The Science of What Muscle Growth Actually Is
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- čas přidán 4. 06. 2024
- 0:00 Intro
1:14 Structure of a Muscle
2:00 Myofibrillar Hypertrophy
4:27 Sarcoplasmic Hypertrophy
5:31 Myofibrillar Packing
7:13 Mini-Review
7:45 Muscle Hyperplasia
8:48 Increase in Muscle Length
11:55 Summary
Resistance training, be it with barbells, dumbbells, machines, or even bodyweight, often produces an increase in muscle size. But, have you ever wondered what, within the muscle, drives an increase in whole muscle size?
In this video, we explore this. In the human body, muscles increase in size via increasing in cross-sectional area. By my count, there appear to be five ways in which this can occur: myofibrillar hypertrophy, sarcoplasmic hypertrophy, myofibrillar packing, muscle hyperplasia, and an increase in muscle length.
Firstly, before detailing what these are, we need to understand muscles are organized in hierarchical layers. Namely, within whole muscles are fascicles, within fascicles are muscle fibers, and within muscle fibers are myofibrils. Myofibrils consist of an array of sarcomeres, and sarcomeres are what generate muscle force.
Myofibrillar hypertrophy is where at the muscle fiber level, the myofibrils and sarcoplasm grow at the same pace, meaning the relative space taken up by both remains the same.
Myofibrils may grow by increasing in number, or by increasing the cross-sectional area of pre-existing myofibrils. In the latter case, it's believed myofibrils can increase in cross-sectional area through adding sarcomeres below or above pre-existing sarcomeres. This phenomenon has been called an increase in sarcomeres in parallel).
Sarcoplasmic hypertrophy is where at the muscle fiber level, the sarcoplasm grows at a greater pace than the myofibrils, meaning the relative space taken up by the sarcoplasm becomes greater (and concurrently the relative space taken up by the myofibrils would decrease).
Myofibrillar packing is where at the muscle fiber level, the myofibrils grow at a greater pace than the sarcoplasm, meaning the relative space taken up by the myofibrils becomes greater (and concurrently the relative space taken up by the sarcoplasm decreases).
All three of these (myofibrillar hypertrophy, sarcoplasmic hypertrophy, and myofibrillar packing) are related, as all of them have the capacity to increase muscle fiber cross-sectional area (and subsequently the whole muscle's cross-sectional area).
Muscle hyperplasia is a little more different. This is where the number of muscle fibers is increased within a muscle (either via the creation of completely new muscle fibers or the splitting of pre-existing muscle fibers). Now, it's important to mention that currently, the research on whether muscle hyperplasia occurs in humans is far from clear.
An increase in muscle length literally refers to an increase in the length of the whole muscle. Now, in the human body, muscles are attached to bones via tendons. These attachment locations do not change. Thus, any increase in muscle length is not visually apparent. Rather, due to these fixed attachment locations, a longer muscle would bulge outwards, and we can consider this an increase in cross-sectional area. As some extra detail, it seems that an increase in whole muscle length can be explained by events at the muscle fiber level. Specifically, myofibrils (which, as we've established, are within muscle fibers) can increase in length via adding sarcomeres in a serial line. This phenomenon has been called an increase in sarcomeres in series. Now, although there is indirect evidence to support the notion that an increase in whole muscle length can occur with resistance training (and there may be specific ways to train for it, as we see in another video), there is evidence that it may be limited.
References:
Haun et al. - www.frontiersin.org/articles/...
Muscle contraction details - www.ncbi.nlm.nih.gov/books/NB...
Jorgenson et al. - www.mdpi.com/2073-4409/9/7/16...
Haun et al. (2) - www.frontiersin.org/articles/...
Phillips et al. - pubmed.ncbi.nlm.nih.gov/10932...
Kubo et al. - www.jstage.jst.go.jp/article/...
INFANTOLINO et al. - anatomypubs.onlinelibrary.wil...
Music:
Song 1) L'Indécis - Soulful chll.to/64a098ba
Song 2) L'Indécis - Departure chll.to/e8099930
/ lindecis - Sport
Your content is just close to perfection... Really good, well explained and accurate info. + the really clean editing makes it easier to swallow. You've earned a sub here!
Thank you so much my friend, that's very kind of you!
I have been delinquent in watching these videos. I am sorry. I moved at the end of May and Work got ridiculous after that. I am very appreciative of these. Much of what I have read is being easily explained here. Thank you!
I never thought of it classed as all these ways. Looking forward to the rest of this series. God bless your work!
No need to apologise, haha!
Thank you for you kind words and interest in these videos, it's really great to hear!
Thanks for the post. Looking forward to the series!
Thank you for watching, awesome to hear! :)
Thank you for watching!
There's hardly any solid and detailed information on what muscle growth actually is on CZcams.
I hope this series of videos can provide this while also be interesting and informative to all!
As a side point, for the math aficionados out there, the muscle fibers shown in this video do not show the proportions they're meant to. For example, the muscle fiber shown at 2:50 is far from 85% myofibrils and 15% sarcoplasm. The reason the image of the muscle fiber does not truly equate to the percentages mentioned is simply due to visual reasons. The images used make it much simpler to for me to clearly animate and depict what myofibrillar hypertrophy, sarcoplasmic hypertrophy, and myofibrillar packing are.
Bro you should do a video on the igf1/mgf mechanism of hyperplasia!!!
I can see so much of hard work in putted in making this video. Hats off
Thank you my friend!
Super hyped for the series man, can't wait 🙌
Really awesome to hear, thank you for tuning in!
