RESUMEN

Electromyography (EMG) was used to study the role of antagonist cocontraction of the quadriceps muscles of 24 normal subjects during constant velocity muscle performance tests on a KIN/COM dynamometer. The hypothesis tested the dependence of antagonist cocontraction on joint angle, limb velocity and type of contraction. Seated subjects performed two dynamic tests of resisted muscle shortening and lengthening of the knee flexors through a 65 degrees range of knee motion under two constant velocity conditions in a single session. Each test consisted of four repetitions of maximum voluntary contractions (MVC) of constant velocity muscle shortening and lengthening of the knee flexors; one test was performed at 30 degrees s(-1), the other at 90 degrees s(-1). The sequence of velocity testing was randomized. Normalized (%Max) values of peak amplitude EMG of knee extensors were measured every 5 degrees in the constant velocity phase of each test and compared in a paired manner for each angle, contraction type and velocity, by split-plot two-way analysis of variance (ANOVA). The level of antagonist quadriceps cocontraction was low, ranging from 5-8% Max between 70 degrees and 15 degrees of knee flexion for both velocities and contraction types. Antagonist quadriceps activity was found to be velocity dependent during agonist muscle shortening (P < 0.02). However, no other effects of angle, contraction type, or velocity were found for antagonist quadriceps. It is concluded that antagonist quadriceps and the previously reported hamstrings(46) respond differently under typical constant velocity test conditions, and these differences need to be accounted for when intepreting muscle performance tests.

RESUMEN

Electromyography (EMG) was used to study the role of antagonist cocontration of the hamstring muscles of 24 normal subjects during constant velocity muscle performance tests on a KIN COM (™) dynamometer. The hypothesis tests whether antagonist cocontraction varies dependent on joint angle, limb velocity, and type of contraction. Seated subjects performed two dynamic tests of resisted quadriceps muscle shortening and lengthening through a 65° range of knee motion under two constant velocity conditions in a single session. Each test consisted of four repetitions of maximum effort constant velocity muscle shortening and lengthening of the knee extensors; one test performed at 30° s(-1), the other at 90° s(-1). The sequence of velocity testing was randomized. Normalized values of peak amplitude EMG of knee flexors were measured every 5° in the constant velocity phase of each test and compared in a paired manner between each angle, contraction type, and velocity, by split-plot 2-way ANOVA. Antagonist hamstrings cocontraction was found to be contraction type, and velocity dependent. Cocontraction was greater at larger angles of knee flexion and at higher velocity. These results do not support the hypothesis that such activity is a function of muscle moment-arm, but are consistent with the idea that antagonist muscle function is controlled by muscle spindles and perhaps Golgi tendon organs. Because antagonist cocontraction ranged up to a mean of 32% of maximum agonist activity in normal individuals, it should be taken into consideration when interpreting clinical muscle performance tests.

RESUMEN

The test-retest reliability of a specific test protocol for the measurement of peak torque of the knee flexors using a Kin/Com dynamometer was evaluated. The maximum voluntary torque generated by the left knee flexors during constant velocity resisted-muscle shortening (RMS) and muscle lengthening (RML) was measured in a sitting position in 11 healthy women with no history of knee pathology. Each subject performed two tests at each of two velocities (30 degrees/sec and 180 degrees/sec) in a single session. All subjects repeated these four tests one week later. A test consisted of four complete RMS/RML cycles through a range of 65 degrees. The peak torque generated from each test was used to measure test-retest reliability. All data were gravity compensated. Intraclass correlation coefficients (ICCs) were calculated from ANOVA tests for RML and RMS at both velocities. The within sessions ICCs ranged from .94 to .98 for 30 degrees/sec and from .92 to .97 at 180 degrees/sec. The ICCs between sessions were generally lower and ranged from .79 to .90 for 30 degrees/sec, and from .75 to .88 for 180 degrees/sec. It is concluded that using these test protocols, peak torques for both RMS and RML can be measured with a high degree of reliability at two commonly used velocities.

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RESUMEN

This study investigated the effectiveness of videotaped versus written discharge summaries in communicating patient information to rural physiotherapists. Twenty-seven rural Manitoba physiotherapists were randomly divided into two groups and tested after viewing videotapes and reading written summaries on four patients with neurological conditions. Group I saw the videotapes on the four patients first, then answered multiple choice questions regarding the patients' problems, goals and treatment for physiotherapy. Group II read the written reports first, then answered the same questions. The process was then repeated in reverse order. A statistically significant difference existed between Group I's videotape scores and Group II's written summary scores (t = 4.69, 25 d.f., p = 0.002, 1-tailed unpaired t test). There was no significant difference between Group I and Group II's videotapes score. A rating scale of the videotapes by the physiotherapists strongly supported videotaped communication. This study has relevance to those who need to communicate patient information to health care workers in distant locales.

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RESUMEN

Walking ability and limb hemodynamics were studied in 56 patients with intermittent claudication in an exercise program. Patients walked 1 hour 3 times a week for 3 to 6 months. Ankle and brachial pressures were measured at rest and after a standard walk, and walking ability on the treadmill and during free walking was determined. Average maximal distance on the treadmill increased from 0.59 to 1.00 km after training (p less than 0.0001). Also, after training 84% of patients were able to walk continuously more than 2 km without severe discomfort. The attained walking ability of individual patients could not be predicted from pressure measurements. Small pressure changes after training suggested that factors other than increased development of collateral vessels were important in determining walking ability. Practically useful walking ability was achieved in patients with aortoiliac and femoropopliteal arterial obstruction in the presence or absence of coronary disease and in patients taking beta-blockers. The results indicate that walking exercise is a valuable treatment for many patients with claudication who are not candidates for arterial reconstruction.

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RESUMEN

Twenty-six ultrasound therapy devices in clinical use in Manitoba and Northwestern Ontario were tested for performance compliance with Canadian government standards of functioning. The performance characteristics measured were the temporal average acoustic power output, the electrical impulse frequency to the transducer, and the timer accuracy. Twenty-one of the 26 units (81%) had power levels which differed by more than +/- 20% of the indicated output, and only five units (19%) had all tested power levels within +/- 20% of the indicated output. Seven units (27%) had inaccurate timers, but only one unit (of the 13 tested) had an unacceptable frequency reading. This study supports the results of other investigations which have suggested that the majority of ultrasound therapy units in clinical use are in need of calibration. This situation needs to be corrected immediately if patients are to receive the prescribed doses of ultrasound radiation for treatment purposes both safely and effectively. Possible courses of action for rectifying these problems are discussed.

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