Measuring handgrip strength in school children: inter-instrument reliability between Takei and Jamar.

The aim of this study was to determine inter-instrument reliability between Takei and Jamar dynamometers in school children. Fifty-six five grade participants aged eleven to twelve (n = 32 boys, n = 24 girls) performed handgrip strength test on two different occasions, with a 5-day gap between them, as test-retest. The Pearson correlation coefficient showed very large to almost perfect correlation between both devices (r = 0.76-0.91) which was graphically confirmed by Bland-Altman method. Test-retest also showed high reliability (ICC = 0.78-0.85) for Jamar and Takei. Trivial, nonsignificant differences (p > 0.05) were observed between for test-retest trials for Takei left hand (ES = 0.04), right hand (ES = 0.12) and Jamar left hand (ES = 0.15). According to the results, both the Jamar and Takei dynamometers are valid and reliable for measuring schoolchildren, and both devices may be used to assess a student's handgrip strength for this age group.

Reliability, Concurrent Validity, and Minimal Detectable Change of the Hand-Held Dynamometry for the Assessment of Knee Muscle Strength in Patients With Revision Total Knee Arthroplasty.

OBJECTIVE: To determine the concurrent validity, reliability, and minimal detectable change (MDC) of the hand-held dynamometry (HHD) for knee strength measurement in patients with revision total knee arthroplasty (r-TKA). DESIGN: A reliability and validity analysis. SETTING: Orthopedic and physical therapy services of university hospital. PARTICIPANTS: The study included 42 patients with r-TKA (N=42). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Knee muscle strength assessments were performed by 2 physiotherapists in 3 different sessions by using HHD. Participants were instructed to exert a maximal force for lasting 5 seconds against HHD. The first examiner performed the strength testing, and after 30-minutes rest, the second examiner performed the same procedure for inter-examiner reliability. One hour after the initial testing, the first examiner reperformed the strength testing for intra-examiner reliability. The correlations of the knee extensors and knee flexors strength with 50-foot walking test and 30-second chair stand test were assessed for concurrent validity. RESULTS: The inter-examiner reliabilities of knee extensors and flexors strength measurements were 0.97 and 0.95, respectively. The SEM and the minimal detectable changes at 95% confidence level (MDC95) for knee extensors were 10.39 and 28.65 Newton-meters (Nm), and SEM and MDC95 for knee flexors were 8.70 and 23.99 Nm, respectively. The intra-examiner reliabilities of knee extensors and flexors strength measurements were 0.96. SEM and MDC95 for knee extensors were 12.00 and 33.09 Nm, and SEM and MDC95 for knee flexors were 7.78 and 21.45 Nm, respectively. The knee muscle strength showed strong significant correlations with physical performance tests (all, P<.05). CONCLUSIONS: The HHD is a reliable and valid method for assessment of static knee strength after r-TKA. The HHD can be used to quantify changes in knee strength and also assists the clinicians to determine the effect of rehabilitation programs on muscle strength following r-TKA surgery.

Maintenance-Free Smart Hand Dynamometer.

Grip strength measurement is one of the most accessible methods for measuring overall muscle strength, and many studies have shown a link between low grip strength and future diseases. In recent years, devices for grip strength measurements that can connect to digital devices for automatic data recording have been developed. However, such devices have high development costs and require daily maintenance. Therefore, this we propose a grip strength measurement method using the capacitance sensor of a smartphone and no electronic parts on the measurement device side.

A portable articulated dynamometer for ankle dorsiflexion and plantar flexion strength measurement: a design, validation, and user experience study.

Monitoring ankle strength is crucial for assessing daily activities, functional ability, and preventing lower extremity injuries. However, the current methods for measuring ankle strength are often unreliable or not easily portable to be used in clinical settings. Therefore, this study proposes a portable dynamometer with high reliability capable of measuring ankle dorsiflexion and plantar flexion. The proposed portable dynamometer comprised plates made of aluminum alloy 6061 and a miniature tension-compression load cell. A total of 41 healthy adult participants applied maximal isometric dorsiflexor and plantar flexor forces on a Lafayette Handheld Dynamometer (HHD) and the portable dynamometer. The results were cross-validated, using change in mean, and two independent examiners evaluated the inter-rater and test-retest reliabilities in separate sessions using intraclass correlation coefficients, standard error of measurement, and minimal detectable change. Both dorsiflexion and plantar flexion measurements demonstrated a strong correlation with the HHD (r = 0.827; r = 0.973) and showed high inter-rater and test-retest reliabilities. Additionally, the participant responses to the user experience questionnaire survey indicated vastly superior positive experiences with the portable dynamometer. The study findings suggest that the designed portable dynamometer can provide accurate and reliable measurements of ankle strengths, making it a potential alternative to current methods in clinical settings.

