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Asymmetry of psoas and quadratus lumborum unrelated to injury

PainSci » bibliography » Hides et al 2010
updated
Tags: back pain, strain, structuralism, pain problems, spine, anatomy, spine pain, injury, muscle, biomechanical vulnerability, risks, etiology, pro, .content-type

Four pages on PainSci cite Hides 2010: 1. Does Posture Matter? 2. The Complete Guide to Low Back Pain 3. The Complete Guide to Muscle Strains 4. Your Back Is Not Out of Alignment 

PainSci commentary on Hides 2010: ?This page is one of thousands in the PainScience.com bibliography. It is not a general article: it is focused on a single scientific paper, and it may provide only just enough context for the summary to make sense. Links to other papers and more general information are provided wherever possible.

Researchers used MRI to measure the size of kicking muscles in 54 Australian Football League players — very serious athletes, these guys, playing a very rough sport — and found that “asymmetry of the psoas and the quadratus lumborum muscles exists in elite AFL players.” Such asymmetries are widely believed by therapists to be clinically significant. Manual therapists, if they suspected such a distinct asymmetry in muscle mass, would enthusiastically and almost unanimously embrace this significant lack of “balance” as a major risk factor for injury, and a likely suspect in whatever injury or pain problem a person might happen to be experiencing.

However, the researchers also found that “asymmetry in muscle size was not related to number of injuries.”

~ Paul Ingraham

original abstract †Abstracts here may not perfectly match originals, for a variety of technical and practical reasons. Some abstacts are truncated for my purposes here, if they are particularly long-winded and unhelpful. I occasionally add clarifying notes. And I make some minor corrections.

OBJECTIVE: In this study, asymmetry relative to the preferred kicking leg was determined if it exists for the psoas and quadratus lumborum muscles among elite Australian Football League (AFL) players.

DESIGN: AFL players were assessed at three time points from 2005 to 2007 (start of preseason, end of season and end of preseason training). MRI was used to determine the cross-sectional areas (CSAs) of the psoas and quadratus lumborum muscles at the L4-L5 vertebral level (psoas) and the L3-L4 vertebral level (quadratus lumborum).

SETTING: MRI was performed in a hospital setting.

PARTICIPANTS: 54 professional AFL players were eligible to participate in this study. The number of subjects at each of the three time points was 36 for time 1 (T1 Nov 2005), 31 for time 2 (T2 Aug 2006) and 43 for time 3 (T3 Feb Mar 2007).

RISK FACTORS: The repeated measures factor in the analyses was "asymmetry", defined as "ipsilateral" or "contralateral" to preferred kicking leg. Number of injuries (coded as 0, 1, 2 or more) was also included as a risk factor.

MAIN OUTCOME MEASUREMENTS: The dependent variables were the CSAs of the psoas and quadratus lumborum muscles.

RESULTS: At all three time points, the CSA of the psoas muscle was significantly greater ipsilateral to the kicking leg, while the CSA of the quadratus lumborum muscle was significantly greater on the side contralateral to the kicking leg. Asymmetry in muscle size was not related to number of injuries.

CONCLUSIONS: Asymmetry of the psoas and the quadratus lumborum muscles exists in elite AFL players.

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