|Year : 2019 | Volume
| Issue : 1 | Page : 9-13
Reliability of modified sphygmomanometer for measurement of maximum isometric shoulder muscle strength
Sakina Bhinderwala, Nilima Bedekar
Department of Musculoskeletal PT, Sancheti Institute College of Physiotherapy, Sancheti Healthcare Academy, Pune, Maharashtra, India
|Date of Submission||26-Apr-2018|
|Date of Acceptance||18-Apr-2019|
|Date of Web Publication||29-Jun-2019|
Dr. Nilima Bedekar
Sancheti Healthcare Academy, Thube Park, Shivajinagar, Pune - 411 005, Maharashtra
Source of Support: None, Conflict of Interest: None
BACKGROUND: To evaluate the changes in muscle performance, precise, reliable, and valid methods to assess muscle performance should be applied. Sphygmomanometer is an easily available instrument; it has been used to evaluate the isometric strength of various muscles in various conditions. The reliability of the method can be compromised by insufficient examiner's strength and insufficient stabilization of the sphygmomanometer and participant. The objective of this study was to investigate test–retest reliability of the sphygmomanometer to assess shoulder maximum voluntary isometric contraction (MVIC) against stable surface.
METHODS: It was a cross-sectional study design using purposive sampling; 112 healthy individuals were recruited for strength testing. Over 3 days' interval, the MVIC of the shoulder flexor, abductor, extensor, external rotator, and internal rotator muscles strength was evaluated with an aneroid sphygmomanometer against the stable surface in sitting position.
RESULTS: The results indicated excellent test–retest reliability (intraclass correlation coefficient = 0.995–0.999) with nonsignificant P value for (0.12) extensor and (0.179) internal rotator and significant P value for (0.01) flexor, (0.000) abductor, and (0.006) external rotator sphygmomanometer to assess the shoulder muscle strength against stable surface.
CONCLUSION: A sphygmomanometer was found to have excellent test–retest reliability to assess the MVIC of shoulder muscles.
Keywords: Manual muscle testing, maximum voluntary isometric contraction, reliability, sphygmomanometer
|How to cite this article:|
Bhinderwala S, Bedekar N. Reliability of modified sphygmomanometer for measurement of maximum isometric shoulder muscle strength. Physiother - J Indian Assoc Physiother 2019;13:9-13
|How to cite this URL:|
Bhinderwala S, Bedekar N. Reliability of modified sphygmomanometer for measurement of maximum isometric shoulder muscle strength. Physiother - J Indian Assoc Physiother [serial online] 2019 [cited 2019 Jul 19];13:9-13. Available from: http://www.pjiap.org/text.asp?2019/13/1/9/261814
| Introduction|| |
Muscle strength testing is an essential component of physical therapy examination. Muscle performance testing is done to determine the presence of any deficits and capability to produce movements that are required for normal functioning.
Manual muscle testing (MMT) has been used since decades to assess strength under various conditions. Since MMT is a subjective method, it does not give accurate and sensitive readings. Ceiling effect occurs when an individual attains greatest score on a given test. Hence, subjects are scored more despite strength deficits that can be detected with more objective tests. This phenomenon restricts the ability of MMT to confirm changes in due course. Accurate and reliable measurements are of fundamental interest on normal subjects in the study of joint mechanics and muscle integrity and may be of concern in specific complications which have their application in clinical work. Precise information of strength measurements is also of value outside the clinical field; the athletes are assessed in community settings having higher strength than the normal population; normal values for the strength and amplitude of movements have become increasing importance in the design of equipment and machinery.
The muscle strength evaluation may be accomplished using various equipment: hand-held dynamometer (HHD), strain gauge, cable tensiometer, and sphygmomanometer. Even though advantages of these equipment are its portability and lack of attachments required to assess upper and lower muscle groups, there is a major disadvantage. The consistency of the strength evaluation is subjected to the strength of the examiner and their expertise to sustain the testing position while countering to the opposition of a subject. Depending on the strength of the examiner, he/she may not be able to quantify the subject's maximum strength.,, Bohannon in his study described that information on the strength of examiner, such as body weight and grip strength, was strong enough to resist forces produced by the subjects. Hence, suggested that for strength test to be valid, the examiner's strength should not be a factor, especially in clinical practice where the patient is not treated by the same clinician. Hence, innovative techniques were executed where stabilization devices were used to ensure steadiness and identical strength application by the examiner and subject.,,,
The isokinetic dynamometry is considered a gold standard for strength testing. It consists of large apparatus that stabilizes the subjects and provides controlled resistance from a mechanical component. The regular isokinetic systems include Biodex, Cybex, and Kincom. These options lack practicality in clinical settings due to cost, lack of portability, and space requirements. A more clinically viable alternative is HHD.
