Zródło

Bressel E. et al., Effect of instruction, surface stability, and load intensity on trunk muscle activity, „Journal of Electromyography & Kinesiology” 2009, 19, 500–504.
Comfort P., Pearson S.J., Mather M., An electromyographical comparison of trunk muscle activity during isometric trunk and dynamic strengthening exercises, „The Journal of Strength & Conditioning Research” 2011, 25(1), 149–154.