Fast Twitch Fibre Indicators

Apart from muscle biopsy, is it fairly accurate to detect the presence of fast twitch fibre through how many reps can be achieved at certain percentages of 1rm in the weight room?
My strength training partner and myself are a great case in point (for a number of reasons). We often pontificate on who out of the two of us has the most fast twitch fibre. I can beat him easily in 60- 100 metre sprints, and he can whup me in anything over this distance, notably the 200m. My 100m pb is 10.61 and his is i think about 10.8 something.
I am white/english and he is a black/jamaican living in england. I would have thought that genetically it is more than likely that he has a higher percentage of fast twitch fibre, but i am not so sure. I would be interested to hear anyones views on this topic after reading the following.
We are very good for comparison because i am 5’10" and he is 5’11", and we both hover around 90kg bodyweight (incidentally he appears to be carrying a little less fat than myself). We both train together and follow the same program more or less. What’s more, our 1rm is remarkably similar on a number of lifts. We differ remarkably on the number of reps we are able to perform. For example, we both have a max of bwt + 70kg x 3 reps in the FULL parallel bar dip. He can do 50 perfect dips with just his bodyweight, whilst i can only do 15(yes 15!) and i start to noticeably fatigue at 10. This happens no matter how much i work on reps and rest before attempting, etc. I’ve seen my training partner not train for 6 weeks due to study committments and yet still come back in and do over 40 perfect dips. I wouldn’t dare call it a feat of endurance (maybe power endurance?) because he does them amazingly fast and smooth, looking as fast on rep 45 as he does on rep 5. I have seen him twice miss 95kg in the power clean in a workout a few years back, only to come back a few minutes later and execute 8 perfect reps at 90kg. This i find very strange. We both chin with 50kg attached for 1 perfect rep yet, he can do 25 deadhang at bodyweight and i can do 13 (i have a chinning bar at home and have actually worked on reps in an effort to beat him, all in vain however). Who would you say has proportionately the most fast twitch fibre?

Well take a look how you and him jump normally.

I feel the amount of knee flexion used is a good indicator of fiber type. High % Fast twitch guys hardly bend the legs at all to jump regardless of the jump height achieved. Their muscles can contract fast enough to utilise the stretch reflex maximally and generate force from a shallow flexion. Also their CNS can react much quicker - but is probably not related to fiber type :slight_smile:

Wheras slower fiber type guys need more time for the muscles to contract and thus need a deeper dip to jump.

Thanks for the info. I can beat him in a standing jump for height, as i can reach a few inches above the rim of a basketball hoop, whilst he can just touch the rim. Also you are right, i can almost equal my best height without dipping much or without even ‘psyching’ up for the jump.

I think that there are too many other contributing factors to try to make a judgement based upon physical abilities. Lever length, mount points, size and efficiency of motor units, co-ordination (the list goes on) all contibute to the types of activities mentioned in the thread.

In the end, what difference does it make? You’ve got what your got and at the end of the day you gotta make do …

This sounds okay in theory, but I’ve seen guys who can jump through the roof and who show other characteristics of “FT-dominant” individuals (rapid strength development, good numbers on oly lifts, excellent starting sprint speed) and they dip a lot before jumping. This might be an okay indicator for some, but I think there are too many individual differences at play to make it reliable.

They’re probbaly mixed fiber, but just have so much fiber count that it doesn’t matter either way :smiley:

ie man A has 1000 fibers with a fast twitch % of 90% vs Man B who has 2,000 fibers but is 50/50 :slight_smile:

Or they’re fast twitch and simply have lever lengths that favour a deeper dip. Or their insertion points dictate that their muscles receive a greater myostatic reflex when they dip deeper. There are too many variables for any indirect field test to accurately assess fibre type.

Everyone seems to talk so much about determining fiber makeup, but what does it really tell you that is so important. Aren’t the ramifications of having a certain fiber makeup more important than actual percentages. I think they are, and for this reason I think field tests of fiber makeup are more appropriate than biopsies.

I say why not use a simple test like, determine your 1 rep max in a given exercise (eg. bench) by warming up with 2-3 sets up to 80% of what you think your max is, and then doing a double with 90%, single at 95% and keep repeating singles with more weight until you think you’ve hit close to your max.
Then take 90% of what you think your max is and see how many reps you can do with it, after resting 7-10 minutes from the max testing. Tables seem to indicate that the average person does 3 reps with 90% of the maximum, so you see what you do and extrapolate from there. If you do more reps you have a greater work capacity at a given percentage of your maximum and should adjust your training to suit that.