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Benefits of VO2 Max Testing

The single most critical factor that determines the benefit of aerobic exercise is intensity – how hard you exercise.  Training at the correct intensity for each type of workout optimizes the body's response, giving you the greatest workout efficiency.

Most people exercise too hard.  Whether attempting to improve endurance, lose weight, or increase sustainable speed, almost everyone goes harder than is ideal.  Testing is the only way to learn the most efficient workout intensities for your unique physiology and get the most out of every workout.

In any structured workout program, each workout should have a specific purpose.  To achieve the ideal response from the body, the stimulation must be specific to the desired adaptation and must allow quick recovery for the next key workout.  Intensity, more than any other variable, determines the body's response to the training stimulus.  See Implementing the Results for further details.

This absolutely does not mean that harder is better.  The optimal training schedule for anyone provides the lowest volume and intensity that will stimulate the desired adaptation, not the highest that the individual can sustain.  This is a major paradigm shift for many people who grew up hearing, "No pain, No gain."  If working out at a certain intensity is good, then even harder would be better.  Wrong!

Training efficiently means balancing the cost and benefit of each workout.  Every workout has a cost, in terms of recovery.  Every workout also increases fitness.  Efficient workouts provide training benefits that are worth the recovery cost.  Everyone, at any point in time, has certain recovery resources.  While smart athletes develop habits to maximize these resources, they will always be finite, and need to be budgeted.  Anything that is going to expend these resources needs to provide a proportionate benefit.

Recovery resources include, among other things:

Glycogen Storage:  Glycogen is the form of carbohydrate, stored in our muscles and in our liver that serves as the primary fuel for endurance exercise.  Hard or long workouts expend tremendous amounts of glycogen and demand full fuel tanks at the beginning of the workout.  Maintaining optimal intensity makes best use of this limited resource.

Muscular Recovery:  Muscles sustain damage during running workouts.  Lactic acid accumulation damages the muscles chemically and impact stress damages the muscles mechanically, producing tiny tears called micro-trauma.

Connective Tissue Damage:  Every workout, but especially a run workout, stresses and damages connective tissues.  These tissues need to heal and rebuild adequately between workouts.

Injury Risk:  Injuries are an ever-present risk in any workout, especially run workouts.  During high-volume or high-intensity workouts, risk for injuries increases.

Maintaining optimal intensity during every workout is a key aspect of managing these risks. 

  • Psychological Factors: While everyone wants to think they are more motivated than the next guy, even for the most motivated person in the world, this is a finite resource.  Whatever effort you put in to your workouts needs to provide a proportional benefit.

These are all limited resources, and exercising at the right pace during each workout makes the best use of them.  This allows you to benefit maximally from each workout and gets you ready sooner for the next key workout.

Humans have three types of muscle fibers.  There are three training intensities that most efficiently work the three categories of muscle fiber.  The only way to accurately determine these three most efficient intensities is testing aerobic threshold, lactate threshold, and VO2 max.

Each muscle in our bodies is composed of thousands of muscle fibers.  These muscle fibers come in three basic types.  Each of our muscles is composed of some combination of these three types, the percentage of each type depending on individual genetics.

Slow twitch muscle fibers are our endurance fiber.  They can keep going all day long, but they are not big, fast, strong, or powerful.  Slow twitch muscle fibers are able to burn either fat or carbohydrate for fuel, depending on the intensity.

Fast twitch muscle fibers are our sprint fibers.  They are big, fast, strong, and powerful, but they fatigue very quickly.  Fast twitch muscle fibers cannot burn fat for fuel.

Our muscles also have an intermediate fiber which produces more power than slow twitch fibers and has greater endurance than fast twitch fibers.  These fibers are called F.O.G. fibers (fast oxidative glycolytic) and I refer to them as your speed-endurance fibers.

Every muscle in an our bodies is composed of many thousands of muscle fibers.  When the muscle contracts, each fiber either contracts with its full force capability, or remains relaxed.  When an athlete picks up a one pound dumbbell, very few fibers are required to contract, but those that do contract just as powerfully as when they pick up a seventy pound dumbbell. 

After aerobic plateau, which requires several minutes at the beginning of each workout (and each shift in intensity during a workout), the athlete's body will recruit muscle fibers according to the power or speed requirement of the activity.  The endurance fibers will be recruited first.  At low intensity only a few endurance fibers will be recruited.  As intensity increases, the speed endurance fibers will be recruited next, and finally the sprint fibers.

When an athlete first begins to exercise, the fast twitch muscle fibers are preferentially recruited.  After about two minutes, the body prepares for the exercise to be continuous and preferentially recruits the slow twitch fibers based on how hard the exercise is.

It is most efficient to work out these muscle fibers together in groups.  This allows us to focus on overloading one thing at a time in our workouts. 

Endurance or fat-burning workouts should be conducted at an intensity that requires full use of all the slow twitch muscle fibers, but none of the more powerful fibers.  These workouts need to be done at a very light intensity, called aerobic threshold.

Speed-endurance workouts are hard, steady efforts of moderate duration.  These should be done at an intensity that requires full use of the slow twitch and the F.O.G. fibers, but not the sprint fibers.  This intensity is called lactate threshold and is a very efficient level at which to exercise.

Interval training increases the aerobic power of the sprint fibers.  These fibers are mostly anaerobic, but they do have some aerobic capabilities.  Interval training should occur at 90-95% of VO2 Max and is a very powerful tool for improving aerobic fitness.  Most people do these workouts too hard for maximal benefit.

Learning aerobic threshold, lactate threshold, and VO2 Max takes the guesswork out of aerobic exercise and enables anyone to monitor exercise intensity to get the most out of each workout.

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