Spatial Distribution And Activity Of The Erector Spinae Muscles In Cyclists With Recent History Of Low Back Pain

Overactivation of erector spinae (ES) muscles has been identified as one of the potential major causes of low back pain (LBP) in cyclists. However, less is known about cyclists’ lumbar region activation patterns. Accordingly, in this cross-sectional study, we compared the activation and spatial distribution of ES muscles in cyclists with and without a recent history of LBP. Based on Oswestry Disability Index (ODI-I), participants were assigned to either an LBP or to an asymptomatic group (CG). They performed an incremental cycling test characterized by 4 bouts of 3 min at 70, 80, 90, and 100% of their FTP. Concurrently, the ES activity was recorded bilaterally through HDsEMG and synchronized at source with an electro-goniometer to characterize the pedal strokes. The average normalized RMS amplitude, the entropy, and the y-axis barycenter (y-bar) of the RMS maps were extracted. RESULTS: Statistical analyses revealed differences in RMS amplitude between 70-100% (+19%, p=.010), 80-100% FTP (+21%, p=.004) in the LBP group, and between LBP and CG at 100% FTP (9.6%, p=.049). Similarly, entropy differed significantly between 70-100% FTP (-8.4%, p=.002) and 80-100% FTP (-8.5%, p=.002) in the LBP only. Our results suggest that greater magnitude and reduced homogeneity of ES activity during an incremental cycling test may reflect an inefficient recruitment strategy of ES in cyclists with a recent history of LBP

<i>In vivo</i>, morphological and clinical effects of a desensitizing agent

Objectives: This study evaluated the in vivo effectiveness of Universal Dentin Sealant (UDS), a new resin-based material, as dentinal desensitizing agent on dentin morphology and clinical symptoms. Materials and methods: Thirty premolars, exhibiting non-carious cervical lesions, and scheduled for extraction for periodontal reasons, were selected for the ultrastructural study. These samples were randomly divided into three groups (n = 10): group 1, brushing with UDS; group 2, brushing with Flor-Opal® Varnish (FOV); and group 3, untreated control. After 7 days, teeth were extracted and samples processed for SEM and TEM comparative observations. The in vivo study was carried out on 90 teeth with non-carious cervical lesions. The assessment method used to quantify sensitivity was the cold air syringe, recorded using the visual analogue scale (VAS), prior to treatment (baseline) and after 7 days. Teeth were randomly assigned to three groups (n = 30): group 1, UDS; group 2, FOV; and group 3, untreated control. Analysis was based on the Student's t-test for paired data, with a 5% significance level. Results: The ultrastructure of UDS/dentin interface was characterized by a superficial porous layer of spherical clusters immersed in a loose matrix that fully covered the superficial dentin. A poorly crystalline aspect of peritubular and intertubular fibrils with sealed tubular orifices was observed. The FOV/dentin interface showed an irregular layer of precipitates with partial exposure of the dentin surface. The presence of intratubular crystals partially occluding the tubular orifices and densely mineralized peritubular fibrils was also noted. Untreated control dentin showed a superficial thin layer of smear with porous plugs within the tubular orifices. Comparing clinical results, the statistical analysis revealed significant differences between both the tested materials (p &lt; 0.001) and the control group (p &gt; 0.05) in term of the periods of examination. Conclusions: The application of UDS resulted in effective and stable dentinal tubular occlusion, leading to a statistically significant decrease in clinical discomfort of particular relevance to cases of dentinal hypersensitivity