Friday, October 29, 2010

Power to Weight Ratios

During yesterday's workout I was suffering from a bit of a sore back - which is definitely linked to pulling up on the pedals. Injuries in any sport usually happen when you are learning and you get a movement slightly wrong.

Usually, when changing technique, the sign that something is "right" is that it makes the job easier. I noticed when climbing that by keeping the upper body slightly more horizontal and allowing it to rotate gently, there was a sudden ease of movement, increase of pace and reduction of back pain. Normally on the bike I'd have my pelvis very static, but here there is about the same amount of motion as there would be when running. This appears to ease the strain on the psoas muscles and the spine while freeing up the body to make a much more fluid and powerful movement engaging muscles right up through the trunk. I also noticed that failure to rotate the pelvis like this actually seems to act as a blocking action which slows you down - so you lose power fighting against yourself. This slightly "rotary" movement is very similar to the rotary sensation of the body when swimming front crawl - when the hips have to rotate in the water. It also feels like trying to pull your leg out of a bog - whilst simultaneously trying to force the other leg in as far as possible. It's not easy to find this action all the time - it's slightly elusive - but it's very clear when you get it.

There is a striking similarity to skiing here. In skiing it is common wisdom that the upper body should remain still. This is a major error. There is an optical illusion of the body remaining still during short turns - but the best skier is extremely active with the upper body. Not only that but the pushing forward of a ski causes the hip to move backwards - so the "pull up" on a pedal is exactly the same movement as as short turn when absorbing a mogul (bump) on a ski, or "retracting" at the end of a slalom turn.

Here is a clear summary of power to weight ratios...

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