Journal of Orthopaedic & Sports Physical Therapy - Ray Burdett, PT, PhD

Reliability of lsokinetic Muscle Endurance Tests

Mon, 15 Sep 2008 00:00:00 EST

Ray Burdett, Jessie VanSwearingen
The reliabilities of two methods of measuring quadriceps endurance were tested at two speeds using the Cybex II®. These were the work ratio of the work done during the last 5 of 25 maximum contractions to the work done during the first five, and the number of contractions until peak torque fell below 50% of initial peak torque. The reliability of work ratio in measuring hamstring endurance was also tested. Thirty-six healthy young adults were tested twice at 180°/sec and twice at 240°/sec using both methods, with only one test per day and at least 2 days rest between tests. Test-retest correlation coefficients indicated that peak torque, absolute work, and average power were more reliable measurements than either endurance measurement, and that the number of contractions was more reliable in measuring muscle endurance than was the work ratio. These results suggest that the work ratio may not be a reliable method of measuring muscle endurance during rehabilitation.

J Orthop Sports Phys Ther 1987;8(10):484-488.

Effects of Muscle Group and Placement Site on Reliability of Hand-Held Dynamometry Strength Measurements

Tue, 09 Sep 2008 00:00:00 EST

Lori Mitchell McMahon, Ray Burdett, Susan L. Whitney
Studies of measuring muscle strength with hand-held dynamometers have produced a variety of results. The purpose of this research was to further investigate the effect of muscle group and placement site on reliability. The purpose of Part I of this study was to examine reliabilities of force measurements generated by four specific muscle groups using a hand-held dynamometer (HHD). Part II's purpose was to determine the effects of HHD placement site on the variability of HHD force measurements. In Part I, two testers obtained measurements of right shoulder abductor, wrist extensor, hip flexor, and ankle dorsiflexor forces in 20 subjects. Two-way analysis of variance indicated a main effect due to tester, but no tester by session interaction and no main effect due to session (p < 0.5). Intraclass correlation coefficients ranged from .76-.93 for within-session, intratester reliabilities, .67-.84, for between-session intratester reliabilities, and .30-.83 for within-session, intertester reliabilities. Reliability tended to be higher when HHD placement sites were farther from joint centers. Part II explored the hypothesis that HHD forces would be less variable if measured distally. One tester measured shoulder abductor forces for 30 subjects at three sites on the upper extremity. Bartlett's Test for homogeneity of variance indicated a lower variability at the distal placement site (p < 0.05).

J Orthop Sports Phys Ther 1992;15(5):236-242.

Key Words: muscle strength, reliability, hand-held dynamometer

Lower Extremity Muscular Flexibility in Long Distance Runners

Mon, 08 Sep 2008 00:00:00 EST

Sharon S. Wang, Susan L. Whitney, Ray Burdett, Janine E. Janosky
Muscle tightness is often considered to be a predisposing factor in muscle injuries. The purpose of this study was to assess the muscle flexibility of the hamstrings, rectus femoris, iliopsoas, gastrocnemius, and soleus muscles in long distance runners. Range of motion measurements of five movements, including hip flexion with knee extended, hip extension with knee flexed, hip extension with knee extended, ankle dorsiflexion with knee extended, and ankle dorsiflexion with knee flexed, were evaluated to determine muscle tightness. Twenty runners and 20 nonrunners volunteered for the study. Each group consisted of 10 males and 10 females. The observed means were compared between runners and nonrunners, males and females, plus the dominant and nondominant leg using a three-way analysis of variance. The runners were found to have tighter hamstrings (p < .05), and soleus (p < .05) muscles than nonrunners. There was no significant difference in rectus femoris and iliopsoas muscle tightness in runners compared with nonrunners. In addition, the males had tighter hamstring muscles than the females in both runners and nonrunners (p < .05). The hamstring muscles of the dominant leg were tighter than the hamstrings of the nondominant leg in all subjects (p < .05). In conclusion, long distance runners appear to have posterior muscle tightness in the lower extremity.

J Orthop Sports Phys Ther 1993;17(2):102-107.

