What constitutes CNS intensive activity?

[jijin]

I'm curious. I hear the term CNS intensive sessions thrown here and there, but what constitutes a CNS intensive session, and what doesnt?

So far I know ME sessions and DE sessions are CNS intensive, but what about RE sessions or body weight circuits?

[Lisa~]

An important function of the CNS is motor control. Any activity that taxes or improves motor control can be CNS intensive. What's difficult for any particular individual can vary a lot. But we generally think of the CNS being taxed by speed with heavy load--Olympic lifts, plyometrics, acceleration work, and the ME lifts you mentioned. Generally think of it as short duration (a few seconds) with high intensity (>90%) requiring longer rest intervals to recover.

RE would not usually tax the CNS. Don't confuse physical fatigue with CNS work. Longer drills with shorter rest intervals and moderate loads (<85%) would be physical work.

[jijin]

Originally Posted by Lisa~

An important function of the CNS is motor control. Any activity that taxes or improves motor control can be CNS intensive. What's difficult for any particular individual can vary a lot. But we generally think of the CNS being taxed by speed with heavy load--Olympic lifts, plyometrics, acceleration work, and the ME lifts you mentioned. Generally think of it as short duration (a few seconds) with high intensity (>90%) requiring longer rest intervals to recover.

RE would not usually tax the CNS. Don't confuse physical fatigue with CNS work. Longer drills with shorter rest intervals and moderate loads (<85%) would be physical work.

Thanks Lisa! You're always a great help!

So basically conditioning type workouts, like sled dragging or light circuits with short rest intervals, are physically taxing but don't tax the CNS. Did I get that right?

[Lisa~]

Originally Posted by jijin

Thanks Lisa! You're always a great help!

So basically conditioning type workouts, like sled dragging or light circuits with short rest intervals, are physically taxing but don't tax the CNS. Did I get that right?

Yes

[Jason B]

But be careful. While high rep work done properly it is not taxing to the CNS, but a lot of volume training to failure will still wear it out, it's still recruiting a lot of muscle fibers. This type of training is non-productive anyway though. 99% of the time, going to failure in a fatigued state (after several reps) is not a good idea, it also increases risk of injury.

[RacerBill]

I believe EDT is also considered CNS-intensive.

Now that I think about it, that fits Lisa's "short duration with high intensity requiring longer rest intervals to recover" definition.

[umass]

Originally Posted by RacerBill

I believe EDT is also considered CNS-intensive.

Now that I think about it, that fits Lisa's "short duration with high intensity requiring longer rest intervals to recover" definition.

I don't think it's CNS intensive given that you are working around 10rm which is a relatively low intesity as compared with 1rm and the rest periods are actually short since you are just going for as many reps in a time period. It's very physically fatiguing, but I wouldn't classify it as CNS intensive.

[karky]

the fact that the CNS gets more fatigued with heavy lifting and speed lifting than light lifting, like bw squats, and stuff like that.. does that have anything to do with that when you do speed and heavy work, your recruit more muscle fibers? If you do BW squats, you probobly just need to activate the slow twitch fibers, right? But if you do heavy squats or speed squats, you have to activate all the way up to fast twitch (IIB) fibers. Could that be an explaination as to WHY it is like that? The CNS has to work harder to activate more monitor units and more muscle fibers..

[Lisa~]

Originally Posted by karky

the fact that the CNS gets more fatigued with heavy lifting and speed lifting than light lifting, like bw squats, and stuff like that.. does that have anything to do with that when you do speed and heavy work, your recruit more muscle fibers? If you do BW squats, you probobly just need to activate the slow twitch fibers, right? But if you do heavy squats or speed squats, you have to activate all the way up to fast twitch (IIB) fibers. Could that be an explaination as to WHY it is like that? The CNS has to work harder to activate more monitor units and more muscle fibers..

exactly

[Jason B]

Originally Posted by karky

the fact that the CNS gets more fatigued with heavy lifting and speed lifting than light lifting, like bw squats, and stuff like that.. does that have anything to do with that when you do speed and heavy work, your recruit more muscle fibers? If you do BW squats, you probobly just need to activate the slow twitch fibers, right? But if you do heavy squats or speed squats, you have to activate all the way up to fast twitch (IIB) fibers. Could that be an explaination as to WHY it is like that? The CNS has to work harder to activate more monitor units and more muscle fibers..

Yes the CNS has to work harder to fire more motor units and fire them faster. This can be accomplished in a few different ways though. Like you said, heavy lifting and speed lifting accomplish this. But explosive bodyweight movements do as well. Anything where you are trying to put maximum force into the movement is CNS intensive. Remember force = mass x acceleration, so only one of those needs to be maximal to get a large force production. Sprints and jumping are CNS intensive because even though they are bodyweight, acceleration is maximal so force is high. A 1RM is slow, but the mass is maximal so force is high.

I think another player in all this is inter-muscular coordination. The CNS must work harder when it needs to activate muscle fibers from several different muscles simultaneously to accomplish the task. A heavy set of squats will be more CNS intensive than the same relative intensity of curls. This gets back to the total amount of muscle recruited, it's not solely dependent on how much you hit a particular motor unit, how many motor units you hit is very important as well.

So even though I see no training benefit or reasoning behind it, you could get away with a lot more maximal work with isolation exercises than big compound lifts. You may be maximally taxing every fiber your biceps have got, but in terms of the CNS, that ain't much.

[karky]

now im proud, i figured that out all by myself

I got another theory :p at the same time i thought about that, i also thought about speed. You know, you need speed to be able to move big weights. does speed have anything to do with your CNS capability of quickly activating the fast twitch fibers? I mean, if your fast twitch fibers are strong, but your CNS uses too long to activate the fibers up to fast twitch, wont that result in the weight not being lifted? If you catch my drift..

sorry for a bit off topic here.

[JoshDunn]

Kind of. As you get stronger you recruit more fibres in order to help with the load as well as an increased speed of the recruitment. You want be "strong" if the fibres aren't recruited. Does that make sense?

Speed of the actual lift is alittle different as the fatigue rate of the fast twitch fibres is relatively quick. If you try a heavy load (say >80%) but try to do it slow then the biggest, strongest, fibres will fatigue and then be left to the type IIA and I.

Another thing with speed is the stretch shortening cycle. That basically is you store energy in your muscles during the lowering phase that can then be released for extra bang during the concentric phase. If you lower slowly you lose some of this energy as heat.

Summary:
-lift as fast as you can for max strength.

Keep thinking Karky always someone who can try to answer your questions.