You can speculate all you want about what makes an elite Crossfit athlete elite, but it’s all theoretical until you actually check under the hood. After-all, it’s easy to pontificate about what you believe to be happening in a workout when you’re sitting in your office chair writing workouts, but it’s a whole different story when you see the data unfold in front of your eyes.
When conducting physiological assessments I'm primarily trying to understand how an athlete solves the problems imposed by whole-body exercise. For example, regulating arterial blood pressure, supplying oxygenated blood to the brain, heart, and vital organs, and dealing with changes in intra-thoracic pressure and blood flow. All of which are large determining factors of Crossfit performance. Some athletes have better ways of solving these problems than others, but make no mistake - everyone has a limit.
Over the past few years i've conducted physiological assessments on dozens of Crossfit athletes ranging from recreational competitors to top games competitors.
Some things i've learned over this time are...
Maximal tissue oxygen extraction and cardiac output do not always develop in tandem with one another. This can pan out in one of two ways. Some athletes present with great cardiac output, but a poor ability to utilize oxygen in the working muscle at a fast rate. On the flip side, we also have athletes who have excellent local muscular oxygen extraction, but couldn't deliver enough blood and oxygen to the working muscle if their life depends on it (in some ways, it does...). Often times the former come from endurance or field sport backgrounds like soccer and lacrosse. The later often come from sports like hockey and football, or have extensive weight training experience.
A lot of 'bubble' level games and sanctional athletes have great mitochondrial and capillary density, but lack sufficient cardiac output. When these athletes perform whole body, high-intensity, exercise the sympathetic nervous system restrains blood flow to the extremity muscles through a processed called sympathetic vasoconstriction, which allows for the maintenance of arterial blood pressure. The result? A lot of 'pumping out' or 'blowing up' in workouts that involve alternation of muscle groups. This makes me question if these athletes should really be doing a lot of repeat sprint work, high end strength training, or 'anaerobic' work. Aren't we just making the problem much worse ? Instead, i’d use the interventions discussed in a previous article titled, Training The Delivery Limited Athlete.
A lot of high level athletes in the sport present with great cardiovascular control, great mitochondrial and capillary density, but a lagging respiratory system. Oxygen supply in the muscle will lag during gas exchange at the highest intensities or under heavy fatigue. Maybe that's why these athletes don't benefit (and get worse) from the hypoxic breath work (Wim Hoff, power speed endurance, etc) that has gained so much traction in the Crossfit realm over the past few years.
Elite Crossfit athletes have excellent cardiac output, a well developed respiratory system, high levels of sport-specific strength, high mitochondrial and capillary density, and optimal sympathetic drive. This results in steady blood flow trends even during mixed work. These athletes turn mixed work into cyclical work inside the muscle.
We may not be able to change an athletes genetics, but we can certainly augment what they have if we know what we're dealing with. My approach is as follows…
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