Key Words: flexibility, running, joint motion

The Effects of Foot Orthotics on the EMG Activity of Selected Leg Muscles During Gait

Fri, 05 Sep 2008 00:00:00 EST

Joseph E. Tomaro, Ray Burdett
This study was supported in part by a student research grant from the School of Health Related Professions, University of Pittsburgh, Pittsburgh, PA.

Foot orthotics have been successfully used to treat muscular overuse leg injuries in athletes. The purpose of this study was to examine the effects of foot orthotics on the electromyographic (EMG) activity of the tibialis anterior, peroneus longus, and gastrocnemius muscles during walking. Ten volunteers with leg symptoms resulting from compensatory subtalar joint pronation were fitted with foot orthotics. The duration of tibialis anterior EMG activity following heel strike and the average EMG activity of the tibialis anterior, peroneus longus, and gastrocnemius muscles were collected with surface electrodes. Comparisons were made between the orthotic and nonorthotic conditions. A t-test for nonindependent samples with a significance level of p < 0.05 was used for data analysis. There was a statistically significant increase in the duration of tibialis anterior activity following heel strike in the orthotic condition. There were no significant differences in the average EMG activity for any of the three muscles between the orthotic and the nonorthotic conditions. This study suggests that foot orthotics had minimal effects on the muscles studied and that further research is necessary to determine the effectiveness of orthotics on the EMG activity of other leg muscles.

J Orthop Sports Phys Ther 1993;18(4):532-536.

Key Words: orthotics, electromyography, gait

Durkan Gauge and Carpal Compression Test: Accuracy and Diagnostic Test Properties

Mon, 05 Feb 2007 09:45:00 EST

Michael L. Boninger, Ganesh Balu, Ray Burdett, Wendy Helkowski, Robert S. Wainner

Study Design: A prospective, criterion-based validity study. Objectives: To assess the diagnostic properties of the carpal compression test (CCT) when performed with the Durkan carpal tunnel syndrome (CTS) gauge, and to determine the measurement validity of the gauge. Background: The CCT has been reported to be highly sensitive (.87-.89) and specific (.93-1.0) in the diagnosis of CTS when it is done with thumb pressure. The accuracy of measurements with the Durkan CTS gauge, however, has not been established and the diagnostic sensitivity and specificity of the CCT when the gauge is used has not been independently confirmed. Methods and Measures: The study sample included 33 women and 19 men, aged 18 to 85 years (45.7 ± 13.5 years). The accuracy of the gauge was determined with a force dynamometer and holding frame. Standard nerve conduction studies (NCS) and the CCT were performed on the symptomatic extremity of all subjects. A compatible history and the NCS results were used to confirm CTS. Results: The Durkan gauge registered pressures of 11.94 psi and 15.25 psi at the 12 and 15 psi gauge marks, respectively. Test sensitivity and specificity were 0.36 (95% CI = 0.17-.54) and 0.57 (95% CI = 0.39-0.74), respectively. Conclusions: Pressure measurements obtained with the Durkan CTS gauge were accurate. The CCT when performed with the Durkan gauge, however, was neither sensitive nor specific for the diagnosis of CTS.

J Orthop Sports Phys Ther. 2000;30(11):676-682.

Key Words: carpal compression test, carpal tunnel syndrome

An Electromyographic Study of Vastus Medialis Oblique and Vastus Lateralis Activity While Ascending and Descending Steps

