Active recovery is the process of recovery through decreased activity instead of just stopping altogether. In this fashion it is typically part of a cool
down or mixed into your intervals. It is also used on off days in order to aid recovery. I’ll focus on the former.
The act of moving to recover just doesn’t make sense at first. However I will soon explain that moving in order to recover makes perfect sense. Active recovery is often some sort of easy jogging or activity such as jumping jacks after an effort. You do these lower intensity exercises to assist your body in cooling down and returning to a normal resting period. So…the question becomes “Why do we keep moving in order to help us stop?”
The answer comes from your physiology.
When the heart pumps blood it has a certain amount of blood pumped per heart beat. This is determined by how hard the heart contracts, how much blood is in the heart chamber and also how much pressure the heart is pumping against. The pressure that it is pumping against and how hard it is pumping are variables that are not affected by active recovery, but the amount of blood in the heart chamber is directly affected by active recovery.
The venous system is a passive system. It does not actually pump the blood forward through the system at all. Instead it has valves in it in order to keep the blood from going backwards. The way blood gets pushed forward is through the contractions of your muscles. Therefore, when you are working intensely and moving a lot the blood flows freely through your body, supplying your heart with more blood to be recirculated out to the rest of the body, but when you stop moving so does your blood flow to the heart. This decreases the amount of available blood in your heart to pump, which then requires the heart to work harder to move the same amount of blood, which dramatically increases the workload of the heart.
Now, a quick departure so that makes more sense. The circulatory system is a brilliantly functioning system. It takes deoxygenated blood, pumps it into the right atria, then to the right ventricle, through the lungs in order to oxygenate the blood, then into the left atria, left ventricle and then out to the body to disseminate the blood into the capillaries and tissues of the body. After being disseminated it then enters the venous system and starts all over again. The amount of blood available to be pumped into the arterial system is directly influenced by the amount of blood returning from the venous system.
With the decrease of returning blood volume, due to the slowing down of the flow in the venous system, you increase the work of your heart. Requiring it to pump harder and faster to maintain the blood pressure in your body. This is why it is recommended to continue a cool down effort after the bulk of your workout to let the system reset itself without adding additional strain to your body.
While not a perfect analogy, it can be discussed in terms of a hose. While the pressure is high (intense activity) the hose would have good flow, however if you decrease the activity the amount of water would decrease dramatically from
the hose. The problem is that if the blood decreases like the water in the hose does then the heart is required to work much harder to maintain the same pressure with the decreased amount of volume.
That is why active recovery is so important to your workouts.