Validity and reliability of Squegg device in measuring isometric handgrip strength.

OBJECTIVE: The quantitative measurement of handgrip strength is important in assessing and charting the progress of patients with neuromuscular diseases. The aim of this research was to determine the intra-rater and inter-rater reliability and the validity of the Squegg digital dynamometer. SUBJECTS AND METHODS: Twenty-one females and nine male participants with an age range between 18 and 40 years volunteered for the study. Three testers each took three measurements with a Squegg device and a Jamar dynamometer using standardized measurement techniques. Intra- and inter-tester reliability were calculated using the intra-class correlation coefficient (ICC). To investigate the relationship between hand measures and isometric handgrip strength, the Pearson correlation coefficient test was used. To determine the agreement between the two devices, a Bland Altman plot was constructed, and the concurrent validity of Squegg was calculated. RESULTS: The intra-rater reliability coefficients for both Jamar and Squegg were greater than 0.99 for all three testers, indicating excellent intra-rater reliability. The inter-rater reliability of Jamar (ICC=0.93) and Squegg (ICC=0.87) was excellent. With an ICC of 0.844 and an r-value of 0.720, Squegg with Jamar demonstrates good validity and statistical significance (p=0.001). CONCLUSIONS: The isometric handgrip strength and hand measures showed a moderate correlation in the study population. The Squegg isometric handgrip dynamometer has good concurrent validity and great intra- and inter-rater reliability in healthy individuals. The validity of Squegg in patients with neuromuscular diseases that affect hand function has to be investigated further.

Isometric Shoulder Testing Using a Forcemeter Is a Reliable Method of Strength Evaluation.

Isometric strength testing using a digital dynamometer is reliable for muscle function evaluation. It allows us to objectify manual strength assessment measurement. We tested intra- and inter-observer reliability of a user-friendly efficient digital dynamometer-the Forcemeter-equipped with a computer program to monitor the measurements and to store the data. Abduction, forward flexion, and external and internal rotation of both shoulders were tested three times in 20 healthy volunteers with no record of shoulder trauma. Isometric contracture was recorded in newtons. The first and the third test were carried out by Examiner A (intra-rater reliability); the second test, by Examiner B (inter-rater reliability). Good reliability was shown for intra-class correlation coefficient (ICC) values which mean moderate to high correlations (r = 0.66-0.93) for both examiners. Moderate to high correlations (r = 0.72-0.91) were found for comparisons between the results obtained by Examiner A.

Study of Reliability and Validity of the Load Cell-Type Hand Dynamometer Compared to the Jamar Dynamometer and the Number of Reliable Grip Strength Measurements.

Background: Standardised measurement protocols for grip strength remained unclear due to variations in values depending on the device and measurement method. The load cell hand dynamometer has recently been developed. This study aims to investigate the reliability of the load cell dynamometer by comparing it to the Jamar dynamometer, which is considered the gold standard, and to identify a reliable and practical measurement method. Methods: This study included 80 healthy hospital workers (mean age of 40.1 years). All measurements were performed seated, with the elbow flexed 90° and the grip span at the second handle (approximately 50 mm) for the Jamar dynamometer, and with the elbow extended and the grip span fixed at 55 mm for the load cell dynamometer. Grip strength was measured three times on each hand using two dynamometers, and the same tests were repeated on different days. Test-retest reliability, the association between the two devices and the agreement between the two measurement methods were assessed using the intraclass correlation coefficient (ICC), Pearson correlation and the Bland-Altman analysis. Results: The ICC of the one measurement was lower than that of three measurements for both dynamometers, but was above 0.858 in all groups, indicating sufficient reliability with one-time measurement. Additionally, the ICC for different days revealed good reliability (Jamar: >0.830, load cell: >0.772). The load cell dynamometer showed significantly lower values in all measurements despite the excellent correlation (r > 0.70) and the agreement between the two dynamometers. Conclusions: This study revealed sufficient reliability of the load cell dynamometer with the standardised measurement method, but it should be noted the lower values compared to the Jamar dynamometer. Additionally, one-time measurement reliability is adequate for practical use by standardising the measurement methods for both dynamometers. Level of Evidence: Level III (Diagnostic).

