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Background and Aim: Muscular fatigue is common problem that an athlete faces repeatedly during sport competition or therapeutic exercise. Undoubtedly¸ fatigue affects the precision of subjects’ performance and limits the range of physical and sport activities. Muscle fatigue advantages and disadvantages have been reviewed in many previous studies. To challenge this controversy fatigue evaluation requires reliable, stable and precise methods of analysis itself. Researches on muscle strength and subject’s perception of fatigue have been done in many studies. Therefore researchers in this study focus on temporal stability of both subjective perception of fatigue and produced muscle torque after fatigue.
Materials and methods: Fifteen healthy female between 20-30 years of age, who at least had some nonprofessional light sporting activities once a week, volunteered in this research. Each of volunteers was evaluated in 3 different sessions. The first session was to familiarize the volunteers with the Isokinetic tests. For the main test, each of the volunteers was evaluated once and then after one week interval. At each session after warm up, perceived fatigue was measured using Visual Analog Scale. Then Average peak torque and average power maximal concentric Isokinetic of quadriceps were measured at the velocity of 60 degrees per second. To perform the fatigue protocol, subjects were asked to perform successive maximal quadriceps contractions until the three subsequent quadriceps torque output drop below 50 percent of maximal torque output. Afterwards, for re-measurement average peak torque, average power and perceived fatigue were evaluated similarly.
Results: The interaclass correlation coefficient (ICC) of average peak torque¸ average power and visual analog scale before performing fatigue protocol were calculated %81.6, %87.4 and %47.9 respectively. The repeated ICC after fatigue has estimated %59.9 ¸%64.4 and %96.6 respectively.
Conclusion: This research demonstrated that Isokinetic temporal stability parameters were high before fatigue. In other words, both torque and power are reliable in two repetition times in a session, as well after one week interval between. After fatigue the stability rate of torque and power recorded by Isokinetic were repeatable and this repeatability has been moderate to high. However VAS showed a completely opposite results, in which before fatigue the stability of imagined local fatigue perception has been very low and was not significant, although after fatigue the VAS showed high repeatability.

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Background and aim: Knee joint has a major role in various lower extremity activities. Among different elements of knee joint complex more interest was seen to anterior cruciate ligament because of its alignment, structural complications, more nerve receptors and susceptibility to injury. After injury of this ligament, knee extensor torque decreases but it is believed that this decrease compensated for by muscles of hip and ankle joints. This suggestion has not investigated by isokinetic studies. Therefore, the aim of this research was that if quadriceps muscle torque decreases in spite of rehabilitation process and if this decrease compensated for by hip extensors and ankle plantar flexors?

Materials and methods: 10 healthy men (age: 22-35 years old) and 10 patients with ACL deficiency (age: 23-42 years old) participated in this study. Plantar flexor muscle strength, quadriceps muscle strength and hip extensor muscle strength were tested by Isokinetic Biodex System 3 at 60 and 180 degrees of angular velocities. Also functional vertical jump test was done for each lower extremity.
Results: Will coxson test and Spearman correlation coefficient were used. Results showed that there was no significant difference between mean strength of gastrosoleus, hip extensors and sum of mean strength of gastrosoleus, quadriceps and hip extensors of patient's injured and sound limbs (P>0.05). Results showed that there was significant difference between mean strength of quadriceps of injured and sound limbs (P> 0.01). There was no relationship between gastrosoleus, quadriceps and hip extensor summation and vertical jump functional test in the patients and normal subjects (P>0.05).
Conclusion: The results show that compensation occurs in the ankle plantar flexors and hip extensors of injured lower extremity. Thus in spite of significant decrease in quadriceps strength in the injured limb, sum of mean strength of gastrosoleus, quadriceps and hip extensor muscles between injured and sound limbs was not statistically significant. Also there was no relationship between functional test and isokinetic parameters. Thus functional vertical jump test can not be used instead of isokinetic test.

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Abstract

Background and Aim: Patients with anterior cruciate ligament (ACL) deficiency are divided to coper and noncoper groups. The purpose of this study was to compare the efficacy of perturbation training with traditional rehabilitation on functional tests of lower extremity and knee muscles isokinetic peak torque ratio in two groups of patients with ACL-deficient: coper and noncoper

Materials and Methods: In this clinical trial study, 24 patients with ACL-deficient were divided to two groups: coper and noncoper. They participated in a management plan for 4 weeks, three times a week, including perturbation exercises and traditional rehabilitation (stretching, strengthening, and endurance exercises). Lower extremity functional tests through hop tests and knee muscles isokinetic peak torque ratio were evaluated.

 Results: After 4 weeks, all the functional tests improved significantly in both groups and timed 6-meter hop test showed significant improvement in coper group with respect to noncoper grouop (p< 0.05). There was no significant difference between two groups in knee flexors to extensors isokinetic peak torque ratio but this ratio was lower and close to normal values in coper group.

Conclusion: Perturbation training with traditional rehabilitation improves functional abilities of lower extremity in both groups of coper and noncoper of the patients with ACL-deficient. Probably, the patients of noncoper ACL-deficient have chance to return in some daily activities too.

Keywords: anterior cruciate ligament, perturbation training, functional tests, knee isokinetic peak torque

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Background and Aim : The tracking tests are a known method to measure and quantify the performance of the neuromuscular system. They are also one of the accurate and flexible methods for measurement of the performance capacity of sensory-motor control or sensory-motor coordination. The purpose of the present study was to examine reliability of the torque error during trajectory tracking tasks in trunk region in torque-time plane in healthy subjects.

  

Materials and Methods: Twenty healthy subjects (7 female and 13 male) randomly performed target tracking tasks with two patterns (sinusoidal and saw shape). The sinus and saw tracking tasks had two periodic cycles included 10 seconds (3 cycles) and 15 seconds (2 cycles). The amplitude of the signal was set at about 30% to 70% of Maximum Voluntary Exertions (MVE) of each participant. The tracking tasks were performed in 6 directions of uniaxial exertion (flexion, extension, left and right rotation, and left and right lateral bending). Absolute error mean and the performance of the tracking task were determined by calculating Relative Root Mean Square Error (RRMSE) for each participant during each trial. Relative reliability (Intraclass Correlation Coefficient: ICC) of the error mean and RRMSE for all participants was determined. Also absolute reliability (Standard Error of Measurement: SEM) and Minimal Detected Change ( MDC₉₅ ) were computed.

  

Results: The results have shown that ICC, SEM and MDC₉₅ for error mean ranged from 0.5 to 0.87, 0.002 to 0.006 and 0.007 to 0.016, respectively. Also these variables for RRMSE ranged between 0.5- 0.86, 0.05- 0.024 and 0.065- 0.139, respectively.

  

Conclusion: The repeatability analysis showed high and very high reliability for torque errors ( Error Mean, RRMSE ) measures during trajectory tracking tasks in torque time plane in asymptomatic subjects. Therefore this performance can be used for quantification of trunk controllability and also mentioned variables as reliable parameters in researches.

  

Keywords: Reliability, Trajectory tracking tests, Torque error, Isometric trunk exertion