T Nation

Triggering Type II Muscle Fibers


I've been reading this lone study:

Low-Load High Volume Resistance Exercise Stimulates Muscle Protein Synthesis More Than High-Load Low Volume Resistance Exercise in Young Men

Sure it's a single study. But do you guys think one could trigger muscle growth through endless "light" reps as efficiently as hard heavy lifting? So instead of triggering type II muscle fibers right away with heavy lifting, couldn't you trigger them once your type I are out of the game after let's say the 12th reps?

I personnaly feel my muscles working better out of 15ish reps than heavy 1-5 reps.


............I wish to have read that study BEFORE buying all that plates/discks,trap-bar and power rack......................


So do I, 4000$ of gym membership thoughout these years was all a waste...


I know right ... all that heavy lifting ... just a waste of time ...


When considering what works better the question always comes up. Do I do high weight for low reps or low weight for high reps when you should really consider the ideal of using high weight for high reps. Those who manage to accomplish it have massive size. Take Tom Platz for example


You must be on teh creatinez to be getting gainz from such stupid things like lifting heavyz.


I'd like to hear from someone who had success with this training protocol, if any?

There seems to be some logic behind the whole escalading trigger of muscle fibers, the cost being mental focus and overall energy expenditure...


What training protocol???

Light weight high reps isnt a 'training protocol'. It's a group of 4 words that are related to bodybuilding in one way or another.

Post the study. Or the % of 1RM that is described as 'light' or 'heavy'


I work with much less then maximal weights. I haven't even done a 1 rep max since 2007 when I was required for football weight training. Progressive overload, (i.e. increasing work density or more work done in less time) which is the key to muscle growth is not measured strictly by the amount weights you use. Although increasing the weight used on an exercise allows you to increase the amount of work done in the same time frame it is not the only way more work can be done. If this is a life long endeavor for you focus on the long term plan of getting to the ideal of high weights for high reps. Another example besides Tom Platz's thighs would be Casey Viator's chest. He was known to do 330 lbs for 20 reps on the incline BB press


like bonez indicated, light and heavy is all relative to the %of 1RM, and as most of you know typical hypertrophy "protocols" call for 6-8 reps with a lighter weight then what is called for in a strength building "protocol" which usually calls for the 1-3 rep range with near maximal weight.


heres a chart i saved off of TNation, but i don't remember what article, and unfortunately it does not show weight %


Here's the link of the study:

Low-Load High Volume Resistance Exercise Stimulates Muscle Protein Synthesis More Than High-Load Low Volume Resistance Exercise in Young Men

Methodology/Principal Findings

Fifteen men (21±1 years; BMI = 24.1±0.8 kg/m2) performed 4 sets of unilateral leg extension exercise at different exercise loads and/or volumes: 90% of repetition maximum (1RM) until volitional failure (90FAIL), 30% 1RM work-matched to 90%FAIL (30WM), or 30% 1RM performed until volitional failure (30FAIL). Infusion of [ring-13C6] phenylalanine with biopsies was used to measure rates of mixed (MIX), myofibrillar (MYO), and sarcoplasmic (SARC) protein synthesis at rest, and 4 h and 24 h after exercise.

Exercise at 30WM induced a significant increase above rest in MIX (121%) and MYO (87%) protein synthesis at 4 h post-exercise and but at 24 h in the MIX only. The increase in the rate of protein synthesis in MIX and MYO at 4 h post-exercise with 90FAIL and 30FAIL was greater than 30WM, with no difference between these conditions; however, MYO remained elevated (199%) above rest at 24 h only in 30FAIL.

There was a significant increase in AktSer473 at 24h in all conditions (P = 0.023) and mTORSer2448 phosphorylation at 4 h post-exercise (P = 0.025). Phosporylation of Erk1/2Tyr202/204, p70S6KThr389, and 4E-BP1Thr37/46 increased significantly (P<0.05) only in the 30FAIL condition at 4 h post-exercise, whereas, 4E-BP1Thr37/46 phosphorylation was greater 24 h after exercise than at rest in both 90FAIL (237%) and 30FAIL (312%) conditions. Pax7 mRNA expression increased at 24 h post-exercise (P = 0.02) regardless of condition. The mRNA expression of MyoD and myogenin were consistently elevated in the 30FAIL condition.


These results suggest that low-load high volume resistance exercise is more effective in inducing acute muscle anabolism than high-load low volume or work matched resistance exercise modes.