Validation of a bluetooth-enabled load cell for objective and accessible assessment of lower extremity strength.

High magnitude loading from performing resistance-based exercise has been found to improve tendon strength and reduce symptoms of Achilles tendinopathy (AT) but is difficult to quantify without specialist equipment. Here, we assess the validity and reliability of a novel AT rehabilitation tool (the "PhysViz" system) compared to a "gold-standard" dynamometer for assessing plantarflexion maximal voluntary isometric contractions (MVIC). 41 participants aged 18-60 completed the study. A within-subject test-retest study design was used to examine and compare the validity and reliability of the two systems during plantarflexion MVICs. Test - retest reliability of the two methods were determined by calculating intra-class correlation coefficients (ICCs) and 95% confidence intervals. Method agreement was assessed with Bland - Altman Limits of Agreement (LoA) analysis. The PhysViz demonstrated excellent test-retest reliability; ICC, SEM and MDC were numerically comparable to the dynamometer (ICC 0.93 vs. 0.92; SEM 2.01 vs. 2.95 kg and MDC 5.58 vs. 8.18 kg, respectively), indicating that the novel system is valid and reliable for measuring plantarflexor MVICs. Future studies should address its utility in monitoring AT rehabilitative loading remotely over time.

Can Clinicians Trust Objective Measures of Hip Muscle Strength From Portable Dynamometers? A Systematic Review With Meta-analysis and Evidence Gap Map of 107 Studies of Reliability and Criterion Validity Using the COSMIN Methodology.

OBJECTIVE: To summarize the evidence on reliability and criterion validity of hip muscle strength testing using portable dynamometers. DESIGN: Systematic review with meta-analysis. LITERATURE SEARCH: Five databases were searched from inception to March 2023. STUDY SELECTION CRITERIA: We included studies investigating reliability or criterion validity of hip flexor, extensor, abductor, adductor, or internal/external rotator strength testing with portable dynamometers in injury-free individuals or those with pelvic/lower limb musculoskeletal disorders. DATA SYNTHESIS: We performed meta-analyses for each muscle group, position, and method of fixation. We rated pooled results as sufficient (>75% of studies with correlations ≥0.70), insufficient (>75% of studies with correlations <0.70), or inconsistent (sufficient/insufficient results). We assessed the quality of evidence, created evidence gap maps, and made clinical recommendations. RESULTS: We included a total of 107 studies (reliability 103, validity 14). The intrarater and interrater reliability for hip muscle strength testing across different positions and methods of fixation was sufficient (intraclass correlation coefficient = 0.78-0.96) with low- to high-quality evidence. Criterion validity was less investigated and mostly inconsistent (very low-to moderate-quality evidence) with a wide range of correlations (r = 0.40-0.93). CONCLUSION: Hip muscle strength testing using portable dynamometers is reliable. The use of portable dynamometers as clinical surrogates for measuring strength using an isokinetic dynamometer requires further investigation. Clinicians testing hip muscle strength with portable dynamometers should use external fixation seated for hip flexors, prone or supine for hip extensors, side-lying or supine for abductors and adductors, and prone and seated for internal and external rotators. J Orthop Sports Phys Ther 2023;53(11):655-672. Epub 3 October 2023. doi:10.2519/jospt.2023.12045.

Interinstrument Reliability Between the Squegg® Smart Dynamometer and Hand Grip Trainer and the Jamar® Hydraulic Hand Dynamometer: A Pilot Study.

