I posted a blog in December of last year entitled "The Perfect Stroke" that you may want to read (see archive on the left side of the blog page). This IS the time of the year (training season) to work on perfecting your pedal stroke. (It's also not a bad time to check your bike fit. Yeah, I hear ya...you already got fitted to your bike years ago when you bought it. But, that's the problem..you got fitted years ago..and your body DOES change. Can't hurt to re-check your fit at your LBS.)
This colored graphic (above) highlights/illustrates the muscles that do the work- in each position of the pedal stroke. You'll see the Quads engage from 12 to 5 o'clock, the Glutes from 1 to 6 o'clock, Calves 1:30 to 6:30, etc. But, check out the position in which the Hamstrings do the work (6 to 10) or more importantly the Hip Flexors (9-11). Also, check out the thicknesses of each colored plot- which shows the relative amount of useful power that each muscle produces. Now you know why you read all those cycling articles about how you should be scraping mud off your shoes, pulling on the upstroke, pedaling with eggshells under your feet (that you don't want to crush), etc. when you pedal. All of these articles are intended to help teach you how to pedal in a more balanced complete circle while developing the lessor used Hamstrings and Hip Flexors.
Now I know why my Hip Flexors were hurting on my Sunday ride. It's from all of the Isolated Leg Training/Drills (ILT) I've been doing the past couple weeks- in addition to the high cadence riding. I supposed my Hip Flexors really are underdeveloped/out-of-shape and need some strengthening. I bet you yours are too (underdeveloped), unless of course you consciously pedal in full-circles when you ride. I know I don't. I'm probably like the masses where each leg mashes on the downstroke (12-6) and recovers on the upstroke. Isn't that how you pedal? C'mon admit it. The real advantage, in my opinion, of developing the lessor-used Hammies and Hip Flexors is that it will give your Quads and Calves a break (while you're racing or suffering in that tough group ride) while still maintaining a high intensity/power output. And, that little break may be all that your over-worked Quads need to flush out some lactic acid and continue working at such a high level.
In case you didn't know, that's the whole idea with Power Cranks. For more info. on Power Cranks, click here: http://www.powercranks.com/#muscles I'm not a Power Crank user, nor do I know anyone that trains with them. But, I'm sure they can't hurt. I'm just not a fan of shelling-out $1000+ for them when I can work on the same concept with my home ergometer using ILT.
Power ON! Coach Rob