Exercise balls have been used for many years in fitness and therapy. Most popularly used to enhance core strength, the exercise ball provides an unstable surface that elicits more activation of the abdominals compared to a traditional abdominal crunch (Vera-Garcia et al. 1999). However, no studies have compared muscle activation on an exercise ball to an abdominal machine.
Danish researchers wanted to compare activation of core and thigh muscles during abdominal crunches performed on a Thera-Band exercise ball with added elastic resistance and on an isotonic abdominal training machine. They published their findings in the International Journal of Sports Physical Therapy.
42 healthy, untrained adults performed an abdominal crunch with a 10 repetition maximum (RM) resistance using a combination of Thera-Band elastic resistance tubing (red, green, blue, black and gray colors) stretched to 100%; this was done to ensure the resistance was the same as obtained on the Technogym abdominal machine.
Muscle activation levels were normalized to percent of a maximal isometric contraction (MVIC):
The exercise ball with elastic tubing crunch activated the abdominal and gluteal muscles more than on the machine, including significantly greater activation of the rectus abdominus by 24%. In addition, the abdominal crunch on an exercise ball with elastic tubing resulted in significantly less activation of the hip flexors (rectus femoris) by 160%. The abdominal:hip flexor activation ratio was also much higher in the exercise ball and elastic tubing exercise. This is important since abdominal exercises should minimize hip flexor activation to better isolate abdominal muscle activation.
Abdominal:Hip Flexor activation ratios (based on %MVIC):
Thera-Band Exercise Ball and Tubing
Technogym Abdominal Machine
The researchers speculated that the 90-degree sitting position of the abdominal machine promoted activation of the hip flexors compared to the neutral hip position using the exercise ball. They stated, “The current data indicate that sitting crunches in an exercise machine designed to isolate the abdominal muscles does not target this muscle group to the same extent as the supine crunch on the Swiss ball although both exercises caused high activation.”
Sundstrup and colleagues added, “abdominal crunches performed on an exercise machine in a seated position may not be desirable for individuals with lumbar disk pathologies, low back pain, or weak abdominal musculature.” Interestingly, participants in the study, either with and without back pain, benefited equally from the exercises. Furthermore, younger and older subjects demonstrated similar results regardless of their age.
This study is significant because it again demonstrates that readily available, inexpensive, and portable exercise equipment such as Thera-Band exercise balls and elastic tubing can produce similar if not better results compared to bulky and expensive exercise machines.
REFERENCE: Sundstrup E, Jakobsen MD, Andersen CH, Jay K, Andersen LL. Swiss ball abdominal crunch with added elastic resistance is an effective alternative to training machines. Int J Sports Phys Ther. 2012 Aug;7(4):372-80.
Disclosure: Thera-Band Academy provided the products used in this study