SynthesisEuropean spine journal : official publication of the European Spine Society, the European Spinal Deformity Society, and the European Section of the Cervical Spine Research Society2022
The flexion relaxation phenomenon in nonspecific chronic low back pain: prevalence, reproducibility and flexion-extension ratios. A systematic review and meta-analysis.
Synthesis in European spine journal : official publication of the European Spine Society, the European Spinal Deformity Society, and the European Section of the Cervical Spine Research Society, 2022. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 24 papers, 3 of them syntheses that pooled it.
What it found
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
24 citing papers in PubMed, 3 syntheses or guidelines pooled it.
- The Effects of Lumbar Delayed Onset Muscle Soreness on Clinical, Biomechanical and Neuromuscular Outcomes: A Systematic Review and Meta-Analysis.European journal of pain (London, England) · 2026Pooled it
- Exercise Therapy Versus Manual Therapy for the Management of Pain Intensity, Disability, and Physical Function in People With Chronic Low Back Pain: A Systematic Review With Meta-Analysis and Meta-Regression.European journal of pain (London, England) · 2025Pooled it
- Changes of trunk muscle stiffness in individuals with low back pain: a systematic review with meta-analysis.BMC musculoskeletal disorders · 2024Pooled it
- Associations between trunk mobility, pain, and quality of life in individuals with chronic low back pain treated with different therapeutic protocols: Potential clinical parameters.Journal of back and musculoskeletal rehabilitation · 2026Trial
- Effect of Acupuncture for Chronic Nonspecific Low Back Pain: Study Protocol for a Randomized Double-Blind, Placebo-Controlled Trial.JMIR research protocols · 2026Article
- A new logistic regression model for the detection of chronic low back pain, based on a case-control study in the Spanish population.Asian spine journal · 2026Article
- From mechanotransduction to manual therapy: advances in piezo/TRP channels and lumbar degeneration.Frontiers in physiology · 2026Review
- Effects of Pilates Matwork Core Exercises on Functioning in Middle-Aged Adult Women with Chronic Nonspecific Low Back Pain Through Flexion Relaxation Phenomenon Analysis: A Pilot RCT.Journal of functional morphology and kinesiology · 2025Article
- The importance of the posterior osteoligamentous complex of the lumbar spine: dogma changing biomechanical insights.European spine journal : official publication of the European Spine Society, the European Spinal Deformity Society, and the European Section of the Cervical Spine Research Society · 2025Article
- Subgrouping People With Acute Low Back Pain Based on Psychological, Sensory, and Motor Characteristics: A Cross-Sectional Study.European journal of pain (London, England) · 2025Article
- A review and empirical findings of fasciae and muscle interactions in low back pain.Frontiers in physiology · 2025Article
- Article
- Biomechanical effects of soft and rigid passive back occupational exoskeletons during load-carrying and static trunk bending tasks in the aeronautics industry.Wearable technologies · 2025Review
- Article
- Differential Back Muscle Flexion-Relaxation Phenomenon in Constrained versus Unconstrained Leg Postures.Bioengineering (Basel, Switzerland) · 2024Article
- Understanding the flexion-relaxation phenomenon in non-specific chronic low back pain patients throught immersive virtual reality feedback approach.Scientific reports · 2024Article
- Quality of Life in Patients with Chronic Low Back Pain and Differences by Sex: A Longitudinal Study.Journal of personalized medicine · 2024Article
- Central mechanisms of muscle tone regulation: implications for pain and performance.Frontiers in neuroscience · 2024Article
- Age-dependent flexion relaxation phenomenon in chronic low back pain patients.Frontiers in bioengineering and biotechnology · 2024Article
- Exploring knowledge, perception, and use of surface electromyography in physiotherapy post graduate trainees in Italy: a single center preliminary survey.Frontiers in rehabilitation sciences · 2024Article
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
6 authors.
Funding
No grant is acknowledged in the PubMed record.
Abstract
purposeThe flexion relaxation phenomenon (FRP) is characterized by the reduction of paraspinal muscle activity at maximum trunk flexion. The FRP is reported to be altered (persistence of spinal muscle activity) in nonspecific chronic low back pain (NSCLBP) and is considered a promising biomarker. The aim of this systematic review was to synthetize current knowledge on FRP in the NSCLBP population regarding prevalence, the reliability of FRP measurement using surface electromyography (sEMG), the average value, and variation of the relaxation ratios (RR).
methodsFive databases were searched (PubMed, EMBASE, Web of Sciences, Cochrane Library, Pedro). A qualitative analysis was done for all included studies and meta-analysis studying prevalence, mean value of flexion relaxation ratio (FRR) and extension relaxation ratio (ERR), and difference between asymptomatic and NSCLBP FRR.
resultsTwenty-seven studies were included for qualitative analysis and 21 studies for meta-analysis. The prevalence of the altered FRP was 55% (95%CI [32-79%]) in the NSCLBP population. The studies on reliability reported good within-session and between-session reproducibility. In the NSLBP population, the mean FRR was 2.96 (95%CI [2.02; 3.90]) and the mean ERR was 4.07 (95%CI [2.08; 6.07]). The difference between asymptomatic and NSCLBP FRR was - 1.19 (95%CI [- 1.92, - 0.45]). In all meta-analysis, the I
conclusionAn altered FRP is frequently found in NSCLBP population using sEMG and the test has a good reproducibility. The difference between asymptomatic and NSCLBP FRR was significant. Nevertheless, considering the high heterogeneity observed, additional research is required to confirm the value of RR.
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Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.