Search

This study compared handheld dynamometry (HHD) at the weakest point of the strength curve for hip extensors, hip abductors, and knee extensors in older adults and onerepetition maximum (1RM) of that same muscle groups with cuff weights. Fifty participants (62-94 years) were tested. Paired t tests indicated no significant differences between the 2 measures. Reliability testing for absolute agreement between 1RM and HHD yielded intraclass correlations of good to excellent. This demonstrates HHD at or near the weakest point of a muscle group provides an accurate measure of older individual's 1RM for knee extension, hip extension, and hip abduction. [ABSTRACT FROM AUTHOR]

This study aimed to assess the combination of video-based kinematic variables adjusted by intrinsic covariates to predict the relative eccentric force (RelF) during the Nordic curl. The participants (n = 21) performed Nordic curls (3 trials; 3-min rest) on a device measuring the eccentric force. The peaks were normalized by body weight. Kinovea software was used to track angular and linear velocity and acceleration from recorded videos. Two prediction models with multiple linear regression equations associated kinematic, anthropometric, and age variables to adjust the actual RelF. The equations obtained the predicted RelF. The actual RelF was inversely correlated with height (r = −.52), tangential (r = −.50) and centripetal accelerations (r = −.715), and angular velocity (r = −.70). The best prediction models combined angular velocity with age (F2,18 = 15.1, P =.001, r =.792, r2 =.627) and with height (F2,18 = 14.5, P =.001, r =.785, r2 =.616). No differences were observed between actual and predicted values (P =.993−.994), with good levels of agreement and consistency (intraclass correlation coefficient =.77−.78; Cronbach α =.86−.87). Bland–Altman results showed high levels of agreement and low biases. The standard error of measurement and minimal detectable change ranges were 0.46 to 0.49 N/kg and 1.28 to 1.36 N/kg, respectively. Also, the percentage of standard error of measurement was below 10% (7.92%–8.35%). The coefficient of variation analysis returned a 14.54% and 15.13% for each model, respectively. Kinematic analysis offers portability and low cost to current expensive or technical impaired dynamometry-based techniques to assess the RelF. [ABSTRACT FROM AUTHOR]

Overhead athletes require strenuous shoulder activity in nonneutral cervical spine positions to eccentrically decelerate the throwing/striking arm following ball release/contact. We therefore aimed to compare eccentric shoulder rotation strength through a 90° arc between neutral and rotated positions. Fifty-two participants (19 M, 34 F 170±10 cm; 73±18 kg, 21.9±2.9 years) without shoulder or cervical spine pathology participated. Isokinetic eccentric shoulder rotation strength was measured through a 90° arc with the shoulder elevated 90° in frontal plane (frontal plane), and 45° anterior to the frontal plane (scapular plane) in neutral and rotated cervical spine positions. Cervical spine position was obtained by instructing participants to maximally rotate their respective side. Frontal plane eccentric external rotated strength differed between neutral and contralaterally positions in the first 10° of the motion, near forearm vertical (p+=+0.029). Internal rotation strength differed between neutral and contralaterally rotated positions from 55–60° external rotation (p+=+0.004). Scapular plane eccentric external rotation differed between cervical positions between 21–67° shoulder external rotation (p<0.001). Scapular plane internal rotation strength differed between cervical positions between 22–60° shoulder external rotation (p<0.001). In populations requiring strenuous use of their shoulders in altered cervical spine positions, sports medicine clinicians should consider including strength testing that reflects the functional positions of their patients during an orthopedic examination. [ABSTRACT FROM AUTHOR]

Purpose: Concentric hip and eccentric knee joint mechanics affect sprint performance. Although the biarticular hamstrings combine these capacities, empirical links between swing phase mechanics and corresponding isokinetic outcome parameters are deficient. This explorative study aimed (1) to explain the variance of sprint velocity, (2) to compare maximal sprints with isokinetic tests, (3) to associate swing phase mechanics with isokinetic parameters, and (4) to quantify the relation between knee and hip joint swing phase mechanics. Methods: A total of 22 sprinters (age = 22 y, height = 1.81 m, weight = 77 kg) performed sprints and eccentric knee flexor and concentric knee extensor tests. All exercises were captured by 10 (sprints) and 4 (isokinetics) cameras. Lower-limb muscle balance was assessed by the dynamic control ratio at the equilibrium point. Results: The sprint velocity (9.79 [0.49] m/s) was best predicted by the maximal knee extension velocity, hip mean power (both swing phase parameters), and isokinetic peak moment of concentric quadriceps exercise (R2 = 60%). The moment of the dynamic control ratio at the equilibrium point (R2 = 39%) was the isokinetic parameter with the highest predictive power itself. Knee and hip joint mechanics affected each other during sprinting. They were significantly associated with isokinetic parameters of eccentric hamstring tests, as well as moments and angles of the dynamic control ratio at the equilibrium point, but restrictedly with concentric quadriceps exercise. The maximal sprints imposed considerably higher loads than isokinetic tests (eg, 13-fold eccentric knee joint peak power). Conclusions: Fast sprinters demonstrated distinctive knee and hip mechanics in the late swing phase, as well as strong eccentric hamstrings, with a clear association to the musculoarticular requirements of the swing phase in sprinting. The transferability of isokinetic knee strength data to sprinting is limited inter alia due to different hip joint configurations. However, isokinetic tests quantify specific sprint-related muscular prerequisites and constitute a useful diagnostic tool due to their predicting value to sprint performance. [ABSTRACT FROM AUTHOR]

Context: Hip pain is associated with reduced hip muscle strength, range of movement (ROM), and decreased postural stability. Singleleg squat is a reliable and valid method to measure dynamic balance. Objective: To evaluate the influence of physical characteristics and use of a decline board on squat performance in a hip pain population. Design: Cross-sectional study setting. Clinical Patients: In total, 33 individuals scheduled for arthroscopic hip surgery were matched with 33 healthy controls. Interventions: Hip and ankle ROM, hip strength, and trunk endurance were assessed, along with knee and trunk kinematics during squat on flat and 25° decline surfaces. Main Outcome Measures: Between-group and surface differences in alignment, between-group strength and ROM, and associations between alignment and physical characteristics were assessed and determined using mixed model analysis of variance and Pearson R. Results: The hip pain group had significantly less strength and ROM for all directions except abduction strength and ankle dorsifiexion (P > .02). No differences existed between lire 2 groups for trunk (P < .70) or knee displacement (P < .46) during squat on either surface. When the 2 groups were combined (n = 66), decline squat significantly reduced knee medial displacement in both limbs by approximately 1 cm (P < .01). Decline squat reduced uxink lateral movement on 1 side only (P = .03). Reduced knee displacement during decline squat showed fair association with less hip-extension strength (r = -29), hip-flexion strength (r = -.25), and less dorsifiexion (r = -.24). Strength and range were not associated with trunk displacement. Conclusions: Decline squat reduced medial knee and lateral trunk displacement regardless of hip pain. Reductions may be greater in those with lesser hip muscle strength and dorsifiexion. Use of a decline board during squat for improving knee and trunk alignment should be considered as a goal of exercise intervention. [ABSTRACT FROM AUTHOR]

