Incomplete hill training
One of the basic fundamentals of exercise physiology is a term known as Specificity of training . “…. if you focus your training on a specific part of your sport, improvements will be seen in that part and that part only.” This concept applies to both the activity itself and the intensity of the training. I did not address or take into account the effect of downhill segments (especially steep and/or elongated descents) beforehand even though I know how damaging downhill running is to the quads and the negative impact it has on leg strength. Since I run most of my weekday runs on our treadmill, I do a lot of hill work, but TM hills only flatten out, there is no actual descent work being done.
When you are running downhill, your quads are eccentrically contracting to control the force of gravity pulling you downhill. During an eccentric contraction, the muscle fibers are being stretched as they are contracting (contraction creates force) which also causes tiny fiber tearing! Some research suggests that more fast-twitch fibers are recruited during eccentric contractions relative to concentric contractions. Concentric contractions are the shortening of muscle fibers during muscle contraction such as what happens to your biceps when performing a bicep curl. Using this same example, when you bring the weight back down to it’s starting position (during a bicep curl), your biceps are lengthening but still contracting to control the force of gravity.
As fast-twitch fibers are geared more for explosive and powerful movements and can only use glucose as fuel, the finding that more fast-twitch fibers are recruited during eccentric contractions coincides with findings of a decrease in strength and power in the quads with downhill running because these fiber types get fatigued quickly. Concentric contractions and movements requiring less power and more endurance recruit primarily slow-twitch fibers which can use fat and glucose as fuel. Read more about muscle fiber types here !
The lack of downhill training on my part definitely contributed to an inability to keep my pace up, in addition to the GI issues. As seen in the Garmin data below, it is clear that my cardiovascular fitness was not a limiting factor in this race. My average HR of 135 (73% of HRmax) over the course of the race, only increasing with the burst of power in the last 1.3 miles. It is obvious to me I need to work on leg strength and include eccentric work. By including eccentric leg work, I’ll be improving my ability to generate more power (fast-twitch fiber recruitment) which will also positively affect uphill and speed as well.
Between a 38 minute PR and coming in under 5 hours despite these challenges is a victory for me, and I am coming around on it. The lessons I learned here are big and I’m actually glad I was presented with them in Marathon #2, very early on in my Marathon career.
In closing, none of it really matters…. “I’m only doing this so I can post a picture on Facebook”. LOL! I’m just kidding of course, but this is one funny shirt from One More Mile Running Apparel !
Next marathon: Watch out 2011 San Diego Rock-n-Roll Marathon. I'm coming for you!