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The flexion-relaxation phenomenon (FRP) refers to the deactivation of back muscles during deep forward trunk bending. This study examined the effects of back muscle strength, individual flexibility, and trunk angle on FRP in the back muscles. Forty male participants were classified into four groups according to toe-touch flexibility and back muscle strength. Lumbar erector spinae (LES) activity and the lumbosacral angle (LSA) were measured at incremental trunk flexion angles (0°–90°, with increments of 15°) to analyze FRP. Results indicated significant effects of back muscle strength, flexibility, and trunk angle on LES activity (all p < 0.001). Flexibility (p < 0.05) and trunk angle (p < 0.001) also influenced LSA. Additionally, an interaction between flexibility and trunk angle impacted LES activation (p < 0.001). Flexibility mainly determined FRP onset, while back muscle strength influenced efforts during moderate trunk flexion (30°–60°). These findings indicate that differences in lower back load among individuals with varying back muscle strengths become apparent even at relatively small trunk flexion angles (approximately 30°). When prolonged static trunk flexion in workplace settings places considerable strain on the lower back, we recommend utilizing toe-touch flexibility and back muscle strength assessments as practical screening tools for identifying early and subtle indicators of the FRP in workers. [ABSTRACT FROM AUTHOR]

Background: The influences of age and sex on properties of lumbar erector spinae have not been previously studied. Changes in the performance of lumbar erector spinae properties associated with age represent a valuable indicator of risk for lower-back-related disease.Objective: To investigate the lumbar erector spinae properties with regard to age and sex to provide a reference dataset.Methods: We measured muscle tone and stiffness of the lumbar erector spinae (at the L3–4 level) in healthy men and women (50 young people, aged 20–30 years; 50 middle-aged people, aged 40–50 years; and 50 elderly people, aged 65–75 years) using a MyotonPRO device.Results: In general, there are significant differences in muscle tone and stiffness among young, middle-aged, and elderly participants, and there were significant differences in muscle tone and stiffness between men and women, and there was no interaction between age and sex. The muscle tone and stiffness of the elderly participants were significantly higher than those of the middle-aged and young participants (P < 0.01), and the muscle tone and stiffness of the middle-aged participants were significantly higher than those of the young participants (P < 0.01). In addition, the muscle tone and stiffness of men participants were significantly higher than that of women participants (P < 0.01).Conclusion: Our results indicate that muscle tone and stiffness of the lumbar erector spinae increase with age. The muscle tone and stiffness of the lumbar erector spinae in men are significantly higher than in women. The present study highlights the importance of considering age and sex differences when assessing muscle characteristics of healthy people or patients.

Background: The influences of age and sex on properties of lumbar erector spinae have not been previously studied. Changes in the performance of lumbar erector spinae properties associated with age represent a valuable indicator of risk for lower-back-related disease. Objective: To investigate the lumbar erector spinae properties with regard to age and sex to provide a reference dataset. Methods: We measured muscle tone and stiffness of the lumbar erector spinae (at the L3–4 level) in healthy men and women (50 young people, aged 20–30 years; 50 middle-aged people, aged 40–50 years; and 50 elderly people, aged 65–75 years) using a MyotonPRO device. Results: In general, there are significant differences in muscle tone and stiffness among young, middle-aged, and elderly participants, and there were significant differences in muscle tone and stiffness between men and women, and there was no interaction between age and sex. The muscle tone and stiffness of the elderly participants were significantly higher than those of the middle-aged and young participants (P < 0.01), and the muscle tone and stiffness of the middle-aged participants were significantly higher than those of the young participants (P < 0.01). In addition, the muscle tone and stiffness of men participants were significantly higher than that of women participants (P < 0.01). Conclusion: Our results indicate that muscle tone and stiffness of the lumbar erector spinae increase with age. The muscle tone and stiffness of the lumbar erector spinae in men are significantly higher than in women. The present study highlights the importance of considering age and sex differences when assessing muscle characteristics of healthy people or patients. [ABSTRACT FROM AUTHOR]

