A Gender Comparison of Central and Peripheral Neuromuscular Function After Exercise

2012 ◽  
Vol 21 (3) ◽  
pp. 209-217 ◽  
Author(s):  
Ashley Stern ◽  
Chris Kuenze ◽  
Daniel Herman ◽  
Lindsay D. Sauer ◽  
Joseph M. Hart
Keyword(s):  
Outcome Measures ◽  
Motor Evoked Potentials ◽  
Cruciate Ligament ◽  
Peak Torque ◽  
Surface Emg ◽  
Knee Extension ◽  
Ligament Injury ◽  
Exercise Protocol ◽  
Peripheral Muscle ◽  
Increase Risk

Context:Central and peripheral muscle fatigue during exercise may exacerbate neuromuscular factors that increase risk for noncontact anterior cruciate ligament injury.Objective:To compare lower extremity motor-evoked potentials (MEPs), muscle strength, and electromyography (EMG) activation after an exercise protocol.Design:Pretest, posttest group comparison.Setting:University laboratory.Participants:34 healthy volunteers (17 female, age = 21.9 ± 2.3 years, weight = 77.8 ± 3.0 kg, height = 171.1 ± 6.6 cm, and 17 male, age = 23.4 ± 6.5 years, weight = 81.6 ± 3.3 kg, height = 179.6 ± 7.3 cm).Intervention:A standardized 30-min exercise protocol that involved 5 repeated cycles of uphill walking, body-weight squatting, and step-ups.Main Outcome Measures:Quadriceps and hamstring MEP amplitude (mV) and transmission velocity normalized to subject height (m/s) were elicited via transcranial magnetic stimulation and measured via surface EMG. Quadriceps and hamstring peak EMG activation (% MVIC) and peak torque (Nm/kg) were measured during MVICs. Separate ANCOVAs were used to compare groups after exercise while controlling for baseline measurement.Results:At baseline, males exhibited significantly greater knee-extension torques (males = 2.47 ± 0.68 Nm/kg, females = 1.95 ± 0.53 Nm/kg; P = .036) and significantly higher hamstring MEP amplitudes (males = 223.5 ± 134.0 mV, females = 89.3 ± 77.6 mV; P = .007). Males exhibited greater quadriceps MEP amplitude after exercise than females (males = 127.2 ± 112.7 mV, females = 32.3 ± 34.9 mV; P = .016).Conclusions:Males experienced greater peripheral neuromuscular changes manifested as more pronounced reductions in quadriceps torque after exercise. Females experienced greater central neuromuscular changes manifested as more pronounced reduction in quadriceps MEP amplitude. Reduced central neural drive of the quadriceps coupled with knee-extension torque preservation after exercise may increase risk of knee injury in females.

Differences in Isokinetic Strength of the Knee Extensors and Flexors in Men With Isolated and Combined Cruciate-Ligament Knee Injury

2015 ◽  
Vol 24 (3) ◽  
pp. 268-277 ◽  
Author(s):  
Ewa Kaminska ◽  
Tomasz Piontek ◽  
Marzena Wiernicka ◽  
Grazyna Cywinska-Wasilewska ◽  
Jacek Lewandowski ◽  
...  
Keyword(s):  
Anterior Cruciate Ligament ◽  
Outcome Measures ◽  
Body Mass ◽  
Cruciate Ligament ◽  
Knee Extension ◽  
Ligament Injury ◽  
Knee Extensors ◽  
Isokinetic Testing ◽  
Ligament Tear ◽  
Anterior Cruciate

