Recovery of Contractile Properties of the Knee-Extensor Muscles after Arthroscopic Partial Meniscectomy

2001 ◽  
Vol 10 (4) ◽  
pp. 298-307 ◽  
Author(s):  
Helena Gapeyeva ◽  
Mati Pääsuke ◽  
Jaan Ereline ◽  
Vallo Vaher ◽  
Aivar Pintsaar ◽  
...  
Keyword(s):  
Outcome Measures ◽  
Repeated Measures ◽  
Knee Extensor ◽  
Voluntary Contraction ◽  
Partial Meniscectomy ◽  
Extensor Muscle ◽  
Knee Extensors ◽  
Arthroscopic Partial Meniscectomy ◽  
Voluntary Strength ◽  
Contractile Characteristics

Context:Contractile characteristics of the knee extensors after arthroscopic meniscectomy are poorly understood.Objective:To measure the recovery of knee-extensor-muscle contractility after arthroscopic partial meniscectomy.Design:Single-group repeated measures.Setting:Kinesiology and biomechanics laboratory.Subjects:Fourteen patients with arthroscopic partial medial meniscectomies.Main Outcome Measures:Maximal isometric voluntary contraction (MVC) force, rate of force development (MRFDES), and half-relaxation time (HRTES) of evoked tetanic contraction preoperatively and during 6 months postoperatively.Results:Two weeks postoperatively, a reduction in MVC force of 27.1% and in MRFDESof 17.8% and a prolongation of HRTESof 34.0% in the injured leg were found. A significant MVC-force deficit (17.5%) was observed 3 months postoperatively.Conclusions:The recovery of knee-extensor-muscle voluntary strength is more delayed than are evoked tetanic-contractile characteristics after partial meniscectomy. The rehabilitation protocol seems to be insufficient to attain effective recovery of knee-extensor-muscle voluntary strength.

Posttetanic Potentiation in Knee Extensors after High-Frequency Submaximal Percutaneous Electrical Stimulation

2005 ◽  
Vol 14 (3) ◽  
pp. 249-257 ◽  
Author(s):  
Bernardo Requena ◽  
Jaan Ereline ◽  
Helena Gapeyeva ◽  
Mati Pääsuke
Keyword(s):  
Electrical Stimulation ◽  
High Frequency ◽  
Repeated Measures ◽  
Knee Extensor ◽  
Voluntary Contraction ◽  
Knee Extensors ◽  
Posttetanic Potentiation ◽  
Tetanic Contraction ◽  
Before And After ◽  
Human Muscles

Context:The understanding of posttetanic potentiation (PTP) in human muscles induced by percutaneous electrical stimulation (PES) is important for effective application of electrical stimulation in rehabilitation.Objective:To examine the effect of 7-second high-frequency (100-Hz) submaximal (25% of maximal voluntary contraction force) direct PES on contractile characteristics of the knee-extensor (KE) muscles.Design:Single-group repeated measures.Setting:Kinesiology laboratory.Subjects:13 healthy men age 18–27 years.Measurement:Peak force (PF), maximal rates of force development (RFD) and relaxation (RR) of supramaximal twitch, and PF of doublet and 10-Hz tetanic contractions before and after direct tetanic PES.Results:A significant potentiation of twitch, doublet, and 10-Hz tetanic-contraction PF has been observed at 1–5 minutes posttetanic. Twitch RFD and RR were markedly potentiated throughout the 10-minute posttetanic period.Conclusions:A brief high-frequency submaximal tetanic PES induces PTP in KE muscles associated with small increase at 1–5 minutes.

scholarly journals Hyperthermia and central fatigue during prolonged exercise in humans

2001 ◽  
Vol 91 (3) ◽  
pp. 1055-1060 ◽  
Author(s):  
Lars Nybo ◽  
Bodil Nielsen
Keyword(s):  
Core Temperature ◽  
Maximal Oxygen Consumption ◽  
Knee Extensor ◽  
Central Fatigue ◽  
Knee Extension ◽  
Voluntary Contraction ◽  
Voluntary Activation ◽  
Knee Extensors ◽  
Total Force ◽  
Impaired Performance

