T Nation

Reliability of testing for fibre makeup

Everyone knows about testing the fibre make up of a particular muscle/group by seeing how many reps they can crank out a % of their 1RM (I think its 80% but some may use higher). From the results you either identify as predominantly fast twitch, intermediate or slow twitch. And the theory goes once you have this knowledge you will know which intensity and consequent rep ranges you will best respond to. I was wondering how accurate everyone had found this to be. Whether for themselves or for their clients. Have the recommended intensity/rep ranges the test provided proven correct? Have they been completely wrong? Have they changed with your training age? The more responses, the more accurate a picture we can form. For my part the test has proven spot on. Where I test predominantly fast twitch I respond best to high weight low rep. Any other type of training gets me nowhere fast. For those muscles which test a intermediate make up the story is the same with a lighter weight (around 8RM) producing the best results, though I have noticed as I progress in my training age higher intensites (5RM) are also proving very effective. What have you found?

Ive never done any rep testing actually. The only testing ive ever done was a vertical jump. I feel like i am very fast twitch as i have no muscle endurance at all. I can also jump pretty high and can run pretty fast for my size. I can probably close grip 315 right now and the other day i did four easy reps with 255. Im guess that i might could have gotten 260 or 265 for 4 which puts me right around 82-84% of my 1RM. I think that makes me pretty fast twitch but not on a world class level. Maybe a little more fast twitch than average. But thats only if you trust these tests. I for one dont because the effects are trainable.

I don’t think the tests are 100% reliable but they are still a useful tool. They don’t take speed of contraction into consideration, results can be trainable, results can be influenced by the nervous system rather than the muscular system and the results can also be heavily influenced by mechanical factors( a long armed guy doing bench press for example )

Good point about the trainability factor guys, after all bodybuilders have been shown to be able to complete more reps at lighter intensities than powerlifters. Their training must obviously contribute to this. Familiarity with exercise and other factors such as you mentioned Kelly would also play a contributing factor. But then there’s the trainee who may only be able to crank out 3 reps at 80% while another performs 18. This would have to indicate that a completely different regimen would be optimal for each. Perhaps as you suggest Kelly the test can be a useful indicator but that you shouldn’t be prepared to take the results it provides as carved in stone, as it is quite possible that the intensity recommendations it offers aren’t optimal. As the old saying goes the proof is in the pudding. And you should still be prepared to experiment and assess the results.