Context:The extent of knee extensor and flexor weakness after disruption of knee ligaments affects a rehabilitation output and functional recovery and may give prognostic information on a possible risk of development of knee osteoarthritis.Objective:The hypothesis tested was whether patients with a multiple-ligament tear would have larger abnormalities in strength of the knee extensors and flexors than patients with an isolated-ligament rupture.Design:Cross-sectional study, level III.Setting:Outpatient orthopedic clinic.Participants:3 groups of recreationally active men: noninjured control (CON, n = 12), with an anterior cruciate ligament injury (ACLI, n = 10), and with combined anterior and posterior cruciate ligament injury (APCLI, n = 9), matched according to age, body mass, and height.Intervention:All patients received conservative treatment and rehabilitation and awaited ligament reconstruction surgery.Main Outcome Measures:Isokinetic maximum-repetition peak torque per body mass (PT/BM) and total work (TW), PT and TW limb-symmetry index (LSI), and flexor-to-extensor PT ratio were evaluated during concentric knee extension-flexion movements at lower (60°/s) and higher (240°/s) isokinetic velocities.Results:The main finding was that compared with the individuals with ACLI, patients with APCLI produced in their injured limbs lower mean TW (extension: 30.3%, flexion: 28.2%) and had lower mean TW LSI (extension 74% in APCLI vs 91.6% in ACLI; flexion 61.3% in APCLI vs 90.8% in ACLI) at the higher but not lower speed of isokinetic testing. However, at the lower velocity the quantified size of reduction in PT/BM and TW was greater in subjects with APCLI than ACLI as compared with the CON individuals.Conclusions:After bi-cruciate-ligament injury the capacity to produce torque by concentric muscle contractions throughout knee-extension and-flexion movements performed with high speed is lower in injured limbs than after isolated anterior cruciate ligament tear.

Lower Extremity Joint Moments of Collegiate Soccer Players Differ between Genders during a Forward Jump

2008 ◽  
Vol 17 (2) ◽  
pp. 137-147 ◽  
Author(s):  
Joseph M. Hart ◽  
J. Craig Garrison ◽  
Riann Palmieri-Smith ◽  
D. Casey Kerrigan ◽  
Christopher D. Ingersoll
Keyword(s):  
Lower Extremity ◽  
Internal Rotation ◽  
Outcome Measures ◽  
Cruciate Ligament ◽  
Ligament Injury ◽  
Initial Contact ◽  
Joint Angles ◽  
Joint Moments ◽  
Heel Contact ◽  
Hip Internal Rotation

Context:Lower extremity kinetics while performing a single-leg forward jump landing may help explain gender biased risk for noncontact anterior cruciate ligament injury.Objective:Gender comparison of lower extremity joint angles and moments.Design:Static groups comparison.Setting:Motion analysis laboratory.Patients or Other Participants:8 male and 8 female varsity, collegiate soccer athletes.Intervention:5 single-leg landings from a 100cm forward jump.Main Outcome Measures:Peak and initial contact external joint moments and joint angles of the ankle, knee, and hip.Results:At initial heel contact, males exhibited a adduction moment whereas females exhibited a abduction moment at the hip. Females also had significantly less peak hip extension moment and significantly less peak hip internal rotation moment than males had. Females exhibited greater knee adduction and hip internal rotation angles than men did.Conclusions:When decelerating from a forward jump, gender differences exist in forces acting at the hip.

scholarly journals Brain-Behavior Mechanisms for the Transfer of Neuromuscular Training Adaptions to Simulated Sport: Initial Findings From the Train the Brain Project

2018 ◽  
Vol 27 (5) ◽  
Author(s):  
Dustin R. Grooms ◽  
Adam W. Kiefer ◽  
Michael A. Riley ◽  
Jonathan D. Ellis ◽  
Staci Thomas ◽  
...  
Keyword(s):  
Virtual Reality ◽  
Injury Risk ◽  
Cruciate Ligament ◽  
Knee Extension ◽  
Ligament Injury ◽  
Leg Press ◽  
Landing Mechanics ◽  
Anterior Cruciate ◽  
Movement Mechanics ◽  
Risk Reducing