Context: Resistance training exercise prescription is often based on exercises performed at a percentage of a 1-repetition maximum (1RM). Following knee injury, there is no consensus when a patient can safely perform 1RM testing. Resistance training programs require the use of higher loads, and loads used in knee injury rehabilitation may be too low to elicit gains in strength and power. A maximum isometric contraction can safely be performed during early stages of knee rehabilitation and has potential to predict an isotonic knee extension 1RM. Objective: To determine whether a 1RM on an isotonic knee extension machine can be predicted from isometric peak torque measurements. Design: Descriptive laboratory study. Setting: University research laboratory. Participants: A total of 20 (12 males and 8 females) healthy, physically active adults. Main outcome measures: An isokinetic dynamometer was used to determine isometric peak torque (in N⋅m). 1RM testing was performed on a knee extension machine. Linear regression was used to develop a prediction equation, and Bland-Altman plots with limits of agreement calculations were used to validate the equation. Results: There was a significant correlation (P < .001, r = .926) between peak torque (283.0 [22.6] N⋅m) and the knee extension 1RM (69.1 [22.6] kg). The prediction equation overestimated the loads (2.3 [9.1] kg; 95% confidence interval, -15.6 to 20.1 kg). Conclusions: The results show that isometric peak torque values obtained on an isokinetic dynamometer can be used to estimate 1RM values for isotonic knee extension. Although the prediction equation tends to overestimate loads, the relatively wide confidence intervals indicate that results should be viewed with caution. [ABSTRACT FROM AUTHOR]

Context: Previous investigations have examined the reliability, normalization, and underlying projection mechanics of the seated single-arm shot-put (SSASP) test. Although the test is believed to reflect test limb strength, there have been no assessments determining whether test performance is directly associated with upper-extremity strength. Objective: To determine the relationship between isokinetic pushing force and SSASP performance and conduct a method comparison analysis of limb symmetry indices between the 2 tests. Design: Controlled laboratory study. Setting: Biomechanics laboratory. Patients (or Other Participants): Twenty-four healthy and physically active men (n = 12) and women (n = 12). Intervention(s): Participants completed the SSASP and isokinetic pushing tests using their dominant and nondominant arms. Main Outcome Measures: SSASP distance and isokinetic peak force. Results: Significant moderate to strong relationships were revealed between the SSASP distances and isokinetic peak forces for both limbs. The Bland–Altman analysis results demonstrated significantly (P < .002) greater limb symmetry indices for the SSASP (both medicine balls) than the isokinetic ratios, with biases ranging from −0.094 to −0.159. The limits of agreement results yielded intervals ranging from ±0.241 to ±0.340 and ±0.202 to ±0.221 from the biases. Conclusions: These results support the notion that the SSASP test reflects upper-extremity strength. The incongruency of the limb symmetry indices between the 2 tests is likely reflective of the differences in the movement patterns and coordination requirements of the 2 tests. [ABSTRACT FROM AUTHOR]

The main aims of this study were to compare the magnitude of inter-limb asymmetry (ILA) and the relation with self-reported knee function between maximal and explosive knee extensor strength outcomes in professional soccer players. Forty-six male soccer players completed different maximal isokinetic and isometric contractions of the knee extensors for the assessment of maximal strength (peak torque and maximal voluntary contraction (MVC) torque) and explosive strength (early, intermediate, late, and peak rate of torque development (RTD)). Self-reported knee function was assessed with the International Knee Documentation Committee (IKDC) and Lysholm knee scoring scales. Peak torque and MVC torque showed comparable ILAs (8-9%), both being significantly lower than all RTD ILAs (16% on average; p < 0.001). ILAs for early RTD (21%) and peak RTD (19%) were significantly higher than all the other variables (p < 0.05). Only early and intermediate RTD were significantly correlated – though weakly – with both IKDC (rho = 0.32 for both) and Lysholm (rho = 0.36 and 0.30, respectively) scores. We conclude that explosive knee extensor strength – early RTD in particular – exhibited larger ILAs and better relations with self-reported knee function than peak torque and MVC torque in professional soccer players. These results confirm the validity and functional relevance of early RTD and the need for its inclusion in routine performance testing for soccer players. Highlights Professional soccer players exhibited larger inter-limb deficits in knee extension strength for explosive actions than for the widely-used isokinetic test. Self-reported knee function was significantly correlated with explosive strength of the knee extensor muscles but not with maximal strength. The first 50 ms of an explosive knee extension seem to be crucial for self-perceived sport performance and possibly for injury prevention. [ABSTRACT FROM AUTHOR]

Isometric strength and endurance performance of cervical flexor and extensor muscles were compared in women with (n = 30) and without (n = 30) idiopathic neck pain at the craniocervical and cervicothoracic axes. Strength and endurance time (time to task failure in seconds) at 50% maximal voluntary contraction were recorded in 4 directions (craniocervical flexion/extension and cervicothoracic flexion/extension) and 6 strength and endurance ratios were calculated. Participants in both groups were matched for body mass index. The idiopathic neck pain group demonstrated significantly less strength for the cervicothoracic flexors and extensors (1.58–4.7 N·m [12.4%–17.9%] less, P <.04) and significantly less endurance time for the cervicothoracic and craniocervical flexors (10.77–10.9 s [23.3%–27.5%] less, P <.03). The cervicothoracic extension to craniocervical flexion strength ratio was also lower in the idiopathic neck pain group (P =.01); however, no other strength or endurance ratio was significantly different between groups. This exploratory study suggests assessing specific performance parameters accounting for regional muscular differences in the upper and lower neck is potentially informative to understanding impairments in neck pain conditions, particularly as impairments may not be uniform across muscle groups. [ABSTRACT FROM AUTHOR]

Context: What is the correct resistive load to start resistive training with elastic resistance to gain strength? This question is typically answered by the clinician's best estimate and patient's level of discomfort without objective evidence. Objective: To determine the average level of resistance to initiate a strengthening routine with elastic resistance following isometric strength testing. Design: Cohort. Setting: Clinical. Participants: 34 subjects (31 ± 13 y, 73 ± 17 kg, 170 ± 12 cm). Interventions: The force produced was measured in Newtons (N) with an isometric dynamometer. The force distance was the distance from center of joint to location of force applied was measured in meters to calculate torque that was called "Test Torque" for the purposes of this report. This torque data was converted to "Exercise Load" in pounds based on the location where the resistance was applied, specifically the distance away from the center of rotation of the exercising limb. The average amount of exercise load as percentage of initial Test Torque for each individual for each exercise was recorded to determine what the average level of resistance that could be used for elastic resistance strengthening program. Main Outcome Measures: The percentage of initial test torque calculated for the exercise was recorded for each exercise and torque produced was normalized to body weight. Results: The average percentage of maximal isometric force that was used to initiate exercises was 30 ± 7% of test torque. Conclusions: This provides clinicians with an objective target load to start elastic resistance training. Individual variations will occur but utilization of a load cell during elastic resistance provides objective documentation of exercise progression. [ABSTRACT FROM AUTHOR]

This study aimed to assess intra- and inter-visit reliability of a novel EasyForce dynamometer for assessment of maximal strength in knee extension and flexion, and hip abduction and adduction tasks. Young healthy participants (n = 50; 25 males, 25 females; age: 23.4 ± 2.1 years) were measured for maximal joint torque with EasyForce dynamometer and rigid isometric dynamometers with external fixation, in two-sessions (5–10 days apart). The intra-visit reliability was high (ICC) = 0.84–0.95 knee; 0.90–0.94 hip), with absolute reliability sometimes exceeding the acceptable threshold (CV = 6.9–10.6% knee; 7.8–11.8% hip). Inter-visit reliability was excellent for all tasks (ICC = 0.95–0.97 knee; 0.95–0.96 hip). Although the EasyForce values were different compared to rigid dynamometers, the correlations between the devices were high (r = 0.64–0.75 knee; 0.70–0.75 hip). In conclusion, the EasyForce dynamometer provides reliable means of assessing knee (extension and flexion) and hip (abduction and adduction) muscle strength. [ABSTRACT FROM AUTHOR]

