In this short article, we discuss how to best recover for repeated bouts of exercise. There’s some science content, and if that doesn’t interest you (and you only want to know the practical implications), you can skip straight to the highlighted text.
To truly express fitness, it is important not just to be able to express this fitness in a single bout, but in multiple repeated bouts of exercise. The implications of this are important in particular for sport requiring varying intensities, including CrossFit.
Increases in heart rate and cardiac output occur during exercise – thus increasing blood flow and the ability of the body to deliver oxygen to muscle cells and remove carbon dioxide. When you cease exercise, this blood flow reduces rapidly, and if inactivity follows the exercise, blood can pool in the muscles – not returning to the heart.
We want to promote this return of blood to the heart (venous return) for two primary reasons:
- The blood transports lactate to the liver to go through the Cori Cycle which converts the lactate to pyruvate to be used in the mitochondria for aerobic metabolism (fueling exercise).
- We want to transport CO2 out of the blood. If the blood is saturated with CO2 excess CO2 will remain in the muscles which will inhibit energy production and therefore exercise.
So, knowing that venous return is important, there are three mechanisms that cause it, the respiratory pump, the counter-current flow mechanism and (specific to recovery for multiple bouts of exercise) the muscle pump. The muscle pump involves the contraction of muscles adjacent to veins which squeezes these veins and promotes the return of blood to the heart. This brings us to the recommendations to maximise short term recovery.
Continuing to contract the muscles involved in the exercise being completed during rest intervals will promote venous return and maximise the performance in subsequent bouts of exercise. In rest intervals, athletes should continue to complete similar movements to those involved in the activity at a lower intensity.
This is particularly relevant for exercise that is primarily fuelled by fast and slow glycolysis, and less important for very short or very long bouts of exercise (where hydrogen ions are not produced as a byproduct of exercise).
The take-home lesson. Active recovery will maximise upcoming exercise output.