Context: A limiting factor for reducing anterior cruciate ligament injury risk is ensuring that the movement adaptions made during the prevention program transfer to sport-specific activity. Virtual reality provides a mechanism to assess transferability, and neuroimaging provides a means to assay the neural processes allowing for such skill transfer. Objective: To determine the neural mechanisms for injury risk–reducing biomechanics transfer to sport after anterior cruciate ligament injury prevention training. Design: Cohort study. Setting: Research laboratory. Participants: Four healthy high school soccer athletes. Interventions: Participants completed augmented neuromuscular training utilizing real-time visual feedback. An unloaded knee extension task and a loaded leg press task were completed with neuroimaging before and after training. A virtual reality soccer-specific landing task was also competed following training to assess transfer of movement mechanics. Main Outcome Measures: Landing mechanics during the virtual reality soccer task and blood oxygen level–dependent signal change during neuroimaging. Results: Increased motor planning, sensory and visual region activity during unloaded knee extension and decreased motor cortex activity during loaded leg press were highly correlated with improvements in landing mechanics (decreased hip adduction and knee rotation). Conclusion: Changes in brain activity may underlie adaptation and transfer of injury risk–reducing movement mechanics to sport activity. Clinicians may be able to target these specific brain processes with adjunctive therapy to facilitate intervention improvements transferring to sport.

Hip Adduction Does not Affect VMO EMG Amplitude or VMO:VL Ratios during a Dynamic Squat Exercise

2006 ◽  
Vol 15 (3) ◽  
pp. 195-205 ◽  
Author(s):  
Michelle Boling ◽  
Darin Padua ◽  
J. Troy Blackburn ◽  
Meredith Petschauer ◽  
Christopher Hirth
Keyword(s):  
Outcome Measures ◽  
Knee Flexion ◽  
Healthy Subjects ◽  
Vastus Lateralis ◽  
Test Session ◽  
Surface Emg ◽  
Knee Extension ◽  
Emg Amplitude ◽  
Squat Exercise ◽  
History Of

Context:Clinicians commonly attempt to facilitate vastus medialis oblique (VMO) activity by instructing patients to squeeze a ball between their knees during squatting exercises.Objective:To determine whether VMO activation amplitude and the VMO to vastus lateralis (VL) activation ratio (VMO:VL) were altered when performing active hip adduction during a dynamic squat exercise.Design:Single test session.Participants:Fifteen healthy subjects, with no history of knee pain, volunteered for this study.Intervention:Surface EMG of the VMO, VL, and hip adductor (ADD) muscles were recorded while subjects performed 10 consecutive squats against their body weight through a range of 0° to 90° of knee flexion. Subjects performed the squat exercises during two different conditions: (1) active hip adduction and (2) no hip adduction.Main Outcome Measures:Average VMO EMG amplitude and VMO:VL ratio were determined during the knee flexion (0° to 90°) and knee extension (90° to 0°) phases of the squat exercise.Results:Active hip adduction did not significantly change VMO amplitude or VMO:VL ratio during the knee flexion or knee extension phases of the dynamic squat exercise.Conclusions:Based on these results, we conclude that VMO amplitude and the VMO: VL ratio are not influenced by performing active hip adduction during a dynamic squat exercise in healthy subjects.

scholarly journals CORRELATION BETWEEN ECCENTRIC TRAINING AND FUNCTIONAL TESTS IN SUBJECTS WITH RECONSTRUCTED ACL

2018 ◽  
Vol 24 (6) ◽  
pp. 471-476
Author(s):  
Heleodório Honorato Santos ◽  
Catarina de Oliveira Sousa ◽  
Christiane Lanatovitz Prado Medeiros ◽  
José Angelo Barela ◽  
Ana Maria Forti Barela ◽  
...  
Keyword(s):  
Acl Reconstruction ◽  
Cruciate Ligament ◽  
Control Level ◽  
Case Series ◽  
Peak Torque ◽  
Knee Extension ◽  
Triple P ◽  
Eccentric Training ◽  
Isokinetic Training ◽  
Level Of Evidence

