Body Stuff Core Training

: Transversus abdominis and core stability - has the pendulum swung?

Allison GT, Morris SL.

Curtin University, Australia.

In the past decade there has been a focus on isolated transversus abdominis activation and how it contributes to lumbo-pelvic stability. Not only has this rationale influenced the management of chronic low back pain (LBP), it has also been included in exercises for many other pathologies of the lower and upper limb and also for prophylaxis in pain free subjects.

PMID: 18603579 [PubMed - as supplied by publisher]

: Development and reliability of two core stability field tests.

Cowley PM, Swensen TC.

Department of Exercise and Sport Sciences, Ithaca College, Ithaca, New York, USA. pmcowley@syr.edu

Because of the recognized link between core stability and back and lower extremity injury in sport, additional field tests that assess the strength and power component of core stability are needed to identify athletes at risk of such injury. To that end, we developed and tested the reliability of the front and side abdominal power tests (FAPT and SAPT), which were adapted from plyometric medicine ball exercises. The FAPT and SAPT were performed by explosively contracting the core musculature using the arms as a lever to project a medicine ball. Twenty-four untrained young women (aged 20.9 +/- 1.1 year) completed three trials each of the FAPT and SAPT on separate nonconsecutive days. The average distance the medicine ball was projected on each day was recorded; power was inferred from this measure. There was an approximately 3% increase in the mean distance between the testing sessions for the FAPT and SAPT; this was not significant and indicates there was no learning effect in the measurement protocol. Heteroscedasticity was present in the SAPT data but not the FAPT data. For the FAPT, the intraclass correlation coefficient was 0.95, standard error of measurement was 24 cm, and random error using the limits of agreement method was 67.5 cm. For the SAPT, the intraclass correlation coefficient was 0.93, mean coefficient of variation was 9.8%, and the limits of agreement ratio was 36.8%. The FAPT and SAPT displayed excellent test-retest reliability, as well as acceptable measurement error. These findings suggest the FAPT and SAPT are reliable tests and may be used to assess the power component of core stability in young women.

PMID: 18550982 [PubMed - in process]

3: J Orthop Sports Phys Ther. 2008 May;38(5):228-37. Epub 2007 Dec 14.

Feedforward responses of transversus abdominis are directionally specific and act asymmetrically: implications for core stability theories.

Allison GT, Morris SL, Lay B.

School of Physiotherapy, Curtin University, Perth, Western Australia, Australia. G.Allison@Curtin.edu.au

STUDY DESIGN: Experimental laboratory study supplemented with a repeated case study. OBJECTIVE: To examine bilateral muscle activity of the deep abdominals in response to rapid arm raising, specifically to examine the laterality and directional specificity of feedforward responses of the transversus abdominis (TrA). BACKGROUND: Based on the feedforward responses of trunk muscles during rapid arm movements, authors have concluded that the deep trunk muscles have different control mechanisms compared to the more superficial muscles. It has been proposed that deep trunk muscles such as TrA contribute substantially to the stability of the lumbar spine and that this is achieved through simultaneous bilateral feedforward activation. These inferences are based on unilateral fine-wire electromyographic (EMG) data and there are limited investigations of bilateral responses of the TrA during unilateral arm raising. METHODS AND MEASURES: Bilateral fine-wire and surface EMG data from the anterior deltoid, TrA, obliquus internus (OI), obliquus externus, biceps femoris, erector spinae, and rectus abdominis during repeated arm raises were recorded at 2 kHz. EMG signal linear envelopes were synchronized to the onset of the anterior deltoid. A feedforward window was defined as the period up to 50 ms after the onset of the anterior deltoid, and paired onsets for bilateral muscles were plotted for both left and right arm movements. RESULTS: Trunk muscles from the group data demonstrated differences between sides (laterality), which were systematically altered when alternate arms were raised (directional specificity). This was clearly evident for the TrA but less obvious for the erector spinae. The ipsilateral biceps femoris and obliquus externus, and contralateral OI and TrA, were activated earlier than the alternate side for both right and left arm movements. This was a consistent pattern over a 7-year period for the case study. Data for the rectus abdominis derived from the case study demonstrated little laterality or directionally specific response. CONCLUSION: This is the first study to show that the feedforward activity of the TrA is specific to the direction of arm movement and not bilaterally symmetrical. The asymmetry of TrA activity during arm raising suggests that the interpretation of the role of TrA as a bilateral stabilizer during anticipatory postural adjustments needs to be revised. Future research needs to examine muscle synergies associated with the asymmetrical function of the TrA and the underlying mechanism associated with low-load stability training. LEVEL OF EVIDENCE: Therapy, level 5.

Publication Types:

Research Support, Non-U.S. Gov't

PMID: 18448877 [PubMed - in process]

4: Curr Sports Med Rep. 2008 Feb;7(1):39-44.