The management of refractory acute medical pain can be challenging, especially if severe and decompensated systemic pathologies contraindicate neuraxial techniques and deep peripheral blocks. In this case report, we propose a continuous ultrasound-guided lumbar erector spinae plane block (ESPB) for multimodal analgesia of thigh cellulitis. The patient was an 80-year-old male, admitted to the intensive care unit due to septic shock originating from cellulitis of the right lower limb, associated with multiorgan dysfunction. To address refractory pain in the thigh, an ultrasound-guided lumbar ESPB at L3 was performed, with the placement of a perineural catheter and administration of 30 mL of 0.5% ropivacaine, followed by 30 mL boluses of 0.375% ropivacaine every six hours with progressive weaning. The patient maintained controlled pain without the need for rescue analgesia. Continuous ultrasound-guided lumbar ESPB is an effective and safe alternative for thigh analgesia in patients with refractory acute medical pain and systemic pathologies that contraindicate other regional techniques., Competing Interests: Human subjects: Consent was obtained or waived by all participants in this study. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work., (Copyright © 2024, Lopes Dinis et al.)

Flexion relaxation (FR) is characterized by the lumbar erector spinae (LES) becoming myoelectrically silent near full trunk flexion. This study was designed to: (1) determine if decreasing the lumbar moment during flexion would induce FR to occur earlier; (2) characterize thoracic and abdominal muscle activity during FR. Ten male participants performed four trunk flexion/extension movement conditions; lumbar moment was altered by attaching 0, 5, 10, or 15lb counterweights to the torso. Electromyography (EMG) was recorded from eight trunk muscles. Lumbar moment, lumbar flexion and trunk inclination angles were calculated at the critical point of LES inactivation (CPLES). Results demonstrated that counterweights decreased the lumbar moment and lumbar flexion angle at CPLES (p<0.0001 and p=0.0029, respectively); the hypothesis that FR occurs earlier when lumbar moment is reduced was accepted. The counterweights did not alter trunk inclination at CPLES (p=0.1987); this is believed to result from an altered hip to spine flexion ratio when counterweights were attached. Lumbar multifidus demonstrated FR, similar to LES, while thoracic muscles remained active throughout flexion. Abdominal muscles activated at the same instant as CPLES, except in the 15lb condition where abdominal muscles activated before CPLES resulting in a period of increased co-contraction. [ABSTRACT FROM AUTHOR]

ABSTRACT Introduction: During lumbar flexion, the fiber orientation of the lumbar erector spinae (LES) muscle becomes oriented more along the spine compressive axis. It is unknown how changes in LES activation effect fiber orientation. Methods: Ultrasound images of LES were collected during 2 sets of experimental conditions: (1) varying levels of LES activation while lying prone; and (2) varying spine and hip angles while seated. Electromyographic activity and lumbar spine and hip angles were also recorded. Results: As LES activation increased, increases in fiber orientation (signifying increased orientation along the posterior shear axis) were found ( P < 0.001). Compared with the relaxed sitting posture, decreases in fiber orientation were found with full spine flexion and combined spine and hip flexion ( P < 0.001), but there were no changes with full hip flexion alone. Conclusions: Activation magnitude and spine posture both affect LES fiber orientation, thus modifying its ability to protect the spine against anterior shear forces. Muscle Nerve 51: 426-433, 2015 [ABSTRACT FROM AUTHOR]

Abstract: The objective of this study was to investigate the effects of whole-body vibration on multiple tissues simultaneously in fourteen healthy women. On three separate days, participants were exposed to frequencies, 3, 4.5, or 6Hz (at 0.9gr.m.s acceleration in vertical direction) per day on a simulator for 16min. While sitting ‘with’ and ‘without’ backrest support, participants also performed handgrip contractions for 1min. Cerebral and lumbar muscle oxygenation and blood volume responses were measured using near-infrared spectroscopy. Cardiorespiratory responses were collected using a metabolic cart. In general, cerebral and cardiorespiratory responses increased with vibration compared to without vibration, whereas in the lumbar region oxygenation and blood volume responses decreased. Greatest cerebral responses were observed at 6Hz (P <0.05). When compared to exposure to vibration without performing work, significant decrease in lumbar responses was observed during handgrip contractions in both conditions of sitting ‘with’ and ‘without’ a backrest (P <0.05). Such decreases in the lumbar responses suggest postural load due to prolonged sitting combined with physical activity during vibration, might reduce vascular supply to the paraspinal muscles. This study reiterates the importance of understanding the physiological basis for various health disorders in women due to exposure to whole-body vibration. [Copyright &y& Elsevier]