ABSTRACT Introduction: Eccentric training and jump tests are widely used to recover and measure deficits in knee strength and functionality after anterior cruciate ligament (ACL) reconstruction. Objective: To correlate knee extension and flexion torque generated by eccentric isokinetic training, with functional jump tests in subjects with reconstructed ACL. Method: Sixteen men with unilateral ACL reconstruction were assessed before and after 12 weeks of eccentric isokinetic training of knee flexors and extensors (3×10 MVC, 2x/week) at 30°/s for extension and flexion torque (isometric; concentric and eccentric at 30 and 120°/s) and functional jump tests (single, triple, cross and figure of 8). Inter- and intra-limb pre- and post-training mean peak torque (MPT), distance and jump test times were compared along with the correlations between these variables, considering P<0.05. Results: The affected limb (AL) showed significant gain of extension and flexion torque (P<0.01) in the different test categories and velocities evaluated. In the non-affected limb (NAL), this only occurred in the eccentric category (30 and 120°/s), in the extension (P<0.01) and flexion (P<0.05 and P<0.01) torques, respectively. In the jumps, there was an increase in distance (single and triple; P<0.05) and a decrease in time (crossed and figure of 8; P<0.01), however, MPT x Jump correlations were weak (r<0.3) in the pre and post-training period in both limbs. Conclusion: Despite the gain in knee extension and flexion torque and jumping performance, the expected correlation was not satisfactory, suggesting that knee functionality involves other variables inherent to motor control. Level of Evidence IV; Type of study: Case series.

scholarly journals Rate of Muscle Activation in Power-and Endurance-Trained Boys

2011 ◽  
Vol 6 (1) ◽  
pp. 94-105 ◽  
Author(s):  
Cameron Mitchell ◽  
Rotem Cohen ◽  
Raffy Dotan ◽  
David Gabriel ◽  
Panagiota Klentrou ◽  
...  
Keyword(s):  
Muscle Activation ◽  
Peak Torque ◽  
Surface Emg ◽  
Knee Extension ◽  
Endurance Athletes ◽  
Group Differences ◽  
Electromechanical Delay ◽  
Cross Sectional ◽  
Isometric Knee Extension ◽  
Muscle Cross Sectional Area

Previous studies in adults have demonstrated power athletes as having greater muscle force and muscle activation than nonathletes. Findings on endurance athletes are scarce and inconsistent. No comparable data on child athletes exist.Purpose:This study compared peak torque (Tq), peak rate of torque development (RTD), and rate of muscle activation (EMG rise, Q30), in isometric knee extension (KE) and fexion (KF), in pre- and early-pubertal power- and endurance-trained boys vs minimally active nonathletes.Methods:Nine gymnasts, 12 swimmers, and 18 nonathletes (7–12 y), performed fast, maximal isometric KE and KF. Values for Tq, RTD, electromechanical delay (EMD), and Q30 were calculated from averaged torque and surface EMG traces.Results:No group differences were observed in Tq, normalized for muscle cross-sectional area. The Tq-normalized KE RTD was highest in power athletes (6.2 ± 1.9, 4.7 ± 1.2, 5.0 ± 1.5 N·m·s–1, for power, endurance, and nonathletes, respectively), whereas no group differences were observed for KF. The KE Q30 was significantly greater in power athletes, both in absolute terms and relative to peak EMG amplitude (9.8 ± 7.0, 5.9 ± 4.2, 4.4 ± 2.2 mV·ms and 1.7 ± 0.8, 1.1 ± 0.6, 0.9 ± 0.5 (mV·ms)/(mV) for power, endurance, and nonathletes, respectively), with no group differences in KF. The KE EMD tended to be shorter (P = .07) in power athletes during KE (71.0 ± 24.1, 87.8 ± 18.0, 88.4 ± 27.8 ms, for power, endurance, and nonathletes), with no group differences in KF.Conclusions:Pre- and early-pubertal power athletes have enhanced rate of muscle activation in specifically trained muscles compared with controls or endurance athletes, suggesting that specific training can result in muscle activation-pattern changes before the onset of puberty.

scholarly journals Recovery of preoperative absolute knee extension and flexion strength after ACL reconstruction

