Why Aren't The Last Reps Easiest?

Magarhe · June 21, 2007, 10:14am

[quote]jsbrook wrote:
If the last reps were the easiest, you could continue lifting all day forever. Your body can’t simply withstand unlimited stress. Muscles fatigue. Think about it. It’s only common sense.[/quote]

You CAN lift all day forever, IF you are using a weight light enough that it is not causing enough overload that your supply systems cannot overcome and replenish the muscles with nutrients, oxygen, glucose, you name it.

Isn’t the whole point of this article whether or not it is beneficial to go to exhaustion?

Tim_Henriques · June 21, 2007, 11:11am

[quote]Chad Waterbury wrote:
The point is that if the last few reps really did recruit larger more powerful muscle fibers, then those reps would be easier. In fact, if your understanding of the size principle was correct, then you would never reach failure because the more reps/fatigue encountered in a set the stronger you would get. Therefore, he is suggesting that this line of thinking is incorrect.

Also, unfortunately your graph is also incorrect. The bars should be up near the “Theoretical Maximal Recruitment” line right from rep #1. And, the orange should start from the top down, not the bottom up. The smallest most fatigue resistant fibers/MU’s that are always recruited during any physical movement are ridiculously fatigue resistant. They can literally go on for days. Just think, can you walk for longer, or run for longer. Why? After all you are using the same muscles?

Hope this helps to clear things up.

Good training,

Sentoguy

Outstanding post![/quote]

Except that it is not correct.

Wayland · June 21, 2007, 11:21am

I think when the water clears it’ll be obvious that is “new method” can be cycled in ala conjugate training methodologies (seems awfully similar to Dynamic effort modalities), problem is people jump the gun and start believe its going to be the be all and end all

Shadowzz4 · June 21, 2007, 2:37pm

[quote]Professor X wrote:
Shadowzz4 wrote:
Chad’s article would be great if it were applied to strength and not so much to muscle hypertrophy. But then again I think it has been well established that high velocity reps with moderate to heavy weight builds speed and strength.

One of the main points is that, the more you are pushing hypertrophy, for many people anyway, the nervous system is not as important as it is made out to be, and TUT and fatigue is fairly important. Sure this is not optimal for running, jumping etc… but all that goes out the window when hypertrophy is the primary and sometimes only goal.

I disagree. I think the person who believes his CNS is that far down on the list of priorities when training for hypertrophy is also the guy who won’t be seeing too much growth. He definitely won’t ever stand out as “extreme”.[/quote]

Obviously, the CNS is important when training for hypertrophy. The point was that the CNS is focused on much more than fatigue and time under tension especially here on T-Nation. If you are focusing too much on either you are probably going to miss out on maximizing your muscle building capability.

As a general rule you could say your nervous system is in a pretty good place if you can increase the weight you are moving consistently over a reasonable amount of time. If you can couple that with pushing yourself to near fatigue, from a hypertrophy standpoint, you cant ask for much more than that.

Shadowzz4 · June 21, 2007, 2:50pm

[quote]bushidobadboy wrote:
“If the last few reps of a high intensity set really do recruit extra muscle fibers, then why aren’t the last few reps the easiest?”

If I understand correctly, the reason that reps become harder is due to factors such as:

Lactic acid buildup interfering with nervous signal transmission along the muscle surface.

Calcium depletion, or more precisely, ability to release and reuptake Ca into/from t-tubules.

Depletion of acetylcholine (ACH) by acetylcholinesterase to clear the synaptic cleft receptors, and the consequent depletion of vesicles leads to so-called CNS fatigue.

My own countermeasures include taking Choline as a precursor to ACH synthesis facilitates re-synthesis of ACH, and huperzine inhibits ACHesterase action. Spike or modafinil also offer a partial solution to the CNS fatigue issue.

bushy[/quote]

Ok, so here you have the reasons why the last reps become the hardest. The real question is, what is the benefit of doing the last few reps, from a strength or hypertrophy standpoint?

Ok, lets look at it this way. If the most powerful fibers are fatiguing some may have already completely fatigued, during your last few reps you have the slow-twitch fibers which are contributing a negligible amount of force I would assume, and your some of your rapidly fatiguing, but still serviceable fast twitch fibers.

