Research Summary by Brent Brookbush MS, PES, CES, CSCS, ACSM H/FS
Muscle Activation During Four Pilates Core Stability Exercises in Quadruped Position
Bergson C. Queiroz, MSc, Mariana F. Cagliari, PT, César F. Amorim, PhD, Isabel C. Sacco, PhD
Arch Phys Med Rehabil 2010;91:86-92.
Reasons Why the Study was Performed:
This study was designed to compare the activity of trunk and hip stabilizing musculature in 4 variations of Pilates exercises in the quadruped position. Although studies have been done to compare muscle activity in the quadruped position, no studies have specifically tested the role of pelvic position as described in Pilates based exercise. Exercises in the quadruped position is recommended to individuals in both rehabilitation and exercise settings. Dynamic control, strength, and stabilization of the trunk musculature may have an impact on performance of daily activities, sport, and may reduce the occurrence of various orthopedic maladies from low back pain to shoulder impingement. It is hypothesized the different positions of the pelvis used in the 4 variations may have an impact on muscular recruitment and the results of this study could guide the choice of exercise in the rehabilitation process.
The Methodology That Was Employed:
19 healthy subjects (mean age 31yo) with a minimum of 2 years experience and no occurrence of back pain lasting longer than a week were recruited for the study. Surface Electromyographic signals of the iliocostalis, multifidus, gluteus maximus, rectus abdominis, and external and internal oblique muscles were recorded in 4 variations of the quadruped position – retroverted (posterior pelvic tilt) pelvis with flexed trunk; anteverted (anterior pelvic tilt) pelvis with extended trunk; neutral pelvis with inclined trunk; and neutral pelvis with trunk parallel to the ground. Root mean square values of each muscle and exercise in both phases of hip extension and flexion, normalized by the maximal voluntary isometric contraction were recorded.
The results and conclusions of the investigators:
The posterior pelvic tilt position with flexed trunk position increased activity of the external oblique and gluteus maximus muscles. The anterior pelvic tilt with trunk extension significantly increased multifidus (lumbar extensor) muscle activity. The neutral position led to significantly lower activity of all muscles. Rectus abdominis muscle activation did not change in any position. The investigators concluded that the pelvic and trunk positions in the quadruped position exercises change the activation pattern of the multifidus, gluteus maximus, rectus abdominis, and oblique muscles. The lower level of activity rectus abdominis muscle suggests that pelvic stability is maintained in the 4 variations.
A critique of the study with suggestions for further research
The multifidus, internal oblique, and iliocostalis surface electrode placement was questionable. Both the multifidi and internal obliques are deep to superficial musculature that may have confounded the data points. However, if the internal obliques are considered as a second data point for the oblique group, and the multifidi are viewed as an electrode for lumbar extensors the same conclusions may be made from the study. The iliocostalis electrode placement was placed so far lateral to the spine it is doubtful that the iliocostalis was actually recorded in this study, and in this study there is no significant change in electrode readings for the iliocostalis with all 4 positions.
The study has significant practical relevance in regard to cueing and muscle activity. Core exercises are regularly recommended for individuals with low back pain, postural dysfunction, and are often recommended to athletes. The assumption that a strong and stable core will reduce the risk of injury, improve neuromuscular efficiency, and improve force transfer between upper and lower extremities is gaining support as new research becomes available. If this assumption is true, it can only be realized by those individuals who perform core exercise with optimal form; reinforcing the optimal recruitment of core musculature and reducing the propensity to reinforce faulty recruitment patterns caused by postural dysfunction. Noting that the least amount of muscle activity was required to maintain a neutral position may be evidence that this is the most efficient position for articular, muscular, and fascial systems, and reinforces training that will lead to optimal alignment of the lumbar spine and pelvis during movement. The increase in lumbar extensor activity noted during the anterior pelvic tilt position reinforces the idea of poor posture leading to back pain; specifically an individual who maintains an anterior pelvic tilt during activities of daily living is likely to increase lumbar extensor activity, leading to
pattern overload and muscle soreness.
What a Cue Can Do For You?
The posterior pelvic tilt effectively increased oblique and gluteus maximus recruitment, and reduced lumbar extensor recruitment. The gluteus maximus and obliques are often termed phasic (have a propensity toward inhibition, lengthening, and/or weakness), and the lumbar extensors are often termed tonic (have a propensity toward over-activity, shortening, and trigger point development). Cueing that increases the activity of phasic muscle and reduces the activity of tonic musculature is beneficial for those individuals with postural dysfunction. A posterior pelvic tilt is easily taught during a quadruped and may be a way to improve recruitment patterns in those individuals with low back pain, and or an anterior pelvic tilt.
Further research should be done to note the effect of cueing a posterior pelvic tilt on muscle recruitment in other positions, including standing and sitting. More populations including symptomatic individuals should be studied, and long-term follow-up should be done to study the effect of learning this cue on rehabilitation and performance.
© 2011 Brent Brookbush
Questions, comments, and criticisms are welcomed and encouraged