There are a handful of performance markers in exercise science that overlap many sports. These measures have dozens of training methods designed to push them to the limits and get the most out of an athlete’s abilities. In this article, I’m going to talk about three of them:

• VO2 max
• Lactate Threshold
• Metabolic Flexibility

Each one of these measures a component of metabolic function that directly impacts the body’s ability to produce energy consistently based on the intensity, duration, and type of activity it is doing.

I am spending an enormous amount of time reading studies right now. I’m working on a master’s degree and researching and writing for three papers I’m trying to get published. I see a lot of games being played in the logic applied to ketogenic research in sports performance. There is a cognitive disconnect in these studies that I feel needs to be addressed.

VO2 max is the maximum amount of oxygen your body can process to power your workouts. Your body will use fat as fuel for longer and at higher intensities in a workout when your VO2 max is higher. It is generally considered an improvement to increase your VO2 max.

• VO2max Trainability and High Intensity Interval Training in Humans: A Meta-Analysis — PMC
• (PDF) Comparing VO2max Improvement in Five Training Methods

Lactate Threshold (LT) is the point where the body is unable to clear lactate build up in the muscle. The higher intensity that this occurs during exercise, the longer an athlete can perform. As lactate is a byproduct of anaerobic glycolysis, LT is an indicator of how much the body is relying on fat or glycogen for energy.

• Using Lactate threshold Data
• Anaerobic Threshold: Its Concept and Role in Endurance Sport — PMC

Metabolic Flexibility (MF) is how well the body can utilize various energy substrates to produce ATP and meet the energy needs of athletic effort. Improvements in MF are evident when metabolic markers, measured during exercise, indicate high efficiency regardless of which substrate is being utilized.

• Differences in muscle energy metabolism and metabolic flexibility between sarcopenic and nonsarcopenic older adults
• Metabolic flexibility in health and disease

In the current performance coaching and training mindset, each of these three measures is considered improved as they extend or indicate an extension of fat utilization and a delay or reduction in glycogen utilization during exercise.

There are literally thousands of studies and papers written about improving these measures. Whole camps have formed to champion Lactate Threshold training vs. Interval Training as the optimal method to improve performance. Training protocols and coaching programs by the hundreds are being sold to athletes to help them achieve their best.

Here’s the question

Study after study, article after article, I see the same conclusions. There are many authors and researchers who claim that a ketogenic diet has a detrimental impact on performance based on concepts that directly contradict the data showing improvements in each of these three measures. (Movement Economy Article)

If training programs designed to improve VO2 max, Lactate Threshold, and Metabolic Flexibility are good for performance, why is a dietary protocol that does the same thing bad for performance?

Time and again, a low-carb/ketogenic diet has demonstrated improvement in each of these measures. Yet, the conclusions by researchers repeatedly support the narrative that a ketogenic diet has a negative result in sports performance. Here is a sample of studies and analyses that support and describe how a ketogenic diet improves these measures of performance:

• Effect of low-carbohydrate-ketogenic diet on metabolic and hormonal responses to graded exercise in men — PubMed
• Low carbohydrate high fat ketogenic diets on the exercise crossover point and glucose homeostasis — PMC
• Metabolic characteristics of keto-adapted ultra-endurance runners — PubMed
• The Effects of a Ketogenic Diet on Exercise Metabolism and Physical Performance in Off-Road Cyclists — PMC
• High fat diet improves metabolic flexibility during progressive exercise to exhaustion (VO2max testing) and during 5 km running time trials — PMC
• Nutritional Ketosis Alters Fuel Preference and Thereby Endurance Performance in Athletes
• Effects of Ketogenic Diet on Muscle Metabolism in Health and Disease
• Effect of a four-week ketogenic diet on exercise metabolism in CrossFit-trained athletes
• The Three-Month Effects of a Ketogenic Diet on Body Composition, Blood Param

If training adaptations specifically designed to enhance VO2 Max, Lactate threshold, and Metabolic Flexibility are lauded, why is a ketogenic diet discredited for doing the same thing?

It is incomprehensible to me that the exercise science community is so entrenched in its philosophy that it would actively suppress or discount a nutrition intervention that shows such a massive ability to potentiate the effect of training methods, enhance recovery, and improve overall performance.

This discussion matters whether you play soccer or pickleball, run marathons, compete in local CrossFit comps, or run in obstacle course races.

What if you could get better at your sport without training more?

How much potential is being wasted because athletes are being turned away from a potentially transformative methodology?