BACKGROUND: The capacity to produce force should be promoted especially for the fastest swimming events. AIM: This study aimed to analyze the effects of different test periods in mean, maximal and coefficient of force variation and to correlate the coefficient of force variation and 50 m front crawl time. METHOD: Twelve well trained swimmers (age: 22.33 ± 8.08 years, 1.69 ± 0.48 m height, body mass 56.08 ± 7.86 kg) randomly performed three maximal 30 s repetitions of full swimming and lower limbs actions in front crawl swimming technique with ~15 min resting period. A load cell system permitted the continuous measurement of exerted tethered forces, and 50 m time was registered as the best time obtained at the 12 months before the test. RESULTS: Mean swimming force was greater at 10 s compared to 20 and 30 s period (26.40 [20.66-54.20], 25.33 [21.70-52.35] and 21.39 [17.91-43.98] respectively, p < 0.05). Mean, maximal and force coefficient variation at tethered test with full swimming were higher than lower limbs (24.37 vs. 12.71, 77.97 vs. 39.78 and 0.77 vs. 0.49 respectively, p < 0.05). Strong and inverse correlations were noticed between coefficient of force variation at 10 s during full swimming, at 20 s during kicking and performance (28.75 s [26.20 - 30.68 s]; r = - 0.75; p < 0.01). Very strong correlation was noticed between coefficient of force variation during swimming at 20 s, 30 s and performance (r = -0.91 and -0.92; p < 0.0001). CONCLUSION: Mean swimming force at full swim and lower limbs is affected by the period of the 30 s maximal tethered swimming test and is associated with performance. Data reported may be used as reference for setting training strategies at short distance events. [ABSTRACT FROM AUTHOR]

This study examined isometric strength (maximal voluntary contraction [MVC]) and endurance of cervical flexor and extensor muscles in healthy individuals at the craniocervical (CC) and cervicothoracic (CT) axes. MVC and endurance measures (time to task failure in seconds [s]) at 50% MVC were recorded in 4 directions (CC flexion, CC extension, CT flexion, and CT extension) in 20 males and 20 females, and 6 strength and endurance ratios were calculated. The findings showed that the cervical extensor muscles are not only much stronger than the flexors (1.3-2 times greater MVC), but also have greater capacity for endurance (2-2.4 times greater). While males produced significantly greater MVC recordings than females (P < .003), strength ratios (P > .06) and endurance measures (P > .11) were similar. Endurance ratios were also similar except the CT extension to CC flexion ratio, which was significantly larger in females compared with males (P = .03). These findings demonstrate that substantial but normal variation exists in strength and endurance parameters between cervical flexor and extensor muscles. This is informative to clinicians when evaluating the performance of these neck muscles or when deciding on exercise parameters (eg, load, duration) when training their performance. [ABSTRACT FROM AUTHOR]

Introduction: Maximum grip strength (MGS) is a reliable biomarker of overall health and physiological well-being. Therefore, an accurate and reliable measurement device is vital for ensuring the validity of the MGS assessment. This paper presents GripAble, a mobile hand grip device for the assessment of MGS. GripAble's performance was evaluated using an inter-instrument reliability test against the widely used Jamar PLUS+ dynamometer.Methods: MGS data from sixty-three participants (N = 63, median (IQR) age = 29.0 (29.5) years, 33 M/30 F) from both hands using GripAble and Jamar PLUS+ were collected and compared. Intraclass correlation (ICC), regression, and Bland and Altman analysis were performed to evaluate the inter-instrument reliability and relationship in MGS measurements between GripAble and Jamar PLUS+ .Results: GripAble demonstrates good-to-excellent inter-instrument reliability to the Jamar PLUS+ with ICC3,1 = 0.906 (95% CI [0.87-0.94]). GripAble's MGS measurement is equivalent to 69% (95% CI [0.67-0.71]%) of Jamar PLUS+'s measurement. There is a proportional difference in mean MGS between the two devices, with the difference in MGS between GripAble and Jamar PLUS+ increasing with MGS.Conclusion: The GripAble is a reliable tool for measuring grip strength. However, the MGS readings from GripAble and Jamar PLUS+ should not be interchanged for serial measurements of the same patient, nor be translated directly from one device to the other. A new normative MGS data using GripAble will be collected and accessed through the software for immediate comparison to age and gender-matched subpopulations. [ABSTRACT FROM AUTHOR]

Background: Grip strength has been identified as an important indicator of health status and predictor of clinical outcomes. The gold standard for measuring grip strength is the JAMAR® Hydraulic Hand Dynamometer. Less expensive dynamometers are available but have not been validated within a hospital setting. Objectives: To validate the Camry Digital Handgrip Dynamometer (Model EH101) against the validated JAMAR® Dynamometer (Model J00105) in a hospital population. Methods: A cross-sectional observational study with a randomised single-blind cross-over component was conducted on consenting adult patients admitted to general hospital wards. The best of three measurements taken using the dominant hand was used for analysis. Results: Fifty-one participants (median [interquartile range] age 42 [30–58] years; n = 27 [52.9%] female) were included. The mean difference between the Jamar® and Camry measurements was 1.9 kg ± 3.6 kg (t -value 0.9; p = 0.4). There was a strong positive correlation between the Jamar® and the Camry devices (R = 0.94; r ² = 0.88; p < 0.0001). Excellent agreement was found between Jamar® and Camry measurements (interclass correlational coefficient 0.97, 95% CI 0.94–0.99, p < 0.0001). Hand dominance significantly affected the agreement between devices (p = 0.002). Conclusions: The Camry Digital Handgrip Dynamometer is a valid tool for assessing grip strength in hospitalised adult patients. Clinical implications: The Camry Digital Handgrip Dynamometer could be used as an inexpensive tool to measure grip strength. [ABSTRACT FROM AUTHOR]

Context: Collecting torque data using a multimode dynamometer is common in sports-medicine research. The error in torque measurements across multiple sites and dynamometers has not been established. Objective: To assess the validity of 2 calibration protocols across 3 dynamometers and the error associated with torque measurement for each system. Design: Observational study. Setting: 3 university laboratories at separate institutions. Equipment: 2 Biodex System 3 dynamometers and 1 Biodex System 4 dynamometer. Interventions: System calibration was completed using the manufacturer-recommended single-weight method and an experimental calibration method using a series of progressive weights. Both calibration methods were compared with a manually calculated theoretical torque across a range of applied weights. Main Outcome Measures: Relative error, absolute error, and percent error were calculated at each weight. Each outcome variable was compared between systems using 95% confidence intervals across low (0-65 Nm), moderate (66-110 Nm), and high (111-165 Nm) torque categorizations. Results: Calibration coefficients were established for each system using both calibration protocols. However, within each system the calibration coefficients generated using the single-weight (System 4 = 2.42 [0.90], System 3a = 1.37 [1.11], System 3b = -0.96 [1.45]) and experimental calibration protocols (System4 = 3.95 [1.08], System 3a = -0.79 [1.23], System 3b = 2.31 [1.66]) were similar and displayed acceptable mean relative error compared with calculated theoretical torque values. Overall, percent error was greatest for all 3 systems in low-torque conditions (System 4 = 11.66% [6.39], System 3a = 6.82% [11.98], System 3b = 4.35% [9.49]). The System 4 significantly overestimated torque across all 3 weight increments, and the System 3b overestimated torque over the moderate-torque increment. Conclusions: Conversion of raw voltage to torque values using the single-calibration-weight method is valid and comparable to a more complex multiweight calibration process; however, it is clear that calibration must be done for each individual system to ensure accurate data collection. [ABSTRACT FROM AUTHOR]

