The flexion relaxation phenomenon in nonspecific chronic low back pain: prevalence, reproducibility and flexion–extension ratios. A systematic review and meta-analysis

Purpose: The 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). Methods: Five 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

A tool to improve functional outcome assessment of a multimodal program for patients with chronic low back pain: A study on walk tests (at comfortable and fast speed)

International audienceBACKGROUND:Tools for functional assessment of chronic low back pain (LBP) are lacking.OBJECTIVE:To determine the correlations and the responsiveness of the 400 m comfortable walk test (400 mCWT) and the 200 m fast-walk test (200 mFWT) in the functional assessment of a multimodal program.METHODS:One hundred and twenty-seven participants (68 females) with LBP and with or without radicular pain completed a Quebec back pain scale, a Sorensen test, a Shirado test, a 400 mCWT and a 200 mFWT, at baseline and at the end of the program.RESULTS:No significant side effect was reported during walk tests. Walking speed was significantly increased after the program (0.18 ± 0.15 m.s-1 for the 400 mCWT and 0.17 ± 0.17 m.s-1 for the 200 mFWT). Clinical parameters were also significantly improved (82.02 ± 83.1 seconds for the Shirado, 92.1 ± 100.1 seconds for the Sorensen, -14.0 ± 12.9 for the Quebec scale). A significant relationship was found between the increase in walking speed for the two walk tests and the improvement of the Quebec scale. The gait speed improvement was close to the minimal clinically important change (95% confidence interval: 0.14-0.22) determined from the Quebec Scale threshold (minimum detectable change).CONCLUSIONS:Both 400 mCWT and 200 mFWT are correlated with functional parameters and are responsive for the functional assessment of LBP

Sensitivity and specificity of the flexion and extension relaxation ratios to identify altered paraspinal muscles’ flexion relaxation phenomenon in nonspecific chronic low back pain patients

Background: Among the main methods used to identify an altered flexion relaxation phenomenon (FRP) in nonspecific chronic low back pain (NSCLBP), it has been previously demonstrated that flexion relaxation ratio (FRR) and extension relaxation ratio (ERR) are more objective than the visual reference method. Objective: To determine the sensitivity and specificity of the different methods used to calculate the ratios in terms of their ability to identify an altered FRP in NSCLBP. Methods: Forty-four NSCLBP patients performed a standing maximal trunk flexion task. Surface electromyography (sEMG) was recorded along the erector spinae longissimus (ESL) and multifidus (MF) muscles. Altered FRP based on sEMG was visually identified by three experts (current standard). Six FRR methods and five ERR methods were used both for the ESL and MF muscles. ROC curves (with areas under the curve (AUC) and sensitivity/specificity) were generated for each ratio. Results: All methods used to calculate these ratios had an AUC higher than 0.9, excellent sensitivity (&gt;90 %), and good specificity (80-100 %) for both ESL and MF muscles. Conclusion: Both FRP ratios (FRR and ERR) for MF and ESL muscles, appear to be an objective, sensitive and specific method for identifying altered FRP in NSCLBP patients.</p

Number of raised steps: A tool to assess brief and intense effort involving anaerobic metabolism

International audienceBackground: Although the initial anaerobic component of exercise adaptation is unavoidable, no specific functional test is available for use in routine non-sporting practice to evaluate it.Objective: To assess the bioenergetic and biomechanical properties of the Short and Fast Step Test (SFST), which consists of walking up and down a step as many times as possible in 1 minute and to analyse its ability to explore the initial anaerobic component of effort in comparison to a reference self-paced step test.Methods: Overall, 31 healthy subjects (19 women; mean [SD] age, 32.4 [10.2] years) completed a testretest of a self-paced step test and the SFST, with pre- and post-test measurement of blood lactate concentration and continuous recording of VO2 and modelling of excess post-exercise oxygen consumption (EPOC), near-infrared spectroscopy (NIRS) of the quadriceps and mechanical power (estimated by the number of steps climbed and 3-D motion analysis).Results: Both step tests were well tolerated. The reliability of the bioenergetics parameters, number of raised steps, mechanical power and NIRS tissue saturation index was good. Indirect mechanical power (estimated from number of steps) was correlated with direct power (computed from the centre of mass). Lactate accumulation was significantly increased during exercise with only the SFST (mean [SD] increase, 3.86 [3.26] mmol L 1 from resting values, P < 0.05). EPOC was higher with the SFST than the self-paced step test (P < 0.05). Only the SFST showed significant correlations between number of steps climbed and EPOC (r = 0.84; P < 0.001) and decreased tissue saturation index (NIRS) and EPOC area (r = -0.39; P < 0.05).Conclusions: SFST is feasible, well tolerated, reliable and responsive to explore a brief exercise involving anaerobic metabolism at submaximal intensity. The number of steps taken in 1 minute seems a suitable parameter for practical application