The present study investigated the effects of hyperthermia on the contributions of central and peripheral factors to the development of neuromuscular fatigue. Fourteen men exercised at 60% maximal oxygen consumption on a cycle ergometer in hot (40°C; hyperthermia) and thermoneutral (18°C; control) environments. In hyperthermia, the core temperature increased throughout the exercise period and reached a peak value of 40.0 ± 0.1°C (mean ± SE) at exhaustion after 50 ± 3 min of exercise. In control, core temperature stabilized at ∼38.0 ± 0.1°C, and exercise was maintained for 1 h without exhausting the subjects. Immediately after the cycle trials, subjects performed 2 min of sustained maximal voluntary contraction (MVC) either with the exercised legs (knee extension) or with a “nonexercised” muscle group (handgrip). The degree of voluntary activation during sustained maximal knee extensions was assessed by superimposing electrical stimulation (EL) to nervus femoralis. Voluntary knee extensor force was similar during the first 5 s of contraction in hyperthermia and control. Thereafter, force declined in both trials, but the reduction in maximal voluntary force was more pronounced in the hyperthermic trial, and, from 30 to 120 s, the force was significantly lower in hyperthermia compared with control. Calculation of the voluntary activation percentage (MVC/MVC + EL) revealed that the degree of central activation was significantly lower in hyperthermia (54 ± 7%) compared with control (82 ± 6%). In contrast, total force of the knee extensors (MVC + force from EL) was not different in the two trials. Force development during handgrip contraction followed the same pattern of response as was observed for the knee extensors. In conclusion, these data demonstrate that the ability to generate force during a prolonged MVC is attenuated with hyperthermia, and the impaired performance is associated with a reduction in the voluntary activation percentage.

Improvement of Outcomes With Nonconcurrent Strength and Cardiovascular-Endurance Rehabilitation Conditioning After ACI Surgery to the Knee

2014 ◽  
Vol 23 (3) ◽  
pp. 235-243 ◽  
Author(s):  
Andrea Kay Bailey ◽  
Claire Minshull ◽  
James Richardson ◽  
Nigel P. Gleeson
Keyword(s):  
Outcome Measures ◽  
Repeated Measures ◽  
International Knee Documentation Committee ◽  
Knee Extensors ◽  
Electromechanical Delay ◽  
Cardiovascular Endurance ◽  
Patient Reported ◽  
Chondrocyte Implantation ◽  
Hop Test ◽  
Single Leg Hop Test

Context:Autologous chondrocyte implantation (ACI) aims to restore hyaline cartilage. Traditionally, ACI rehabilitation is prescribed in a concurrent (CON) format. However, it is well known from studies in asymptomatic populations that CON training produces an interference effect that can attenuate strength gains. Strength is integral to joint function, so adopting a nonconcurrent (N-CON) approach to ACI rehabilitation might improve outcomes.Objective:To assess changes in function and neuromuscular performance during 48 wk of CON and N-CON physical rehabilitation after ACI to the knee.Setting:Orthopedic Hospital NHS Foundation Trust.Design:Randomized control, pilot study.Participants:11 patients (9 male, 2 female; age 32.3 ± 6.6 y; body mass 79.3 ±10.4 kg; time from injury to surgery 7.1 ± 4.9 mo [mean ± SD]) randomly allocated to N-CON:CON (2:1).Interventions:Standardized CON and N-CON physiotherapy that involved separation of strength and cardiovascular-endurance conditioning.Main Outcome Measures:Function in the single-leg-hop test, patient-reported outcomes (Knee injury and Osteoarthritis Outcome Score [KOOS], International Knee Documentation Committee subjective questionnaire [IKDC]), and neuromuscular outcomes of peak force (PF), rate of force development (RFD), electromechanical delay (EMD), and sensorimotor performance (force error [FE]) of the knee extensors and flexors of the injured and noninjured legs, measured presurgery and at 6, 12, 24, and 48 wk postsurgery.Results:Factorial ANOVAs with repeated measures of group by leg and by test occasion revealed significantly superior improvements for KOOS, IKDC, PF, EMD, and FE associated with N-CON vs CON rehabilitation (F1.5,13.4 GG = 3.7−4.7, P < .05). These results confirm increased peak effectiveness of N-CON rehabilitation (~4.5−13.3% better than CON over 48 wk of rehabilitation). N-CON and CON showed similar patterns of improvement for single-leg-hop test and RFD.Conclusions:Nonconcurrent strength and cardiovascular-endurance conditioning during 48 wk of rehabilitation after ACI surgery elicited significantly greater improvements to functional and neuromuscular outcomes than did contemporary concurrent rehabilitation.

scholarly journals Neuromuscular factors contributing to in vivo eccentric moment generation

1997 ◽  
Vol 83 (1) ◽  
pp. 40-45 ◽  
Author(s):  
Sandra Webber ◽  
Dean Kriellaars
Keyword(s):  
Linear Relationship ◽  
Knee Extensor ◽  
Motor Units ◽  
Voluntary Contraction ◽  
Contractile Element ◽  
Knee Extensors ◽  
Activation Level ◽  
In Series

