Changing the pattern of the back-muscle flexion–relaxation phenomenon through flexibility training in relatively inflexible young men

Although several studies have investigated the back-muscle flexion–relaxation phenomenon (FRP), the effect of individual flexibility on the FRP has been discussed infrequently, with very limited data on the influence of flexibility training on the FRP. This study thus examined the effect of flexibility training on the change of back-muscle FRP pattern in relatively inflexible young men. We collected and analyzed the valid data from 20 male participants (10 each with high and low flexibility included in the control and trained groups, respectively) when flexing their trunks at seven trunk flexion positions (0°–90°, in increments of 15°); their erector spinae and hamstring activation, pelvic tilt, and lumbosacral angle were then recorded. After 7 weeks of flexibility training for the low-flexibility group, no difference in flexibility was discovered between this group and the control (originally high-flexibility) group. The trunk flexion experiment was then repeated. The results showed that before the training stage, the low-flexibility group had lower erector spinae and higher hamstring activation, a larger pelvic tilt, and a smaller lumbosacral angle. By contrast, after training, the erector spinae and hamstring activation, pelvic tilt, and lumbosacral angle were significantly changed, and no intergroup differences were observed in FRP patterns. The study results suggest that flexibility training changes lumbopelvic movement and thereby reduces the degree of the back-muscle FRP when trunk flexion is performed.

Comparison of Flexion Relaxation Phenomenon Between Female Yogis and Matched Non- Athlete Group

Background: Trunk flexion is a common exercise during daily activities. Flexion relaxation phenomenon (FRP) occurs during forward bending in which there is a sudden silence of erector spinae (ES) muscles. The pattern of forward bending differs in yoga practitioners. This learned pattern probably predisposes yogis to injuries.The hypothesis of this study was that FRP differs in yogis in comparison to non-yogis individuals.Methods: This observational cross-sectional study was performed on 60 women assigned into yogis and non-athlete groups. Each participant was asked to bend forward and then return to the initial position. ES activity was recorded at L3 level, 4 cm from mid line during the trial. Trunk inclination and lumbar flexion angles were calculated at FRP onset and cessation moments. Results: The FRP phenomenon occurred in 80% of yoga practitioners in comparison to 96.7% in the control group. Trunk inclination angle was significantly greater at FRP initiation in yogis compared to control group. Lumbar flexion angle was not different between the groups. Conclusions: It is concluded that the altered pattern of forward bending observed in yogis may change patterns of ES muscles activity if it becomes part of a person's daily lifestyle which might predispose these muscles to fatigue and subsequent injuries.

Patients with Axial Spondyloarthritis Show an Altered Flexion/Relaxation Phenomenon

Axial spondyloarthritis (axSpA) is a chronic rheumatic disease characterized by the presence of inflammatory back pain. In patients with chronic low back pain, the lumbar flexion relaxation phenomenon measured by surface electromyography (sEMG) differs from that in healthy individuals. However, sEMG activity in axSpA patients has not been studied. The purpose of this study was to analyze the flexion relaxation phenomenon in axSpA patients. A study evaluating 39 axSpA patients and 35 healthy controls was conducted. sEMG activity at the erector spinae muscles was measured during lumbar full flexion movements. sEMG activity was compared between axSpA patients and the controls, as well as between active (BASDAI ≥ 4) and non-active (BASDAI < 4) patients. The reliability (using intraclass correlation coefficients (ICC)), criterion validity and discriminant validity using the area Under the curve (AUC) for the inverse flexion/relaxation ratio (1/FRR) were evaluated. Significant differences (p < 0.05) were observed between axSpA patients and the control group in lumbar electric activity, especially during flexion, relaxation, and extension and in FRR and 1/FRR (0.66 ± 0.39 vs. 0.25 ± 0.19, respectively). In addition, significant differences were found between active and non-active but also between non-active and healthy subjects. The sEMG showed good reliability (ICC > 0.8 for 1/FRR) and criterion validity. ROC analysis showed good discriminant validity for axSpA patients (AUC = 0.835) vs. the control group using 1/FRR. An abnormal flexion/relaxation phenomenon exists in axSpA patients compared with controls. sEMG could be an additional objective tool in the evaluation of patient function and disease activity status.

Patients With Axial Spondyloarthritis Show an Altered Flexion/Relaxation Phenomenon

