Study: Elastic resistance abdominal crunch exercise more effective than machine-assisted exercise
December 11, 2012 — Weak abdominal muscles can negatively impact overall strength, stability, and mobility, and are often associated with medical issues such as low-back pain.1
Strengthening these core muscles is vital in supporting and stabilizing the spine during even the most mundane activities such as standing and sitting. The common abdominal crunch exercise, often performed on an exercise machine, can be effective in strengthening the abdominal muscles, but the machine’s physical dimensions and cost limit its use to gyms or hospital settings.
Danish researchers,2 looking for a viable alternative, recently compared muscle activation while performing ab crunches on an easy-to-use, inexpensive Thera-Band exercise ball with added elastic resistance and on an isotonic abdominal training machine. Their study demonstrated that the Thera-Band products can produce similar, and often times, better results.
Previous research showed that an exercise ball is useful for stability enhancement, balance assessment, and inducing proprioceptive alteration making it an appropriate exercise for improving joint position, posture and balance, but not for increasing muscle strength. For this study, the researchers elected to add elastic resistance to the exercise ball crunch believing it would provide adequate additional loading and result in an effective muscle strengthening exercise.
A group of 42 untrained adults, 24 women and 18 men, aged 28 to 67 years with various workplace responsibilities, participated in the study. The participants were asked to rate their low-back pain, if any, during the last three months on a 10-point Visual Analog Scale where 0 is “no pain” and 10 is “worst pain imaginable.” All participants performed both ab-crunch exercises — elastic resistance on a Thera-Band exercise ball and isotonic abdominal training machine.
The researchers compared muscle activation of core and thigh muscles during the exercises and hypothesized that they would find no statistically significant EMG differences between the two. EMG activity was measured in 13 muscles during three repetitions; the order of performance of the exercises was randomized.
The study showed that the Thera-Band exercise ball with Thera-Band elastic tubing crunch activated cores muscles more than on the machine, including significantly greater activation of the abdominal muscles by 24 percent.
In addition, the abdominal crunch on an exercise ball with elastic tubing resulted in significantly less activation of the hip flexors by 160 percent. The
abdominal-to-hip flexor activation ratio was also much higher in the exercise ball and elastic tubing exercise, providing yet another benefit over the exercise machine. Abdominal exercises should minimize hip flexor activation to better isolate abdominal muscle activation.
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 exercise ball.”
The researchers 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 or 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 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,” stated Dr. Phil Page, director of clinical education and research for Performance Health. “This allows anyone with access to an exercise ball and elastic tubing to increase their abdominal strength, which may increase the stability of the spine, enhance an individual’s overall physical strength, and decrease the occurrence of lower-back pain.
“We are grateful to the researchers, including Lars Andersen, for their work on this study, just one of countless studies validating the effectiveness of our Thera-Band resistance products,” continued Page. “But it’s particularly gratifying when our products work to together and prove to provide multiple benefits, such as this study does.”
Source: Performance Health, theraband.com
1Warden SJ, Wajswelner H, Bennell KL. Comparison of Abshaper and conventionally performed abdominal exercises using surface electromyography. Med Sci Sports Exerc 1999. November;31(11):1656–64. [PubMed]
2Sundstrup 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.