IMPORTANCE: Occupational therapists need dependable and accurate instruments for remote assessments and monitoring of hand functionality. These assessments monitor progress, evaluate interventions, and guide independence goals. OBJECTIVE: To assess the interinstrument reliability and concurrent validity of the Squegg® Smart Dynamometer and Hand Grip Trainer and the Jamar® Hydraulic Hand Dynamometer. DESIGN: Repeated-measures design. SETTING: Individual clinic in Bucharest, Romania. PARTICIPANTS: Forty middle-age and older adult volunteers, healthy and free from any neuromuscular, orthopedic dysfunction that affected hand strength. OUTCOMES AND MEASURES: Participants' maximal grip strength (MGS) for both their dominant and nondominant hands was measured with both devices. Participants with odd-numbered IDs were measured with the Squegg first and the Jamar second, and those with even-numbered IDs were measured in opposite sequence. RESULTS: Paired-samples t tests on overall mean MGS and mean MGS (three measures on each hand) showed no statistically significant differences between the two devices. Intraclass correlation analysis showed good to excellent interinstrument agreement. Pearson correlations between measurements across all participants, and hands, indicated strong agreement. CONCLUSIONS AND RELEVANCE: The Squegg shows promise for health care professionals, including occupational therapists, for grip strength assessment in clinical contexts. What This Article Adds: These results offer initial psychometric data for a new remote MGS measurement device. MGS is crucial for assessing the physical function of aging adults. Reliable measurements from such a device are vital for occupational therapists to guide treatment interventions and assess hand function's impact on daily activities.

Muscle Properties, Gross Motor Performance, and Quality of Life in Children With Sickle Cell Disease.

PURPOSE: To explore muscle properties, gross motor performance, and quality of life (QoL) in children with sickle cell disease (SCD) compared with controls and to assess relationships among these outcomes. METHODS: A cross-sectional study of 24 children assessed muscle properties including: knee extension strength by dynamometry; vastus lateralis (VL) and rectus femoris (RF) muscle thickness by ultrasonography; and VL and RF neuromuscular activation (rate of muscle activation [RoA]) by electromyography (EMG). Gross motor performance and QoL were assessed by standardized tests and questionnaires. RESULTS: Children with SCD had impaired knee extension strength, VL EMG RoA, gross motor performance, and QoL compared with children without SCD. Relationships among muscle properties, gross motor performance, and QoL were identified. CONCLUSIONS: These findings indicate that comprehensive muscle properties, gross motor performance, and QoL assessments should be considered to support and develop individualized physical therapy plans for children with SCD.

The Single Leg Bridge Test does not replace handheld dynamometer hamstring tests in a clinical setting.

OBJECTIVE: To examine the correlation of Single Leg Bridge Test (SLBT) scores with maximum isometric strength values obtained in handheld dynamometer (HHD) hamstring tests performed in a clinical setting. DESIGN: Cross-sectional study. SETTING: Physical therapy clinic. PARTICIPANTS: Fifty healthy and physically active men. MAIN OUTCOME MEASURES: Correlation between SLBT scores and force values found in three HHD hamstring tests: test 'A', volunteer in prone with hip in neutral position and the knee flexed at ∼90°; test 'B', volunteer in supine with hip and knee flexed at ∼90°; and test 'C', volunteer in the same position used to perform the SLBT. RESULTS: The volunteers' SLBT score was 27.55 ± 7.81 repetitions. The SLBT scores were poorly associated with mean (r = 0.246) and peak (r = 0.321) results provided by HHD test 'A'. There were no significant correlations between the SLBT scores and mean or peak values obtained in tests 'B' and 'C' (p > 0.05). Similarly, the SLBT between-limb asymmetry was not associated with asymmetries found in HHD hamstring tests (p > 0.05). CONCLUSIONS: HHD hamstring tests should not be replaced by the SLBT. We recommend for clinicians to applying such tests in a complementary way to assess the hamstring's functional status.

Motor Strength Measurements Obtained Using an Inexpensive Spring Tensiometer and a Clinical Dynamometer Correlated Well: A Prospective Cohort Study.

OBJECTIVE: Manual muscle strength testing is the primary method for testing muscle strength in clinical settings but is highly subjective. An objective measure of muscle strength can be obtained using a handheld dynamometer, but its cost inhibits its widespread usage. We hypothesized that a spring tensiometer (ST) could be an objective tool that can be used as a viable alternative to a dynamometer. METHODS: Twenty-six outpatients were included, and the strengths of several muscle groups were measured using tensiometers and dynamometers. A paired t-test and Pearson's correlation coefficient and Bland-Altman plot analyses were used to estimate the reliability and measurement accuracy of both tools. Multiple regression analysis was performed to identify the factors contributing to the measurement gap between the two instruments. RESULTS: A total of 260 muscle force values were evaluated. Pearson's correlation coefficient and Bland-Altman analyses indicated that the measurements of the two instruments were strongly correlated and highly accurate. In the multiple regression analysis, the gap between the two instruments was significantly related to the original muscle strength and muscle part but was not significantly related to sex, age, body mass index, or laterality. For biceps and triceps muscle groups, the correlations were particularly strong and accurate, indicating that a tensiometer could be well substituted for a dynamometer. CONCLUSIONS: Our data show that a ST is similar to a dynamometer in terms of precision. A ST is an inexpensive alternative to a dynamometer and more accessible for clinical use than a dynamometer.