Axial spondyloarthritis (axSpA) is a chronic rheumatic disease characterised by the presence of inflammatory back pain. In patients with chronic low back pain, the lumbar flexion relaxation phenomenon measured by surface electromiography (sEMG) differs from that in healthy individuals. However, sEMG activity in axSpA patients has not been studied. The purpose of this study was to analyse the flexion relaxation phenomenon in axSpA patients. A study evaluating 39 axSpA patients and 35 healthy controls was conducted. sEMG activity at the erector spinae muscles was measured during lumbar full flexion movements. sEMG activity was compared between axSpA patients and the controls, as well as between active (BASDAI&ge;4) and non-active (BASDAI&lt;4) patients. The reliability (using intraclass correlation coefficients (ICC)), criterion validity and discriminant validity using the area Under the curve (AUC) for the inverse flexion/relaxation ratio (1/FRR) were evaluated. Significant differences (p&lt;0.05) were observed between axSpA patients and the control group in lumbar electric activity, especially during flexion, relaxation and extension and in FRR and 1/FRR (0.66&plusmn;0.39 vs. 0.25&plusmn;0.19, respectively). In addition, significant differences were found between active and non-active but also between non-active and healthy subjects. The sEMG showed good reliability (ICC&gt;0.8 for 1/FRR) and criterion validity. ROC analysis showed good discriminant validity for axSpA patients (AUC=0.835) vs. the control group using 1/FRR. An abnormal flexion/relaxation phenomenon exists in axSpA patients compared with controls. sEMG could be an additional objective tool in the evaluation of patient function and disease activity status.

Comparison of the Beta-Band Intermuscular Pool Coherence Between Chronic Non-specific Low Back Pain and Healthy Subjects

Objectives: The current study aimed to compare between the chronic non-specific low back pain (CNSLBP) and healthy subjects during four phases of the trunk flexion-extension task (standing, flexion, relaxation, and extension phases) by using pool coherence as well as pairwise coherence of Beta band Intermuscular coherence (Bb-IMC) and flexion relaxation phenomena. Methods: Twenty-four men with CNSLBP and 20 healthy men voluntarily participated in this study. All subjects performed three tests of Flexion-extension task (F-ET) while the surface electromyography (sEMGs) were recorded from the right erector spinal muscle of the lumbar region “1”, left erector spinal muscle of the lumbar region “2”, right gluteus maximus muscle”3”, left gluteus maximus muscle”4”, right hamstring muscle”5” and left hamstring muscle”6”. Accordingly, group A contains muscles 1, 4, and 6 and group B consists of muscles 2, 3, and 5. The pool coherence (PC) and the pairwise coherence (PWC) for all the above-mentioned muscles were calculated using Beta-band intermuscular coherence analysis. Thereafter, the mean pool coherence (mPC) was considered for group A and group B for four phases of F-ET in three groups as following: CNSLBP patients group, healthy subjects group and the third group included all subjects that participated in this study, whether patients or healthy and it was called the general group. Moreover, the mean pairwise coherence (mPWC) among each pair of group A and B muscles was calculated for four phases of F-ET using Bb-IMC in CNSLBP patients and healthy subjects. Results: These results indicated a high value of A mPC in the general group and healthy subjects in the flexion phase, whereas the same A mPC in CNSLBP patients was high in all phases of F-ET. On the other hand, while B mPC was high in the general group and healthy subjects in the extension phase; it was high in all phases of F-ET in CNSLBP patients; B mPC in CNSLBP patients was high in extension, standing, and flexion phases. A mPWC and B mPWC were not significantly different between CNSLBP patients and healthy subjects in all phases of F-ET. However, only A mPWC “1 - 4” and the A mPWC “4 - 6” were significantly smaller in CNSLBP patients compared to the healthy subjects in the relaxation and flexion phases, respectively. Hence, we suggest pool coherence of Bb-IMC, not pairwise coherence of Bb-IMC, to compare CNSLBP patients and healthy subjects. Conclusions: According to the present findings, we suggest using the pool coherence of Bb-IMC in the clinical examination for CNSLBP patients and studying the probable cortical effects and the effectiveness of various treatments on corticospinal tract function in CNSLBP.

Cervical flexion relaxation phenomenon in patients with and without non-specific chronic neck pain

BACKGROUND: The cervical flexion relaxation phenomenon (FRP) is a myoelectric silence of neck extensor muscles which occurs after a certain degree of flexion. Impaired flexion relaxation can impose the vertebral structures to excessive loading resulting from the persistence of muscular contraction. OBJECTIVE: This study aimed to investigate the incidence or absence of FRP in cervical erector spinae (CES) and upper trapezius muscles in patients with chronic neck pain (CNP). METHODS: Twenty-five patients with CNP and 25 healthy volunteers were recruited. They accomplished cervical flexion and extension from a neutral position in four phases in the sitting position. The surface electromyography activity of both CES and upper trapezius muscles was recorded in each phase. Cervical flexion and extension movements were simultaneously measured using an electrogoniometer. RESULTS: FRP in CES was observed in 84% and 36% of healthy subjects and CNP patients, respectively. Flexion relaxation ratio (FRR) in CES was lower in CNP patients than in healthy subjects (mean diff = 1.33; 95% CI: 0.75–1.91) (P< 0.001). Only in CNP patients, FRR in right erector spinea was significantly higher than that in the left erector spinea (P= 0.04). CONCLUSIONS: FRP incidence in CNP patients was less than in healthy subjects. Moreover, this phenomenon begins later in CNP patients than in healthy subjects indicating prolonged activity of CES muscles during flexion in the CNP group. The difference between FRR in the right and left sides of erector spinea muscles can result in CNP.