Mon, 05 Feb 2007 09:45:00 EST

Patrick Sheehy, Ray Burdett, James J. Irrgang, Jessie VanSwearingen

Imbalances in the firing pattern and contraction intensity of the vastus medialis oblique (VMO) and the vastus lateralis (VL) have been considered important factors contributing to patellofemoral joint dysfunction. Vastus medialis oblique and vastus lateralis electromyographic (EMG) activity were measured for 15 individuals without patellofemoral pain (asymptomatic group) and 13 subjects with patellofemoral pain (symptomatic group) while ascending and descending steps. The peak VMO/VL ratios of EMG activity and the difference in peak VMO and VL onset times were measured. Two-way mixed-model analyses of variance (ANOVA) were used to determine the main effects of group (asymptomatic and symptomatic), phase (concentric phase ascending and 2 eccentric phases descending stairs), and the interaction between group and phase. The ANOVAs indicated no difference between groups for the peak VMO/VL EMG ratio or for the onset timing between peak VMO and VL muscle activity. Combining groups, the peak VMO/VL EMG ratio was less for the eccentric weight acceptance phase of descent compared with the concentric phase of ascent. These findings suggest no differences between asymptomatic and symptomatic individuals, but differences may exist between concentric and eccentric VMO/VL ratios. Further research is needed to determine if VMO and VL muscle imbalances contribute to patellofemoral dysfunction.

J Orthop Sports Phys Ther. 1998;27(6):423-429.

Key Words: patellofemoral, electromyography, kinetic chain

Electromyographic Analysis of the Squat Performed in Self-Selected Lower Extremity Neutral Rotation and 30� of Lower Extremity Turn-Out From the Self-Selected Neutral Position

Mon, 05 Feb 2007 09:45:00 EST

Joel C. Ninos, James J. Irrgang, Ray Burdett, Jeffery R. Weiss

Little research is available on the muscle activity patterns of the lower extremity muscles during dynamic closed chain squatting activities. The purpose of this study was to examine the effect of lower extremity position during an Olympic squat on the muscle activity patterns of the vastus medialis, vastus lateralis, semimembranosus/semitendinosus, and biceps femoris. Twenty-five healthy, untrained subjects, 18-35 years old, were randomly assigned initial squatting positions of either self-selected neutral or 30° of lower extremity turn-out from the self-selected neutral position. Surface electromyography and motion analysis data were collected simultaneously in 10° intervals and analyzed from 10-60° of knee flexion in both the ascending and descending phases of the squat. A 4-way analysis of variance indicated that the main effects of lower extremity position and the interaction of extremity position and knee joint angles were not found to cause significant changes in muscle activity patterns. Significant changes in muscle activity did occur with changes in knee flexion angles in the vastus medialis and vastus lateralis but not in the semimembranosus/semitendinosus or biceps femoris.

J Orthop Sports Phys Ther. 1997;25(5):307-315.

Key Words: squat, electromyography, joint motion, lower extremity

The Effect of Sudden Inversion Stress on EMG Activity of the Peroneal and Tibialis Anterior Muscles in the Chronically Unstable Ankle

Mon, 05 Feb 2007 09:45:00 EST

Melissa Ebig, Ray Burdett, Mark C. Miller, Danny M. Pincivero, Scott M. Lephart

Residual symptoms resulting from recurrent episodes of inversion-type ankle sprains may be attributed to a decreased neuromuscular response of the peroneal or tibialis anterior muscles, thereby increasing the probability for reinjury. The purpose of this study was to examine the electromyographic (EMG) response time of the peroneal and tibialis anterior muscles in response to sudden plantar flexion/inversion stress in the chronically functional unstable and normal ankle. Subjects for this study consisted of 13 athletically active individuals (5 males and 8 females, mean age = 19.2 ± 1.51 years) with a previous history of a unilateral inversion-type ankle sprain. A specially designed platform that allows each foot to drop into plantar flexion/inversion from a standing neutral position was used. Reaction time in milliseconds for the peroneal and tibialis anterior muscles to sudden plantar flexion/inversion was measured via surface EMG. A paired t test was performed with the Bonferroni-Dunn correction factor to determine differences between the peroneal and tibialis anterior as well as between the chronically unstable and contralateral normal ankle. The results indicated no significant differences between the stable and unstable ankles for the peroneal or the tibialis anterior muscles. The results also indicated no significant differences existed between the tibialis anterior and peroneal muscles in either the stable or unstable ankles. The findings from the present study suggest that self-reported functional ankle instability may not result in a diminished reflex response time of the peroneal and tibialis anterior muscles to sudden plantar flexion/inversion stress.

J Orthop Sports Phys Ther. 1997;26(2):73-77.

Key Words: electromyography, ankle, inversion, instability