Thursday 13 February 2014

Quadriceps theory

On Tuesday I was a research subject for a colleague's project at work. The study was designed to investigate certain effects of muscle soreness. The setup was to run downhill on a treadmill for 30 minutes to subject the legs to extensive eccentric work. As I am pretty welltrained but do not run much, I was a given subject. The run was OK, the last 9 minutes @ 16 km/h on a 7 degree downhillslope. At the end it felt like my quadriceps were bashing down onto the floor at each impact, but it wasn't a problem running the full time.

But what an amazing muscle soreness I got yesterday! I've never felt anything like it; walking downstairs is nearly impossible, each quadriceps component feels like it is being shaven off the bone, each step results in spasms of pain, I can feel the strain in each individual muscle fiber whenever I move. Wow. I carefully plan what to do at work to try and avoid walking, especially in stairs. For the first time ever I have started taking the lift at work. Today I'm even wearing compression tights at work in a desperate attempt to keep the quadriceps attached to my femora.

I gathered up all the muscle bits lying on the floor and stuffed them inside these tights. Definitely feels better than without tights.

The funny thing though is that cycing works fine! It hurts a little bit to really push myself, so I can wait with that, but pedalling with normal concentric quadriceps work is no problem at all and even feels like it might be helping. Riding to work today I started wondering how, in exactly the same muscle fibers, eccentric contraction can hurt like h-ll, while concentric contractions are fine? Both are obtained by contractions of the same sarcomeres with the same actin and myosin interactions, so how can one contraction cause pain and not the other? Are the pulling myosin heads direction senstive? Are they asymmetric so that pulling one way causes pain on one side while being pulled the other way unloads that side and does not cause pain?

Luckily I'm a biomechanist, not a muscle physiologist, otherwise I'd have to solve that now :-). Feel free to help with comments if you have some ideas though!

/Toni

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