2020 ◽  
Author(s):  
Ramana Piussi ◽  
Daniel Broman ◽  
Erik Musslinder ◽  
Susanne Beischer ◽  
Roland Thomée ◽  
...  
Keyword(s):  
Muscle Strength ◽  
Acl Reconstruction ◽  
Cruciate Ligament ◽  
Peak Torque ◽  
Knee Extension ◽  
Ethical Review ◽  
Psychological Traits ◽  
Patient Reported ◽  
Strength Tests ◽  
Healthy Knee

Abstract BackgroundThe recovery of muscle function after an Anterior Cruciate Ligament (ACL) reconstruction is most commonly reported as limb-to-limb differences using the Limb Symmetry Index (LSI), which is not free from limitations. The purpose of this study was to compare the proportion of patients who recover their Preoperative Absolute Muscle Strength (PAMS) 8 and 12 months after ACL reconstruction with the proportion of patients who recover their symmetrical knee strength. A secondary aim was to assess the relationship between psychological Patient-Reported Outcomes (PROs) and recovering PAMS at 8 and 12 months after ACL reconstruction and rehabilitation.MethodPreoperative, 8- and 12-month results from quadriceps and hamstring strength tests and PROs for 117 patients were extracted from a rehabilitation registry. Individual preoperative peak torques from strength tests were compared with results from the 8- and 12-month follow-ups respectively. Patients were defined as having recovered their PAMS upon reaching 90% of their preoperative peak torque for both quadriceps and hamstring strength. Patients were defined as having recovered their LSI upon reaching a value ≥ 90% when comparing the results for their injured knee with those of their healthy knee. Correlations between the recovery of PAMS and PROs at 8 and 12 months were analyzed.ResultsThere was no difference in the proportion of patients who recovered their PAMS compared with patients who recovered their LSI. In all, 30% and 32% of the patients who recovered their LSI had not recovered their PAMS at 8 months and 12 months respectively. In the patients who had recovered their PAMS, 24% and 31% had not recovered their symmetrical LSI at 8 months and 12 months respectively. There was no significant correlation between the recovery of PAMS and psychological PROs. ConclusionThe use of both PAMS and LSI provides more detailed information on the recovery of muscle strength after ACL reconstruction. The recovery of PAMS was not correlated with psychological traits, which implies that both PROs and PAMS are important when evaluating patients after ACL reconstruction.Trial RegistrationEthical approval has been obtained from the Regional Ethical Review Board in Gothenburg, Sweden (registration numbers: 265-13, T023-17).

What Determines the Magnitude of the Q Angle? A Preliminary Study of Selected Skeletal and Muscular Measures

2000 ◽  
Vol 9 (1) ◽  
pp. 26-34 ◽  
Author(s):  
Timo Byl ◽  
Jennifer A. Cole ◽  
Lori A. Livingston
Keyword(s):  
Outcome Measures ◽  
Peak Torque ◽  
Knee Extension ◽  
Quadriceps Strength ◽  
Femur Length ◽  
Q Angle ◽  
Preliminary Study ◽  
The Right ◽  
Knee Extension Exercise

Context:Q-angle size has been found to correlate poorly with skeletal measures of pelvic breadth and femur length. Because the patella is exposed to the forces of quadriceps contraction, muscular forces might also affect Q-angle magnitude.Objective:To compare bilateral measurements of the Q angle with selected skeletal and muscular strength measures.Design:In vivo study of anthropometric and quadriceps peak torque measures.Setting:Research laboratory.Participants:Thirty-four healthy men and women, mean age 20.9 ± 2.7 years.Main Outcome Measures:Q angles, pelvic breadths, femur lengths, and peak torque during dynamic knee-extension exercise, normalized to body weight.Results:Significant differences in Q-angle magnitude, femur length, and peak torqueBW were observed between sexes, but not between limbs. Pelvic breadth did not differ significantly between sexes. Correlational analysis revealed a weak, yet significant, linear relationship between Q angle and peak torqueBW in the right lower limb.Conclusions:These findings lend some support to the notion that Q-angle magnitude is inversely related to quadriceps strength.

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