Gripwise Versus Jamar: The Challenge of a New Dynamometer Assessing Handgrip Strength.

BACKGROUND: Sarcopenia diagnosis is partly based on handgrip strength (HGS) assessment. The gold-standard dynamometer for this measurement is the Jamar. The electronic Gripwise is a smaller and lighter one, and its measurements are correlated with the Jamar's in laboratory tests. Our study aimed to confirm this correlation in aged patients. METHODS: This monocenter cross-sectional study was performed in patients of 65 years and older admitted at the University Hospital. Participants were assessed either in a seated or bedridden position, randomly allocated to begin the measurements with the Jamar or the Gripwise. RESULTS: Among 649 aged inpatients assessed for eligibility, 348 were included (mean age: 79 ±â€…9; 52% females). The intraclass correlation coefficient was 0.93 (95% confidence interval [CI] 0.92-0.94, p < .001) for the maximum value measured with both devices and 0.94 (95% CI 0.93-0.95, p < .001) for the mean values. However, there was a significant difference in detecting low values (<16 kg in women, <27 kg in men), found in 48% of patients with Jamar, and 71% with Gripwise (p < .001). Thus, we determined alternate cutoffs for diagnosing HGS low values with the Gripwise (<12 kg in women, <22 kg in men), further validated in a supplementary validation population (n = 70). The diagnostic performances of these alternative cutoffs were high (93% sensitivity and 87% specificity in women; 94% sensitivity and 96% specificity in men). CONCLUSIONS: The correlation of the Gripwise with the Jamar was confirmed in aged inpatients. However, lower values recorded with the Gripwise require alternate cutoffs for a relevant low HGS diagnosis.

Development and validation of a portable articulated dynamometry system to assess knee extensor muscle strength.

Muscle strength assessment is important in predicting clinical and functional outcomes in many disorders. Manual muscle testing, although commonly used, offers suboptimal accuracy and reliability. Isokinetic dynamometers (IKDs) have excellent accuracy and reliability; but are bulky and expensive, offering limited accessibility. This study aimed to design a portable dynamometer that is accessible, accurate and reliable, and to validate the device in a general population. The portable articulated dynamometry system (PADS) is a portable device with an embedded high-precision load cell, designed to measure muscle strength with optimal accuracy. Seventy-two participants underwent maximal isometric and isokinetic knee extensor torque measurement with the PADS and IKD, respectively. The PADS results were cross-validated against IKD results using change in mean (CIM). Interrater and intra-rater reliabilities were assessed using intraclass correlation coefficients, standard error of measurement, and minimal detectable change. The PADS maximal knee extensor strength results were not significantly different from those by IKD (CIM: - 2.13 Nm; 95% CI - 4.74, 0.49 Nm). The PADS showed interrater reliability (Pearson's r: 0.958; ICC: 0.979; SEM: 5.51%) and excellent intra-rater reliability (Pearson's r: 0.912; ICC: 0.954; SEM: 8.38%). The proposed PADS may be an effective alternative to IKD, offering good accuracy, reliability, and potentially better accessibility.

Reliability and criterion validity of handheld dynamometry for measuring trunk muscle strength in people with and without chronic non-specific low back pain.

BACKGROUND: Evaluating trunk strength is an important aspect of the physical examination of people with low back pain (LBP). Thus, reliable, valid, and easily applied measurement tools are needed to quantify trunk muscle strength and monitor changes in response to interventions. OBJECTIVES: To determine within-day and between-day test re-test reliability and criterion validity of a handheld dynamometer (HHD) to evaluate maximum isometric trunk strength in people with chronic LBP and asymptomatic individuals. DESIGN: Reliability and criterion validity study. METHODS: Twenty adult participants with chronic, non-specific LBP and 35 asymptomatic individuals participated. Isometric trunk flexion, extension, and rotation strength were evaluated with the HHD (Active force 2) and the within-day and between-day reliability were determined with intraclass correlation coefficients (ICC2,1) and the standard error of the measurements (SEM), minimal detectable change (MDC), and the limits of agreement (LOA) using Bland-Altman plots. Criterion validity was evaluated using Pearson correlation coefficients to compare HHD measurements to isokinetic dynamometry for both isometric trunk flexion and extension strength. RESULTS: Good to excellent within-day and between-day reliability was observed for people with LBP and asymptomatic individuals with (ICC2,1) of 0.73-0.93 and 0.62-0.92 respectively. A moderate to strong correlation was found between measurements with the HHD and the isokinetic dynamometer with a correlation of r = 0.68-0.78 and r = 0.56-0.59 for people with LBP and asymptomatic participants respectively. CONCLUSION: A HHD is a reliable, valid, and clinically applicable tool for the measurement of trunk strength in adults with and without chronic LBP.