Webber, Sandra, and Dean Kriellaars. Neuromuscular factors contributing to in vivo eccentric moment generation. J. Appl. Physiol. 83(1): 40–45, 1997.—Muscle series elasticity and its contribution to eccentric moment generation was examined in humans. While subjects [male, n = 30; age 26.3 ± 4.8 (SD) yr; body mass 78.8 ± 13.1 kg] performed an isometric contraction of the knee extensors at 60° of knee flexion, a quick stretch was imposed with a 12°-step displacement at 100°/s. The test was performed at 10 isometric activation levels ranging from 1.7 to 95.2% of maximal voluntary contraction (MVC). A strong linear relationship was observed between the peak imposed eccentric moment derived from quick stretch and the isometric activation level ( y = 1.44 x + 7.08; r = 0.99). This increase in the eccentric moment is consistent with an actomyosin-dependent elasticity located in series with the contractile element of muscle. By extrapolating the linear relationship to 100% MVC, the predicted maximum eccentric moment was found to be 151% MVC, consistent with in vitro data. A maximal voluntary, knee extensor strength test was also performed (5–95°, 3 repetitions, ±50, 100, 150, 200, and 250°/s). The predicted maximum eccentric moment was 206% of the angle- and velocity-matched, maximal voluntary eccentric moments. This was attributed to a potent neural regulatory mechanism that limits the recruitment and/or discharge of motor units during maximal voluntary eccentric contractions.

Changes in Isokinetic Muscle Strength of the Lower Extremity in Recreational Athletes with Anterior Cruciate Ligament Reconstruction

2002 ◽  
Vol 11 (4) ◽  
pp. 252-267 ◽  
Author(s):  
Yukio Urabe ◽  
Mitsuo Ochi ◽  
Kiyoshi Onari
Keyword(s):  
Muscle Strength ◽  
Lower Extremity ◽  
Acl Reconstruction ◽  
Outcome Measures ◽  
Repeated Measures ◽  
Whole Body ◽  
Knee Extensors ◽  
Joint Movement ◽  
Isokinetic Muscle Strength ◽  
Dependent Variables

Objective:To investigate changes in muscle strength in the lower extremity after ACL reconstruction.Design:Prospective case series.Dependent Variables:Isokinetic muscle strength measured in 6 movements (hip extension/flexion, hip adduction/abduction, knee extension/flexion) and circumference of the thigh/calf.Setting:Clinic and home.Patients:44 (24 men, 20 women) between the ages of 16 and 47 years with an ACL rupture. All underwent reconstruction via a semitendinosus autograft.Main Outcome Measures:The peak torque for each joint movement was recorded. Repeated-measures ANOVA and power analysis were conducted to detect significant interaction effects.Results:The decline of muscle strength after ACL reconstruction remained not only in the knee extensors and flexors but also in the hip adductors.Conclusion:Rehabilitation programs that address the behavioral patterns and physiological characteristics of an ACL injury will benefit the athlete’s whole body and lead to a full recovery.

scholarly journals A Biomechanical Investigation of A Single-Limb Squat: Implications for Lower Extremity Rehabilitation Exercise

2008 ◽  
Vol 43 (5) ◽  
pp. 477-482 ◽  
Author(s):  
Jim Richards ◽  
Dominic Thewlis ◽  
James Selfe ◽  
Andrew Cunningham ◽  
Colin Hayes
Keyword(s):  
Repeated Measures ◽  
Knee Flexion ◽  
Knee Extensor ◽  
Rectus Femoris ◽  
Knee Extensors ◽  
Emg Activity ◽  
Repeated Measures Design ◽  
Biomechanical Investigation ◽  
Rehabilitative Intervention ◽  
Integrated Emg

Abstract Context: Single-limb squats on a decline angle have been suggested as a rehabilitative intervention to target the knee extensors. Investigators, however, have presented very little empirical research in which they have documented the biomechanics of these exercises or have determined the optimum angle of decline used. Objective: To determine the involvement of the gastrocnemius and rectus femoris muscles and the external ankle and knee joint moments at 60° of knee flexion while performing a single-limb squat at different decline angles. Design: Participants acted as their own controls in a repeated-measures design. Patients or Other Participants: We recruited 10 participants who had no pain, injury, or neurologic disorder. Intervention(s): Participants performed single-limb squats at different decline angles. Main Outcome Measure(s): Angle-specific knee and ankle moments were calculated at 60° of knee flexion. Angle-specific electromyography (EMG) activity was calculated at 60° of knee flexion. Integrated EMG also was calculated to determine the level of muscle activity over the entire squat. Results: An increase was seen in the knee moments (P &lt; .05) and integrated EMG in the rectus femoris (P &lt; .001) as the decline angle increased. A decrease was seen in the ankle moments as the decline angle increased (P  =  .001), but EMG activity in the gastrocnemius increased between 16° and 24° (P  =  .018). Conclusions: As the decline angle increased, the knee extensor moment and EMG activity increased. As the decline angle increased, the ankle plantar-flexor moments decreased; however, an increase in the EMG activity was seen with the 24° decline angle compared with the 16° decline angle. This indicates that decline squats at an angle greater than 16° may not reduce passive calf tension, as was suggested previously, and may provide no mechanical advantage for the knee.

