Split stance is used to vary activation of the core stabilisers and reduce onset of fatigue by being in just one position. It challenges us to stabilise the pelvis / hips and trunk in different ways, particularly in the bicep track. It is important however that you balance out the `split` and ensure you change which foot is forward to maintain balance in muscle activation between left and right sides. The stance is reletavely short with more weight on the front leg and a definite knee bend in that front leg to activate the deep core stabilisers which help maintain the trunk in a rigid position to isolate the biceps during the curl movement and reduce any momentum / throwing of the bar!
We ALWAYS promote a split stance in the shoulder track for the overhead work as it is a stronger position to reduce hyperextension in the lumbar spine. Our core stabilisers are at their most fatigued by this point in the class! normal `set` stance, whillst being stable in terms of equal activation left & right, allows a greater degree of hyperextension. As our deltoids tire, the bodys natural tendency is to `lean back` (hyperextend) in an attempt to engage the upper chest mussels to assist in driving the bar up. This puts excessive pressure into the lower back as well as detracting from maintainig the load in the deltoids which are the targeted muscle group for the track! In this particular case, the split stance described above, with more weight on the front foot enables us to `lean` slightly into the work, keeping the load in the deltoids and reduces the amount of hyperextention possible in comparrison to normal `set`, thus we reduce the risk of injury / destabilisation of the pelvis and increase the chances of maintaining the load in the deltoids.
its very easy to check: stand in `set` position, push a bar overhead as in shoulder press and notice how much you can hyperextend the lower back (also the pelvis will anteriorly tilt!!!)! now do the same with a short split stance, with more weight in the front leg and a definate fixed knee bend... you cannot hyperextend as much (and the pelvis remains stable)!!!
With regard to this split stance, a common mistake is to stand too long and put the back heel on the floor! this will actually cause the trunk to lean backwards (and pelvis to rotate)! Always keep the back foot just behind the front heel ensuring the back heel stays raised up of the floor (back foot on tip-toe) with about 70% bodyweight on front leg.
Hope this helps... happy, safe & effective pumpin
S
KIA KAHA
`Animal`