Marmon et al. in 2013 mentioned the shortcomings of assessing strength with HHD manually. They found that plantar flexor force measured was significantly different for HHD and electromechanical dynamometers (P < 0.01) and not correlated for either limb (R2≤ 0.09). They concluded that the ailing effect of assessing strength manually with HHD had shown tester's strength to be more reflective than that of the subject.
Similarly, Reed et al. established a strong association (r = 0.72–0.85) between hand-held isometric and isokinetic, but hand-held isometric scores were found to be variable. Reed et al. accredited this measurement variability to the lack of stability of the HHD and suggested the use of fixed instrumentation for clinical studies.
Numerous studies are done to establish validity and reliability of modified sphygmomanometer (MS) with normal healthy population as well as ailing conditions such as stroke and Parkinsonism More Details.,,,, As mentioned above, the application of this equipment has influence of the tester's strength on the measurements scored. Hence, this study is being done to assess the reliability of sphygmomanometer to assess maximum voluntary isometric contraction (MVIC) against stable surface to provide an immovable form of resistance. The testers' force which can be varied is a negative factor in using HHD for checking MMT.
| Methods|| |
It was a cross-sectional study design using purposive sampling technique. The study recruited 112 healthy (self-declared or reported and asymptomatic) students within the age group of 18–25 years; participants were excluded if they had any shoulder pathology or injury to the shoulder in the past 6 months.
Aneroid sphygmomanometer was used for the evaluation by modifying into cuff method wherein the bladder of the cuff was folded into four equal parts, producing a cuff 14-cm long, 7.5-cm wide, and 2.5-cm thick. The cuff was inflated to 20 mmHg as a baseline reading. The equipment was calibrated as per the requirements.
According to the STARD guidelines, the procedure was carried out after ethical committee approval from the institution. Written consent was taken from all the subjects. Dominant arm of the subjects were tested for shoulder flexors, shoulder abductors, shoulder extensors, internal rotators, and external rotators, over 3 days' interval. Three readings were taken for all the movements; then, the mean of the three was recorded. The order of muscle group was randomly assigned by chit method, and the same order was followed for the next testing session.
Subjects were instructed to perform MVIC for 5 s with a rest interval of 30 s between measures and a break of 2 min between muscle groups.
Subjects were seated on an armless high back chair; a stabilizing belt was tied across the chest and the chair to prevent any trunk movements; a towel was placed between the arm and the thorax.
Shoulder flexor – The subject sat facing the wall with shoulder at 10° of flexion to eliminate co-contraction of the trunk muscles, elbow flexed to 90°, forearm in midprone wrist neutral, and fingers flexed. The subject was instructed to push against the cuff with the fist of the hand [Figure 1].
Shoulder abductor – The Subject sat next to to the wall with arm in 10° of abduction, elbow flexed at 90°, and forearm in midprone wrist neutral with fingers flexed. The subject was instructed the push against the cuff which was above the elbow joint on the lateral aspect of the arm as shown in [Figure 2].
Shoulder extensor – Subject sat facing their back to the wall with arm extended 20°, elbow flexed at 90°, forearm in midprone wrist neutral, and fingers flexed. The subject was instructed to push against the cuff which was above the elbow joint on the posterior aspect of the arm as shown in [Figure 3].
Shoulder external rotator – Subject sat at the door way with arm abducted to 10°, elbow flexed at 90°, forearm in midprone wrist in neutral, and fingers flexed. The subject was instructed to push against the cuff which was above the wrist joint on the dorsal aspect of the forearm as shown in [Figure 4].
