Cardiovascular fitness is a desired benefit of any proper exercise regimen. People commonly spend hours per week jogging, biking, swimming, or on a machine at the gym in pursuit of heart health, lung health, and improved fitness.
However, it turns out that strength is the best activity to perform for global metabolic conditioning and improve your VO2 Max, a potent predictor of longevity.
What is VO2 Max?
Simply stated, VO2 Max is a measurement that represents how much oxygen your body can absorb and use during exercise. It measures your aerobic fitness levels.
It is now well-understood in the scientific literature that VO2 Max levels have a direct causative relationship with longevity.
So how do we increase our VO2 Max and maximize the amount of oxygen we’re able to use? How can we use exercise to improve our fitness and longevity?
It turns out that safe, high-intensity strength training is the answer we’ve been looking for.
What Causes Improved VO2 Max?
Many people will point to breathing exercises, diaphragmatic breathing, and other methods for increasing the body’s uptake of oxygen. And while it’s important to breathe properly during the day and during exercise, these methods are actually downstream of a far more important priority.
The cardiovascular system’s purpose is to serve your working muscles, and high-intensity strength training places demands on those muscles most efficiently and most safely as compared to all other types of exercise.
A great example of this is a 2012 meta-analysis in the Journal of Exercise Physiology that found that the types of adaptations one would expect from traditional endurance-type aerobic exercise can be acquired just as completely through strength training.
These adaptations include (but are not limited to):
- an up-regulation of mitochondrial enzymes
- increased time-to-exhaustion
- enhanced mitochondrial proliferation
- phenotypic conversion from type IIx towards type IIa muscle fibers
- vascular remodeling (including capillarization)
To understand why strength training can have all the same cardiovascular benefits as traditional “cardio,” it is necessary to understand that the cardiovascular adaptations we’re after are produced by the body in proportion to the intensity with which the muscles are made to contract.
For example, all things being equal, higher intensities of exercise (high-intensity strength training rather than jogging, for instance) are more effective for improving VO2 Max, a primary determinant of cardiovascular fitness.
It was also found that, at a sufficient intensity, six minutes of exercise can be just as effective for cardiovascular fitness and condition as an hour of daily moderate activity.
Time and time again the literature suggests that less-intense, longer-duration exercise carries no benefit when compared to more intense — yet brief — exercise.
Enhanced VO2 Max is a Muscle Improvement
The most important point to understand is that when an improvement is observed in someone’s “cardiovascular fitness,” regardless of the activity being performed, what’s actually being observed is an improvement inside the working muscles.
The muscles are where the VO2 Max improvement occurs, not the cardiopulmonary system.
When you fatigue during exercise and are forced to reduce your effort or terminate the exercise entirely, it’s not that your heart and lungs are failing to deliver sufficient oxygenated blood to the muscles. It’s that the byproducts of fuel use inside the muscles have accumulated to the point that the muscles can no longer continue at their current rate.
An elegant study was performed in 1976 in which the experimenters recruited thirteen subjects and trained them on a stationary bike. But crucially, each participant only trained one leg for the entire study.
The trained leg employed a sprint and/or a low-intensity steady-state protocol. The subjects performed four or five of these workouts per week for four weeks.
After the study, when the researchers tested the subjects’ VO2 Max by having them repeat the exercise with the trained limb, they noted an increase in VO2 Max of twenty-three percent.
Now, the one-legged exercise used during the study was supposed to produce a full-body heart-and-lung improvement, but when the experimenters tested the subjects’ untrained legs, they discovered that there was no improvement in VO2 Max at all.
But wait a minute. If “cardio” improves the heart and the lungs, shouldn’t the full body receive this VO2 Max benefit? Why didn’t the heart and lungs show the same twenty-three percent improvement during the tests of both legs?
The answer is the same point made above, which is that when an improvement is observed in someone’s “cardiovascular fitness” or VO2 Max, what’s actually being observed is an improvement inside the muscles, not the heart or lungs.
This is why jogging will give you a better result than walking, running will give you a better result than jogging, and sprinting will give you a better result than running.
A greater demand is being placed on the muscles as you move faster, and as a result, the cardiovascular adaptations become more robust.
The tradeoff here is that you must reduce your total volume of exercise as you increase the intensity, in order to avoid overtraining and injury.
And while this may seem like a bug — “I want to work out for longer, but I can’t!” — it’s actually a huge feature. It means that by briefly placing an intense demand on your muscles and hustling between exercises, you can provoke every desirable cardiovascular adaptation of which your body is capable.
And what’s the best way to place a brief but very intense demand on the muscles?
Answer: strength training.
And what’s the safest and most efficient method for performing strength training?
Training with me!
The Best Way to Improve Your VO2 Max
We now know that the muscles are where the action is. In fact, it appears impossible to access or stimulate the heart and lungs for the purpose of administering an exercise stimulus without the involvement of the muscles.
The conclusion, then, is unavoidable.
If your goal is to maximally stimulate the cardiovascular system to build your VO2 Max and maximize your longevity, you need to maximally stimulate the muscles that our cardiovascular system serves and supports.