One of the best markers for predicting overall health and longevity is aerobic capacity. In this article, we’ll discuss what aerobic capacity is, why it matters, and how you can improve your own aerobic capacity.
Aerobic capacity is defined as the maximum amount of oxygen the body can use at a given time. To give some context, let’s first review what happens in the body when you do physical activity.
The main organs involved in oxygen delivery and utilization are the heart, lungs, and skeletal muscles. When you exercise, your body uses more oxygen and produces more carbon dioxide as a by-product. To manage this increased demand, your breathing rate increases. At rest, the adult breathing rate is around 15 breaths per minute. During exercise, this increases to about 40-60 times per minute. Heart rate also increases to speed up circulation of oxygen to be delivered to muscles.
Increasing aerobic capacity has a multitude of benefits. These include promoting heart health, cognitive health, supporting a healthy weight, and supporting healthy blood sugar levels.
Oxygen is essential in all functions of the body, particularly in energy generation in the mitochondria, the energy powerhouses in the body’s cells. Increasing oxygenation in the body through increasing aerobic capacity enhances overall health.
In particular, increasing aerobic capacity can enhance athletic performance. In a 2008 study on recreationally active individuals, 6 weeks of HIIT training significantly increased training power output.
Aerobic capacity is also related to quality of life with aging. While the maximal possible lifespan is still fixed by genetics, regular exercise training can increase the chances to reach the later end of the natural lifespan through prevention of certain health issues and giving more quality of life to later years. In fact, aerobic capacity, or VO2 max, is the strongest predictor of life expectancy in both healthy and cardiorespiratory-compromised individuals.
Increased aerobic capacity also enables more glucose uptake into muscle cells during exercise, which is a useful way to support healthy blood sugar levels.
There are multiple factors that impact aerobic capacity, including gender, age, body composition (levels of body fat and muscle), genetics, elevation, and fitness level.
On average, women have about 70-75% the aerobic capacity of that of their male counterparts.
Age is known to play a role in aerobic capacity, which typically declines with natural aging. While aerobic capacity naturally declines with age, the findings of a longitudinal study suggest that increasing aerobic exercise can be a successful way to offset the natural decline in cardiovascular health that accompanies the normal aging process.
Fitness level is associated with aerobic capacity as well. Physiological factors that influence aerobic capacity include the total ability of the cardiorespiratory system to deliver oxygen to the muscle, as well as the ability of muscles to use oxygen to produce energy.
To be able to utilize more oxygen, and thus increase aerobic capacity, the body needs a multitude of functions working together. Skeletal muscles as well as lung muscles must be strong and contain a high density of mitochondria to meet the demand of the workload. Exercise itself is a major factor in building strong muscles and increasing mitochondrial density in muscles. Therefore, regular exercise increases our ability to complete more exercise in part through increasing our aerobic capacity.
Aerobic capacity is also known in research calculations as VO2 max, which is the maximal ability to transport and utilize oxygen during exercise. So aerobic capacity and VO2 max are really one in the same.
As the rate of exercise increases, oxygen uptake increases until an individual hits their VO2 max level. With more exercise, one’s VO2 max level can be increased.
Although aerobic capacity and aerobic endurance are similar, they are two separate elements of aerobic metabolism. Aerobic capacity is the maximum amount of oxygen your body can use at a particular moment. Aerobic endurance is how long your body can sustain certain moderate and high intensity activities over a period of time.
The difference may be likened to speed versus stamina. For example, someone with high aerobic capacity can likely run a mile at high speed. On the other hand, to be able to run many miles at a moderate pace, one needs aerobic endurance. In many cases, to be able to perform best, both aerobic capacity and endurance are needed.
The most accurate way to test aerobic capacity is to calculate the volume of oxygen consumed per minute (mL/min) per kilogram of body weight. While this is best done in a lab to get accurate results, we can also estimate aerobic capacity in easier ways.
The 1.5 mile and 12 min walk/run tests are two validated and easier alternatives for estimating cardiorespiratory fitness. These tests involve either completing a 1.5 mile distance in the shortest time possible, or testing how much distance you can run/walk over a 12-minute duration. Your time results can tell you whether you have poor to superior aerobic capacity overall. You can then predict your VO2 max by using the calculation VO2 max = (483 / your time) + 3.5.
In addition, certain wearable fitness devices can estimate your VO2 max using markers including heart rate, which has been shown to be a good predictor of VO2 max.
The major way to increase aerobic capacity is through exercise. The general recommendation for exercise to support general health is at least 150 minutes/week. To increase aerobic capacity, however, there are more nuanced ways to exercise.
A 2016 review study showed that high intensity interval training (HIIT) improved aerobic capacity more effectively than moderate-intensity continuous training. In addition, endurance training studies have frequently shown only modest changes in VO2 max.
Doing high-intensity near-maximal exercise (about 80-92.5% VO2 max) may be the best exercise intensity range for improving VO2 max, according to observations from a 2016 study.
A 2008 study showcased an example of a HIIT workout regimen that significantly increased aerobic capacity as well as increased whole-body ability to burn fat and carbohydrates. The regimen consisted of a one-hour HIIT workout of 10 x 4 minute intervals with 2 minute breaks in between.
Research suggests that aerobic cross-training, or doing a variety of aerobic workouts, may enable maintaining VO2 max despite a change in the specific workout. This is good news for those who want to increase overall fitness as well as supplement alternative workouts during periods of overtraining or rehabilitation from physical injury.
There are plenty of cardio exercises that you can do to increase aerobic capacity. These include swimming, running, biking, jump roping, burpees, and more. You can always talk to a fitness trainer for specific exercises tailored to personal goals, growth, and physical injury support.
Aerobic capacity is linked to a multitude of health benefits, including long-term cardiovascular health, increased exercise capacity, and supporting a healthy weight. While certain factors like current fitness level affect aerobic capacity, the good news is that we can confidently increase our aerobic capacity through aerobic exercises, especially when done in intervals at high intensity, which seem to provide the greatest benefit.