Why do we do long runs? To improve our aerobic capacity! Why is this important?
Muscles are very complex structures built upon a molecular framework that mainly uses oxygen as a substrate to assist with the converting stored energy into usable energy. Sugar or glycogen is what people normally think of as giving us energy to run. This is correct. But raw sugar cannot be used to contract our muscles. Our body needs to convert the energy into a usable substance called ATP. We need oxygen for this reaction, most of the time.
Our bodies are amazing and complex. Fortunately our muscles can create energy for short periods of time without oxygen. This is called anaerobic. The method for this is called the Krebs Cycle which is super complicated. The main take home point is that the by product from the Krebs Cycle is lactic acid which really sucks. That is what makes our legs hurt when we train hard.
Why does this matter? When we go out for a long slow run we are using our aerobic system. We are training our body to use oxygen in combination with stored energy to move our muscles. When we go faster our muscles start to work harder and we need to feed the engine more energy. At a certain point (lactate threshold) our cardiovascular system cannot pump enough oxygenated blood to our muscles to create energy and we start using the Krebs Cycle and produce lactic acid which makes our legs burn and tired. Theory suggests that by training the aerobic system we can improve it so that we can eventually run either longer or faster before our body starts to use the anaerobic system to fuel our muscles.
To conclude, the whole point of long runs is to improve the ability of the heart and lungs to bring oxygen to our muscles. Without oxygen in our muscles we can move but with lots of fatigue and pain.
Today I had my long run and it was great. I managed to avoid the omnipresent rain which has made Vancouver very green and wet. I am into the part of my training when I love running and while I am running I often think of running more. I was imagining running races while out on my run and this may have been why I ran a bit on the quick side. I must ensure I stay aerobic!
I have also registered for some races. I am a bit anxious to race again. I do not know what to expect though I know I am getting fit. I ran a great workout on Saturday morning and I felt I had the ability to put the hammer down at the end of the workout. It will be interesting.