The hypothesis requires that ATP is depleted to levels that limit cross bridge detatchment and this has to be proven. I don’t think ATP is a limiting factor in a muscle contraction, accumulation of inorganic phosphate is probably more important.

Paul, how can you be sure that concentric failure caused by ATP depletion?
I think failure is more neurological then chemistry

Karky - 16 May 2010 09:43 AM

That sounds a bit weird. Low ATP would activate AMPK, which isn’t associated with hypertrophy.

Any more details? Why would ATP depletion damage muscle cells?

AMPK stands for AMP (adenosine mono phosphate) activated protein kinase.  After intense exercise, AMPK decreases.  Hypertrophy happens during rest not during ANY kind of exercise. 

ATP is required for cross bridge detachment.  If you are lowering a weight that requires more ATP than is available due to diminished ATP regeneration due to say depleted PCr, then cross bridges will be forcibly broken apart resulting in microtrauma.  During adequate rest, supercompensation will ensue.

Anatoly - 21 December 2010 11:04 AM

Paul, how can you be sure that concentric failure caused by ATP depletion?
I think failure is more neurological then chemistry

I did not say ATP was depleted.  I said creatine phosphate gets depleted during intense anaerobic exercise.  Depleted PCr causes a drop in power output due to a decline in the rate of ATP REGENERATION.  Anaerobic glycolysis regenerates ATP at a slower rate.  So, deplete PCr and then do some negatives to induce microtrauma with the weight that you just went to concentric failure with.  I think that the amount of negative work done immediately after con failure should be measured and recorded (eg weight times negative reps). 

Peace

This would still require a great deal of ATP depletion and ATP doesn’t really go much below 20-30% of resting levels, at least at the muscle fiber level. Is this enough to cause some semi rigor mortis state?

You need some scientific support to back up your hypothesis. You’re saying that cross bridges won’t detatch, and this would be due to a low level of ATP (ATP depletion). You need data showing significant ATP depletion with strength training as well as data showing that this depletion is enough to make the cross bridges not be able to detach.

Whether it is too slow ATP regeneration or ATP depletion is really the same thing, as the point is there will have to be less ATP than needed for cross bridge detachment.

Karky,

I did a pubmed search for creatine phosphate depletion and limited the search to just the entries with the terms in the title.  Three papers came up and none of them included anything about eccentric muscle actions.  The research to answer the question “Does doing negatives with the load that concentric failure was attained with immediately after con failure cause microtrauma and how and why?” simply has not been done.  I can only piece things together from various seemingly unrelated articles.  I’ll see what I can do. 

In spite of the dearth of research, I think it is reasonable to hypothesize that if you cannot lift the weight after each negative rep and if you cannot stop the weight from descending through the dropping zone then the amount of ATP is inadequate at that moment for the task at hand.  The demand for ATP is greater than the supply at that precise moment. 

ATP is required for the detachment of the cross bridges.  If there is not enough ATP to enable the detachment of all of the cross bridges then something has to give such as actin getting torn from the z line and causing z line streaming. 

I am currently in the midst of a cycle in which I am doing one set of continuous tension reps per exercise to concentric failure and then doing negatives immediately after with the same weight.  My body weight at the beginning of the cycle was 210lbs and now it is at 220.  My concentric work power product has been steadily increasing throughout.  I continually increase the amount of negative work done after con failure too.  I’ll share more about the hows and whys of my training if anyone is interested. 

This style of training seems to be effective for me without endangering my 46 year old joints. 

Peace,
Paul

“In spite of the dearth of research, I think it is reasonable to hypothesize that if you cannot lift the weight after each negative rep and if you cannot stop the weight from descending through the dropping zone then the amount of ATP is inadequate at that moment for the task at hand.  The demand for ATP is greater than the supply at that precise moment. ” this statement presumes that ATP depletion is the cause of muscle fatigue, but I’m not sure that it is. There are a lot of factors that contribute to fatigue that lie upstream of ATP in the muscle excitation contraction coupling.

I’m not doubting that it works for you, I’m just not convinced if the ATP depletion hypothesis is the reason why it works.. It’s an interesting thought, though and it’s too bad there hasn’t been done any research on it.