Fiber types vs. capillary density

Brak

New Member
Hiya,

I have read Bryan’s article on targeting different fiber types. In that article, it is explained that a light weight will only activate the type one (slow twitch) fibers and a heavy weight will keep those fibers activated while also activating the type two (fast twitch) fibers. The type two fibers have the greatest potential for hypertrophy and we would also see our best strength gains by lifting heavy. Right, so the science says, lift heavy, HST principles also say increase the weight or RBE will get to you, so we do purposely back it off to a lighter weight in the beginning, but the goal is always ramping up to a heavy weight until RBE does get to us, right? We want to lift heavy.

So can someone speak to this:

This is from the publishers of Men’s Health, it is a little mini-guide called the Home Workout Bible, it came as a free gift with my copy of the AbsDiet book I ordered (which I am incidentally sending back, no way is it worth $40). The quote from the Home Workout Bible is in a section called “6 NewRules to Sculpt Your Body”. Rule 3 reads: “Lift Light. Capillaries, those small blood vessels, supply your muscles, helping them recover-and grow-faster. Heavy weight training decreases capillary density. Do high repetition sets with light weights. Using only 25% of the amount you can lift once, target whatever muscle group is lagging. It’ll increase the number of capillaries in your working muscles, allowing better nutrient transfer.”

Sound like hogwash? Certainly doesn’t jive with the ideas put forth in my first paragraph about how heavier weights are better at activating a greater range of muscle types, including the ones with the greatest potential for hypertrophy. It seems that lifting this light would only activate the slow twitch fibers and one would have a very tough time growing in this manner. But if he is on to something with this capillary density stuff…

I suspect many on this site will immediately cry foul and say this is bunk, but I have to wonder, before you heard about the principles of HST and studied why they work, you might have thought they sounded crazy at one time too. Could there be data supporting this assertion about capillary density out there? If so, I can’t find it, but without this site and the resources people like Bryan, Dan et al seem to have, I wouldn’t be able to find anything to support HST either.

With that in mind, experts with resources; does this sound like something you’ve read about elsewhere, have you come across or could you come across anything supporting this assertion? For now I am inclined to call it hogwash, but ever since I was convinced of the seemingly counterintuitive methods of HST I try to keep an open mind.

Reactions, opinions, and especially data supporting or refuting this claim will be welcomed.

Thanks,

Brak
 
[b said:
Quote[/b] ]
Do high repetition sets with light weights. Using only 25% of the amount you can lift once, target whatever muscle group is lagging. It’ll increase the number of capillaries in your working muscles, allowing better nutrient transfer.”

I'm not so sure about what it's talking about and certainly I'm no expert, but it seems that the issue here is bringing up metabolic work for lagging bodyparts. When the weight is heavy and the number of reps is naturally low, MAPKerk1/2 activity decreases dramatically. Although less a contributor (much less) than MAPKp38, it does seem to relate to hypertrophy. Consequently, bringing up metabolic work (by doing high-rep sets and thus increasing erk1/2 activity) can give a boost to your gains by allowing better nutrient partitioning and recovery.

So, in other words, it states that bringing up metabolic work for a lagging bodypart may help its overall development, which is true (when the weight is heavy and the number of reps low). However, this should be done IN ADDITION to your normal work sets. Hope this help a bit.
 
Well capillary increases have been shown with Aerobic training.

In resistance training some show increases some don't. One study showed no increase in density with a 6RM (but did show an increase in number) another showed an increase in density and number with a 10RM.

It seems, and I have not compiled anything to look at it, that density corresponds to hypertophy, IE capillaries in contact with a fiber can feed a larger area of the fiber and hence no need to add more capilaries to the same fiber area.

The really good news and probably the only thing I've seen that seems to be concluded by all is the density doesn't decrease with resistance training nor is it needed to increase hypertrophy of the fiber.

Also understand that there are other issues at play when looking at fiber type, namely type I, are endurance type isoforms so his comment on using lower loads higher reps is correct IF you are trying to acheive increases in capillarization but as I said above this isn't needed to increase the size of the fiber only the quality (efficiency changes that increase how much work can be performed in a given amount of time).
 
So, are capillary increases related to activation of the erk1/2 pathway? I remember reading that this pathway contributes more to muscle quality (and not so much size). Or is it something different?

Maybe I'm completely lost here, in which case I apologize for my stupid questions.
blush.gif

Just trying to get some things straight. Thanks.
 
Well not sure really.

It's seems that both ERK and Capillary Increases stem from simular activity. But I don't think ERK CAUSES capillary changes, but I'm not saying they don't as ERK's are not just muscle kinases and impact many cell types.
 
It may be of some interest to you guys that some studies have found that bodybuilders have a higher percentage of type I fibers than type II fibers in relation to cross sectional area. These studies reflect those who use moderate loads and high volume. Meaning if you use light to moderate loads, your type I's will be the main source of growth, OR you could be bigger still if you would train with higher loads and moderate volume targeting the type II's which have a greater affinity for growth. Not sure which demographic was used and what the researchers criteria was for "bodybuilder", but I have had 7 biopsies done on my vastus lateralis and each time my type II's make up about 70% of the cross sectional area. Explains why I love sprints but my VO2 max sucks!
 
Interesting... I always thought that bodybuilders have a higher percentage of type II fibers, not type I. Wrong definition of the term, I suppose.
 
But Biz is unique, that's the real reason, he's just too modest to say it.

Biz, what's up.

The thing is though, capillarization changes weren't fiber type specific in resistance training that induced hypertrophy both Type I and II had increases in capillaries in some studies and none in others. Neither was mitochondrial density, indicating that oxidative capacity wasn't changed. Now, just assuming here, I would imagine this would and could change based on RT protocol, IE intensity and work output.
 
Improving capillary density can definitely help speed recovery from set to set and between workouts as nutrient rich blood delivery will be enhanced. Lactate removal will also improve recovery and if a person were training at an intensity that increased capillary density, we can assume they probably increased their rate of lactate removal as well. This alone will not cause much of an increase in size as study upon study points to the strong correlation between progressive loading with 70-80% of 1RM and hypertrophy, not capillary density and hypertrophy.

HI DAN!!!
 
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