Context: Muscle imbalances aid in the identification of athletes at risk for lower-extremity injury. Little is known regarding the influence that leg preference or playing position may have on lower-extremity muscle strength and asymmetry. Purpose: To investigate lower-extremity strength profiles in rugby union athletes and compare isokinetic knee- and hip-strength variables between legs and positions. Methods: Thirty male academy rugby union athletes, separated into forwards (n = 15) and backs (n = 15), participated in this cross-sectional analysis. Isokinetic dynamometry was used to evaluate peak torque, angle of peak torque, and strength ratios of the preferred and nonpreferred legs during seated knee extension/flexion and supine hip extension/flexion at 60°/s. Results: Backs were older (ES = 1.6) but smaller in stature (ES = -0.47) and body mass (ES = -1.3) than the forwards. The nonpreferred leg was weaker than the preferred leg for forwards during extension (ES = -0.37) and flexion (ES = -0.21) actions and for backs during extension (ES = -0.28) actions. Backs were weaker at the knee than forwards in the preferred leg during extension (ES = -0.50) and flexion (ES = -0.66) actions. No differences were observed in strength ratios between legs or positions. Backs produced peak torque at longer muscle lengths in both legs at the knee (ES = -0.93 to -0.94) and hip (ES = -0.84 to -1.17) than the forwards. Conclusions: In this sample of male academy rugby union athletes, the preferred leg and forwards displayed superior strength compared with the nonpreferred leg and backs. These findings highlight the importance of individualized athletic assessments to detect crucial strength differences in male rugby union athletes. [ABSTRACT FROM AUTHOR]

Background Ulnar collateral ligament injuries are rampant in the sport of baseball where kinetic chain impacts, stemming from misappropriation of stride length or changes that occur in competition due to fatigue, have not been evaluated for dynamic elbow stability effects. Hypothesis/Purpose To examine the relationship between clinical measures of grip strength and altered stride length in baseball pitchers. It is believed that shorter stride lengths would reduce grip strength in baseball pitchers. Study Design Crossover Study Design Methods A total of 19 uninjured pitchers (15 collegiate and 4 high school) (age 18.63 ± 1.67 years, height 1.84 ± 0.054 m, mass 82.14 ± 0.054 kg) threw two simulated 80-pitch games at ±25% of their desired stride length recorded by motion capture with two force plates and a radar gun to track each throw. A handheld grip dynamometer was used to record the mean change in grip strength after games from baseline measures. Pairwise comparisons at baseline and post-game denoted grip strength changes and dominant grip strength offsets for stride length conditions. Results Subjects with shorter stride lengths revealed a significant decline in grip strength in the dominant arm from baseline (pre-game; 45.1 kg vs. post-game; 43.2 kg, p=0.017, ES=0.28), however all other tests involving dominant grip strength changes and offset analyses were not statistically different for under-stride and over-stride length conditions. Conclusions Clinical evaluation of grip strength has the potential to identify altered lower body mechanics and may be considered as a safe and effective monitoring strategy to integrate with motion capture in determining optimal stride lengths for baseball pitchers. [ABSTRACT FROM AUTHOR]

Purpose: While several studies have documented isokinetic knee strength in junior and senior rugby league players, investigations of isokinetic knee and hip strength in professional rugby union players are limited. The purpose of this study was to provide lower-extremity strength profiles and compare isokinetic knee and hip strength of professional rugby league and rugby union players. Participants: 32 professional rugby league and 25 professional rugby union players. Methods: Cross-sectional analysis. Isokinetic dynamometry was used to evaluate peak torque and strength ratios of the dominant and nondominant legs during seated knee-extension/ flexion and supine hip-extension/flexion actions at 60°/s. Results: Forwards from both codes were taller and heavier and had a higher body-mass index than the backs of each code. Rugby union forwards produced significantly (P < .05) greater peak torque during knee flexion in the dominant and nondominant legs (ES = 1.81 and 2.02) compared with rugby league forwards. Rugby league backs produced significantly greater hip-extension peak torque in the dominant and nondominant legs (ES = 0.83 and 0.77) compared with rugby union backs. There were no significant differences in hamstring-to-quadriceps ratios between code, position, or leg. Rugby union forwards and backs produced significantly greater knee-flexion-to-hip-extension ratios in the dominant and nondominant legs (ES = 1.49-2.26) than rugby union players. Conclusions: It seems that the joint torque profiles of players from rugby league and union codes differ, which may be attributed to the different demands of each code. [ABSTRACT FROM AUTHOR]

Background Knee flexion strength may hold important clinical implications for the determination of injury risk and readiness to return to sport following injury and orthopedic surgery. A wide array of testing methodologies and positioning options are available that require validation prior to clinical integration. The purpose of this study was to 1) investigate the validity and test-retest reliability of isometric knee flexion strength measured by a fixed handheld dynamometer (HHD) apparatus compared to a Biodex Dynamometer (BD), 2) determine the impact of body position (seated versus supine) and foot position (plantar- vs dorsiflexed) on knee flexion peak torque and 3) establish the validity and test-retest reliability of the NordBord Hamstring Dynamometer. Study Design Validity and reliability study, test-retest design. Methods Forty-four healthy participants (aged 27 ± 4.8 years) were assessed by two raters over two testing sessions separated by three to seven days. Maximal isometric knee flexion in the seated and supine position at 90o knee flexion was measured with both a BD and an externally fixed HHD with the foot held in maximal dorsiflexion or in plantar flexion. The validity and test-retest reliability of eccentric knee flexor strength on the NordBord hamstring dynamometer was assessed and compared with isometric strength on the BD. Results Level of agreement between HHD and BD torque demonstrated low bias (bias -0.33 Nm, SD of bias 13.5 Nm; 95% LOA 26.13 Nm, -26.79 Nm). Interrater reliability of the HHD was high, varying slightly with body position (ICC range 0.9-0.97, n=44). Isometric knee flexion torque was higher in the seated versus supine position and with the foot dorsiflexed versus plantarflexed. Eccentric knee flexion torque had a high degree of correlation with isometric knee flexion torque as measured via the BD (r=0.61-0.86). The NordBord had high test-retest reliability (0.993 (95%CI 0.983-0.997, n=19) for eccentric knee flexor strength, with an MDC95 of 26.88 N and 28.76 N for the left and right limbs respectively. Conclusion Common measures of maximal isometric knee flexion display high levels of correlation and test-retest reliability. However, values obtained by an externally fixed HHD are not interchangeable with values obtained via the BD. Foot and body position should be considered and controlled during testing. [ABSTRACT FROM AUTHOR]

Background: Trauma and management of injuries can result in reduction or loss of mobility, which can lead to skeletal muscle deconditioning and sustained disability. Prior investigators have examined changes in skeletal muscle due to injury and immobility separately. The muscular consequences of combined immobility and trauma have not been systematically investigated. Objective: The purpose of this study was to explore the association of time to first ambulation with skeletal muscle size and strength in patients after major trauma. Methods: Adults (N = 19) admitted for major trauma (Injury Severity Score [ISS] > 15) provided daily measures of muscle size (ultrasound) and strength (dynamometry) during hospitalization. Participants were grouped based on time to first ambulation. Repeated measures analysis of variance was used to compare muscle measures between the groups across 5 days while controlling for age and gender. Results: Participants were primarily male (63%) aged 40 ± 17 years with a mean ISS of 21 ± 4. Early ambulation was associated with a 10% increase from baseline in bicep size on Days 3 and 4 and a 15% increase from baseline on Day 5. There were no changes in rectus femoris size in either group. The early ambulation group was significantly stronger than the delayed ambulation group throughout the study in measures taken with the biceps (22%–37%) and quadriceps (26%–46%). Conclusion: Early ambulation following major trauma was associated with increased bicep size and greater muscle strength in the biceps and quadriceps muscles over time. [ABSTRACT FROM AUTHOR]

Introduction: Objective information on longitudinal disease progression in inclusion body myositis (IBM) is lacking.Methods: Longitudinal dynamometry and functional status data were collated from a cohort of IBM patients. Annual change was calculated by means of linear modeling. Trajectories of change in grip, knee extension, IBM Functional Rating Scale (IBM-FRS) and Neuromuscular Symptom Score (NSS) were identified by means of latent growth mixture modeling.Results: Data were collated from 75 IBM patients (348 person-years follow-up). Annual strength loss was greatest for pinch (-10%) and knee extension (-4%). Functional deterioration was greatest for males. Three distinct trajectory groups were identified. Rapid deterioration trajectory for grip strength was associated with younger diagnosis age. Rapid deterioration for knee extension strength was associated with older age of diagnosis.Discussion: This study has quantified strength change in IBM and identified distinct trajectory groups, which will aid prognostication and stratification for inclusion into future clinical trials. [ABSTRACT FROM AUTHOR]

