INTRODUCTION: Manual muscle testing (MMT) is utilized in different fields like physical therapy and other fields that require diagnosis of a person’s muscular strength and progression over time. MMT involves stabilization of a certain part of the body while external resistance is provided by the manual muscle tester. Muscular activity is graded on a 0 to 5 scale. Another way to measure muscle activation is by electromyography (EMG). EMG uses electrodes to record electrical activity produced by a muscle.
PURPOSE: The purpose of the study was to determine the relationship between ratings of muscular activity by prephysical therapy students and actual EMG readings on the peroneus longus.
METHOD: Eight subjects (4 males and 4 females) from the Kinesiology department at UTA volunteered to participate in this study. Subjects practiced MMT of the peroneus longus on one another and completed an isokinetic contraction test on the Biodex on the first day of the study. During the second day, subjects were asked to perform a MMT and rate the contraction either 25%, 50%, 75%, or 100%. The subject contracting the peroneus longus was contracting by attempting to match the reference line on the computer. Without looking at the computer where the percent of contraction was displayed, the manual muscle tester rated the contraction.
RESULTS: Mean values for the peak torque, average power, and agonist/antagonist ratio on the Biodex were 10.7 ±
2.88, 14.4 ± 3.82, and 85.6 ± 16.09 respectively. Alpha level was set at .05 to test for significance between EMG readings and manual muscle tester ratings. Data were analyzed with SPSS 21 by using intraclass correlation coefficient (ICC) using a two factor mixed effects model and absolute agreement. With the Wilcoxon Signed Rank Test, a p value of 1.00 was established. Since the p value was greater than .05, significant difference in ratings from EMG and manual muscle testers were not found.
CONCLUSION: The results of this study indicated that there was no significant difference in EMG readings and manual muscle tester ratings performed by pre-physical therapy students on the peroneus longus.
The purpose of the study was to determine the relationship between ratings of muscular activity by pre-physical therapy students and actual EMG readings on the peroneus longus.
• Electrodes were placed on the muscle belly of the peroneus longus and tibia (ground electrode) for EMG readings.
• MMT technique (proper form, hand placement, locating subtalar neutral, and anatomical information), instructions for operating the Biodex and EMG system were provided by Dr. Ricard and Dr. Trowbridge.
• The subject’s that were contracting their foot had access to a computer that utilized a real time EMG program that provided an output of the maximum force produced by their peroneus longus. Different percentages based off of the maximum contraction were calculated and reference lines appeared on the screen.
• Each subject practiced contracting their peroneus longus based on the reference lines of 25%, 50%, 75%, and 100% by resisting the manual muscle tester.
• On the second and final day of the study, subjects performed a MMT where the person contracting performed 3 maximum contractions.
• After determination of the maximum percentage, each subject were told to perform either 25%, 50%, 75%, or 100% by matching the reference line on the computer during the MMT. Without access to the computer or the % of contraction, three contractions were performed and the manual muscle tester rated the test.
Statistical Analysis
• Data were analyzed using SPSS 21.0.
• Reproducibility of rating of % maximum contraction recorded by EMG was analyzed to compute the intraclass correlation coefficient using a two factor mixed effects model and absolute agreement.
• Differences between rating of % contraction were analyzed using Wilcoxon nonparametric test.
Demographic Variables:
Variable
Age (years)
Height (m)
Weight (kg)
Mean
22.38
1.67
66.57
± SD
1.19
0.09
14.96
Performance Variables:
Variable
Peak Torque (ft/lbs)
Average Power (W)
Agonist/Antag Ratio (%)
Mean
10.7
14.4
85.6
ICC was .887 with a 95% confidence interval from .527 - .976.
Wilcoxon Signed Rank nonparametric test: W(7) = .000, p = 1.00
± SD
2.89
3.82
16.09
Subjects:
• 4 male and 4 female kinesiology students from the University of Texas at Arlington participated in the study.
• Subjects signed an informed written consent form before testing began.
Protocol:
• On the first day of the study, subjects performed an isokinetic eversion/inversion contraction test at 120 deg/sec on the Biodex that measured peak torque, power, and agonist/antagonist ratio. This test was performed by having the foot inverted for the starting position on the Biodex. The test consisted of three repetitions of full contractions from inversion to eversion and back.
• Subjects were also trained on how to perform a manual muscle test (MMT) on the peroneus longus by having one hand against the side of the leg for stabilization and the other against the inside and sole of the foot. The manual muscle tester applied resistance to invert the foot while the other subject everts their foot. The subjects were instructed to start at subtalar neutral position (equal amount of protrusion of the talus bone on both sides of the foot). Maintaining the foot at the neutral position by matching each other’s resistance was the main goal of the test.
• Wilcoxon Signed Rank nonparametric test showed no significant difference (p>.05) in testing for % of muscular contraction by pre-physical therapy students performing manual muscle testing and EMG readings on the peroneus longus.
• More research on the reliability of manual muscle testing and how it correlate with
EMG readings should be conducted.
• Instead of testing just one muscle, testing of multiple muscles should be implemented in future studies.
• To test for validity and avoid error, replication of this study is recommended.
• Limitations
• Prior to the study, subjects have never performed manual muscle testing, so proper form and technique may not have been achieved.
• Incorporation of physical therapist or more experienced manual muscle testers during the testing phase may be of assistance for the subjects.
• A longer time frame for practice with manual muscle testing would also be of benefit for the study (class in manual muscle testing).