scholarly journals Lower extremity muscle activation onset times during the transition from double-leg stance to single-leg stance in anterior cruciate ligament reconstructed subjects

2016 ◽  
Vol 35 ◽  
pp. 116-123 ◽  
Author(s):  
Bart Dingenen ◽  
Luc Janssens ◽  
Steven Claes ◽  
Johan Bellemans ◽  
Filip F. Staes
Keyword(s):  
Anterior Cruciate Ligament ◽  
Lower Extremity ◽  
Muscle Activation ◽  
Cruciate Ligament ◽  
Lower Extremity Muscle ◽  
Single Leg Stance ◽  
Anterior Cruciate

scholarly journals Volitional Spine Stabilization During a Drop Vertical Jump From Different Landing Heights: Implications for Anterior Cruciate Ligament Injury

2016 ◽  
Vol 51 (12) ◽  
pp. 1003-1012 ◽  
Author(s):  
Ram Haddas ◽  
Troy Hooper ◽  
C. Roger James ◽  
Phillip S. Sizer
Keyword(s):  
Anterior Cruciate Ligament ◽  
Lower Extremity ◽  
Injury Risk ◽  
Muscle Activation ◽  
Cruciate Ligament ◽  
Vertical Jump ◽  
Ligament Injury ◽  
Lower Extremity Muscle ◽  
Anterior Cruciate ◽  
Drop Vertical Jump

Context:Volitional preemptive abdominal contraction (VPAC) during dynamic activities may alter trunk motion, but the role of the core musculature in positioning the trunk during landing tasks is unclear.Objective:To determine whether volitional core-muscle activation incorporated during a drop vertical jump alters lower extremity kinematics and kinetics, as well as trunk and lower extremity muscle activity at different landing heights.Design:Controlled laboratory study.Setting:Clinical biomechanics laboratory.Patients or Other Participants:Thirty-two young healthy adults, consisting of 17 men (age = 25.24 ± 2.88 years, height = 1.85 ± 0.06 m, mass = 89.68 ± 16.80 kg) and 15 women (age = 23.93 ± 1.33 years, height = 1.67 ± 0.08 m, mass = 89.68 ± 5.28 kg).Intervention(s):Core-muscle activation using VPAC.Main Outcome Measure(s):We collected 3-dimensional ankle, knee, and hip motions, moments, and powers; ground reaction forces; and trunk and lower extremity muscle activity during 0.30- and 0.50-m drop vertical-jump landings.Results:During landing from a 0.30-m height, VPAC performance increased external oblique and semitendinosis activity, knee flexion, and knee internal rotation and decreased knee-abduction moment and knee-energy absorption. During the 0.50-m landing, the VPAC increased external oblique and semitendinosis activity, knee flexion, and hip flexion and decreased ankle inversion and hip-energy absorption.Conclusions:The VPAC performance during landing may protect the anterior cruciate ligament during different landing phases from different heights, creating a protective advantage just before ground contact and after the impact phase. Incorporating VPAC during high injury-risk activities may enhance pelvic stability, improve lower extremity positioning and sensorimotor control, and reduce anterior cruciate ligament injury risk while protecting the lumbar spine.

Differences in Kinematics and Electromyographic Activity between Men and Women during the Single-Legged Squat

2003 ◽  
Vol 31 (3) ◽  
pp. 449-456 ◽  
Author(s):  
Brian L. Zeller ◽  
Jean L. McCrory ◽  
W. Ben Kibler ◽  
Timothy L. Uhl
Keyword(s):  
Anterior Cruciate Ligament ◽  
Lower Extremity ◽  
Muscle Activation ◽  
External Rotation ◽  
Cruciate Ligament ◽  
Rectus Femoris ◽  
Ligament Injury ◽  
Electromyographic Activity ◽  
Men And Women ◽  
Anterior Cruciate

Background Numerous factors have been identified as potentially increasing the risk of anterior cruciate ligament injury in the female athlete. However, differences between the sexes in lower extremity coordination, particularly hip control, are only minimally understood. Hypothesis There is no difference in kinematic or electromyographic data during the single-legged squat between men and women. Study Design Descriptive comparison study. Methods We kinematically and electromyographically analyzed the single-legged squat in 18 intercollegiate athletes (9 male, 9 female). Subjects performed five single-legged squats on their dominant leg, lowering themselves as far as possible and then returning to a standing position without losing balance. Results Women demonstrated significantly more ankle dorsiflexion, ankle pronation, hip adduction, hip flexion, hip external rotation, and less trunk lateral flexion than men. These factors were associated with a decreased ability of the women to maintain a varus knee position during the squat as compared with the men. Analysis of all eight tested muscles demonstrated that women had greater muscle activation compared with men. When each muscle was analyzed separately, the rectus femoris muscle activation was found to be statistically greater in women in both the area under the linear envelope and maximal activation data. Conclusions Under a physiologic load in a position commonly assumed in sports, women tend to position their entire lower extremity and activate muscles in a manner that could increase strain on the anterior cruciate ligament.

Effects of Exercise on Lower Extremity Muscle Function After Anterior Cruciate Ligament Reconstruction

2013 ◽  
Vol 22 (1) ◽  
pp. 33-40 ◽  
Author(s):  
Christopher Kuenze ◽  
Jay Hertel ◽  
Joseph M. Hart
Keyword(s):  
Anterior Cruciate Ligament ◽  
Lower Extremity ◽  
Muscle Function ◽  
Cruciate Ligament ◽  
Knee Extension ◽  
Lower Extremity Function ◽  
Significant Group ◽  
Lower Extremity Muscle ◽  
Extremity Function ◽  
Anterior Cruciate

Purpose:Persistent quadriceps weakness due to arthrogenic muscle inhibition (AMI) has been reported after anterior cruciate ligament (ACL) reconstruction. Fatiguing exercise has been shown to alter lower extremity muscle function and gait mechanics, which may be related to injury risk. The effects of exercise on lower extremity function in the presence of AMI are not currently understood. The purpose of this study was to compare the effect of 30 min of exercise on quadriceps muscle function and soleus motoneuron-pool excitability in ACL-reconstructed participants and healthy controls.Methods:Twenty-six (13 women, 13 men) healthy and 26 (13 women, 13 men) ACL-reconstructed recreationally active volunteers were recruited for a case-control laboratory study. All participants completed 30 min of continuous exercise including alternating cycles of inclined-treadmill walking and bouts of squats and step-ups. Knee-extension torque, quadriceps central activation ratio (CAR), soleus H:M ratio, and soleus V:M ratio were measured before and after 30 min of exercise.Results:There was a significant group × time interaction for knee-extension torque (P = .002), quadriceps CAR (P = .03), and soleus V:M ratio (P = .03). The effect of exercise was smaller for the ACL-R group than for matched controls for knee-extension torque (ACL-R: %Δ = −4.2 [−8.7, 0.3]; healthy: %Δ = −14.2 [−18.2, −10.2]), quadriceps CAR (ACL-R: %Δ = −5.1 [−8.0, −2.1]; healthy: %Δ = −10.0 [−13.3, −6.7]), and soleus V:M ratio (ACL-R: %Δ = 37.6 [2.1, 73.0]; healthy: %Δ = −24.9 [−38.6, −11.3]).Conclusion:Declines in quadriceps and soleus volitional muscle function were of lower magnitude in ACL-R subjects than in healthy matched controls. This response suggests an adaptation experienced by patients with quadriceps AMI that may act to maintain lower extremity function during prolonged exercise.

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