Unstable v. Stable Surface

Many trainers beleive that working on an unstable surface (balance pad, disc, Bosu) increase activation of the "core" muscles. But a recent study completed at Eastern Illinois University looked at that question.  Using 12 trained men for the study.  The subjects were asked to do deadlift, back squat, curl and overhead press on both stable and unstable surfaces.  Two intensities were used as well, 50% of 1-RM and 75% of 1-RM.  Using EMG techniques to determine the amount of activation of the rectus abdominis, transverse abdominis/internal oblique, external oblique and the erector spinae.

There was no difference between the 50% stable or unstable regardless of the lift.  Resceachers did find significant difference in activation of the rectus abdominis and transverse abdominis/internal obliques when comparing the 75% stable to the 50% unstable results.

The study concluded that there is no benefit to training on an unstable surface when attempting to increase "core" muscle activation.  So keep your feet on the floor.

More on this study go to the NSCA Performance Training Journal (Vol 8, Issue 5)