Our body adapts to many things. If we go to a higher altitude for example, our body adjusts and we still receive adequate oxygen. If we get braces put on our teeth our palate/jaw/teeth adapt to the appliance and the oral structures shift.
With running, our body adapts to running stimuli; impact, bounce, muscle tension, etc. Further, running greater distances (or longer time) and running at higher intensities (speed work) are additional stressors to the body. Look at the beginning of a running season versus the end of a running season; the first few runs of the season typically result in sore muscles the next day, but as time goes on, there is less soreness after each run; at the end of the season a runner can go farther and faster than at the beginning. The body adapted. The key to running farther, for longer and/or at a higher intensity without getting injured is applying the running stimulus gradually and at a healthy rate for each individual.
Let’s look at the “10% Rule”. For those who are unaware, the 10% rule states that when you increase your weekly mileage as a runner, increase no more than 10% a week in order to run injury free.
Is the 10% rule tried, tested and true? Yes and No. It works for some, but not all. It can be too aggressive, just right or not aggressive enough. In my opinion, it can be a great starting point, but again, each individual is different and their tolerance for certain stimuli are also different.
If a runner adopts the 10% rule and its too aggressive (ie: they become injured), they should back off the increase in stimulus. Perhaps, instead of increasing each week, run the same amount each week for two weeks then try a 5% increase. It may seem like a tortourus amount of time to increase mileage but, if it allows the body to adapt to the stressors of running then it is definitely a win!
Let me be clear, I am not saying that if you adopt the 10% rule, or something similar, that you will be an injury free runner. There are many dimensions to staying injury free (that is for another blog post). However in terms of increasing mileage, if you do it gradually, at a pace that is right for you, then you are off to a great start!
“The body will adapt itself as long as the applied stress is not greater than the body’s capacity to adapt.” - Blaise Dubois, Prevention of Running Injuries, 2010.