Speed is built on a lot of things. Wheels, aerodynamic frames, nutrition, threshold workouts—you know the list. After all of these have been addressed, what's left? Just the little stuff. Finding that 1 percent. At the upper echelons of the sport, and to some degree in amateur racing as well, the little stuff is everything. For example, have you considered the role and importance of the foot in performance?
I got a slick new pair of shoes awhile back. Carbon soles, various retention systems, white. They are stiff, transfer energy efficiently and look great to boot. They fully cradle my foot ably. Unfortunately, I have feet like a tiny baby and the shoes are so stiff that they actually bruised the first few times I wore them. Make your jokes, but it got me thinking about feet a little. The foot plays such a pivotal role in your cycling, yet you likely don't think much about it, so let's...
The foot is made up of 28 bones and 20 muscles (or 19 depending on how you define the extensor hallucis brevis, but I digress). Bones and muscles whose primary functions are to establish a coupling between the lower leg and the drive train, and to create a rigid lever for transmitting forces of the leg muscle to the drive train by way of a shoe and cleat. Since I'm not that smart I've asked Dr. Kirk Herring, a Spokane based Podiatrist (and long term athlete of mine), for help in clarifying the complex relationship therein.
In this first part, let's break the pedal stroke into phases and talk a bit about planes of movement and applicable terminology (hey, this is fun!). There is some debate about the particulars of muscle activation in the various phases that we'll jump into next time, but for today's purpose let's keep it mostly about the general patterns of movement.
Here is some basic terminology to know:
- Supination: The external rotation of the foot around an axis that runs from heel to toe.
- Pronation: Internal rotation around the same axis.
- Dorsiflexion: Movement that decreases the angle of the foot to the lower leg, lifting your toes up.
- Plantar Flexion: Movement that increases the angle of the foot relative to the lower leg, extending your toes down.
The Power Phase
From the top of the pedal stroke—top dead center—to the bottom is often called the power phase (for obvious reasons). What's important here is that foot function is split between supination, in the early power phase, and pronation through the terminal phase.
Recall, supination is the external rotation of the foot around an axis that runs from heel to toe. Pronation is internal rotation around the same axis. The foot rotates around this axis as it adapts and compensates for "positional and structural abnormalities of the lower extremity" according to Dr. Herring, in an effort to maximize force delivery. This is one of the reasons inserts or "wedges" have come to prominence in the last few years.
The Recovery Phase
Once through the power phase we reach the oft-overlooked recovery phase. This is basically the second half of the circle; the return of the foot to top dead center. In this phase the foot is neutral to supine (externally rotated) in orientation which allows the muscles of the lower leg to act, pull up across a more rigid structure as it prepares to re-stabilize at the top of the stroke.