T Nation

Fast-Twitch, Slow-Twitch?

Hey, can anybody here list which muscles are predominantly slow and fast twitch? Also, how does I determine whether or not their muscles are mostly composed of fast/slow twitch muscles?

For example, Charles Poliquin states that his muscles are mostly fast twitch based. Which explains why he used sets with 3 rep maximums to achieve great muscles hypertrophy.

Thanks

CT has some tests to gauge muscle type dominance (search bar) or you can get muscle biopsy done.

As far as muscles which are what. It depends on the lifter what you respond to best. I would hit the major muscle groups (back, chest, quads, hams, bis, and tris) as if they had plenty of both fibers. Calves and forearms tend to be slow twitch. Smaller groups can probably be hit more frequently depending on how you work them (IE you can probably work shoulders fairly often if you aren’t killing the presses everytime).

Pick a weight thats 75-80% of your 1RM for a bodypart, if you can do lots of reps with that weight = slow twitch, if you can only do say 8 or less = fast twitch, 10ish reps is more a mixture of both.

Why do you care?

I just want to tailor certain exercises to specific muscles groups based on their muscle fibre composition. I basically want to know, for example, is it best to train my chest with high reps or low reps. That sort of thing.

muscle groups are not completely fast twitch or slow twitch, but a a combination of both. You’d do better with focusing on both aspects, high reps AND low reps, for getting the most out of your workouts.

Do some trial and error. That’s what everyone else does man…GENERALLY speaking, the muscles you use VERY often in day-to-day activities (quads/glutes/hammies for walking/running/jogging) tend to have more slow twitch muscle fibers, so if your main goal is size, widowmaker sets are very useful. But IMO, no rep range should be totally neglected for any muscle group.

To put it simply:
Legs are primarily slow-twitch.
Triceps primarily fast-twitch.
Everything else, basically 50-50.

General rule is that the less you use a muscle, the more FT it will be.

There’s obviously individual variation, but not more than 10-15% from the average. In my opinion: genetic freaks like Usain Bolt aside, most differences in muscle contractile properties come from training, not from whether “you’re fast twitch or slow twitch”

[quote]Killa Cam wrote:
To put it simply:
Legs are primarily slow-twitch.
Triceps primarily fast-twitch.
Everything else, basically 50-50.

General rule is that the less you use a muscle, the more FT it will be.

There’s obviously individual variation, but not more than 10-15% from the average. In my opinion: genetic freaks like Usain Bolt aside, most differences in muscle contractile properties come from training, not from whether “you’re fast twitch or slow twitch”[/quote]

Fail.

[quote]GluteusGigantis wrote:

[quote]Killa Cam wrote:
To put it simply:
Legs are primarily slow-twitch.
Triceps primarily fast-twitch.
Everything else, basically 50-50.

General rule is that the less you use a muscle, the more FT it will be.

There’s obviously individual variation, but not more than 10-15% from the average. In my opinion: genetic freaks like Usain Bolt aside, most differences in muscle contractile properties come from training, not from whether “you’re fast twitch or slow twitch”[/quote]

Fail.
[/quote]

A challenger approaches

ohhh, what did i start here!? Haha, thanks to everyone for your input.

[quote]hungry4more wrote:
Do some trial and error. That’s what everyone else does man…GENERALLY speaking, the muscles you use VERY often in day-to-day activities (quads/glutes/hammies for walking/running/jogging) tend to have more slow twitch muscle fibers, so if your main goal is size, widowmaker sets are very useful. But IMO, no rep range should be totally neglected for any muscle group. [/quote]

everything i’ve read about hamstrings is that they are often comprised of mostly fast twitch fibres.

[quote]coolusername wrote:

[quote]hungry4more wrote:
Do some trial and error. That’s what everyone else does man…GENERALLY speaking, the muscles you use VERY often in day-to-day activities (quads/glutes/hammies for walking/running/jogging) tend to have more slow twitch muscle fibers, so if your main goal is size, widowmaker sets are very useful. But IMO, no rep range should be totally neglected for any muscle group. [/quote]

everything i’ve read about hamstrings is that they are often comprised of mostly fast twitch fibres.[/quote]

My bad, as far as I know that would be correct. Didn’t mean to include hammies in there.

I don’t claim to be the ultimate authority on this subject. I just go with what works best for me :slight_smile: What lifting is all about, within certain parameters.

[quote]meds613 wrote:
I just want to tailor certain exercises to specific muscles groups based on their muscle fibre composition. I basically want to know, for example, is it best to train my chest with high reps or low reps. That sort of thing.[/quote]

talk about majoring in the minors. imo, muscle respond best to a combination of both high reps and low reps. if you use a basic progression model, you’ll hit both fairly frequently (ie: pick a rep range, i do 4-10. pick a weight you can do for 4 times and over a few sessions increase reps until you can do that weight 10 times, pile some plates on, and start again the next session at 4 reps). make sense? good.

[quote]hungry4more wrote:
Do some trial and error. That’s what everyone else does man…GENERALLY speaking, the muscles you use VERY often in day-to-day activities (quads/glutes/hammies for walking/running/jogging) tend to have more slow twitch muscle fibers, so if your main goal is size, widowmaker sets are very useful. But IMO, no rep range should be totally neglected for any muscle group. [/quote]

hey h4m, ive been experimenting with widowmakers and i just had a quick question (HIJACKED). where do you place them on leg day? im an idiot and did a widowmaker on my last set of back squats and then still had the rest of my exercises to do. would it make sense to do all my exercises and then widowmaker on a leg press or hack squat before i crawl to the change room?

[quote]actionboy wrote:

[quote]hungry4more wrote:
Do some trial and error. That’s what everyone else does man…GENERALLY speaking, the muscles you use VERY often in day-to-day activities (quads/glutes/hammies for walking/running/jogging) tend to have more slow twitch muscle fibers, so if your main goal is size, widowmaker sets are very useful. But IMO, no rep range should be totally neglected for any muscle group. [/quote]

hey h4m, ive been experimenting with widowmakers and i just had a quick question (HIJACKED). where do you place them on leg day? im an idiot and did a widowmaker on my last set of back squats and then still had the rest of my exercises to do. would it make sense to do all my exercises and then widowmaker on a leg press or hack squat before i crawl to the change room?[/quote]

It varies. But as a rule of thumb, when I do a widowmaker after a workout where I already worked those muscles, I usually do it with a machine, to avoid bad form. Otherwise, I prefer to do free weight widowmakers right at the beginning, while fresh, and then not work those muscle groups the rest of the session. Make sense?

absolutely makes sense.

now, on to my questions about rack chins. jk…kinda.

[quote]actionboy wrote:
now, on to my questions about rack chins. jk…kinda.[/quote]

Just look at videos of big guys doing them on youtube, then video yourself doing them, and modify setup/execution/tempo until they look the same.

ya i was half kidding. i just started doing them and im still tinkering to see what works with my leverages. i watched some of jason wojo’s videos and read dante’s and in-humans description. ass below feet seems to be the main point. correct?

[quote]actionboy wrote:
ya i was half kidding. i just started doing them and im still tinkering to see what works with my leverages. i watched some of jason wojo’s videos and read dante’s and in-humans description. ass below feet seems to be the main point. correct?[/quote]

Yeah, that and the tempo I would say are the most important things.