Reps, sets and microtrauma

[DutchVince]

I'm asking a theoretical question here. I would like some scientific answers.

Why do more than one set, heck why do even more than one rep?
Only if the load is greater than the previous time it will cause micro trauma, right?

So why would an additional rep with the same load cause more micro trauma? Because you use different motor units?
Does each rep use different motor units in the same muscle?
Thus increasing total micro trauma for the whole muscle?

And why would an additional set be usefull? Will it engage other unused motor units?

It all boils down to this:
I now do one set per exercise; and thats all.
Why would I do more?

 

[Bob Evans]

Unscientific answer.

Well at least the way I (a lay person) understands it.

There are two factors here TUT (time undertension) and increasing load. So you do more than one set to increase the time under tension. And over time you have to increase the load. You can do the same weight for more than one work out -- say 3 workouts --but at some point the load needs to be increased. (If you want to get bigger stronger)

Often to a very good questions like yours -- there is no one simple answer. That is not an attempt to avoid the question. It is just that designing an effective workout program is a balancing act. One needs to balance many variables to get the best results. It is a mistake to look only at any one variable.


The whole idea is to create an "environment for growth"...and simply stated that is repeated trauma, and increasing trauma.

But ,for example, TUT is good, time under tension. But if one does too much in one workout one enters the catabolic zone. I think Bryans explanation of HST in the HST and the About tabs gives a good overview how HST is designed to increase the effectiveness of many different variables, without emphasizing one to the detriment of others.

BoB

 

[NWlifter]

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Quote[/b] ]I'm asking a theoretical question here. I would like some scientific answers.
Why do more than one set, heck why do even more than one rep?
Only if the load is greater than the previous time it will cause micro trauma, right?

Nope  

Quote[/b] ]So why would an additional rep with the same load cause more micro trauma? Because you use different motor units?

They are 'activated' to a higher level. (rate coding: firing frequency)

Quote[/b] ]And why would an additional set be usefull? Will it engage other unused motor units?

No it will just subject those fibers to more metabolic and mechanical stress.
The load on the bar isn't what induces more microtrauma, it's that the load causes the fibers to work at a higher level. A fiber can only create so much tension. Whole muscle tension is varied by the amount of fibers activated, and the rate at which they contribute 'their' tension. More load does not increase the tension on each fiber, just the rate at which they create their tension. Once a fiber hits fused tetanus (pulsing so fast it's basically 'on' all the time), it can neither create nor feel any more tension.
But higher rates of work also increase intra-cellular calcium concentrations and those lead to post exercise micro-trauma/remodeling.