Morphological and Compositional Features of Lumbar Multifidus in Athletes with Chronic Non-specific Low Back Pain: A Systematic Review and Meta-Analysis.
Wai Keung Wong, Allan C L Fu, Sharon M H Tsang
Athletes with chronic low back pain did not differ from pain-free peers in lumbar multifidus size, thickness, or fatty content.
One study linked smaller multifidus to more lower-limb injuries; another linked fatty infiltration to lower return-to-sport odds.
Key findings
1Pooled data showed no significant difference in lumbar multifidus cross-sectional area, muscle thickness, or echo intensity (a proxy for fatty infiltration) between athletes with chronic non-specific low back pain and pain-free athletes at L4/5 or L5/S1.
2In one high-quality study, athletes with smaller multifidus cross-sectional area had 25% higher odds of lower-limb injury in the pre-season and 43% higher odds during the competitive season, both classified as small effects.
3In one high-quality study, even mild fatty infiltration of the multifidus (Goutallier grade 1) was associated with 79% lower odds of returning to sport, and more severe infiltration (grade >2) with 90% lower odds.
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What it does not show
GRADE rated the overall evidence as low to very low; the null result may reflect weak methodology rather than a true absence of difference. Five of 18 studies (27.8%) had fewer than 30 participants, limiting statistical power. Only L4/5 and L5/S1 levels were measured; no data span the full lumbar spine. Definitions of chronic low back pain ranged from 3 months to 3 years, mixing early and late structural changes. None of the included studies normalised muscle measurements for body size, height, or BMI, which the authors note likely obscures true differences. Sports were diverse (rowing, ice hockey, judo, running, dancing, basketball, etc.) and pooled without sport-specific subgroup analysis. Only 28% of included studies documented training load, volume, or intensity, making it impossible to separate pain-related atrophy from training-induced hypertrophy. Three studies did not blind the therapist performing ultrasound scans, introducing measurement bias. Ultrasound acquisition parameters (frequency, gain, depth) varied across studies, reducing comparability.
Declared interests
The authors declare no conflict of interest and state that no external funding was received for this study.
The easy way to misread this
Do not read the null meta-analysis as proof that multifidus morphology is irrelevant in athletes with low back pain. The pooled result rests on low-certainty evidence from heterogeneous observational studies that did not control for body size or training load, and the individual studies were split (eight found differences, five did not). The two significant secondary findings (injury risk, return-to-sport) each come from a single study and should not be treated as established effects.
Summarised by AI from the full paper, without a clinician reviewing it. Check it against the source before it changes what you do. Read it on PubMed →