So you finish the set. What is the benefit? Is it not optimal to push these fast twitch fibers to the point where you cannot achieve a fast repetition speed? Does it make these fibers more fatigue resistant? Does the increased time under tension hurt or help that muscle fiber from a hypertrophy stand point?

I would imagine it would help from a hypertrophy standpoint, but, for people that are very fast twitch I would agree that sticking to higher speed reps might be more beneficial.

I have a few clients that are obviously very slow twitch. They might start slowing down on rep number 5, but be able to squeeze out 5 more very very slowly. Should I decrease the weight they use to the point that they can accelerate it for 4-6 reps but are actually using much less weight? That does not make sense. It seems to me that this method could work very well but is not for everyone…

Airtruth · June 21, 2007, 3:31pm

[quote]Tim Henriques wrote:
Chad Waterbury wrote:
The point is that if the last few reps really did recruit larger more powerful muscle fibers, then those reps would be easier. In fact, if your understanding of the size principle was correct, then you would never reach failure because the more reps/fatigue encountered in a set the stronger you would get. Therefore, he is suggesting that this line of thinking is incorrect.

Also, unfortunately your graph is also incorrect. The bars should be up near the “Theoretical Maximal Recruitment” line right from rep #1. And, the orange should start from the top down, not the bottom up. The smallest most fatigue resistant fibers/MU’s that are always recruited during any physical movement are ridiculously fatigue resistant. They can literally go on for days. Just think, can you walk for longer, or run for longer. Why? After all you are using the same muscles?

Hope this helps to clear things up.

Good training,

Sentoguy

Outstanding post!

Except that it is not correct.[/quote]

After many arguments with sentoguy I have realized he merely likes to debate and at times turn your information around just enough to make everybody else see his point.

That being said, while it seems like a fun topic isn’t this all saying what has been around in strength, conditioning, and bodybuilding for a while now?

Affliction · June 21, 2007, 4:01pm

[quote]Tim Henriques wrote:
TPA - thanks for the post. Did you notice number 3?

tpa wrote:
3. HTMUs can also be brought into play when the fatigue in the intermediate threshold fibers leads to an insufficient force production; then the HTMUs must be recruited. This is why during “normal” bodybuilding-type sets, THE MOST EFFECTIVE REPS ARE THE LAST ONES. (emphasis added)
[/quote]

Tim, I think what CW and Sentoguy are asserting is that by adding speed and the intent to move the weight as fast as possible, the HTMU’s will be recruited first rather than last. Therefore, this wouldn’t be a “normal” bodybuilding set as referred to above. If you read the other points besides #3 in Thib’s article, they are in accordance with this point.

If one is exaggerating eccentrics, controlling concentrics, and focusing on the “pump”, then HTMU’s will be recruited last. If we attempt to accelerate the bar as fast as possible, the HTMU’s will be recruited first, and then drop out, leading to the drop-off in bar speed.

derek · June 21, 2007, 4:38pm

This stuff is all quite interesting, it really is. I’m a Discovery Channel, History Channel type of guy so I LOVE the science behind the methodologies.

However, (WARNING: rhetorical question ahead) why is it that the biggest guys, and I mean every single one of them, in the gyms I’ve trained in could’t give too shits about such details?

This point had been brought up many times by many members (Professor X many times himself) but it gets passed over every time a new twist on training comes up. That new twist get debated endlessly yet those bad-asses at gyms all across the world keep getting bigger and stronger.

Professor_X · June 21, 2007, 5:18pm

[quote]derek wrote:
This stuff is all quite interesting, it really is. I’m a Discovery Channel, History Channel type of guy so I LOVE the science behind the methodologies.

However, (WARNING: rhetorical question ahead) why is it that the biggest guys, and I mean every single one of them, in the gyms I’ve trained in could’t give too shits about such details?

This point had been brought up many times by many members (Professor X many times himself) but it gets passed over every time a new twist on training comes up. That new twist get debated endlessly yet those bad-asses at gyms all across the world keep getting bigger and stronger.[/quote]

These debates can only exist as long as you don’t keep pointing that out. I was told by one poster in the other thread that those bodybuilders don’t live in the real world.

That alone lets me know that this individual not only expects less results, but believes that less results should be the goal of “real world” training. Someone like that will debate the scientific aspect endlessly because that helps them feel superior to those huge guys who honestly don’t give a shit about the details.

