Unstable surface or not?

iVillage Member
Registered: 03-20-2003
Unstable surface or not?
Fri, 06-18-2010 - 7:14am

Another article from Fitbits. This one compares using a stable surface to an unstable one. For the plank, unstable uses more muscle but you use your transverse abdominis LESS on a stability ball than on a stable surface. Interesting. I think people are too busy trying not to fall off the ball and don't do as good of a crunch, maybe.

Stability Ball Enhances
Lumbar Stabilization Training
The use of unstable surface training (UST) has come under fire in recent years. Whether misunderstood or misused, there is definitely a need for additional study on UST to determine the best applications in fitness environments. In a recent study, researchers tested the difference in muscle activation during trunk or core exercise both on stable and unstable surfaces.
Researchers used surface EMG to measure muscle recruitment patterns during five traditional lumbar stabilization exercises in 9 subjects. The peak recruitment of 5 core muscles was recorded: rectus abdominus, lumbar multifidus, erector spinae, transverse abdominus, and external oblique. Participants performed the plank, curl-up, side plank, back bridge and birddog on both stable surface and an unstable surface (i.e. stability ball, disc, etc).
The plank increased muscle activity in all muscles when on the unstable surface. When using the unstable surface the quadruped birddog, and side plank, however, saw only increases in superficial muscle activity, and not deep core (i.e. transverse abdominus and multifidus). Interestingly, when the curl-up was performed on a Stability Ball the recruitment of the transverse abdominus decreased, while the external obliques increased.
Unfortunately, the data from this study indicates that the back bridge did not benefit from incorporating the unstable surface.
Although the jury remains "out" on standing UST and performance, there appears to be a useful application for prone and side stabilizing activities. Moreover, as “core neutral” training becomes the dominant form of abdominal strengthening industry-wide, we need to explore ways to increase muscle activity and tension during such exercises for progression. Studies such as this are a step in that direction.
Imai, A. et al (2010) Trunk Muscle Activity During Lumbar Stabilization Exercises on Both a Stable and Unstable Surface. J Orthop Sports Phys Therapy. 40(6):369-375.

iVillage Member
Registered: 07-09-2008
Fri, 06-18-2010 - 8:15am
If I am understanding correctly, core work is distributed among different muscle groups, but when on a stable surface, the deeper muscles are activated more?
iVillage Member
Registered: 03-25-2003
Fri, 06-18-2010 - 8:59am
Interesting. This reaffirms what we already knew: variety is key to fitness.
iVillage Member
Registered: 03-20-2003
Fri, 06-18-2010 - 11:41am
What I've always heard in the past is if you take it on an unstable surface, you'll active the deeper muscles like the transverse abdominis more. But, this shows, not in all cases. So, plank on unstable hits more muscles than stable but crunches, not necessarily so. I would theorize that IF a crunch is performed well on a ball, it can activate the transverse abminis better BUT it's rarely done that well. But, overall, as Jen, said variety is key. I think the best thing would be to do both--start on unstable then move to stable and work harder or reverse the order.