Effects of caffeine on neuromuscular function

1999 ◽  
Vol 87 (2) ◽  
pp. 801-808 ◽  
Author(s):  
J. M. Kalmar ◽  
E. Cafarelli
Keyword(s):  
Repeated Measures ◽  
Isometric Force ◽  
Neuromuscular Function ◽  
Voluntary Contraction ◽  
Voluntary Activation ◽  
Knee Extensors ◽  
Double Blind ◽  
Twitch Interpolation ◽  
Motor Unit Firing ◽  
The Right

This double-blind, repeated-measures study examined the effects of caffeine on neuromuscular function. Eleven male volunteers [22.3 ± 2.4 (SD) yr] came to the laboratory for control, placebo, and caffeine (6 mg/kg dose) trials. Each trial consisted of 10 × 1-ms stimulation of the tibial nerve to elicit maximal H reflexes of the soleus, four attempts at a maximal voluntary contraction (MVC) of the right knee extensors, six brief submaximal contractions, and a 50% MVC held to fatigue. Isometric force and surface electromyographic signals were recorded continuously. The degree of maximal voluntary activation was assessed with the twitch-interpolation technique. Single-unit recordings were made with tungsten microelectrodes during the submaximal contractions. Voluntary activation at MVC increased by 3.50 ± 1.01 (SE) % ( P < 0.01), but there was no change in H-reflex amplitude, suggesting that caffeine increases maximal voluntary activation at a supraspinal level. Neither the force-EMG relationship nor motor unit firing rates were altered by caffeine. Subjects were able to hold a 50% MVC for an average of 66.1 s in the absence of caffeine. Time to fatigue (Tlim) increased by 25.80 ± 16.06% after caffeine administration ( P < 0.05). There was no significant change in Tlim from pretest to posttest in the control or placebo trials. The increase in Tlim was associated with an attenuated decline in twitch amplitude, which would suggest that the mechanism is, at least in part, peripheral.

scholarly journals Joint Flexibility and Isometric Strength Parameters Are Not Relevant Determinants for Countermovement Jump Performance

2021 ◽  
Vol 18 (5) ◽  
pp. 2510
Author(s):  
Andreas Konrad ◽  
Marina Maren Reiner ◽  
Daniel Bernsteiner ◽  
Christoph Glashüttner ◽  
Sigrid Thaller ◽  
...  
Keyword(s):  
Range Of Motion ◽  
Maximum Voluntary Contraction ◽  
Knee Extensor ◽  
Voluntary Contraction ◽  
Knee Extensors ◽  
Plantar Flexors ◽  
Countermovement Jump ◽  
Jump Performance ◽  
Leg Muscles ◽  
Knee Flexors

Vertical jumps are of great importance as a performance predictor for many types of sports that require speed and agility. However, to date, it is not clear if flexibility and/or the strength of the different leg muscles are determinants for countermovement jump (CMJ) performance. Therefore, the purpose of this study was to relate isometric maximum voluntary contraction (MVC) torque and the flexibility of various muscle groups of the lower body with CMJ performance. Thirty-six healthy male volunteers participated in this study. The participants performed MVCs of the knee extensors, knee flexors, and plantar flexors on a dynamometer. Moreover, range of motion of the hip flexors and plantar flexors was assessed with 3D motion capture, and the range of motion of the knee flexors (hamstrings) was assessed with a Sit n’ Reach® box. CMJs were assessed with a force platform. The correlation analysis revealed a significant moderate correlation of CMJ height with the flexibility of the hip flexors (rP = −0.39) and plantar flexors (rP = 0.47), but not the knee flexors. Moreover, we found that absolute MVC values are not related to CMJ height. However, we did find that knee extensor MVC relative to body mass is significantly related to CMJ height (rP = 0.33) with a moderate magnitude. Although we found significant correlations, the magnitudes of correlations vary between trivial and large according to a 90% confidence interval. Thus, this indicates that range of motion or strength of the assessed leg muscles can explain CMJ performance only to a limited extent.

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