The internet helps these debates along simply because you can’t see the other person. I’m a big guy. I started out a skinny guy. Regardless of the “article of the week” I have trained long enough to know my own body, at least enough to grow bigger than the average weight lifter.

Therefore, talking theory alone to me is nonsense, especially since I have the educational background and the gym experience to see both sides.

derek · June 21, 2007, 5:48pm

[quote]Professor X wrote:

Therefore, talking theory alone to me is nonsense, especially since I have the educational background and the gym experience to see both sides.[/quote]

Yeah, but just think. You could be 40 lbs smaller and miserable/jealous if you just spent more time over-analyizing things and less time busting your ass in the gym.

Sentoguy · June 21, 2007, 6:06pm

[quote]Tim Henriques wrote:
Sentoguy wrote:
Sorry, Tim, but your understanding of the size principle is wrong.
Sentoguy

Sentoguy - I don’t believe you read my post correctly. Your description of the size principle and mine are the same as I see it, although we may feel it applies to this situation differently.

Clearly you recruit your smaller, weaker muscle fibers first and then move on to recruit your bigger, larger muscle fibers. I assume you are not debating this?

Sentoguy wrote:
CW’s point in asking the question, “if the last few reps in a high intensity set really do recruit extra muscle fibers, then why aren’t the last few reps the easiest?” is that he is trying to show that you DON’T recruit more muscle fibers during the last few reps of a high intensity set.
Sentoguy

That was the whole point of my post. It should be clear from scientific and practical evidence that you have recruited more motor units after the last reps then the first. I will be happy to disagree with anyone that says otherwise.

Answer this simple question. You could bench 225x2 or 225x10, which set would leave the greatest percentage of the muscle and its motor units untrained?

If you would like to design a more “accurate” chart or if you want me to send it to you to modify I would be happy to look over the changes and share my thoughts on them.

Good luck with your lifting,

Tim[/quote]

Hi Tim,

Well, perhaps either I misunderstood your post, or you are still not understanding mine. Either way I’ll try to point out how I interpreted your post and how my post was supposed to be different.

First, your interpretation of the size principle seemed to me like you were suggesting that you recruit the small MU’s first, and then as they begin to fatigue, you start recruiting the bigger MU’s. Meaning that towards the end of a set you are recruiting the biggest MU’s, while at the beginning of the set you were not.

This however, is not an accurate understanding of the size principle. Yes, you are right in saying that the smaller MU’s are recruited first and the biggest MU’s are recruited last. However, it is the force required to perform the task that determines whether the biggest MU’s are recruited, not the number of reps.

If the force is sufficient (either a high percentage of 1RM or a high velocity), then the biggest MU’s are recruited. If not, they are not, regardless of number of reps.

Wrong, or at least according to the size principle and our current understanding of how your body recruits MU’s it’s wrong. And, it’s in direct contradiction to what CW was saying in his recent article.

Once again, this is an incorrect way of looking at muscle contraction and the physiological processes that occur during resistance training. According to the size principle, if you are lifting enough weight or lifting a weight fast enough, and therefore recruiting the biggest MU’s, then all other smaller MU’s are also recruited.

Yes, your body is efficient, but in this case efficient means that it will only recruit the MU’s required to perform the task, and will do this in a hierarchal fashion based on the size of the MU’s (type of muscle fiber) and the force requirements for the task.

No, that is not the Size Principle in a nutshell. Your first sentence is correct. Your last sentence is false. The smaller motor units don’t get tired first leading to recruitment of the larger motor units. The smaller motor units (as I stated in my initial post) are extremely fatigue resistant. They are the slow twitch (type 1, SO, or endurance) fibers.

If the force requirements of the first rep aren’t sufficient to recruit the biggest MU’s, then (assuming that rep speed is constant) no number of subsequent reps will recruit them.

There are other examples in your OP that illustrate your misunderstanding of the Size Principle but I feel that I have effectively illustrated that your initial understanding of the Size Principle was incorrect. Therefore, all further illustrations of elaborations of your understanding were also incorrect.

Hopefully this post will help you understand the Size Principle itself a little more clearly and therefore allow you to be able to see for yourself how and where your inital post was incorrect.

Wait, so are you saying that your whole point of your post was to agree or disagree with my statement? Because, if it was to agree, then your next couple sentences don’t make any sense. If it was to disagree, then this alone should tell you how your understanding of the Size Principle (and OP) were different from mine (and CW’s).

