Differences in activation properties of the hamstring muscles during overground sprinting

Objectives: The aim of this study was to investigate quadriceps and hamstrings isometric strength at 4, 8 and 12 week time points following ACL Reconstruction (ACLR) and to document the strength changes of these muscles over time. The primary hypothesis was that there would be significant increases in quadriceps and hamstring muscle strengths between the 4th, 8th and 12th weeks following ACLR. The secondary hypothesis was that the quadriceps index would be higher than hamstring index at 12th week after ACLR. Methods: Thirty patients (Mean ± SD [age, 29.1±2.3yrs; weight, 77.3±13.2kg; height, 172.1±7.1cm; BMI, 21.2±3.5kg/m2, time to surgery: 7.1±7.2 months]) who underwent ACLR with Hamstring Tendon Autograft (HTG) were enrolled in this study. The isometric strength of quadriceps and hamstring muscles was measured on an isokinetic dynamometer at 60° knee flexion angle at 4th, 8th and 12th weeks after surgery. The recovery of quadriceps and hamstring muscles strength following rehabilitation was expressed as a Quadriceps Index (QI) and Hamstring Index (HI) and calculated with the following formula:[(maximum voluntary isometric torque of the involved limb / maximum voluntary isometric torque by uninvolved limb) × 100]. Torque output of the involved and uninvolved limbs and quadriceps and hamstring indexes were used for the statistical analysis. A repeated measures of ANOVA was used to determine the strength changes of quadriceps and hamstrings over time. Results: Quadriceps and Hamstrings strengths significantly increased over time for both involved (Quadriceps: F (2,46)=58.3, p<0.001, Hamstring: F (2,46)=35.7, p<0.001) and uninvolved limb (Quadriceps: F(2,46)=17.9, p<0.001, Hamstring: F(2,46)=56.9, p=0.001 ). Quadriceps strength was higher at 12th week when compared to the 8 and 4 week time points for the involved limb (p<0.001), and it was higher at 8th week when compared to 4 week time point for the involved limb (p<0.001). For the uninvolved limb, quadriceps strength was also higher at 12th week when compared to the 8 (p=0.02) and 4 week time point (p<0.001), and higher at 8 week when compared to the 4 week time point (p=0.02). Hamstring strength was higher at 12 week when compared to the 8 and 4 week time points (p<0.001) and it was higher at 8 week when compared to 4 week time point for the involved limb (p<0.001). For the uninvolved limb hamstring strength was also higher at 12 week when compared to 4 week time point (p=0.01). There was no significant difference between the 4 and 8 week time points (p>0.05) or between the 8 and 12 week time points (p=0.07). Quadriceps and hamstring indexes significantly changed from 4th weeks (QI:57.9, HI:54.4 ) to 8th weeks (QI:78.8, HI:69.9 ) and from 8th weeks to 12th weeks (QI:82, HI:75.7 ) (p<0.001); however, there was no difference between indexes at the 12-week time point (p=0.17). Conclusion: Isometric strength of quadriceps and hamstring muscles for the involved and uninvolved limb increased during the early period of ACLR. The results of this study could be a baseline for clinicians while prescribing a rehabilitation protocol for ACLR patients with HTG to better appreciate expected strength changes of the muscles in the early phase.

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Anisotropic diffusion of oxygen in slices of rat muscle

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1984.246.1.r107 ◽

1984 ◽

Vol 246 (1) ◽

pp. R107-R113 ◽

Cited By ~ 2

Author(s):

L. D. Homer ◽

J. B. Shelton ◽

C. H. Dorsey ◽

T. J. Williams

Keyword(s):

Diffusion Coefficient ◽

Fluorescence Quenching ◽

Muscle Fiber ◽

Extracellular Space ◽

Anisotropic Diffusion ◽

Muscle Fibers ◽

Rat Muscle ◽

Hamstring Muscles ◽

Standard Deviations ◽

Diffusion Coefficient Of Oxygen

The diffusion coefficient of oxygen (D) and the fluorescence quenching coefficient (K') of pyrenebutyric acid (PBA) were measured in sections of rat hamstring muscles. Values of D and K' at temperatures (Tc) of 20, 30, and 40 degrees C were determined and referred to the values in water. In sections cut parallel to the muscle fibers, D = DH2O (0.380 +/- 0.038), whereas in sections cut across the grain of the fibers, D = DH2O (0.985 +/- 0.039). Oxygen diffuses along the length of a muscle fiber over twice as rapidly as it diffuses in directions perpendicular to the long axis of the fiber. This suggests that fibers, myofibrils, or myofilaments offer substantial barriers to the diffusion of oxygen, whereas extracellular space and spaces around fibers or myofibrils or myofilaments offer no more resistance than water to the diffusion of oxygen. Corresponding estimates for K' were K' = K'H2O[0.14 (1 + 0.25 Tc)] and K' = K'H2O[0.21 (1 + 0.25 Tc)] for slices cut parallel to the long axis of muscle fibers and across the long axis, respectively. Standard deviations of K' were 9%.