Background although handgrip strength (HGS) is considered an excellent predictor of morbidity and mortality, there are few reference data available, especially across life from young to old populations. Objective to investigate the reference values and determinants for HGS in a large Chinese adult population. Design this cross-sectional study used data from the Tianjin Chronic Low-Grade Systemic Inflammation and Health Cohort Study ranging from 2013 to 2017. Setting and subjects in total, 37,707 Chinese adults aged 18–93 years with measures of HGS were included. Methods HGS was measured using a handheld digital dynamometer. The percentile distribution of HGS, as well as mean (standard deviation) values of HGS, was calculated according to sex and age categories. The Pearson's or Spearman's correlation coefficient and multiple linear regression were also used. Results the peak mean value of HGS was 45.2 ± 6.88 kg in men and 26.8 ± 4.65 kg in women. Different reference values for each sex and age category are present. The prevalence of low HGS was 7.69% in men and 6.46% in women. Multiple regression analysis showed that almost 72.5% of HGS variability can be explained by sex, age, height and weight. Conclusions the HGS reached peak at 40 years old, maintained or slightly lowered between ages 40 and50 and then start an accelerated decline after 50 years old. Reference values of HGS should be stratified by sex and age group. HGS variability can be largely explained by sex, age, height and weight. [ABSTRACT FROM AUTHOR]

The aim of this study was to conduct a systematic review to determine the quality of evidence of studies assessing isokinetic hip muscle strength in adult non-injured individuals. We also aimed to summarise and pool data of normative values for hip muscle strength. The influence of methodological and participant-related factors on hip strength performance was explored as well. Guidelines proposed in the PRISMA were used to undertake a search strategy involving the keyword 'hip' associated with a set of keywords reflecting muscle strength. Five databases were searched: ProQuest, PubMed, Science Direct, Scopus and Web of Science. From the 2,939 records initially retained, 28 articles were included in this systematic review. Eight articles were classified as high quality. This systematic review exposed the methodological fragility of most studies assessing hip strength in non-injured adult population. Only data from studies with a small number of participants are available to be used as reference. A few individual studies suggest no differences in torque parameters between dominant and non-dominant lower limbs; differences in torque parameters between age groups; and between male and female participants. Overall, reference values for hip muscle performance in isokinetic tests are mostly unclear. [ABSTRACT FROM AUTHOR]

The objective of this study was to devise a method of kinetic analysis of the ground reaction force that enables the durations and magnitudes of forces acting during the individual phases of ski turns to be described exactly. The method is based on a theoretical analysis of physical forces acting during the ski turn. Two elementary phases were defined: (1) preparing to turn (initiation) and (2) actual turning, during which the center of gravity of the skier-ski system moves along a curvilinear trajectory (steering). The starting point of the turn analysis is a dynamometric record of the resultant acting ground reaction force applied perpendicularly on the ski surface. The method was applied to six expert skiers. They completed a slalom course comprising five gates arranged on the fall line of a 26° slope at a competition speed using symmetrical carving turns (30 evaluated turns). A dynamometric measurement system was placed on the carving skis (168 cm long, radius 16 m, data were recorded at 100 Hz). MATLAB procedures were used to evaluate eight variables during each turn: five time variables and three force variables. Comparison of the turn analysis results between individuals showed that the method is useful for answering various research questions associated with ski turns. [ABSTRACT FROM AUTHOR]

The purpose of this study was to compare maximal torque exerted about the craniocervical (CC) and cervicothoracic (CT) axes in the sagittal plane using a novel dynamometry device. Maximal voluntary contraction (MVC) recordings in newton-meters (N-m) were measured in 20 males and 20 females for each of 4 tests: CT extension, CT flexion, CC extension, CC flexion. Twenty of the volunteers repeated the testing procedure on a second occasion to determine the test-retest repeatability of the measures. MVC recordings at the CT axis (extension, 30.24 ± 12.15 N-m; flexion, 18.90 ± 8.21 N-m) were 1.4-2 times greater than recordings at the CC axis (extension, 16.46 ± 7.26 N-m; flexion, 13.34 ± 5.97 N-m). Extensor to flexor strength ratios reduced from 1.75 at the CT axis to 1.24 at the CC axis, but were similar for both males and females. Good to excellent test-retest repeatability was demonstrated for all tests (ICC = 0.75-0.99, SEM = 0.50-2.44 N-m). Consistent with differences in the muscle morphology at the CC and CT axes, torque exerted about these axes differ. Separate measurement of torque about these axes potentially offers a more comprehensive profile of cervical muscle strength. [ABSTRACT FROM AUTHOR]

Muscle imbalance and deficit are key parameters for guiding rehabilitation and sports sessions and avoiding injuries. However, the high cost and non-portable nature of most instruments employed for muscle strength assessment frequently hamper an affordable evaluation in field conditions. This study evaluated the validity and reliability of a low-cost digital dynamometer to assess the maximal isometric strength of upper limb muscles. Fourteen physically active volunteers performed the main movements of the upper limb at maximal isometric strength: flexion-extension, internal-external rotation and abduction-adduction of the shoulder; and flexion-extension of both elbow and wrist. Validity was examined by comparing the strength values from the low-cost digital dynamometer and those measured by an isokinetic dynamometer, assumed as the gold standard. The correlation between both devices was perfect (r > 0.913), while Bland-Altman plots showed absolute agreement between both devices, the maximum range of the values of bias was −0.99–1.00 N in wrist extension. Inter-tester and intra-tester reliability were excellent for all movements (ICC ≥ 0.855). The low-cost digital dynamometer showed strong validity and excellent reliability in assessing maximal isometric strength during the main movements of the upper limb. Professionals may use it for an affordable isometric muscle strength assessment in field situations. [ABSTRACT FROM AUTHOR]

Introduction: Quantifying muscle strength is critical in clinical and research settings. A rapid and objective method is ideal. The primary objective of this study was to examine the reliability of a novel device, the rapid objective quantification- tibialis anterior (ROQ-TA), which quantifies the dorsiflexion force of the tibialis anterior, and to assess its validity against isokinetic dynamometry (IKD).Methods: Ankle dorsiflexion of 20 healthy subjects was assessed by 3 modalities, ROQ-TA, manual muscle testing, and isokinetic dynamometry, over 2 testing sessions.Results: The intraclass correlation coefficient [ICC(2,1) ] for reliability was 0.872 (0.677-0.949) for the ROQ-TA and 0.892 (0.728-0.957) for IKD. For validity, the ICC(2,1) values for the ROQ-TA and IKD were in good agreement, with 0.672 (0.17-0.87) in the first testing session and 0.769 (0.42-0.91) in the second session.Discussion: The ROQ-TA is a valid and reliable device to test ankle dorsiflexion force in a healthy population. Muscle Nerve, 2018. [ABSTRACT FROM AUTHOR]

