Why should one run slow if all that most want is to become faster?
It is actually quite simple. No matter what the plans are, be it to run a 5k or a marathon, we will need a good “aerobic” system. If we partake in a longer event, we have a higher need for aerobic energy. In a marathon, 2.5%1 come from the anaerobic system – in a 5k it is already around 16%1.
As the word “aerobic” suggests, it all relates to oxygen and having enough of it. When running “aerobically” it means there is enough oxygen for the body to do all the work. If not, we are running “anaerobically” and are producing debt (which ends in a big fat wall). I do like the comparison Matt Fitzgerald uses in his book “Iron War”: burning matches!
Let’s assume, before we can produce any debt, or burn matches, we have to collect some first. Running aerobically, or easy or slow or whatever we call it, will achieve this.
Why should we want that?
A better Engine – Better Blood, Muscles and more Energy
Capillaries deliver oxygen and nutrients to the muscle tissue and take away waste. Slow running increases their number.
Better Muscle Fibers
Slow Running increases the Myoglobin content (protein that binds the oxygen) in the muscles and therefore gives your muscles more oxygen.
Better and more Mitochondria
Mitochondria are inside the muscle cells and they are the ones that produce the needed energy (ATP). Slow running increases their number as well as their size.
How to do it
If I don’t have a heart rate monitor, I like to use breathing in only through the nose as a check that I am still running aerobically. If you don’t mind talking to yourself, or have a partner, a talk test is even better.
1 (Gastin, P.B. (2001) Energy system interaction and relative contribution during maximal exercise. Sports Medicine 31, 725-741)