Muscle Imbalance Results in an Anterior Pelvic Tilt During Hip Extension

Research Review: Muscle Imbalance Results in an Anterior Pelvic Tilt During Hip Extension

By Stefanie DiCarrado DPT, PT, NASM CPT & CES

Edited by Brent Brookbush DPT, PT, MS, PES, CES, CSCS, ACSM H/FS

Original Citation: Tateuchi, H., Taniguchi, M., Mori, N., Ichihashi, N. Balance of hip and trunk muscle activity is associated with increased anterior pelvic tilt during prone hip extension (2013) Journal of Electromyography and Kinesiology 22 (3). 391-397 - ARTICLE

Note the anterior pelvic tilt occurring with hip extension

Why is this relevant?: Prone hip extension is often used by personal trainers and physical therapists to strengthen hip extensors. This study provides information pertaining to possible muscle imbalances that create compensatory movement during prone hip extension indicating a need to correct these imbalances prior to performance.

Study Summary

Caption: Note the lack of an anterior pelvic tilt in prone hip extension

Note the lack of an anterior pelvic tilt in prone hip extension - http://www.hanslindgren.com/blog/janda-s-pelvic-cross-syndrome/

Review & Commentary:

This study aimed to close a gap in the literature by examining the timing of muscle activation in those individuals with anterior pelvic tilt (APT) by examining kinematic movement of the pelvis during prone hip extension in an otherwise healthy population. Previous research recorded muscle onset timing but none investigated the relation to pelvic motion.

Researchers employed a strong and standardized methodology with clearly defined EMG electrode placements and kinematic reflective marker placements. Hip extension data was recorded as each subject moved from 30° of hip flexion to 10° of hip extension, which was marked by a string the subject would touch with the back of their leg at 10° of extension. Subjects maintained the 10 degrees of hip extension for 3 seconds and performed 5 trials. The authors recorded maximum voluntary isometric contractions for Gmax , ST , ES , TFL , and RF  in order to calculate a normalized muscle amplitude displayed as a % which allowed for the muscle to muscle comparison. A double blinded investigation determined the muscle onset timing to ensure validity of the data. Researchers calculated the relative difference between the activity onset of each muscle and the prime mover. Interestingly enough, the ST  was considered the prime mover for the majority of the movement which the authors explain is due to the increased moment arm of the ST  when the hip begins in a flexed position. As the hip reaches neutral and begins to extend, the moment arm of the Gmax  is greatest and that of the ST  decreases.

Since in this study, subjects began in hip flexion, the ST  was used as the basis of comparison for relative onset activity. Kinematic analysis consisted of a six camera system that allowed for calculation of 3D angular displacements of the pelvis to capture movement in all anatomical planes.

Authors disclose the following limitations: lack of EMG data on all synergists and antagonists of hip extension; EMG data collected from only superficial LM  rather than deep LM , and lack of intersegmental lumbar movement analysis. However, these limitations do not invalidate the data collected and imply further research is needed. Future research should employ a combination of surface EMG electrodes for superficial muscles and needle electrodes for deeper musculature. Further investigation of lumbar segmental movement will provide information on lumbar extension moments that may accompany an APT due to overactivity in the ES .

Authors examined prone hip extension and noted that standing hip extension alone, or hip extension during functional tasks (such as walking) may or may not be susceptible to the same muscle imbalances. Further research is needed to investigate muscle activity and onset during more functional movement patterns, as well as, in a population experiencing low back pain and/or with identified lumbo-pelvic hip dysfunction to achieve results that may be generalized to various activities and populations.

Previous research by Richardson & Hodges demonstrated muscle onset latency may lead to, rather than result from, pain and movement dysfunction . This study examines individuals with pain free lumbopelvic hip complex dysfunction that displayed muscle timing imbalances. It would be interesting for these authors to perform a longitudinal study with consistent follow ups to investigate the correlation between the imbalances found here and future development of lumbo pelvic hip pain.

Why is this study important?

This study is important because it provides quantitative data depicting the correlation between lumbo-pelvic hip complex muscle imbalances and compensatory pelvic motion in an otherwise healthy population. In this study, an APT is associated with increased activity in the TFL  relative to that of the Gmax /ST . This may indicate that overactivity of the TFL may alter reciprocal inhibition, decreasing activity of the prime mover, resulting in compensatory anterior rotation of the pelvis. This is further supported by data depicting decreased activity in the Gmax  when compared to the ST , and a significant correlations between decreased Gmax activity and increased ipsilateral ES  activity (ES contributing to an APT via lumbar extension).

Ipsilateral LM  onset prior to contralateral ES  and then bilateral ES  & LM  EMG activity occurring 100 ms prior to movement to 50 ms after movement indicates a feedforward anticipatory mechanism thought to pre-stabilize the lumbar spine prior to movement. These findings support previous research by Richardon & Hodges (1997) that demonstrate anticipatory firing of the LM  (& TVA ) prior to UE movement. Delayed onset of bilateral LM  and contralateral ES  as compared to ST  onset significantly related to increased APT indicate a possible need for TVA activation prior to prone hip extension to assist in lumbar stability.

How does this affect practice?

Proper implementation of an exercise program is crucial to prevent and recover from injury. Understanding the implication of muscle imbalances may assist the human movement professional in proper sequencing of exercises, i.e. overactivity of an antagonist resulting in inhibition of a prime mover implying release of an antogonist should precede muscle activation techniques. In the case of prone hip extension, one must explore the need to inhibit hip flexors such as the TFL  prior to activation of the Gmax in an exercise like prone hip extension. Additionally, previous research by Oh et al, 2007 found TVA activation  as an effective means of reducing an APT during prone hip extension.

How does it relate to Brookbush Institute Content?

This study supports the predicted model of muscle activity discussed in the Brookbush Institute's predictive model of Lumbo Pelvic Hip Complex Dysfunction. Further, the changes in activity of both agonists and antagonists, as well as, the alterations in muscle timing, support the Brookbush Institute Integrated Movement Prep & Rehabilitation templates, a systematic approach to treatment that includes interventions for decreasing over-activity (release, lengthen, mobilize ), increasing muscle activity and firing rate (activation, reactive activation ) and interventions (integration techniques ) to reinforce optimal neuromuscular control during functional tasks. The following videos depict a sample program (in order) based on the findings of this study, using this systematic approach.

TFL SA Static Release

Kneeling Hip Flexor Static Stretch

Gluteus Maximus Isolated Activation

TVA and Gluteus Maximus Activation and Progressions

Gluteus Maximus Reactive Activation Progressions

Posterior Oblique (Squat to Row)

© 2014 Brent Brookbush

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