Dear Mohamed, unfortunately the only way to do this is by taking a biopsy from the exercised muscle and cut sections, perpendicular to the fiber length. There are various staining methods available to assess the type 2 fibers. After that, you can take photos under a microscope and quantify the cross-sectional area by programs like ImageJ. It's not very simple, but doable if you have some basic lab equipment.

Dear Rob, thank you so much for your response. I think it is painful and I don't think that athletes would accept that.

Dear Mohamed,

the method is pretty common. However, I recommend to limit its use to research with strong hypothesis and sufficient power due to its invasive nature.

Regards

Boris

Dear Boris,

Thanks a lot for your response and advice

Best regards