Effect of crculatory occlusion on time to muscular fatigue.

1968 ◽  
Vol 24 (1) ◽  
pp. 54-59 ◽  
Author(s):  
S J Myers ◽  
W P Sullivan
Keyword(s):  
Muscular Fatigue

scholarly journals Effects of Prolonged Sitting with Slumped Posture on Trunk Muscular Fatigue in Adolescents with and without Chronic Lower Back Pain

Medicina ◽  
2020 ◽  
Vol 57 (1) ◽  
pp. 3
Author(s):  
Kyoung-Sim Jung ◽  
Jin-Hwa Jung ◽  
Tae-Sung In ◽  
Hwi-Young Cho
Keyword(s):  
Back Pain ◽  
Lower Back Pain ◽  
Transversus Abdominis ◽  
Muscular Fatigue ◽  
Trunk Muscles ◽  
Control Group ◽  
Chronic Lower Back Pain ◽  
Median Frequency ◽  
Prolonged Sitting ◽  
Lower Back

Background and Objectives: This study investigated the effects of prolonged sitting on trunk muscular fatigue and discomfort in participants with and without chronic lower back pain (LBP). Material and Methods: This study included 15 patients with LBP and 15 healthy controls. All participants were instructed to sit on a height-adjustable chair with their knee and hip joints bent at 90° for 30 min, in slumped sitting postures. Surface electromyography was used to assess the median frequency of the internal obliques (IO)/transversus abdominis (TrA) and multifidus (MF) muscles. Perceived discomfort was measured using a Borg category ratio-scale. Median frequency of the trunk muscles and perceived discomfort after 30 min of sitting were compared with baseline. Result: There were no significant differences within the group and between both groups in the median frequency of bilateral IO and MF muscles. The LBP group showed significantly greater perceived discomfort after prolonged sitting, as compared to the control group. Conclusions: Prolonged sitting with slumped posture could increase the risk of experiencing lower back discomfort.

The effects of muscle fatigue on bone strain.

1994 ◽  
Vol 188 (1) ◽  
pp. 217-233 ◽  
Author(s):  
T Yoshikawa ◽  
S Mori ◽  
A J Santiesteban ◽  
T C Sun ◽  
E Hafstad ◽  
...  
Keyword(s):  
Muscle Fatigue ◽  
Strain Distribution ◽  
Distal Tibia ◽  
Muscular Fatigue ◽  
Bone Strain ◽  
Significant Shift ◽  
Inverse Association ◽  
Peak Strain ◽  
Exercise Period ◽  
Shear Strains

There is anecdotal evidence that bone strains may increase to the point that bone becomes susceptible to rapid failure when muscles become fatigued. To determine whether neuromuscular response could be a factor in accelerating bone failure, we tested the hypothesis that muscle fatigue causes a significant increase in peak principal and shear strains in bone. Ten adult foxhounds were subjected to rigorous exercise that caused muscular fatigue while myoelectrical activity of the quadriceps and hamstrings and strain on the distal tibia were monitored simultaneously. Ground reaction forces on the dog hindlimbs were measured before and after strain gauges had been applied to the tibia. The data show a significant shift to lower median myoelectrical frequencies in the quadriceps, indicating muscular fatigue, following the 20 min exercise period. In conjunction with this shift, peak principal and shear strains increased on both compressive and tensile cortices of the tibia and shear strain on the tensile cortex increased significantly (P = 0.02). The largest changes were along the anterior and anterolateral surfaces of the tibia, where peak principal strain increased by an average of 26-35% following muscular fatigue. The cross-sectional strain distribution was calculated at the gauge site at peak strain at the beginning of the exercise period and at peak strain after 20 min of exercise. These data show a change in strain distribution when muscle becomes fatigued. Strains on the posterior cortex of the bone showed the greatest change. Correlation analysis demonstrated a significant inverse association between median myoelectrical frequency and bone strain after 20 min of exercise (Spearman r2 = 1.00; P = 0.05). These data show that muscle fatigue may be associated with increased bone strain.

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