Stable Vs unstable lifting

Here's a study out a little while ago I just stumbled upon. Which do you think activates the muscles most - a stable squat or an unstable squat (that is a squat on an unstable surface)........
Ok the answer is you actually get greater muscle activation using a stable squat when you compare it to an unstable squat...that's right the unstable versions tend to cause less muscle activation & so is the inferior training tool if you are after maximum muscle activation! Quite a surprise as I suspect many of you guessed that the unstable version would give you more muscle activation.
Anyway I'll put the abstract of the study below:

Quote :

http://www.ncbi.nlm.nih.gov/pubmed/20625190

Int J Sports Physiol Perform. 2010 Jun;5(2):177-83.
Effect of absolute and relative loading on muscle activity during stable and unstable squatting.

McBride JM, Larkin TR, Dayne AM, Haines TL, Kirby TJ.

Department of Health, Leisure and Exercise Science, Neuromuscular Laboratory, Appalachian State University, Boone, NC, USA.
Abstract

PURPOSE: The purpose of this investigation was to determine the effect of stable and unstable conditions on one repetition maximum strength and muscle activity during dynamic squatting using absolute and relative loading.

METHODS: Ten recreationally weight-trained males participated in this study (age = 24.1 +/- 2.0 y, height = 178.0 +/- 5.6 cm, body mass = 83.7 +/- 13.4 kg, 1RM/body mass = 1.53 +/- 0.31), which involved two laboratory sessions separated by 1 wk. Linear position transducers were used to track bar displacement while subjects stood on a force plate for all trials. Vastus lateralis (VL), biceps femoris (BF) and erector spinae (L1) muscle activity (average integrated EMG [IEMG]) was also recorded during all trials. During the first session subjects complete a one repetition maximum test in a stable dynamic squat (S1RM = 128.0 +/- 31.4 kg) and an unstable dynamic squat (U1RM = 83.8 +/- 17.3 kg) in a randomized order with a 30-min rest period between conditions. The second session consisted of the performance of three trials each for 12 different conditions (unstable and stable squats using three different absolute loads [six conditions] and unstable and stable squats using three different relative loads [six conditions]).

RESULTS: Results revealed a statistically significant difference between S1RM and U1RM values (P < or = .05). The stable trials resulted in the same or a significantly higher value for VL, BF and L1 muscle activity in comparison with the unstable trials for all twelve conditions.

CONCLUSIONS: Unstable squatting is of equal or less (depending on the loading condition) benefit to improving or maximizing muscle activity during resistance exercise.

True. I would have guessed unstable.
I would have assumed that unstable stance would have been the greater challenge to the muscles involved, as it often is when using free-weights.
Opposing this is the image of myself toppling forward from an unstable stance and taking a substantial bite from the gym floor.

It may be because you can load up heavier on a stable surface & so the major muscles can take a bigger load (so activate more fully), whereas there may be some form of built in protection to stop massive overloading on an unstable surface to lessen the risk of that face-plant in the gym? Unstable surfaces may have other functions other than maximum muscle activation like increased proprioception (that basically means better body awareness - where all the bits of you are), better balance & reaction to change etc, so it might not be pointless if those are goals - I don't do that myself as I'm just a basic 'lift big stuff' sort of lifter, I'd just feel wrong standing on a stability ball waving a bit of flexible plastic pipe in one hand while shoulder pressing that 'massive' pink dumbbell

(Damn, I really wanted to find a clip of someone doing that shoulder press on a stability ball with a bodyblade or similar & a dumbbell...but I failed)

This is also relevant though to machines versus free weights or using kettlebells. The body has to focus more on balancing the weight for kettlebells than free weights than machines. I think too much is made of using free weights and kettlebells for that matter.

I think everything must come down to what your goals actually are. Some instability work like using the koji squat



As it states in the click it can simulate the effects of coming out of a heavy front squat without the maximum weights, so could be very useful to an athlete who intends to lift maximum front squats (like an Olympic weightlifter), if using a back squat version it may get a powerlifter some use as well.
So, it's not that I don't like unstable training as such, I'm just not fond of the whole shaking plastic poles while balanced on one leg on a ball type unstable stuff...if others enjoy that, I've no problem, but for me personally I like basic lifting.
Saying that I generally do like chains, bands & other things like that that change exercises while keeping form the same, they can change up a movement, add new challenges & are just plain fun! Plus chains look cool