And to respond to your second sentence. No, scientific evidence does not say that you will have recruited more motor units after the last few reps than the first. Practical evidence doesn’t really either. Once again I’m not suggesting that approaching or reaching failure isn’t beneficial in building muscle (hormonal, chemical, and mental factors have already been mentioned).

But, this doesn’t necessarily mean that you’re recruiting more muscle fibers. As Prof X stated, there are a lot more components to building muscle than simply MU recruitment. So, I guess I’m saying that I look forward to disagreeing with you.

Depends. First, it’s not really as simple as you suggest. There are several details that I would need to know in order to answer that question. For instance, 1RM and rep speed. If 225 was 85% or greater of 1RM in the fist example, then it would recruit all possible (voluntary) muscle fibers.

If both examples applied to a person who 225 was their 10RM and in both examples the lifter lifted the weight slowly (concentrically), then both would recruit the same amount of MU’s. If in both examples the lifter lifted the weight explosively (concentrically), then both would recruit the same amount of MU’s although, the 225x10 lifter would also place more stress on his smaller MU’s (in this case not the smallest, but not the biggest, the type 11A, FOG muscle fibers).

If the 225x2 set was done explosively and the 225x10 set was done slowly, then the 225x2 set would recruit more motor units, and vice versa.

Hopefully you catch my drift by now and I don’t have to keep rambling. Basically I am saying that percentage of 1RM and concentric speed (and even eccentric speed according to CW’s article) are what is important in determining the amount of MU recruitment, not the rep number alone.

As far as the chart, I’m not really a wiz with designing and creating charts on my PC. You certainly know more about how to do that than I do. If I can figure out how to do it I’ll send you a copy. Hopefully though this post will help you see for yourself how your graph should be altered.

Good training,

Sentoguy

Affliction · June 21, 2007, 6:23pm

[quote]Professor X wrote:
These debates can only exist as long as you don’t keep pointing that out. I was told by one poster in the other thread that those bodybuilders don’t live in the real world.

That alone lets me know that this individual not only expects less results, but believes that less results should be the goal of “real world” training. Someone like that will debate the scientific aspect endlessly because that helps them feel superior to those huge guys who honestly don’t give a shit about the details.

The internet helps these debates along simply because you can’t see the other person. I’m a big guy. I started out a skinny guy. Regardless of the “article of the week” I have trained long enough to know my own body, at least enough to grow bigger than the average weight lifter.

Therefore, talking theory alone to me is nonsense, especially since I have the educational background and the gym experience to see both sides.[/quote]

Prof, let me start out by saying that I agree completely with the above. Also, I am not a “fanboy”, nor do I adhere dogmatically to any one author on this site or any one philosophy, and certainly not to the “hot article of the week”.

I pluck things here and there to try them, and if I like them I’ll keep them in, but I almost always have done my own routine. Before I knew how to design my own routine, I would take them from Flex magazine. Again, I’m with you in that I don’t know why this has become taboo, especially for beginners.

I have achieved my physique goals in terms of body weight/composition and hypertrophy for the moment. I am a competing athlete and although I am not weight-bracketed, I would not be better served by carrying ten more pounds.

I have also achieved my strength goals, and although you can never be too strong, I would be in an upper percentile for my position, even in the NFL. This leaves me with my primary focus on speed and sport-related technique to better myself.

The reason I take part in these debates is twofold - for the reasons stated previously, I am primarily concerned with speed at the moment and therefore anything concerning CNS efficiency and fast-twitch fibers peaks my interest. And secondly, because I am an exercise science major, and am always looking to learn more even though I grasp most of this fairly well.

I too am a “big guy”. I turn heads when I enter rooms. I am also a “strong guy”, strong enough to be the center of attention in several gyms at home when I lift. As of late, these discussions have been tainted by people that are neither, and therefore are almost complete wastes of time. Moreover, they don’t have a science background either.

Once my sports career is over, I will return to bodybuilding and certainly won’t waste time obsessing over rep speed, fiber typing, or macronutrient breakdowns of post-workout salads most conducive to six packs. I’m just going to go lift, like I always have. Seems people will never realize that intensity and experience trump methodology every time.

Professor_X · June 21, 2007, 8:24pm

[quote]bushidobadboy wrote:
derek wrote:
However, (WARNING: rhetorical question ahead) why is it that the biggest guys, and I mean every single one of them, in the gyms I’ve trained in could’t give too shits about such details?