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Relationship of Peak Torque to Peak Work and Peak Power of the Quadriceps and Hamstring Muscles in a Normal Sample Using an Accommodating Resistance Measurement Device

Isokinetics and Exercise Science ◽

10.3233/ies-1991-1206 ◽

1991 ◽

Vol 1 (2) ◽

pp. 87-91 ◽

Cited By ~ 2

Author(s):

William D. Bandy ◽

Venita Lovelace-Chandler

Keyword(s):

Peak Power ◽

Peak Torque ◽

Resistance Measurement ◽

Normal Sample ◽

Measurement Device ◽

Hamstring Muscles ◽

Relationship Of

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Analysis of musculoskeletal changes in patients with postural roundback

Coluna/Columna ◽

10.1590/s1808-18512014130300389 ◽

2014 ◽

Vol 13 (3) ◽

pp. 188-192

Author(s):

Débora Pinheiro Lédio Alves ◽

Vera Lúcia dos Santos Alves ◽

Osmar Avanzi

Keyword(s):

Lumbar Spine ◽

Thoracic Kyphosis ◽

Radiographic Examination ◽

Compensatory Mechanism ◽

Moderate Increase ◽

Pectoralis Minor ◽

Shoulder Muscles ◽

Hamstring Muscles ◽

Cobb Method ◽

Radiographic Changes

OBJECTIVE: To analyze the clinical and radiographic changes in patients with postural rounded upper back. METHODS: 30 patients diagnosed with postural rounded upper back were studied, being 22 male and eight female, aged between 10 and 20 years, referred by the outpatient clinic of the Grupo de Cirurgia da Coluna of the Irmandade da Santa Casa de Misericórdia de São Paulo, SP, Brazil. Patients underwent assessment of posture, special tests to check for muscle retractions and radiographic examination to measure the curvatures of spine using the Cobb method. RESULTS/CONCLUSION: It is concluded that in the postural roundback there is a moderate increase of the thoracic kyphosis; the lumbar and cervical curvatures do not increase as a compensatory mechanism; the head appears anteriorized and the shoulder is also anteriorized and medially rotated; muscle retractions are present in the hamstrings, hip flexors, pectoralis minor and adductors of the shoulder muscles; the mobility of the lumbar spine is preserved and there is no relationship between the magnitude of thoracic curvature and the retraction of the hamstring muscles.

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Effect of Global Postural Reeducation Exercise on Pain and Hip Muscle Flexibility in Patients with Chronic Low Back Pain and Movement Control Dysfunction

International journal of basic science in medicine ◽

10.34172/ijbsm.2019.05 ◽

2019 ◽

Vol 4 (4) ◽

pp. 148-154

Author(s):

Bahram Sheikhi

Keyword(s):

Low Back Pain ◽

Back Pain ◽

Movement Control ◽

Rectus Femoris ◽

Low Back ◽

Significance Level ◽

Hip Muscle ◽

Hamstring Muscles ◽

Hip Muscles ◽

Tensor Fasciae Latae

Introduction: Patients with non-specific low back pain (NSLBP) and movement control dysfunction demonstrate alternation in hip muscles flexibility and spinal movement patterns. Therapeutic modalities that augment hip muscles flexibility could help these patients. The aim of this study was to investigate the effect of global postural reeducation (GPR) on pain and hip muscle flexibility in patients with NSLBP and movement control dysfunction. Materials and Methods: A total of 27 men with a mean age of 31.21±2.5147 years, height of 166.44±6.11 cm, and weight of 64.21±5.25 kg participated in this study. The visual analogue scale (VAS) was used to evaluate pain. The flexibility of hip muscles (rectus femoris, tensor fasciae latae, external rotators and hamstring) was measured using universal goniometer. All data were assessed at baseline and after the intervention. The Shapiro-Wilk test and paired t test were used for statistical analysis at significance level of P=0.05. Results: Our results revealed a decline in pain (P<0.004) and an increase in the flexibility of the hamstring muscles in the right (P<0.003) and left (P<0.003) legs. There were no statistically significant differences in the flexibility of rectus femoris muscle, external rotators, and tensor fasciae latae. Conclusion: The results suggest that GPR had a significant effect on the level of pain. Further, it affected the flexibility of hamstring muscles in legs. Using GPR is recommended for pain relief and improving the flexibility of hamstring muscles in patients with NSLBP.

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ROLE OF HAMSTRING MUSCLES IN KNEE JOINT STABILITY PROVIDING AND INJURY PREVENTION

SOCIETY INTEGRATION EDUCATION Proceedings of the International Scientific Conference ◽

10.17770/sie2016vol3.1469 ◽

2016 ◽

Vol 3 ◽

pp. 522

Author(s):

Inese Pontaga

Keyword(s):

Stance Phase ◽

Knee Extension ◽

Swing Phase ◽

Joint Stability ◽

Distance Runners ◽

Leg Extension ◽

Hamstring Muscles ◽

Extreme Extension ◽

Torque Values

The aim of our investigation was to determine the ratio of maximal torque values and the torques in the certain positions of range of movements (ROM) between hamstring (H) and quadriceps femoris (Q) muscles at medium and high velocity of movement in concentric (CC) and eccentric (ECC) action of hamstring muscles. The knee muscles of 15 amateur female short and middle distance runners were tested by the dynamometer system in the isokinetic movements with the angular velocity of 90º/s and 240º/s in CC and at the velocity of 90º/s in ECC H/ CC Q muscles contractions. The torque values produced by the muscles are detected at the different angular positions of the ROM with the step of 10º. The ratios of H/ Q muscles torques are calculated. The H/Q muscles maximal torques ratio is 0.51 ± 0.13 at the velocity of 90º/s in CC and 0.60 ± 0.09 in ECC H/ CC Q muscles contractions, and 0.59 ± 0.09 CC at the velocity of 240º/s. The H/Q maximal torques ratio and this ratio in the knee extreme extension and flexion at the ECC contraction of H is higher due to greater torques produced by the H in comparison with Q muscle. The H must be stronger to decelerate the thigh and lower leg extension in the late swing phase of running and to extend the hip in early stance phase to provide powerful sprint running and prevent the knee and H injury. The H/Q muscles torques ratio in extended knee positions are similar in medium (90º/s) and fast (240º/s) velocity of motions because CC action of H muscles cannot prevent extreme knee extension.

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