Shoulder internal rotator – Subject at the door way with the arm in 10° of abduction, elbow flexed at 90°, forearm in midprone wrist neutral, and fingers flexed. The subject was instructed to push against the cuff which was above the wrist joint on the volar aspect of the forearm as shown in [Figure 5].
Statistical analysis was performed using SPSS statistical package version 16.0.
To test reliability, intraclass correlation coefficient (ICC) was calculated. ICC estimates and their 95% confidence intervals were computed based on a mean-rating (k = 2), absolute-agreement, 2-way mixed-effects model for test–retest reliability.
ICC values < 0.5 are indicative of poor reliability, values between 0.5 and 0.75 indicate moderate reliability, values between 0.75 and 0.9 indicate good reliability, and values >0.90 indicate excellent reliability.
| Results|| |
Of 112 participants who agreed to participate, 100 completed the study. Two participants had fever, one had a fall, and nine participants did not turn up for the second session of assessment.
There were 32 male and 68 female participants with a mean age of 21.65 ± 1.82 years [Table 1].
The sphygmomanometer was found to have excellent test–retest reliability (ICC = 0.995–0.999) with P value nonsignificant (0.124) for extension and (0.179) internal rotation and significant (P < 0.05) for flexion, abduction, and external rotation as indicated by the ICC (3, k) value obtained for shoulder flexion, abduction, extension, external rotation, and internal rotation [Table 2].
| Discussion|| |
The objective of this study was to establish test–retest reliability for sphygmomanometer to assess the MVIC of shoulder muscles strength. The results of this study provide excellent reliability (ICC = 0.995–0.999) for sphygmomanometer strength assessment. Tester's force is not required in this method. A stable surface/immovable surface for test position is needed.
Wikholm and Bohannon. investigate the effect of tester strength on the magnitude and reliability of hand-held dynamometer (HHD) force measurements and reported that the tester strength is a major determinant of the magnitude and reliability of the forces measured with a HHD especially at higher forces. Byl et al. found that strength measured by examiners amplified by 10%–30% when an additional stabilizing procedure was used to test normal elbow flexors and shoulder abductors with HHD.
For measures of isometric muscle strength testing, a HHD had the highest test–retest reliability. However, many clinicians do not have ready access to such a device. In disparity, a sphygmomanometer is often readily accessible and also offers sound reliability.
Toohey et al. in 2017 concluded that excellent correlations were found for criterion validity and intra-rater reliability, which implied that the sphygmomanometer is capable of being used by the clinicians in the daily clinical setting for precise objective shoulder strength assessment.
Bohannon and Lusardi in their study stated that the effect of air compression inside the modified cuff may only become apparent when moderately strong participants push with slender limb segments against the cuff of the sphygmomanometer. In such cases, the weight of the limb segment against the cuff may tend to exceed the underlying pressure within the cuff itself. Additional sources of discrepancy with the MS comprise the examiner's failure to (1) maintain a flat palm on the modified cuff; (2) apply appropriate resistance; or (3) accurately read the mercury column or dial.
In the present study, the contraction time was 5 s with relaxation time 30 s between the contractions and 2 min between the muscle groups, which is similar to the study done by Kolber et al., where they tested shoulder internal rotation and external rotation with stabilization device with 6 s contraction, 10 s relaxation between contractions, and 1 min between muscle groups.
The sphygmomanometer could be integrated within clinical settings for numerous reasons: (i) the aneroid sphygmomanometer is easily found and handy to use in community settings for the assessment by health professionals, (ii) the adaptation is simple; and (iii) the sphygmomanometer is multipurpose equipment, no additional cost required as it is already available with the health professionals to assess blood pressure.
The limitation of this study was that the participant's inconsistency in applying maximum force with adequate instructions and encouragement could not be controlled. Further studies need to be carried out to establish validity of sphygmomanometer to assess shoulder muscle strength against stable surface.
| Conclusion|| |
The sphygmomanometer is a reliable apparatus to use in determining shoulder isometric muscle force production in young healthy adults against stable surface.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form, the patients have given their consent for their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
We would like to thank the Research Coordinators Dr. Rachana Dabadghav and Dr. Dhara Kapoor.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
[Table 1], [Table 2]