.

Perhaps because they don’t have to worry about the details; results come easily to some, so why question it.

Some of us feel that since gains come so slowly, and transiently, that we need to fully understand the process, in order to optimise it.

That’s my take.[/quote]

Or, have you considered your entire approach might be wrong? I just don’t know too many people who got into this, trained with people bigger and stronger than they were, worked their ass off, ate enough to gain weight…but then decided they needed to microanalyze every single detail just to make any progress at all. Usually, the guys who approach things that way started out that way.

As far as results coming easier, I think some of you truly underestimate how hard some people work. I had a guy last night comment on my front delts (really, my shoulders as a whole). He went on and on about how it must be genetic.

I guess the fact that I train them twice a week and haven’t missed more than two days in a row for a training session (aside from when I was out of country) in a decade has nothing to do with it. All of that food? Nope, must be genetics. Training when I didn’t feel like it? Nope, genetics.

wcbird · June 21, 2007, 8:42pm

[quote]Sentoguy wrote:
Tim Henriques wrote:
Sentoguy wrote:
Sorry, Tim, but your understanding of the size principle is wrong.
Sentoguy

Sentoguy - I don’t believe you read my post correctly. Your description of the size principle and mine are the same as I see it, although we may feel it applies to this situation differently.

Clearly you recruit your smaller, weaker muscle fibers first and then move on to recruit your bigger, larger muscle fibers. I assume you are not debating this?

Sentoguy wrote:
CW’s point in asking the question, “if the last few reps in a high intensity set really do recruit extra muscle fibers, then why aren’t the last few reps the easiest?” is that he is trying to show that you DON’T recruit more muscle fibers during the last few reps of a high intensity set.
Sentoguy

That was the whole point of my post. It should be clear from scientific and practical evidence that you have recruited more motor units after the last reps then the first. I will be happy to disagree with anyone that says otherwise.

Answer this simple question. You could bench 225x2 or 225x10, which set would leave the greatest percentage of the muscle and its motor units untrained?

If you would like to design a more “accurate” chart or if you want me to send it to you to modify I would be happy to look over the changes and share my thoughts on them.

Good luck with your lifting,

Tim

Hi Tim,

Well, perhaps either I misunderstood your post, or you are still not understanding mine. Either way I’ll try to point out how I interpreted your post and how my post was supposed to be different.

First, your interpretation of the size principle seemed to me like you were suggesting that you recruit the small MU’s first, and then as they begin to fatigue, you start recruiting the bigger MU’s. Meaning that towards the end of a set you are recruiting the biggest MU’s, while at the beginning of the set you were not.

This however, is not an accurate understanding of the size principle. Yes, you are right in saying that the smaller MU’s are recruited first and the biggest MU’s are recruited last. However, it is the force required to perform the task that determines whether the biggest MU’s are recruited, not the number of reps.

If the force is sufficient (either a high percentage of 1RM or a high velocity), then the biggest MU’s are recruited. If not, they are not, regardless of number of reps.

Really Chad is asking two points. The first is, do the last reps of a tough set recruit extra motor units (muscle fibers)? The answer is absolutely yes, the last few reps do recruit additional motor units.

Wrong, or at least according to the size principle and our current understanding of how your body recruits MU’s it’s wrong. And, it’s in direct contradiction to what CW was saying in his recent article.

I think the easiest way to look at that question is to think about it like this. What percentage of the muscle is left untrained after completing the set? It should be clear that you work a certain percentage of the muscle on the first rep, a larger percentage on the second, and third, etc, so after a tough set you have worked a very large percentage of the overall muscle.

Once again, this is an incorrect way of looking at muscle contraction and the physiological processes that occur during resistance training. According to the size principle, if you are lifting enough weight or lifting a weight fast enough, and therefore recruiting the biggest MU’s, then all other smaller MU’s are also recruited.

Yes, your body is efficient, but in this case efficient means that it will only recruit the MU’s required to perform the task, and will do this in a hierarchal fashion based on the size of the MU’s (type of muscle fiber) and the force requirements for the task.

Chad already explained the Size Principle in his article, but in a brief nutshell it says that you will only recruit the motor units necessary to perform the exercise, starting off with the smaller or weaker motor units. As those motor units get tired you then recruit the bigger and stronger motor units.