muscle fiber activation

[Plata]

Hello,

I am Plata and first of all: sorry if my english is not so good, but I will give my best.

In my last workouts I did some experimenting with weights, sets and reps. What was really interesting for me was this:
when I do for example squats, I usually do it with about 300 lbs. for lets say 5 sets of 6-12 reps.
Now if I change my workout and do all 5 sets with 150 lbs. it is of course easier than the 300 lbs. but it still feels somewhat heavy.

But then in the next workout I did something completely different:
I started to work up slowly to warm up (10 reps with 90 lbs., 5 reps with 150 lbs., 5 reps with 200 lbs.) and when I continued with low-rep heavy sets:
3 reps 250, 2 reps 300, 1 rep 350, 1 rep 350, 1 rep 350

After this heavy singles I put down many plates and go back to 150 lbs.
And here comes the funny thing: the weight now feels so light, it seems almost there is no weight at all. I feel very powerful, like maybe someone would feel on steroids (I am not sure, I never tried them) and now I can do maybe 50% more reps than I usually do with this light weight.

I know that what I did and felt is nothing really new and does not seem to exceptional. Many of you maybe think "of course, if you use very heavy weight at the beginning the lighter weight in the later sets will feel even more light".
But the thing is it does not only feel light, it is lighter now for the body, I can do more (much more) reps than I could usually do with this weight.

What I would like to know is: what is going on in the muscles and the nervous system ? Can someone give me a somewhat scientifically solid explanation for this phenomenon ? Is it because the heavy weight activates more fibers (which then are still active in the later lightweight sets) or is it a higher coding rate or both ..... what is exactly going on in the muscles ?

By the way, I tried this with other exercises (like benchpress, barbell curls, military press and it is the same, but it seems to me the more weight I can use in an exercise the better it works, so maybe concentration curls are not the best choice for this ...).

Thx to everybody who can help me on this one with some good explanation !
Plata

[waynelucky2]

I found out this about three years ago, and always use it now.

The first time I did it right I will ever forget, it was on the Nautilus Multi Biceps, I did the fist set of 30, it was ever so hard, and the pump was like nothing else, after 10 seconds of that set I thought I would never do the second, I then added about 25% to the bar, after three minutes I was ready to go again, but knew I had to wait until five minutes, I hit the heaver set and thought it was going to be hard, sugar it flew up, I immediately checked the weight it was right, so I carried on, it soon got harder on about the 10th rep, but them first few reps or two I will never forget. Then set 3 rested another 5 minutes, added 15% and those first few reps went up very good again.

Then rest another 5 minutes dropped the weight by 50% and like you it felt so dammed light.

Thought I would save you some time All-pro,

All-pro wrote;
Mishap #1. Post-tetanic Facilitation

I'm sure most of you have heard of wave loading. Basically, it consists of using varying levels of maximal loads in an effort to cause immediate strength gains. An example of wave loading looks like this:

Wave 1

Set 1: 5 reps with 300 lbs.
Set 2: 3 reps with 320 lbs.
Set 3: 1 rep with 340 lbs.

Then, with the neural enhancements that occur, you're able to repeat the above sequence with somewhere around 2% more load for each set. In other words, your 5RM, 3RM, and 1RM are enhanced so you can do this:

Wave 2

Set 1: 5 reps with 305 lbs.
Set 2: 3 reps with 325 lbs.
Set 3: 1 rep with 345 lbs.

Pretty cool, eh? Yep, it's a very effective method. Many have extolled the virtues of this method by giving credit to a nervous system response called post-tetanic facilitation. But apparently, post-tetanic facilitation isn't limited to just wave loading, I've heard it used in relation to holding a supramaximal load (ie, a load greater than your 1RM) in order to cause immediate strength gains, among many other methods.

So what's the problem? Well, when they use post-tetanic facilitation in reference to wave loading, supramaximal holds, or some other maximal strength method they don't know what in the hell they're talking about!

http://www.t-nation.com/findArticle....6-054-training

http://www.t-nation.com/findArticle....5-037-training

Wayne

[waynelucky2]

Here is how Poliquin explains it:

"In a nutshell, if you do a 6RM (the maximum load you can lift for 6 reps) load within 3-10 minutes of doing a max single, you can use a greater weight that you could have if you hadn't done the 1RM set."

This is very true and it?s a very effective indeed. But lately many people have asked what exactly is this post-tetanic facilitation phenomenon, so here it is!