"Much of this is based on a physiological principle called the Muscle fiber recruitment hierarchy. This principle states that the body activates only as many muscle fibers as possible to produce movement, beginning with the slow-twitch, or type-1 muscle fibers. As these fibers fatigue (and fatigue is the key word here, as we shall see), other muscle fibers, namely types 2-a and 2-b, also known as fast-twitch muscle fibers, are brought into play.

What activates these fast-twitch fibers are neuromuscular connections. Simply put, when enough resistance is placed on the muscle, a signal is sent to the cerebellum section of the brain requesting more neural input to the muscle fibers in order to recruit the type-2 fibers. For years, it was thought that to recruit the type 2B muscle fibers required a greater neural input, and the best way to do this was to increase the intensity level of the imposed stress on the fibers.

The best way to do this was to lift heavy. Indeed, most exercise physiology textbooks say that the fast-twitch type-2 muscle fibers are the fibers most amenable to gains in muscle size and strength. Type-1 slow-twitch fibers are more related to endurance, and would be activated with lower intensity exercise, such as when doing endurance activity, or when using lighter weights for higher reps.

Again, it was thought that the body wonâ??t recruit the type-2 fibers unless it was necessary. But note that the type-2 fibers can also be brought into play when the type-1 fibers become fatigued."


throw that study away. One exercise. Bid deal. It's hard to give this any consideration when, as a scientific study, they don't even name the exercise correctly. Leg extension?? Muscles contract. Joints flex and extend.


this study uses old terminology. "fibre II B refers to a muscle type that only accounts for about 3% of all muscle fibres" as per my anatomy and physiology professors. you want to talk about Fibre Type II X which is the most abundant fibre type that DIFFERS from type I fibres.

TYPE I, and TYPE II A use aerobic energy systems as there primary source of energy and are very dense with capillaries and therefore blood, oxygen and myoglobin

Type II X uses anaerobic energy system to produce energy and therefore has a lower appearance of capillaries, blood, oxygen, and myoglobin

the next major difference is the type of ATPase that is present in/around the muscle fibres. ATPase is an enzyme that breaks down ATP ( major source of energy, energy is release when ATP breaks down into ADP and Pi )
- TYPE I has a slower form of ATPase, which means that the muscle won't be able to contract as often because the energy is not released from ATP as often
- TYPE II X has a fast form of ATPase, which means the muscle can contract much more frequently because the energy is released from ATP much more often.

according the fibre type recruitment hierarchy, the major fibre types are recruited in this order:

however it is VERY rare for the body to do anything in a manner that uses only one system at a time, which means that as TYPE I fibres are being activated to their full potential, the others are ramping up force production as well. eventually TYPE I fatigues and TYPE II X will take over, but this is not the best way to activate or train the TYPE II X fibres

TYPE II X fibres are uniquely adapted to handling training stimulus in which the participant is willfully TRYING to accelerate the bar as fast as possibly, training in this way from the beginning of the set severely shortens the time that TYPE I fibres are the dominant force producers and allows TYPE II X to take over very quickly.

and for the study that states that TYPE I fibres show markers of protein synthesis for a longer period of time ( up to 24H ) this is likely due to the increased capillary network present in TYPE I fibres which supplies more oxygen, blood, and myoglobin to the fibres, this does not mean that TYPE I fibres will grow faster or larger then properly trained TYPE II X fibres.


I have absolutely no idea what you are trying to say here


Damn, so you're saying all these years of my heavy 3 rep leg extension sets have been for naught?

Leg extension?


stop worrying about muscle fiber types

stop watching dbz



You totally fucked that second step up, brah.


Your reply makes me think of CT's I, BOdybuilder.

"Maximum-Force Lifting:

Always lift the weight as hard and as explosive as possible. In other words, each rep, regardless of the weight, should actually be a maximum effort. Acceleration is very important, as well. Try as hard as you can to make sure you actually accelerate the weight on every rep.

Hard. Explosive. Accelerate. Every rep. It's the only way to produce the maximum force possible.

Quality of rep performance, on every single rep, should be your only concern.

This means that for most of your training, you won't be lifting above 85 percent of your 1RM. In fact, the usual training range is somewhere between 50 - 85 percent of 1RM. Just remember, every single rep of every set is performed using maximum force.

Don't worry about training with weights that you might perceive as "lighter" (below 80 percent 1RM). This system will soon enough have you toying with your current personal bests."

But instead of using 3 reps, you'd use more reps which apparently will over tax your CNS.