Dear Guillaume, 

You can check the work of Bosco on the prediction of %fast fibers from performance on repeated jumps.

Pantelis

Thanks Pantelis. I knew this work but it is not very accurate.

We have done some micro biopsy work. It gives a quite good samples, doesn't need any local anesthesia and is rather pleasant for the patient and is quick. Have you tried this?

Hello,

Not absolutely sure because this seems a tough problem, assume this refers to a human muscle group. In principle, one might be able to get some idea of fast-slow mixing in a (human) muscle by examining stimulus intensity versus twitch contractions - if you are organised to do so. See

Ismail & Ranatunga (1978). Isometric tension development in a human skeletal muscle in relation to its working range of movement: The length-tension relation of biceps brachii muscle. Exp Neurol, 62, 595-604.

Hope useful,

KW

many thanks. I will read this article.

Harry, have you a reference for this method?

kindly

But remember that a biopsy samples only a tiny fraction of the muscle and most muscles are not uniform in their fiber distributions, so biopsy can give you very inaccurate estimates of fiber populations.  These other indirect methods are probably better if you are mostly interested in range of function.

I have found the tensiomoygraphy method, which measure the velocity of contraction of muscle without biopsy, with a good accuracy to assess the percentage of slow and fast fibers. Do you know this method?

No - I've never worked with this method, but sounds good if it is reasonably accurate.

Guillaume, I was going to suggest tensiomyography (TMG).

I assume that you have encountered these papers:

Šimunic, B., Degens, H., Rittweger, J., Narici, M., Mekjavic, I. B., & Pišot, R. (2011). Noninvasive estimation of myosin heavy chain composition in human skeletal muscle.

Dahmane, R., Valenčič, V., Knez, N., & Eržen, I. (2001). Evaluation of the ability to make non-invasive estimation of muscle contractile properties on the basis of the muscle belly response.

Lewis, this method sounds great. I will look into this direction. many thanks

You might also be interested in the following: estimation of % type II muscle fiber area via measurement of [carnosine] via H-MRS: http://www.ncbi.nlm.nih.gov/pubmed/21760934

Don't know whether or not a replication study has confirmed the correlation (r=0.71) between H-MRS-based carnosine concentration and type II fiber area. May be worth looking in that direction for your question. 

Cheers,

Stefan

many thanks