Core Strengthening and the Swiss Ball
Escamilla RF, Lewis C, Bell D, et al. Core muscle activation during Swiss ball and traditional abdominal exercises. J Orthop Sports Phys Ther. 2010; 40:265-276.
A study was designed to test the effective ability of 8 abdominal exercises performed on a Swiss ball to activate core musculature. The Swiss ball exercises were compared to 2 traditional abdominal exercises performed on the floor without the ball, to determine which exercises were most effective at recruiting core muscles. Testing was performed on 9 males and 9 females, with minimal body fat to assure optimal quality of the electronic measurements of muscle activation.
The 8 Swiss ball abdominal exercises performed were: Pike, Knee-up, Skier, Decline push-up, Hip extension right, Hip extension left, the Roll-out, and Sitting march. For most of the exercises, subjects were cued to maintain neutral spine, feet together, 90˚ of shoulder flexion, hands shoulder width apart. Proper performance of the exercise was given by following verbal commands. The Swiss ball is positioned under the legs approximately halfway between the knees and ankles for the Pike exercise. The 2 floor exercises used as comparison, assumed a traditional crunch position, and a bent knee sit up.
Results from the study showed that maximal voluntary isometric contractions during the Pike exercise was rated at Very High (>60%) at recruiting external obliques, and high (41-60%) for lower abdominal and internal obliques; and Moderate (21-40%) at recruiting latissimus dorsi. The Roll-out exercises was determined to be Very High (>60%) at recruiting upper abdominals, and High (41-60%) at lower abdominals and external obliques. The Traditional floor crunch proved to be ranked High (41-60%) at recruiting upper abdominals. The least effective in all exercises tested was the sitting march.
Based on these results, use of the Pike exercise is the best challenging, well-rounded core exercise for activating a maximal abdominal contraction. The degree of difficulty of the pike may not make it suitable for all rehabilitation patients with decreased upper extremity strength to properly execute the exercise. The second best exercise is the Roll-out, and is better suited for most patients that can kneel and does not appear to require a high degree of upper extremity strength.