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Marathon Question
Mr Daniel Hannett, MCMSc 1/24/2013 5:37:00 PM
Posted: Monday, September 16, 2013 7:50 AM
Joined: 1/24/2013
Posts: 1

Hi, I am currently studying for my CSCS exam in the UK. In the NSCA book and the study questions at the end of chapter 1 there is a question asking,


Which of the following muscle fiber types is the MOST beneficial for a marathon runner?


a) Type I

b) Type IIa

c) Type IIx

d) Type IIc

now the answer in the back says it it c) Type IIx  

Do you agree with this? Is it not a) Type a


Any Explanation stating why Type IIx would be true would be very helpful


Sorry if i have posted this in the wrong place.


Kathryn Russell, MS, ATC, CSCS,*D 8/22/2012 12:05:
Posted: Tuesday, September 17, 2013 5:18 PM
Joined: 8/22/2012
Posts: 1

In review of the textbook, the answer is correctly identified as: a) Type I.

The question does pose a discussion though and the following information may help:

When working with the majority of marathon runners whose times are in the range of 3 to 4 hours, Type I fibers are the predominant fiber utilized: slow contraction speeds with high fatigue resistance. 


When working with highly elite marathon runners whose times are closer to 2 hours or just over 4 minute miles, then Type IIa fibers are more predominant: fast contraction speeds with intermediate fatigue resistance. 


Furthermore, with endurance training it has been found that Type IIx gradually convert to Type IIa thereby providing a greater number of muscle fibers that can contribute to aerobic endurance performance. (p129, Essentials of Strength Training and Conditioning, 3rd edition)

I hope this helps!


(NSCA Education Coordinator)