Background: A hand-held dynamometer (HHD) offers a reliable and valid method to quantify quadriceps strength in a clinical environment. While measures of peak strength provide functional insights, most daily activities are performed quickly and do not require maximum strength. Rate of torque development (RTD) measures better reflect both the demands of daily activity and athletic movements. The capacity to obtain RTD measures in clinical settings is possible with an HHD, but the validity of RTD measures has not been quantified. Hypothesis/Purpose: To determine the validity of an HHD to measure quadriceps isometric strength metrics compared to isometric strength measures obtained on an isokinetic dynamometer. It was hypothesized that the HHD would be a valid measure of peak torque and RTD at all time intervals when compared to the isokinetic dynamometer. Study Design: Descriptive laboratory study. Methods: Twenty healthy participants (12 male, 8 female) (age=23.7±2.9 years, height=174.6±10.1 cm, mass=76.4±15.9 kg, and Tegner=6.7 ±1.2) performed maximum isometric quadriceps contractions on an isokinetic dynamometer and with an HHD. Outcome measures included quadriceps peak torque and RTD at three intervals (0-100, 0-250 ms, and average). Pearson product-moment correlation coefficients and Spearman's rank correlation coefficient were used to determine relationships between devices. Bland-Altman Plots with Limits of Agreement (LOA) calculations were used to quantify systematic bias between measurement techniques. Results: There was a significant correlation between the isokinetic dynamometer and the HHD for peak torque (p<.001, r=.894) and all RTD measurements (p<.002, r=.807; ρ=.502-.604). Bland-Altman plot LOA indicated the HHD overestimated peak torque values (19.4±53.2 Nm) and underestimated all RTD measurements (-55.2±190.7 Nm/s to -265.2±402.6 Nm/s). Conclusion: These results show it is possible to obtain valid measures of quadriceps peak torque and late RTD using an HHD. Measures of early RTD and RTDAvg obtained with an HHD were more variable and should be viewed with caution. Level of Evidence: Diagnostic, Level 3 [ABSTRACT FROM AUTHOR]

Rendos, NK, Harriell, K, Qazi, S, Regis, RC, Alipio, TC, and Signorile, JF. Variations in verbal encouragement modify isokinetic performance. J Strength Cond Res 33(3): 708-716, 2019-Verbal instruction and encouragement are common in exercise testing; however, the verbiage used during exercise testing is rarely controlled despite the likelihood it may affect the participant's performance. Although variations in verbal cuing based on rate and intensity have been examined during isometric contractions, they have not been examined during isokinetic testing, which is a standardized assessment of muscle performance in athletic, rehabilitation, and research settings. This study examined the effects of 4 variations in verbal encouragement during isokinetic knee flexion and extension exercises. Twenty-three healthy participants (aged 19-34 years) completed 4 isokinetic testing sessions on a Biodex isokinetic dynamometer. Each session consisted of 5, 10, and 15 repetitions at 1.05 rad⋅s-1 (60°⋅s-1), 3.14 rad⋅-1 (180°⋅s-1), and 5.24 rad⋅s-1 (300°⋅s-1), respectively, separated by 5-minute passive recoveries. The variations in verbal encouragement randomized during each testing session used the following statements: (a) ''as fast as you can" (FAST); (b) "as hard as you can" (HARD); (c) "as hard and as fast as you can" (BOTH); and (d) no verbal encouragement (NO CUE). Repeated-measures analyses of variance with a Bonferroni post hoc analysis revealed that the FAST and BOTH verbal cues produced greater work, peak torque, and power at all 3 speeds of isokinetic testing. These findings indicate the verbal cues "as fast as you can" and "as hard and as fast as you can" should be used to maximize performance during isokinetic testing. [ABSTRACT FROM AUTHOR]

Introduction: Muscle weakness and functional disability have not been evaluated in a population-based study of patients with myasthenia gravis (MG).Methods: All patients with MG in a well-defined catchment area were identified in the Danish National Patient Registry. Of the 175 eligible patients, 90 participated and were studied using MG-specific scales, isometric dynamometry, and functional tests. Fifty age- and sex-matched subjects served as controls.Results: Muscle strength was reduced by 13%, 21%, and 12% for shoulder abduction, knee extension, and ankle extension, respectively (P < 0.05). Chair stand and 400-meter walking were impaired by 24% and 23%, respectively (P < 0.05). Muscle strength and functional performances were related to MG-specific scales.Discussion: MG patients have moderately reduced isometric muscle strength and impaired physical performance. Muscle weakness and functional tests relate closely to MG-specific scales, suggesting that dynamometry and functional tests can be used to monitor MG patients and as efficacy parameters in clinical trials. Muscle Nerve 59:218-223, 2019. [ABSTRACT FROM AUTHOR]

BACKGROUND: The diagnostic accuracy of manual muscle testing (MMT) has been examined- but not for grip strength. OBJECTIVE: Determine the diagnostic accuracy of MMT relative to grip dynamometry for identifying patients with weak grip strength. METHODS: This study involved the secondary analysis of grip strength data obtained from 61 patients managed in a home care setting. The concordance between weakness identified using MMT and grip dynamometry was examined. RESULTS: The agreement between MMT and dynamometry was about 70%. Kappa suggested fair agreement beyond chance. Sensitivity and specificity ranged from 66.7 to 73.4 percent. CONCLUSIONS: Grip strength measured using MMT lacks sufficient diagnostic accuracy to advocate its use – at least with patients seen in a home setting. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate knee muscle strength characteristics in players from a high-level youth football Academy. In total, 110 players (aged 8-15 years) underwent muscle strength assessments carried out by a research physiotherapist using a computer-linked hand-held dynamometer. Results indicated that isometric hamstrings and quadriceps strength increased with age, whereas the isometric hamstring to quadriceps (H/Q) ratio decreased with age. A number of youth football players (n = 20; 18%; 95% CI: 11-27%) demonstrated isometric H/Q ratios of less than 0.60, as well as muscle strength asymmetries between limbs for the hamstrings (n = 40, 36%; 95% CI: 27-46%) and quadriceps (n = 51, 46%; 95% CI 37-56%), potentially increasing injury risk. This study provides new evidence that the isometric H/Q ratio reduces with advancing age during adolescence which may have important implications for junior athlete development and long-term injury prevention in football. [ABSTRACT FROM AUTHOR]

Objective: Open-label data suggest that intravenous immunoglobulin (IVIG) might improve lowerextremity strength in human immunodeficiency virus (HIV)-associated myelopathy (HIVM), a rare but debilitating neurologic complication of HIV. We sought to determine the feasibility of testing the efficacy of IVIG for HIVM more rigorously. Design: We conducted a randomized, double-blind, placebocontrolled feasibility trial of IVIG for HIVM, using dynamometry as an outcome measure (Clinical Trial No. NCT01561755). Setting: The study took place in an academic medical center in New York, New York Participants: Only 12 participants were enrolled in four years; critical impediments to the study were the rarity of patients with new HIVM diagnoses and prior exposure to IVIG in patients with an established diagnosis. Measurements: Dynamometry of hip flexion, knee flexion, and ankle dorsiflexion were measured; the HIV Dementia Motor Score (HDMS); and the two-minute timed walk test were utilized. Results: Recruitment was the major feasibility issue. Dynamometry was generally well-tolerated, had good test-retest reliability (r=0.71-0.86, p<0.02 for all muscle groups), and good inter-item reliability as judged by the correlations between the muscle groups (r=0.76-0.81, p=0.001-0.005). Dynamometry was valid and clinically meaningful based on its correlations with the HDMS and the two-minute timed walk test. Conclusion: We conclude that an adequately powered clinical trial of IVIG for HIVM would likely require a prolonged recruitment period and multiple participating sites. Lower limb dynamometry is a useful outcome measure for HIVM, which might also be useful in other HIV-related gait disorders. [ABSTRACT FROM AUTHOR]

