improving their VO2 max, since simply logging more miles on a consistent basis will naturally raise their oxygen consumption ability. For more advanced runners, the process will require including speed work to your training plan. The key is to reach 95% of your VO2 max level for intervals of 2 to 6 minutes. Aiming for 4 to 8 intervals of 400 meters to 1200 meters works best, with a walk or jog recovery in between each. Faster runners can even use mile repeats, but anything more than 6-minute intervals will require too much time for recovery. Your VO2 max level is considered to be your threshold pace so it should feel significantly hard. 

 A Good Indicator of Health

Studies have shown that higher VO2 max values are favorable if you are looking for overall health benefits. It is a true indicator of fitness, which is solely based on cardiovascular functioning, versus physical looks—what most people will believe “being fit” consists of. Several research studies indicate that individuals with a higher VO2 max generally have lower blood pressure, less risk of stroke, obesity, cardiovascular and pulmonary disease, and a longer life span. Of course, this all has to do with the fact that those who have a higher VO2 max partake in the required physical activity needed in order to reap overall health benefits. 

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 It is beneficial to not base the entirety of your fitness gains on what your VO2 max value is, since it can be affected by several factors such as age, genetics, gender, temperature, body size, and altitude. Males will generally have higher values than females. A person with a larger body type will also have a higher VO2 max given that their heart and lungs are larger in size. Studies have shown that oxygen is more easily transported while exercising in warmer temperatures. It is important to note that the value given on the training devices is an estimate based on the heart rate and intensity of each workout. A true value can only be calculated while performing an activity such as running on a treadmill at maximal intensity with a mask on the face that measures the actual oxygen consumption.

How Many Calories Do Runners Really Need?

Several factors go into being able to improve your performance as a runner. Consistent training with the right mix of speed work, long runs, and easy runs are at the top of the list. Rest and cross training must also be incorporated to recover properly and be prepared for the hard sessions to come. Nutrition plays a large role in performance, as it is what gives us the energy we need to actually perform and to do it well. Consuming the proper amount of carbohydrates and proteins is the key to sustaining energy levels while making sure to include other key nutrients like iron and vitamins.

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You may have been in the situation where you do well during training for a bit but frequently struggle to hit several workouts in a row. This is usually a sign that you are not eating enough. As volume and intensity increases during training cycles, the number of calories your body requires increases as well. Even if you are on top of your nutrition game, it is easy to not meet your recommended calorie intake. Not eating enough calories can leave you fatigued on every run and increase your injury risk. But what is the right amount?

Calorie Intake

The right amount of calories a runner requires will depend on age, sex, weight, and activity level. This means it may be necessary to consume a fluctuating amount each day of the week since the intensity and length of runs and other workouts vary. The recommended daily calorie intake for a sedentary adult male ranges from 2200 to 2600 calories. For females, the range is 1800 to 2000 calories. Therefore some distance runners may need close to 3000 or more calories most days of the week to maintain their weight and energy levels. This may seem like too much, especially to women, but it is what is necessary if you want to perform your best and not risk getting injured.

Weight Loss & Training

If you currently are overweight or obese, then a lower calorie intake is ideal until you reach your goal weight. This should be done carefully, as cutting calories too low can result in limited energy. This will only lead to having to skip workouts and not be able to run your hardest. Having too little calories may also lead to muscle loss, which is what powers us through our workouts. Therefore if weight loss is a goal when training for a race, then it should be done gradually. Unfortunately, it is safest to plan an extremely slow weight loss of about a half pound per week.

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Calorie Requirements Equation

Although calorie calculators you find online are used to get an estimate of the number of calories you need, it is usually in the ballpark of the right amount. The Harris-Benedict equation is a popular formula used to estimate your needs and takes into account your current activity level.

BMR for Men:    (10 x weight in kg) + (6.25 x height in cm) – (5 x age in years) + 5

BMR for Women: (10 x weight in kg) + (6.25 x height in cm) – (5 x age in years) – 161

BMR is your basal metabolic rate, which is the number of calories your body requires in order to function properly. Once you calculate your BMR with this formula, you can multiply by the different values according to daily activity level.

For men and women:

Sedentary/little to no extra activity: BMR x 1.2

Light exercise 1-3x/week: BMR x 1.375

Moderate activity 3-5 days/week: BMR x 1.55

Very active 6-7 days/week: BMR x 1.725

Hard exercise/physical job (2x/day training): BMR x 1.9

This method is a good way to determine how many calories you should have on each training day, since some runners train twice a day a few times per week, but take a full rest day as well. Calorie requirements will be very different for each of these days.

Even with the above formula, the calorie requirement calculation can be wrong—either too high or too low. Everybody is different and some runners burn more calories per hour than others. Fitness levels, genetics, and present medical conditions can impact your calorie-burning rate. A more accurate test is one where you sit for ten minutes with a mask over your face and your breathing is measured to determine how much oxygen you use at rest. Whether you use this method or the formula above, many times it is all about trial and error. It is best for runners to eat more than they think they need at first and see how their body responds rather than under eating to see if it is good enough. You do not want to risk getting injured or wasting too many weeks not making progress due to not eating enough.

Types of Calories

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Once you understand your individual daily calorie requirements, then it is important to fuel your body with the right types of calories. Limiting “empty calories” is key as these are considered calories with no nutritional value. Most packaged snacks, candy, soda, and chips are in this category. Runners should focus on getting the majority of their calories, at least 60%, from high-quality carbohydrates in order to supply the muscles with enough glycogen. The other 40% can be divided evenly between lean proteins and healthy fats. Proper fueling and hydration practices are necessary for performance improvement, injury prevention, and for an overall healthy body.

Sources

Benjamin I. Rapoport , Metabolic Factors Limiting Performance in Marathon Runners, Journal, Dec 26, 2019.