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Robson Dias Scoz, Cesar F. Amorim, Bruno O.A. Mazziotti, Rubens A. Da Silva, Edgar R. Vieira, Alexandre D. Lopes and Ronaldo E.C.D. Gabriel

Some authors have studied isokinetic test’s ability to detect signs of ACL total rupture before a total ACL reconstruction surgery. 12 , 14 – 22 The main reasons for those investigations were to test the stability of the knee joint dynamically, eliminating or at least reducing the subjectivity

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Robert C. Manske, Barbara Smith and Frank Wyatt

Context:

Athletes are often examined for return to sports using a functional-testing algorithm. No research has determined whether a closed kinetic chain (CKC) isokinetic testing bout influences the reliability of functional tests.

Objective:

To determine whether a concentric CKC isokinetic test bout alters test–retest reliability of lower extremity functional testing.

Design:

Subjects participated in velocity-spectrum CKC isokinetic bouts on 2 days 1 week apart.

Setting:

Hospital-based clinic.

Participants:

28 normal subjects (mean age 26.7 years, height 27.2 cm, weight 75.8 kg).

Analysis and Results:

Means and SDs were determined. Intraclass correlation coefficients were used to calculate test–retest reliability and between days 1 and 2 ranged from .91 to .98.

Conclusions:

Even after a CKC isokinetic test bout, test–retest reliability of functional tests is very high. Future research should determine test–retest reliability of functional tests for patients with lower extremity pathology.

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John P. Miller, Kerriann Catlaw and Robert Confessore

The purpose of this study was to examine the effect of ankle position on the electromyographic (EMG) activity, peak torque, and peak knee flexion to extension torque ratio during isokinetic testing of the knee. Twelve healthy female athletes performed six maximal knee extension and flexion repetitions with their dominant legs at 60 and 180°/s with the ankle in a plantar flexed position and again in a dorsiflexed position. Root mean square EMG (rmsEMG) activity was determined by placing bipolar surface electrodes on the quadriceps and the hamstrings. Ankle position had no effect on the rmsEMG activity of the quadriceps or the hamstrings at either 60 or 180°/s. Significant differences were noted for peak flexor torque at 607s (p < .001) and 180°/s (p <.01) and for peak torque flexor/extensor ratio (p < .01), with higher values observed with ankle dorsiflexion. This suggests that ankle position affects knee flexor torque and flexor/extensor ratio but not hamstring activity during isokinetic testing of the knee.

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Rodney Negrete and Jay Brophy

Objectives:

To determine (1) correlations between isokinetic lower extremity strength and functional performance and (2) correlations among different modes of isokinetic testing.

Design and Setting:

A correlational design with 6 measures. A series of strength, power, and agility tests was performed at a hospital-based outpatient physical therapy clinic.

Participants:

A volunteer sample of 29 male and 31 female, college-age subjects participated.

Measurements:

All subjects were tested in the following isokinetic tests: reciprocal leg press, single-leg squat, and knee extension. Performance tests included single-leg hop and vertical jump and a speed/agility test.

Results:

Analysis showed isokinetic knee extension, leg press, and single-leg squat strength significantly correlated to all functional tests. There were significant correlations among the 3 different isokinetic strength measures, as well.

Conclusions:

These results suggest a significant relationship between lower extremity open and closed chain isokinetic strength and functional performance testing.

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Sandro Venier, Jozo Grgic and Pavle Mikulic

a rowing ergometer test. Furthermore, our results indicate that caffeine in the form of chewing gum has an ergogenic effect on most measures of strength and power of the lower-body musculature, as assessed by the isokinetic testing at 2 angular velocities. These results only partially confirm our

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Pascal David, Mohamad Halimi, Isabelle Mora, Pierre-Louis Doutrellot and Michel Petitjean

Ankle sprains are among the most common sport-related injuries and can lead to chronic ankle instability. Impaired sensorimotor function of the ankle musculature is often suggested as a cause. The current study sought to assess and compare the isokinetic performance and electromyographic patterns of evertor and invertor muscles in patients with chronic ankle instability and in a control group. Twelve patients with chronic ankle instability and twelve healthy subjects were included. Isokinetic eccentric and concentric testing at various angular velocities was performed for eversion and inversion movements. The corresponding myoelectric activities of the fibularis longus and tibialis anterior muscles were quantified from surface electromyographic recordings by computing average root mean square values. Patients had lower myoelectric activity of the evertor and invertor muscles than controls did; this difference could account for the eccentric weakness associated with ankle instability. Functional strength ratios revealed a dynamic strength imbalance in unstable ankle patients and that may contribute to recurrent injury. Our findings suggest that rehabilitation programs for unstable ankle patients must be focused on the motor control of eccentric contractions of the ankle evertors and invertors, to boost these muscles’ contribution to ankle stabilization.

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Pekka Kannus, Lauren Cook and Denise Alosa

This study analyzed the normality and variability of the data outputs of isokinetic endurance parameters in 10 healthy men and 10 healthy women. The test consisted of 25 maximal reciprocal contractions of the hamstring and quadriceps muscles. In addition, half of the subjects underwent a 7-week training period after which the endurance test was repeated. The results showed that the consistency of the absolute endurance measurements (work performed during the last 5 repetitions [WL5] and total work during 25 repetitions [TW25] was equal to that of the reference parameter, the peak torque. In addition, the changes after 7 weeks training were very similar; values for all these parameters increased significantly. The relative endurance parameter (WL5/work during the first 5 repetitions) did not change due to training since both WL5 and WF5 improved approximately the same amount. In conclusion, the absolute measurements of muscular endurance can be recommended for clinical use, while the endurance index should not be used routinely.

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Gary B. Wilkerson

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Cale Jacobs and Carl Mattacola

Context:

Decelerating movements such as landing from a jump have been proposed to be a common mechanism of injury to the anterior cruciate ligament (ACL).

Objective:

To compare eccentric hip-abductor strength and kinematics of landing between men and women when performing a hopping task.

Setting:

Research laboratory.

Patients:

18 healthy subjects (10 women, 8 men).

Main Outcome Measures:

Eccentric peak torque of the hip abductors and peak knee-joint angles during a 350-millisecond interval after impact.

Results:

No significant sex differences were present, but there was a significant inverse relationship between women's eccentric peak torque and peak knee-valgus angle (r = –.61, P = .03).

Conclusions:

Women with larger eccentric peak torque demonstrated lower peak knee-valgus angles. By not reaching as large of a valgus angle, there is potentially less stress on the ACL. Increasing eccentric hip-abductor strength might improve knee-joint kinematics during landing from a jump.

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John E. Kovaleski, Robert J. Heitman, Damon P.S. Andrew, Larry R. Gurchiek and Albert W. Pearsall IV

Context:

Isokinetic strength and functional performance are used to assess recovery after rehabilitation. It is not known whether low-speed closed-linear-kinetic isokinetic muscle strength correlates with functional performance.

Objective:

To investigate the relationship between linear closed (CKC) and open (OKC) concentric isokinetic strength of the dominant lower-limb extensors and functional performance.

Design:

Correlational analysis.

Setting:

University laboratory.

Participants:

Thirty uninjured men and women (age = 20.9 ± 2.4 years).

Main Outcome Measures:

Peak CKC and OKC isokinetic strength and best score from a shuttle run for time, single-leg vertical jump, and single-leg hop for distance.

Results:

Neither lower-limb CKC nor OKC isokinetic strength measured at low speeds correlated highly with performance on the functional tasks of jumping, hopping, and speed/agility.

Conclusions:

Although the basis of both closed and open isokinetic strength must be appreciated, they should not be the only determinants of functional performance.