* STUDY DESIGN: Secondary analysis, cross-sectional study. * BACKGROUND: Chronic hip joint pain (CHJP) can lead to limitations in activity participation, but the musculoskeletal factors associated with the condition are relatively unknown. Understanding the factors associated with CHJP may help develop rehabilitation strategies to improve quality of life of individuals with long-term hip pain. * OBJECTIVES: To compare measures of hip abductor muscle volume and hip abductor muscle strength between women with CHJP and asymptomatic controls. * METHODS: Thirty women, 15 with CHJP and 15 matched asymptomatic controls (age range, 18-40 years), participated in this study. Magnetic resonance imaging was used to determine the volume of the primary hip abductor muscles, consisting of the gluteus medius, gluteus minimus, a small portion of the gluteus maximus, and the tensor fascia latae, within a defined region of interest. Break tests were performed using a handheld dynamometer to assess hip abductor strength. During the strength test, the participant was positioned in sidelying with the involved hip in 15° of abduction. Independent-samples t tests were used to compare muscle volume and strength values between those with CHJP and asymptomatic controls. * RESULTS: Compared to asymptomatic controls, women with CHJP demonstrated significantly increased gluteal muscle volume (228 ± 40 cm3 versus 199 ± 29 cm3, P = .032), but decreased hip abductor strength (74.6 ± 16.8 Nm versus 93.6 ± 20.2 Nm, P = .009). There were no significant differences in tensor fascia lata muscle volume between the 2 groups (P = .640). * CONCLUSION: Women with CHJP appear to have larger gluteal muscle volume, but decreased hip abductor strength, compared to asymptomatic controls. [ABSTRACT FROM AUTHOR]

Studies that compared the agreement between Jamar and other models of dynamometers for handgrip strength (HGS) measurement have exhibited variability in the provided results. The lack of comparability between dynamometers led to the development of the Bodygrip dynamometer. This study aims to examine the reliability of the Bodygrip for HGS measurement, to compare it with the Jamar, and to explore the HGS differences between instruments considering the ergonomic effect of using the Bodygrip with 2 different handles. A cross-sectional study was conducted in free-living (n = 114, 18-89 years) and inpatient (n = 50, 65-93 years) volunteers. Nondominant HGS was tested randomly with the Jamar and Bodygrip, the latter using 2 different handles-curved and straight types. Handgrip strength was obtained for each participant under the same conditions. Each individual performed 2 HGS measurements with each dynamometer, and the maximum HGS value was considered for dynamometers comparison. Differences in the maximum HGS value between the 2 devices (Jamar-Bodygrip), intraclass correlation coefficients (ICCs), Bland and Altman plots, and limits of agreement were obtained. Correlation between the highest HGS measurement obtained for the nondominant hand with the Jamar and with the Bodygrip using each handle was excellent (ICCs: 0.93-0.95). Mean differences of -0.5 (limits of agreement: -4.6; 3.5) kgf with the curved handle and of 1.0 (-7.7; 9.7) kgf with the straight handle for the free-living participants were obtained, whereas for inpatients these values were -1.0 (-3.8; 1.9) kgf and 2.1 (-3.3; 7.5) kgf, respectively, for the curved and straight handles. The Bodygrip is comparable to the Jamar in free-living adults and in hospitalized older adults, exhibiting excellent interinstrument reliability. The Bodygrip with the curved handle produces results closer to the Jamar when compared with Bodygrip with the straight handle, which emphasizes the importance of grip handle ergonomics to measurement reliability. [ABSTRACT FROM AUTHOR]

The aim of this study was to propose a new force parameter, associated with swimmers’ technique and performance. Twelve swimmers performed five repetitions of 25 m sprint crawl and a tethered swimming test with maximal effort. The parameters calculated were: the mean swimming velocity for crawl sprint, the mean propulsive force of the tethered swimming test as well as an oscillation parameter calculated from force fluctuation. The oscillation parameter evaluates the force variation around the mean force during the tethered test as a measure of swimming technique. Two parameters showed significant correlations with swimming velocity: the mean force during the tethered swimming (r = 0.85) and the product of the mean force square root and the oscillation (r = 0.86). However, the intercept coefficient was significantly different from zero only for the mean force, suggesting that although the correlation coefficient of the parameters was similar, part of the mean velocity magnitude that was not associated with the mean force was associated with the product of the mean force square root and the oscillation. Thus, force fluctuation during tethered swimming can be used as a quantitative index of swimmers’ technique. [ABSTRACT FROM AUTHOR]

Introduction: The hand grip strength test provides useful and reliable information about overall health. Different studies have investigated the optimal grip span for determining maximal hand grip strength in different populations such as adults, adolescents and children without disabilities.Objective: To ascertain whether there is an optimal grip span for determining maximal hand grip strength in adolescents with Down syndrome (DS).Methods: Twenty-seven right-handed youths with DS (seven females) aged 15.5 ± 3.6 years were evaluated in this methodological study. Each hand was randomly tested on ten times using five different grip spans, allowing one-minute rest between attempts. The hand span was measured from the tip of the thumb to the tip of the small finger with the hand widely opened. To confirm the usefulness of the optimal grip span, a new group of 15 adolescents with DS were recruited.Results: An optimal grip span was identified for the dominant hand in adolescents with DS. The equation relating grip span as a function of dominant hand span in this group is formulated as follows: y = 0.342x - 1.161 cm (r = 0.63, p < 0.05). In the case of non-dominant hand, a tendency towards a linear association (p = 0.058) was found; the equation is formulated as follows: y = 0,210x + 1.324 cm.Conclusion: It is important to standardize the procedure and increase reliability when measuring hand grip strength in DS population. The values stated in this study are recommended to assess hand grip strength in adolescents with Down syndrome. [ABSTRACT FROM AUTHOR]

Four hundred adult claimants underwent medico-legal assessment following upper limb injuries. Dynamometry was performed on each using the Jamar five handle-position test. Injury causes loss of power and there is a significant relationship between the percentage loss of power and the measured whole limb impairment. This paper presents a new approach for the analysis of the tests. The normal physiological length–tension pattern of muscle is maintained in the majority of claimants albeit with modifications due to the specific effects of injury on hand function. This paper provides normative data for the analysis of dynamometry in this population and makes recommendations for parameters that suggest that a test is a true reflection of capacity and thus useable in court. [ABSTRACT FROM AUTHOR]

Introduction: Dynamometry is increasingly used as an objective measurement of muscle strength in neurological diseases. No study has applied dynamometry in untreated newly diagnosed patients with myasthenia gravis (MG).Methods: Isometric muscle strength at the shoulder, knee, and ankle was determined in 21 MG patients before and after initial anti-myasthenic treatment. Isometric strength was compared with MG evaluation scales.Results: Muscle strength was reduced for knee extensors and shoulder abductors but normal for ankle extensors. Isometric muscle strength did not correlate significantly with manual muscle testing (MG Composite). Dynamometry revealed improved muscle strength of up to 50% (median 17%; range -1.8-49.8) despite no change in the MG Composite score.Conclusions: Dynamometry appears to be a more sensitive method of identifying changes in limb strength than MG evaluation scales. This supports the use of dynamometry in MG patients, especially for evaluation of the effect of anti-myasthenic treatment. Muscle Nerve 54: 709-714, 2016. [ABSTRACT FROM AUTHOR]

The evaluation of rate of force development during rapid contractions has recently become quite popular for characterising explosive strength of athletes, elderly individuals and patients. The main aims of this narrative review are to describe the neuromuscular determinants of rate of force development and to discuss various methodological considerations inherent to its evaluation for research and clinical purposes. Rate of force development (1) seems to be mainly determined by the capacity to produce maximal voluntary activation in the early phase of an explosive contraction (first 50-75 ms), particularly as a result of increased motor unit discharge rate; (2) can be improved by both explosive-type and heavy-resistance strength training in different subject populations, mainly through an improvement in rapid muscle activation; (3) is quite difficult to evaluate in a valid and reliable way. Therefore, we provide evidence-based practical recommendations for rational quantification of rate of force development in both laboratory and clinical settings. [ABSTRACT FROM AUTHOR]