Looking forward to it!
Awesome to hear, thank you!
I learned several new things to follow up on. Thank you!
That's awesome to hear dude, thank YOU again!
Great video 👍
Thank you for such a great effort.
No problem! Thank you :)
Excellent content as always.
Thank you!
Can't wait for your series ❤️❤️👍
Really great to hear! Thank you :)
Could you create a similar series explaining how fat cells change over time?
Cover results with resistance bands, that is if someone can get any considerable hypertrophy with resistance bands as primary form of training.
At some point, I will make a video on this :)
Great educational video
Thank you! :)
This is the clearest explanation of muscle growth I've ever seen. Is Sarcoplasmic more temporary ? Is that the pump ? 😳
We'll be covering this over the course of the series. But here's my thoughts: sarcoplasmic hypertrophy most definately can occur in a temporary manner. Specifically, muscle fiber swelling can technically be classfied as sarcoplasmic hypertrophy (as we'll see). But, we'll also see there is evidence for more long-lasting sarcoplasmic hypertrophy that may be related to a disproportionate increase in sarcoplasmic proteins :)
Some books call the sarcoplasm reaction transient hypertrophy, and yeah it's the post exercise pump or swole
@@HouseofHypertrophy Is it virtually impossible to "not have" all forms of Hypertrophy occur at some point through progressive training ?
I don't think it is impossible. It's probably very possible. But unfortunately, the research if far from sufficient to provide a straight answer.
@@HouseofHypertrophy when will you be releasing the next videos ? Once a week ?
Fantastic overview for muscle growth! Thank you for your content and I am looking forward to watching the more in depth videos!
-@Mista.Lifta
Hey dude, thank you for the kind words! :)
Will you be talking about the relationship between muscle fiber types and growth in this series ? I'm curious if one can plateau in growth on a specific muscle fiber type ?
Not in this series of videos unfortunately. I think that's an interesting question. Currently, I don't know the answer as I haven't fully looked at the research in this area. But generally, fibers that can be categorized as "fast-twtich" appear to grow more than fibers categorized as "slow-twitch", thus, perhaps growth of slow-twitch fibers plateaus well before fast-twitch fiber growth plateaus. This is only my current thought and hypothesis, definately not a confirmed fact. Hopefully I'll get around to reading the research in this area and producing content from it :)
@@HouseofHypertrophy if true it may cause a shift in training. Where one starts lifting heavy / low reps to build up fast twitch...which would be underdeveloped compared to one's slow twitch max out.
Great video, I am building a home gym but I have had issues with a shoulder injury in the past so bench pressing (especially heavy) feels uncomfortable, would you recommend getting a smith machine or just benching lighter with a Olympic barbell ?
Thank you, I'm sorry to hear about your shoulder. Either one is probably fine, I'd say do whichever you like. Alternatively, if push-ups are comfortable, they are also a great option (they can be overloaded by weighted plates in a bag pack, resistance bands, or even just working towards one arm variations).
@@HouseofHypertrophy thanks for the advice I never do push ups but I watched your video on push ups vs the bench so I am definitely going to incorporate them , I can also go pretty heavy on dumbbell presses when I have my elbows facing inward more , so hopefully with that and press ups I can do enough to build a good amount of chest size
@@joelwilson4197 DO NOT USE A SMITH FOR BENCH PRESSES!!! I can't believe people think that's OK which only on variable arc Smith machines are they safe for shoulders. If your gym has a variable arc Smith then ok but even still I would switch completely to dumbbells bro!
Also if your gyms seated press feels good then that's OK but either way I would abandon barbell benching? I myself did so due to my shoulder issues and my shoulder health improved. I use dumbbells and machines only (Careful though some machines are junk and cause shoulder harm?)
@@joelwilson4197 I didn't see you were making a home gym sorry. Save yourself a ton of money and just get a good set of dumbells which if you have an adjustable negative 15 to positive 90 bench and dumbells you have a complete home gym!!
That's awesome!....
So what to do to achieve my potential?
That's what this channel is about, haha! At the very simplest level, you want to be resistance training and continually aim to progressive overload. Manipulating/optimizing certain training variables overtime is what drives this.
Are you joking with me?
With all these videos you made you have this little views and subs
You should have by now at least 1 million subs
Your content is amazing but CZcams aren't recommending your videos
Like I searched many topics that were in your channel and didn't find it until yesterday
Maybe CZcams is recommending your channel now who knows
Thank you for your kind words!
Hopefully with time the channel can grow further. But even so, I'm still very grateful to my current subs and anyone who watches the videos :)
So how does the growth actually happens it ot by muscle damage
You didn't cover and made mistakes about understanding density increases because you only covered cross sectional hypertrophy hence volumetric but there is also density hypertrophy that happens as well and you hinted at it several time but making it clear there is no conservation of volume by adding additional material to the muscles?
When's the next part out?
Monday :)
Wait why would myofibrils increase with the sacroplasm decrease? I would think at most the myofibrils would increase and the sacroplasm would stay the same which would cause the ratio to change with some cross-sectional increase? I don't get why the body would increase the ratio of myofibrils to sacroplasm but total volume stay the same? I don't think that's how it works??
I thought about it and actually I like the fact you make no assumptions about anything and keep it to what's well defined and understood which is how science should always work so?
You will be famous
Thank you :)
Is that Nujabes what I´m listening?
Not quite, haha. The two songs in this video are: 1) L'Indécis - Soulful chll.to/64a098ba and 2) L'Indécis - Departure
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