Intra- and inter-rater reliability, agreement, and minimal detectable change of the handheld dynamometer in individuals with symptomatic hip osteoarthritis.

INTRODUCTION: The handheld dynamometer has been validated to measure muscle strength in different muscle groups. However, to date, it has not been tested in individuals who experience pain induced by hip osteoarthritis. The current study aimed to evaluate the intra- and inter-rater reliability, agreement, and minimal detectable change of the Lafayette handheld dynamometer, model 1165, to assess the peak force (Pk) and average peak force (Af) of hip muscles in individuals with symptomatic hip osteoarthritis. METHODS: Twenty participants with hip osteoarthritis (mean ± SD age: 58.7±15.3 years; body mass index: 28.8±4.2 kg/m2) and pain intensity on the Visual Analogue Scale ≥ 4 (8.05±1.2) were recruited to participate in this study. Pk and Af of hip flexors (seated position), abductors and adductors (supine position), and extensors (prone position) were collected in a single day by two independent raters, each one obtaining test and retest in randomly ordered separate sessions. RESULTS: The intra-rater intraclass correlation coefficient (ICC) was classified as good (>0.75) or excellent (≥0.90) for all muscle groups and all inter-rater ICCs were classified as excellent. Rater A had a lower standard error of measurement compared to rater B, ranging from 0.15 to 0.58 kilogram-force (Kgf) compared with 0.34 to 1.25 kg, respectively. However, the inter-rater comparison showed a minimal detectable change (MDC) of < 10% for all Pk and Af measures for hip adductors and extensors. Finally, the inter-rater Bland-Altman analysis demonstrated good agreement for abductors, adductors, and extensors. CONCLUSION: Despite pain and dysfunction related to hip osteoarthritis, the mean of two measures using a handheld dynamometer was shown to be a reliable tool to assess hip muscle strength, with good to excellent intra- and inter-rater ICCs, satisfactory agreement, and small values for MDC.

Validity and Reliability of the Kinvent Handheld Dynamometer in the Athletic Shoulder Test.

CONTEXT: Long-lever shoulder strength tests may aid clinical decision-making regarding return to sport after a shoulder injury. The Athletic Shoulder Test (AST) was developed to measure force production in 3 positions of shoulder abduction (90°, 135°, and 180°) using force plates. However, handheld dynamometers (HHDs) are more portable, affordable, and may provide valid and reliable results which would increase the clinical utility of long-lever tests. HHDs vary in shape, design, and their capacity to report parameters such as rate of force production and require further investigation. The aim of this study was to examine the intrarater reliability of the Kinvent HHD and assess its validity against Kinvent force plates in the AST. Peak force (in kilograms), torque (in Newton meters), and normalized torque (in Newton meters per kilogram) were reported. DESIGN: Validity and reliability study. METHODS: Twenty-seven participants with no history of upper limb injury performed the test in a randomized order using the Kinvent HHD and force plates. Each condition was assessed 3 times, and peak force was recorded. Arm length was measured to calculate peak torque. Normalized peak torque was calculated by dividing torque by bodyweight (in kilograms). RESULTS: The Kinvent HHD is reliable when measuring force (intraclass correlation coefficient [ICC] ≥ .80), torque (ICC ≥ .84), and normalized torque (ICC ≥ .64) during the AST. The Kinvent HHD is also valid when compared with the Kinvent force plates for force (ICC ≥ .79; r ≥ .82), torque (ICC ≥ .82; r ≥ .76), and normalized torque (ICC ≥ .71; r ≥ .61). There were no statistically significant differences across the 3 trials on analyses of variance (P > .05). CONCLUSIONS: The Kinvent HHD is a reliable tool when used to measure force, torque, and normalized torque in the AST. Furthermore, given the lack of significant difference between trials, clinicians can use one test to accurately report relative peak force/torque/normalized torque rather than average 3 separate trials. Finally, the Kinvent HHD is valid when compared with Kinvent force plates.

