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Helena Gapeyeva, Mati Pääsuke, Jaan Ereline, Vallo Vaher, Aivar Pintsaar, and Aalo Eller

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 MRFDES of 17.8% and a prolongation of HRTES of 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.

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Bernardo Requena, Jaan Ereline, Helena Gapeyeva, and Mati Pääsuke

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.

Open access

Tomohiro Yasuda

than in the upper limbs (18–88 y 4 ; 20–89 y 5 ). In addition, recent studies have revealed that sarcopenia is muscle specific and that greater knee extensor muscle loss is found in older adults. 6 – 8 Therefore, periodic assessment of knee extensor muscle strength and size is important for all ages

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Jocelyn F. Hafer, Mark S. Miller, Jane A. Kent, and Katherine A. Boyer

-related decline in knee extensor strength and power compared with males. 4 , 14 , 18 , 19 This sex-specific difference in age-related knee extensor decline could be problematic as these muscles are important for stance phase support and propulsion during locomotion. 20 In addition to a sex-specific difference

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Rachel K. Straub, Alex Horgan, and Christopher M. Powers

extensor moments increases load on the patellar tendon, 15 patellofemoral joint, 16 and the anterior cruciate ligament (ACL). 17 , 18 In addition, high knee extensor moments have been found to predict ACL injury. 10 , 12 Females have been reported to favor use of the knee extensors over the hip

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Nobuaki Tottori, Tadashi Suga, Yuto Miyake, Ryo Tsuchikane, Mitsuo Otsuka, Akinori Nagano, Satoshi Fujita, and Tadao Isaka

, previous studies have shown that a larger quadriceps femoris (QF) may be related to higher sprint performance because of a strong correlation between maximal knee extensor torque and sprint performance ( 4 , 10 , 13 , 21 ). Furthermore, Sugisaki et al ( 34 ) reported that a larger CSA of the adductors (ADD

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Rachel K. Straub, Adam J. Barrack, Jordan Cannon, and Christopher M. Powers

unknown what level of loading is injurious to the knee, previous studies have shown that squatting with the knees forward of the toes (ie, forward shank position) increases the knee-extensor moment (KEM). 1 – 3 Squatting in a way that results in higher KEMs can result in increased patellofemoral joint

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Jocelyn F. Hafer and Katherine A. Boyer

Aging is associated with declining strength, 1 , 2 a downward shift in muscle torque–velocity characteristics, 3 slowing gait speed, 4 , 5 and changes in gait mechanics. 6 In particular, strength or power of the knee extensor muscles correlates with walking speed 4 , 7 , 8 and mobility

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Matt Greig

. 12 Previous research has demonstrated a fatigue effect on muscular strength of the knee extensors, 13 , 14 which might subsequently affect kicking technique and performance. During the soccer kick, the foot rotates about both the mediolateral and longitudinal axes of the body and several mechanisms

Open access

Ling Zhang, Shao-bai Wang, Shuai Fan, Jiling Ye, and Bin Cai

be conducted by physiotherapists. Knee motion during functional activities has also been reported to be related to knee extensor strength after ACL reconstruction. 10 Wang et al 11 hypothesized that PFJ cartilage damage might be related to the recovery of quadriceps strength after ACL