Speed is a function of stride length and stride rate

by Gilbert Keith

Lesson learnt: When performing an activity, decompose it into the various steps and actions necessary and understand the meaning of all the variables that affect the activity.

I ran today. The act wasn’t unusual. I have been running about 4 days a week, 14-15 miles a week. However, for whatever reason, my run felt a little weird. It felt much better to be running today the loop today than it had felt on most previous days. To be sure, I was breathing a little harder and going faster  than I usually do. The cause was confounding me. I had just consumed about 350 mLs of water, so if anything, I should have felt more uncomfortable running faster. I also have a mental beat (a usual 1-2-3-4-5-6-7-8 rhythm) that I run to, and it was pretty much invariant. Identifying changes is rhythm comes easy to me thanks to my Tabla background, and my feet were following this beat, eliminating the possibility that I was taking more steps in the same amount of time.

Then it occurred to me: I was taking longer strides. As simple as that. Speed definitely varies directly with stride length and stride rate. Fixing the stride rate (which I was doing today) and increasing the stride length (which I was also doing) definitely increases speed.

My new running goal should be improving stride length. It takes a lot more effort to swing the legs wider, and the impact of the legs hitting the ground is also larger. Finding the optimal stride length will be the key priority. Running on grass might be the best option, since it seems to me that the impact is relatively low. However, papers such as this one suggest that running on grass might actually have a higher impact since one cannot predict the level of impact of the next step while running on grass.

Anyway, decision will be made, performance will be (mentally) evaluated by moi, and results will be presented in the form of another long blog post.