Test-retest reliability of isometric shoulder muscle strength during abduction and rotation tasks measured using the Biodex dynamometer.

BACKGROUND: The Constant score (CS) is often used clinically to assess shoulder function and includes a muscle strength assessment only for abduction. The aim of this study was to evaluate the test-retest reliability of isometric shoulder muscle strength during various positions of abduction and rotation with the Biodex dynamometer and to determine their correlation with the strength assessment of the CS. METHODS: Ten young healthy subjects participated in this study. Isometric shoulder muscle strength was measured during 3 repetitions for abduction at 10° and 30° abduction in the scapular plane (with extended elbow and hand in neutral position) and for internal and external rotation (with the arm at 15° abduction in the scapular plane and elbow flexed at 90°). Muscle strength tests with the Biodex dynamometer were measured in 2 different sessions. The CS was acquired only in the first session. Intraclass correlation coefficients (ICCs) with 95% confidence interval, limits of agreement, and paired t tests for repeated tests of each abduction and rotation task were calculated. Pearson's correlation between the strength parameter of the CS and isometric muscle strength was investigated. RESULTS: Muscle strength did not differ between tests (P > .05) with good to very good reliabilities for abduction at 10° and 30°, external rotation and internal rotation (ICC >0.7 for all). A moderate correlation of the strength parameter of the CS with all isometric shoulder strength parameters was observed (r > 0.5 for all). CONCLUSION: Shoulder muscle strength for abduction and rotation measured with the Biodex dynamometer are reproducible and correlate with the strength assessment of the CS. Therefore, these isometric muscle strength tests can be further employed to investigate the effect of different shoulder joint pathology on muscle strength. These measurements consider a more comprehensive functionality of the rotator cuff than the single strength evaluation in abduction within the CS as both abduction and rotation are assessed. Potentially, this would allow for a more precise differentiation between the various outcomes of rotator cuff tears.

Psychometric properties of a standardized protocol of muscle strength assessment by hand-held dynamometry in healthy adults: a reliability study.

BACKGROUND: Maximal isometric muscle strength (MIMS) assessment is a key component of physiotherapists' work. Hand-held dynamometry (HHD) is a simple and quick method to obtain quantified MIMS values that have been shown to be valid, reliable, and more responsive than manual muscle testing. However, the lack of MIMS reference values for several muscle groups in healthy adults with well-known psychometric properties limits the use and the interpretation of these measures obtained with HHD in clinic. OBJECTIVE: To determine the intra- and inter-rater reliability, standard error of measurement (SEM) and minimal detectable change (MDC) of MIMS torque values obtained with HHD. METHODS: Intra and Inter-rater Reliability Study. The MIMS torque of 17 muscle groups was assessed by two independent raters at three different times in 30 healthy adults using a standardized HHD protocol using the MEDup™ (Atlas Medic, Québec, Canada). Participants were excluded if they presented any of the following criteria: 1) participation in sport at a competitive level; 2) degenerative or neuromusculoskeletal disease that could affect torque measurements; 3) traumatic experience or disease in the previous years that could affect their muscle function; and 4) use of medication that could impact muscle strength (e.g., muscle relaxants, analgesics, opioids) at the time of the evaluation. Intra- and inter-rater reliability were determined using two-way mixed (intra) and random effects (inter) absolute agreement intraclass correlation coefficients (ICC: 95% confidence interval) models. SEM and MDC were calculated from these data. RESULTS: Intra- and inter-rater reliability were excellent with ICC (95% confidence interval) varying from 0.90 to 0.99 (0.85-0.99) and 0.89 to 0.99 (0.55-0.995), respectively. Absolute SEM and MDC for intra-rater reliability ranged from 0.14 to 3.20 Nm and 0.38 to 8.87 Nm, respectively, and from 0.17 to 5.80 Nm and 0.47 to 16.06 Nm for inter-rater reliability, respectively. CONCLUSIONS: The excellent reliability obtained in this study suggest that the use of such a standardized HHD protocol is a method of choice for MIMS torque measurements in both clinical and research settings. And the identification of the now known metrological qualities of such a protocol should encourage and promote the optimal use of manual dynamometry.