Deadlift "Shudder"

[sirawesomes]

G'day Rip,



I have another stupid question for you; a result of thinking about lifting too much.

The best way I can describe the phenomenon is a "shudder" as one is grinding out a rep of the deadlift, and it appears to be pretty common for maximal deadlifts for many people. An example can be seen here: http://www.youtube.com/watch?v=33dV2...ailpage#t=276s

I'm referring to that slight "shaking" back and forth of the hips as the bar is being locked out.

Basically I was wondering if you had any insight into what causes this.

Feel free to ignore this if you don't care.

[Mark Rippetoe]

I care deeply. The function of the hamstrings in the d4eadlift is largely isometric through the first part of the ROM of the movement: the anchor the back angle by staying the same length as the hips and knees extend. The tremor you see on a heavy pull is the result of hamstring fatigue under a heavy load, but as far as a neurological explanation of why the tremor occurs happens, I don't have one.

[Will Morris]

The tremor is (in my completely uneducated opinion) likely a result of the body's ability to continue activating motor end plates as it continues to recruit more and more motor units to finish the lift. This is something you also tend to see in completely novice lifters on most lifts.

[Mark Rippetoe]

And their repeated reactivation after they fatigue?

[Steve Hill]

I think we've talked about this before. I think it's more a function of what parts of the hamstrings are in contraction as the lift progresses. It's a reflection of one group of motor-units turning off while others turn on as the hamstring changes shape while the hips extend. There may also be some neurological efficiency deficit at play, since by definition, the shudder would come when groups turn off and there is a gap in time as other motor-units turn on to continue the motion. The smoother the lift occurs, the better the coordination of the hand off function is.

[John F Musser]

Way back when, I remember watching athletes unfamiliar with wrestling try to muscle out from under someone. They would try to apply their whole body in the effort, and sometimes they would shake and then experience muscle failure. When the person went limp, it was said they did the “chicken”.

The “big guys” at the local health club explained it was the Golgi Tendon Reflex. This safety mechanism was reported to kick in and make you relax your muscles before you injured yourself on too heavy a load. Persons who wished to lift heavy were instructed they needed to develop their strength of body and will to train past this safety mechanism.

I have seen people shake on other lifts, just not nearly as dramatic as a near max deadlift. Is this similar to the hand not being able to hold what the body cannot move?

I am not certain there is such a thing as a Golgi Tendon reflex, or if there is, if it applies here. The question was interesting, and I am enjoying reading the responses.

[Jordan Feigenbaum]

Way back when, I remember watching athletes unfamiliar with wrestling try to muscle out from under someone. They would try to apply their whole body in the effort, and sometimes they would shake and then experience muscle failure. When the person went limp, it was said they did the “chicken”.

The “big guys” at the local health club explained it was the Golgi Tendon Reflex. This safety mechanism was reported to kick in and make you relax your muscles before you injured yourself on too heavy a load. Persons who wished to lift heavy were instructed they needed to develop their strength of body and will to train past this safety mechanism.

I have seen people shake on other lifts, just not nearly as dramatic as a near max deadlift. Is this similar to the hand not being able to hold what the body cannot move?

I am not certain there is such a thing as a Golgi Tendon reflex, or if there is, if it applies here. The question was interesting, and I am enjoying reading the responses.

There is such a thing as the GTO reflex, which respond to the force being generated by the muscle fibers its anchored to. There are also nuclear bag and chain fibers in the intrafusal muscle fibers that sense stretch/rate of stretch (IIRC). All of these send afferent signals to the spinal cord to synapse and influence various reflex processes in the musculoskeletal system. Shuddering in a deadlift? Probably a combination of reflexive on-off coupling of certain motor units due to the tension generated and stretch of the muscles at specific angles. For instance you rarely see this phenomenon off the floor, but more likely above the knee. Interesting phenomena....I'll have to think about it more

[sirawesomes]

My first thought was it might be related to the Golgi Tendon reflex (though I had completely forgotten the term itself), as if the muscle was "switching on and off" to prevent itself from tearing under load.

However the hamstring fatigue theory also appears to explain the phenomenon, especially as the shudder is usually seen during limit deadlifts (which are slow), or the last reps of a heavy set (which are also slow).

I have seen people shake on other lifts, just not nearly as dramatic as a near max deadlift.

I've never seen this happen with other lifts actually, it only really seems to occur with heavy deadlifts.

[Foobar40]

Is it really either the stretch reflex or fatigue? Why not both? Your muscles get fatigued and start to lengthen. The lengthening triggers a stretch reflex, which allows you to move the weight further. As you are able to make progress, the neuromuscular response is that you no longer need to recruit every possible muscle unit. As you recruit less, and the stretch reflex effect wears off, you start to struggle again. When you're that close to your limits, you might be in the nonlinear part of the force-length curve for muscles -- you can get all kinds of weird limit cycle behavior once things are nonlinear.