The importance of the deepest abdominal muscle, the transversus abdominus (TrA) as a spinal stabilizer has been well established, both in the literature and in clinical practice. In patients with low back pain we often see delayed onset of muscle activity of the TrA with movement of the limbs in all directions, and this change in TrA control occurs irrespective of the specific pathology1,2. Thus, retraining the TrA to increase spinal stabilization is a widely accepted concept in physiotherapy of lumbo-pelvic pain3,4.
Pilates exercises involve activation of the deep, local stabilizing muscles of the trunk via an “imprint” action. Though perhaps cued differently, this action is basically the same as the “abdominal drawing in maneuver” proven through scientific research to activate the TrA in spinal stabilization training. It follows then, that Pilates exercises would be effective in stabilizing the lumbar spine and thus in rehabilitation of patients with lumbo-pelvic pain via improving the neuromuscular control of these deep muscles with this drawing in, or “imprint” action. But is there evidence to support this claim? Does the “imprint” action in Pilates exercises activate the deep abdominal muscles?
A 2008 study by Endelmen and Critchely5 provided the first evidence that specific Pilates exercises do indeed activate the deeper abdominal muscles. The researchers used ultrasound imaging to measure the thickness change of the transversus abdominis (TrA) and Obliquus Internus (OI) when subjects performed a representative set of classical Pilates exercises: imprint, hundreds, roll-up, leg circle on the mat, and hundreds on the Reformer. The researchers found a significant increase in thickness, representing muscle activity, in both TrA and OI during all correctly performed Pilates exercises compared with resting supine. Another interesting finding was that TrA thickness during Reformer hundreds was greater than when performed on a mat, demonstrating that use of the Reformer can result in greater TrA activation in some exercises.
A 2005 study by Herrington and Davies6 provided evidence that Pilates trained subjects could contract the TrA and maintain better lumbo-pelvic control than those who perform regular abdominal curl exercises or no abdominal muscle exercises. The researchers used a pressure biofeedback unit (PBU) to assess performance of the TrA muscle during an abdominal hollowing activity (TrA isolation test) and under limb load (lumbo-pelvic stability test) on 3 groups of asymptomatic females: 12 were Pilates trained, 12 did abdominal curl exercises regularly, and the remaining 12 were the non-training control group. Of the 17 subjects who passed the TrA isolation test 10 were from the Pilates trained group (83% passing rate), 4 were from the abdominal curl group (33%) and 3 were from the control group (25%). Only 5 of the 36 subjects (14%) passed the lumbo-pelvic stability test, and they were all from the Pilates trained group! All of the subjects from the abdominal curl and control groups failed.
These two studies provide evidence that Pilates exercises are effective in recruiting the deep spinal stabilizers in asymptomatic individuals.
Samantha Wood is a licensed physical therapist since 1997, PMA Certified Pilates Instructor, Yoga Alliance certified teacher, and an international educator and Associate Faculty member for BASI Pilates®. Read more about Samantha.
1Hodges P.W. and C.A. Richardson. 1996. Inefficient muscular stabilization of the lumbar spine associated with low back pain. A motor control evaluation of transversus abdominis. Spine 21(22): 2640-50.
2Hodges P.W. and C.A. Richardson. 1998. Delayed postural contraction of transversus abdominis in low back pain associated with movement of the lower limb. J spinal Disord 11(1):46-56.
3Comerford M.J. and S.L. Mottram. 2001.Functional stability re-training: principles and strategies for managing mechanical dysfunction. Man Ther 6(1):3-14.
4Hodges P.W., and C.A. Richardson. 1999. Transversus abdominis and the superficial abdominal muscles are controlled independently in a postural task. Neuroscience Letters 265(2): 91-94
5Endelmen I and DJ Critchley. 2008. Transversus Abdominis and Obliquus Internus Activity During Pilates Exercises: Measurement with Ultrasound Scanning. Archives of Physical Medicine and
Rehabilitation 89: 2205-12.
6 Herrington L. and R. Davies. 2005. The influence of Pilates training on the ability to contract the Transversus Abdominis muscle in asymptomatic individuals. Journal of Bodywork and Movement Therapies 9(1): 52-57.