1. Potentiation
A physical/muscular activity can have an effect on other subsequent activities. The prior activity can either decrease the muscular performance in the later exercise (mostly due to the fatigue factor) or it can increase the performance during the later exercise (Abbate et al. 2000).

In the second case the performance is enhanced via a phenomenon called potentiation.
Potentiation refers to an increase in force output as a result of previous muscular activation (Abbate et al. 2000). There are many kinds of possible potentiation. The two best known ones are post-tetanic potentiation and high-frequency initial pulse potentiation.

2. Post-tetanic potentiation
The tetanus refers to a state of muscular activation that occurs either during a longmuscular contraction (so brought on by muscular fatigue) or a very intense contraction (so brought on by a maximum contraction). The tetanus can be explained as the summation of all the available motor-units.
It has been found that the force of the twitch of a muscle fiber is more important after than before the brief tetanus. This effect is present even 5 minutes after the tetanus (O'Leary et al. 1997). In fact, during a 7 second tetanus, the capacity to apply force decreases by 15% while this capacity is increased by 28% after 1 minute, 33% after 2 minutes and 25% after 5 minutes (O'Leary et al. 1997). So it appears that the capacity to produce force is greater 2-3 minutes after the cessation of the tetanic effort.
This increase in the capacity to produce force after a certain stimulation is called posttetanic potentiation (PTP). The most effective way to promote a large PTP is to place an intense stimulation on a muscle via a maximal effort/maximal tension contraction for a length of 5-10 seconds (Brown and von Euler, 1938, Vandervoort et al. 1983).

PTP can increase contraction strength, especially in fast-twitch fibers (Bowman et al. 1969, Standeart, 1964). PTP also improves the rate of force development (Abbate et al, 2000).

PTP works by increasing the phosphorylation of the myosin light chains, which makes the actin-myosin more sensitive to calcium in the subsequent twitch (Grange et al. 1993, Palmer and Moore 1989, O'Leary et al. 1997). This is not chiefly important, but, if you wish, you can grab a physiology textbook and review the sliding filament theory of muscular contraction to see how this would increase the capacity to produce force.

3. High Frequency Initial Pulse Potentiation (HFIP)
While this phenomenon is outside the scope of this article, understand that HFIP occurs at the start of ballistic movements (Abbate et al. 2000) and that it increases the power output, the rate of force development, and peak force (Mardsen et al. 1971, Burke et al. 1981, Hennig and Lomo, 1985).

4. Post-tetanic Facilitation (or post-tetanic potentiation)
Post-tetanic facilitation (PTF) is simply another term for post-tetanic potentiation. Both mean the same thing. PTF means that the tetanus facilitates a subsequent effort, while PTP means that the tetanus increases the potential for a subsequent effort. So it's basically word play that means the same thing! Just to give you an idea, there

Wayne

[Plata]

Hi waynelucky2,

thank you for your really detailed answers, this helps alot.

Do you still use this loading pattern for your workouts ? If yes, how are the results for you ?

You have very good knowledge of the things that happen inside of the muscle. So maybe you can also help me with my next question that is also related to muscle fiber activation:

when I do training with high volume, I do for example 6 sets of barbell curls for 10-15 reps each.
I will not go to failure in all 6 sets but maybe only in the last 2 or 3. But what exactly happens when I reach failure, rest about a minute and go for the next set ? Why does the muscle fail and give up ? I use somewhat light weight (maybe 50 % of my 1rep max) so from what I know the weight is not heavy enough to really activate a high percentage of my muscle cells, maybe only 40%. But then these 40% cannot do any more, should the body not start to activate the remaining 60% of the cells in this muscle so I can continue the work ? But this is not the case, at least according to my knowledge (thats why they allways say to activate all - or most - of your fibers you must use very heavy loads like 90% of your 1rep max.). So why is the muscle giving up after lets say 15 reps even if not ALL the cells in the muscle have worked to the limit ?
And what happens in the next set ? Which muscle fibers will the muscle use for this new set ? The same that worked in the previous set, after they have now recovered a little bit in the 60-90s ? Or will now additional cells jump in and continue the work ?

Maybe my questions seem somewhat simple, but I would really like to know what is going on inside the muscle during a typical workout (a full workout, not only during 1 set of 5 reps), how are the muscle fibers recruited, I think this can really help to design better workouts.

Perhaps you can also give me some links to good articles that explain these processes in the body. I already googeld alot but I cannot really find what I am looking for.

Thanks in advance for all answers !
Plata

[all pro]

This might help you understand what happened,
http://www.t-nation.com/free_online_...ous_muscle&cr=