Background: Isokinetic dynamometry is a useful tool to objectively assess muscle strength of children and adults in athletic and rehabilitative settings. This study examined test-retest reliability of isokinetic knee strength measurements in children aged 8 to 10 years and defined limits for the minimum difference (MD) in strength that indicates a clinically important change.Hypothesis: Isokinetic knee strength measurements (using the Biodex System 4) in children will provide reliable results.Study Design: Descriptive laboratory study.Methods: In 22 healthy children, 5 maximal concentric (CON) knee extensor (KE) and knee flexor (KF) contractions at 2 angular velocities (60 deg/s and 180 deg/s) and 5 maximal eccentric (ECC) KE/KF contractions at 60 deg/s were assessed 7 days apart. The intraclass correlation coefficient (ICC2.1) was used to examine relative reliability, and the MD was calculated on the basis of standard error of measurement.Results: ICCs for CON KE/KF peak torque measurements were fair to excellent (range, 0.49-0.81). The MD% values for CON KE and KF ranged from 31% to 37% at 60 deg/s and from 34% to 39% at 180 deg/s. ICCs in the ECC mode were good (range, 0.60-0.70), but associated MD% values were high (>50%). There was no systematic error for CON KE/KF and ECC KE strength measurements at 60 deg/s, but systematic error was found for all other measurements.Conclusion: The dynamometer provides a reliable analysis of isokinetic CON knee strength measurements at 60 deg/s in children aged 8 to 10 years. Measurements at 180 deg/s and in the ECC mode were not reliable, indicating a need for more familiarization prior to testing.Clinical Relevance: The MD values may help clinicians to determine whether a change in knee strength is due to error or intervention. [ABSTRACT FROM AUTHOR]

Background: There are conflicting results with respect to the validity and reliability of lower extremity strength measurements using a hand-held dynamometer (HHD) in the healthy population. Previous studies exploring foot inversion and eversion strength using a HHD were carried out with predominantly clinically affected participants in different positions. The question arises whether HHD measurements of isometric foot inversion and eversion strength performed with participants in different positions are valid, reliable and comparable and can be used alternatively. Purpose: The aims of this study were to investigate: a) the intra- and inter-tester reliability of measurements of foot inversion and eversion strength in different participant positions using a belt-stabilized HHD; b) the comparability of results obtained in different positions; and c) the concurrent validity of the aforementioned measurements using an isokinetic dynamometer. Methods: Thirty adults (12 females and 18 males; mean age 22.5 ± 3.9 years) volunteered to participate in this study. Maximal isometric foot inversion and eversion torques (Nm) were measured with participants lying supine, sitting with knees extended and lying on their side using a belt-stabilized HHD. Measurements were performed independently by two physiotherapists over two days and were repeated using an isokinetic dynamometer. Validity and intra- and inter-tester reliability were determined using the intra-class correlation coefficient (ICC). A two-way ANOVA (p<0.05) and post-hoc tests with Bonferroni correction were used to compare data from different positions. Bland-Altman plots were used to demonstrate the range of error and difference between HHD and isokinetic measurements. Results: Intra-tester reliability for inversion and eversion torques was fair to excellent in all positions (ICC = 0.598-0.828). Excellent inter-tester reliability was found for eversion torques in all positions (ICC = 0.773-0.860). For inversion torques, inter-tester reliability was fair to excellent (ICC = 0.519-0.879). ICC values of 0.205 to 0.562 indicated a low to fair concurrent validity. A significant difference was observed between the torques of the supine and side-lying positions as well as sitting and side-lying positions (p<0.05). Bland-Altman plots showed that the mean of the differences for inversion and eversion torques deviates considerably from zero, indicating that measurements with the HHD in the three positions produce lower values compared to using the isokinetic dynamometer. Conclusions: Inversion and eversion strength measurements with subjects in different positions using HHD seem to be reliable, but consistently underestimated torque output when compared with measurements using isokinetic dynamometry. While the HHD outcomes measured in supine and sitting positions seem to be comparable, those measured in supine/sitting and side-lying positions differed. [ABSTRACT FROM AUTHOR]

The purpose of this study was to assess the intra-rater and inter-rater reliability of electronic and manual dynamometry and goniometry in healthy volunteers, and the inter-instrument reliability in the assessment of healthy volunteers and patients recovering after a fracture of the distal radius. Grip strength, grip fatigue, pinch strength and range of motion were assessed in all participants with both the manual and electronic instruments by two physiotherapists and orthopaedic specialist trainee. The measures of dynamometry demonstrated excellent reliability (intra-class correlation coefficient >0.90), with the instruments found to be interchangeable with the exception of the grip fatigue. Variable intra-rater and inter-rater reliability was demonstrated with all planes of movement for the goniometry measures regardless of the instrument used. The results of this study support the continued use of dynamometry in the clinical setting, but raise questions regarding the use of goniometry measurements. [ABSTRACT FROM AUTHOR]

Introduction: It is not known whether a reduction in reachable workspace closely reflects loss of upper extremity strength in facioscapulohumeral muscular dystrophy (FSHD). In this study we aimed to determine the relationship between reachable workspace and quantitative upper extremity strength measures.Methods: Maximal voluntary isometric contraction (MVIC) testing of bilateral elbow flexion and shoulder abduction by hand-held dynamometry was performed on 26 FSHD and 27 control subjects. In addition, Kinect sensor-based 3D reachable workspace relative surface areas (RSAs) were obtained. Loading (500-g weight) effects on reachable workspace were also evaluated.Results: Quantitative upper extremity strength (MVIC of elbow flexion and shoulder abduction) correlated with Kinect-acquired reachable workspace RSA (R = 0.477 for FSHD, P = 0.0003; R = 0.675 for the combined study cohort, P < 0.0001). Progressive reduction in RSA reflected worsening MVIC measures. Loading impacted the moderately weak individuals the most with additional reductions in RSA.Conclusions: Reachable workspace outcome measure is reflective of upper extremity strength impairment in FSHD. [ABSTRACT FROM AUTHOR]

The article presents a study which aims to determine the test-retest reliability of various methods used in assessing the neuromuscular function. Among the methods that were evaluated include the dynamometry, electrical stimulation, and surface electromyography (EMG). Information regarding the study's statistical analysis, muscular activity testing, and menstrual cycle phase assessment, are discussed.

The article presents a study which aims to use valid, reliable, and sensitive measures to test the strength and power among soccer players. It provides details about the suitability of conventional and functional tests. It also addresses the strengths and weaknesses of isokinetic dynamometry, hand-held dynamometry (HHD), repetition maximum, and power testing.

STUDY DESIGN: Controlled laboratory cross-sectional study. OBJECTIVES: To assess strength differences of the hip rotator and abductor muscle groups in young adults with chronic hip joint pain (CHJP) and asymptomatic controls. A secondary objective was to determine if strength in the uninvolved hip of those with unilateral CHJP differs from that in asymptomatic controls. BACKGROUND: Little is known about the relationship between hip muscle strength and CHJP in young adults. METHODS: Thirty-five participants with CHJP and 35 matched controls (18 to 40 years of age) participated. Using handheld dynamometry, strength of the hip external rotators and internal rotators was assessed with the hip flexed to 90° and 0°. To assess external rotator and internal rotator strength, the hip was placed at the end range of external rotation and internal rotation, respectively. Strength of the hip abductors was assessed in sidelying, with the hip in 15° of abduction. Break tests were performed to determine maximum muscle force, and the average torque was calculated using the corresponding moment arm. Independent-sample f tests were used to compare strength values between (1) the involved limb in participants with CHJP and the corresponding limb in the matched controls, and (2) the uninvolved limb in participants with unilateral CHJP and the corresponding limb in the matched controls. RESULTS: Compared to controls, participants with CHJP demonstrated weakness of 15% to 28% (P<.01) in all muscle groups tested in the involved hip. The uninvolved hip of 22 subjects with unilateral CHJP demonstrated weakness of 18% and 16% (P<.05) in the external rotators (0°) and abductors, respectively, when compared to the corresponding limb of the matched controls. CONCLUSION: The results of the present study demonstrate that persons with CHJP have weakness in the hip rotator and hip abductor muscles. Weakness also was found in the uninvolved hip of persons with CHJP. [ABSTRACT FROM AUTHOR]