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Hitting All 3 Fiber Types Simultaneosly

Will I hit all 3 fiber types simultaneously regardless of rep range? If I work chest with high reps for a year then switch to low reps mean I’m starting all over from scratch?

Stop overthinking it. Just go out and train, work out what works for you individually. Make adjustments from there, whether you need more strength, power, hypertrophy or endurance. You are your own science experiment, discard at least for the moment what is not working.
Your goals, and needs will change frequently over the years.
You can’t do everything all the time, at least not efficiently, or effectively.

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Yes. You will activate all 3 fibre types when you load to 5RM / 85-90% 1RM or higher, and/or if you train to within 5 reps (preferably 2-3 reps) of failure.

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If the number of reps determine the types of fibers activated to any significant degree, sprinters would all be using primarily slow twitch fibers.


I really like that way of putting it. I’m gonna steal that

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Some learned scholars believe it’s best to use low reps, medium reps and higher reps in training instead of sticking to just one range.


Heavy lifting will hit all fiber types from fast twitch to in-between to slow twitch, but your slow twitch will only get OVERLOADED through directed endurance training.

Seriously, when doing a heavy lift, your slow twitch fibers get called first, and then they’re like “nu uh, too heavy,” and move the work towards the stronger fibers.

May I ask what your fitness goals are?

Not just that, you gotta have some variety or you’re just gonna end up bored as fuck lol. People overthinking this shit don’t appreciate the fact that this is a long term endeavor for the fulfillment of one’s goals.


Feel free to. It’s original so you won’t be plagiarizing anyone else lol.

Not true

I don’t know the science behind it but… Dude, if slow-twitch fibers get overloaded enough with heavy strength work, then powerlifters will be just as conditioned as elite wrestlers. And we know that’s not true.

I’m sorry. I may be wrong. I’m just making a reasoned assumption here.

Conditioning and muscle fibre type are relatively separate entities.

The Henneman Size Principle will help explain why:

Basically, muscle fibres are recruited from: type 1 to type 1 and 2A to type 1 and 2A and 2B. So, when the impulse demands of the muscle are highest, all motor unit types are activated. Therefore, slow twitch fibres are overloaded by all sufficiently heavy or sufficiently close-to-failure sets.

The reason why lower-intensity, higher-rep work provides a relatively greater training stimulus is because there will be more total time spent without recruiting type 2 motor units. So, there is more total work done by the type 1s, but not necessarily more overload.

The other thing to consider is pretty much anyone who uses weight training as the majority of their physical training - with the exception of certain O-lifters - will approach a type 2A dominance as result of training.

To build muscle through hypertrophy by using the equipment I have at home.

Isn’t it necessary to induce some degree of fatigue in the fibres to stimulate hypertrophy? With slow twitch being the most fatigue resistant you would have to do very high reps to get them to grow, and they are also the most resistant to growth so purposely trying to grow slow twitch fibres is a waste of time.

Also there are some studies and such (I got this from Chris Beardsley’s IG) showing that with higher rep ranges the largest motor units (which contain the fastest-twitch fibres) are not activated even when going to failure. How many reps is going to vary depending on the person, exercise, and various other factors, but if you are using a load light enough to do 15+ reps it’s quite likely you won’t activate the largest motor units.

Those learned scholars sure sound like they know what they are talking about. There are different way to approach that, Mike Israetel advocates not mixing rep ranges within a block of training so you would alternate between “regular” hypertrophy training with most sets in the 8-15 range, strength blocks where you would stick with 3-8 (unless you are a powerlifter, then singles and doubles would be useful too), and you can also do higher rep phases with 15-30 reps.

Other approaches involve mixing rep ranges within a workout, like Fred Hatfield cam up with something he called the ABC method where you work up to a heavy low rep top set, a down set with a bit more reps, then a final super high rep set. Try different things and see what works for you, and remember that not all exercises are suited to all rep ranges. You aren’t going to work up to a 3 rep max on side raises, and you probably don’t want to squat for sets of 30 if you plan on doing anything more in that session.

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I saw a graph that came out of some study that showed bodybuilders having more slow twitch fibers, presumably because they do higher reps than weightlifters or powerlifters. I looked around a little and couldn’t find anyone else saying anything similar. I guess any joker could have made this.


I just finished up using that Hatfield method with the heavy/medium/light weights. Like you/Chris mentioned, it was a bad fit, doing 5 rep lateral raises and 30 rep (machine) squats and deads. It’s was really effective though. The routine was tough, I was always hungry and I gained 5-6 pounds in two months. I also got way stronger on the lifts I was doing.

I’m a believer in throwing some specialized work at the slow twitch fibers now.


The resistance of your equipment at home, unless it has a high ceiling limit, will be eventually outgrown. Until it reaches that ceiling you should be fine. Unless you switch to endurance training when it happens.

That’s what they say, yes, but you also have to realize that it’s not just two types of fibres but rather a spectrum. So elite olympic weightlifters are the ones that generally have the highest proportion of fast twitch explosive fibres (type iix), most powerlifters would have a high proportion of those too but not nearly as much and the slower twitch fibres are still some use because speed is irrelevant as long as you can finish the lift. Bodybuilders aren’t normally doing anything too explosive so those fibres would get less stimulation, especially guys who do higher reps, but slow twitch fibres are very resistant to growth so it’s still the fast twitch fibres that will grow, just not the fastest ones.

Some drugs also induce hypertrophy more in on type than another, but that’s beyond my scope of expertise.

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I’ve never seen this, but I’m interested. I follow Beardsley too. Any chance you’ve got the post bookmarked and are able to link it?

Based on my understanding, if you’re hitting failure within 30 reps, you’ve had to recruit the larger motor units. There’s an increased training volume for the Type 1s because there are lots of reps in a 30RM set that don’t activate the larger motor units, hence greater training stimulus