Measuring isometric shoulder rotational strength is clinically important for evaluating motor disability in athletes with shoulder injuries. Recent evidence suggests that handheld dynamometry may ...provide a low-cost and portable method for the clinical assessment of isometric shoulder strength.
To investigate the concurrent validity and the intrarater and interrater reliability of handheld dynamometry for measuring isometric shoulder rotational strength.
Cross-sectional study.
Biomechanics laboratory.
Thirty-nine young, healthy participants.
The peak isometric strength of the internal rotators and external rotators, measured by handheld dynamometry (in newton) and isokinetic dynamometry (in newton meter).
Maximal isometric shoulder rotational strength was measured as participants lay supine with 90° shoulder abduction, neutral rotation, 90° elbow flexion, and forearm pronation. Measurements were performed independently by 2 different physiotherapists and in 3 different sessions to evaluate interrater and intrarater reliability. The data obtained by handheld dynamometry were compared with those obtained by isokinetic testing to evaluate concurrent validity.
The intraclass correlation coefficients for interrater reliability in measuring maximum isometric shoulder external and internal rotation strength were .914 (95% confidence interval CI, .842-.954) and .842 (95% CI, .720-.914), respectively. The intrarater reliability values of the method for measuring maximal shoulder external and internal rotation strength were 0.865 (95% CI, 0.757-0.927) and 0.901 (95% CI, 0.820-0.947), respectively. The Pearson correlation coefficients between the handheld and isokinetic dynamometer measurements were .792 (95% CI, .575-.905) for external rotation strength and .664 (95% CI, .419-.839) for internal rotation strength.
The handheld dynamometer showed good to excellent reliability and moderate to good validity in measuring maximum isometric shoulder rotational strength. Therefore, handheld dynamometry could be acceptable for health and sports professionals in field situations to evaluate maximum isometric shoulder rotational strength.
Abstract. Purpose This study aimed to determine the validity and reliability of isometric knee extension muscle strength measurements using a belt-stabilized hand-held dynamometer compared to that ...using an isokinetic dynamometer with the participant in a sitting posture. Participants and Methods Forty-two university students participated. The isometric knee extension muscle strength was measured using a hand-held dynamometer and an isokinetic dynamometer. For both measurements, the participants were in the similar sitting posture. The sitting posture maintained trunk stability, with the hands on the bed, and the non-measurement-side toe touching the floor or table. The intra-class correlation coefficient and the relevance were verified. Results Intra-rater correlation coefficient (1, 1) of the two measurements was >=0.75. A significant difference was found in the measurement value between males and females. No significant difference was found between the measurements value of the two devices. A significant positive correlation was found in the measurement value of two devices in the male participants. Conclusion When compared to the standard method of isometric knee extension muscle strength measurements using an isokinetic dynamometer with the participant in the sitting posture, measurements using the belt-stabilized hand-held dynamometer were considered valid and highly reliable in the male participants.
: The purpose of this study was to test the concurrent validity of using hydraulic dynamometers in comparison to the gold standard isokinetic dynamometers in measuring wrist and forearm strength.
: ...Healthy adults between the ages of 18-65 participated, including 24 participants, 8 men and 16 women. The examiner used a handheld dynamometer, forearm/wrist dynamometer, and an isokinetic dynamometer to measure force/torque production in forearm rotation and wrist flexion/extension using a standardized protocol of two handle types for each motion. Sequence of testing was randomized. The data were analyzed using Pearson correlation coefficients and paired
-tests.
: When matched for handle type, three of the four correlations between the strength measurements taken with the different dynamometers were moderate to high with Pearson product moment coefficients ranging from 0.72 to 0.96; the screwdriver handle demonstrated less than acceptable correlation (
= 0.45, 0.67 for wrist flexion and extension, respectively). There were significant differences in most of the force/torque values obtained by different handle types for wrist and forearm motions.
: Overall, the dynamometers demonstrated acceptable correlations supporting concurrent validity for measuring forearm and wrist strength, except with the screwdriver handle. However, different tools, positions, and handle interfaces provided different absolute values, therefore the tools cannot be used interchangeably. It is recommended that repeated measurements to monitor patient progress are taken with the same tool and handle type.
As part of a broad evaluation of the environmental impacts of biodiesel and renewable diesel as alternative motor fuels and fuel blends in California, the California Air Resources Board's (CARB) ...Heavy-duty Diesel Emission Testing Laboratory conducted chassis dynamometer exhaust emission measurements on in-use heavy-heavy-duty diesel trucks (HHDDT). The results presented here detail the impact of biodiesel and renewable diesel fuels and fuel blends as compared to CARB ULSD on particulate matter (PM), regulated gases, and two greenhouse gases emissions from a HHDDT with a 2000 C15 Caterpillar engine with no exhaust after treatment devices. This vehicle was tested over the Urban Dynamometer Driving Schedule (UDDS) and the cruise portion of the California HHDDT driving schedule. Three neat blend stocks (soy-based and animal-based fatty acid methyl ester (FAME) biodiesels, and a renewable diesel) and CARB-certified ultra-low sulfur diesel (CARB ULSD) along with their 20% and 50% blends (blended with CARB ULSD) were tested. The effects of blend level on emission characteristics were discussed on g·km−1 basis. The results showed that PM, total hydrocarbon (THC), and carbon monoxide (CO) emissions were dependent on driving cycles, showing higher emissions for the UDDS cycles with medium load than the highway cruise cycle with high load on per km basis. When comparing CARB ULSD to biodiesels and renewable diesel blends, it was observed that the PM, THC, and CO emissions decreased with increasing blend levels regardless of the driving cycles. Note that biodiesel blends showed higher degree of emission reductions for PM, THC, and CO than renewable diesel blends. Both biodiesels and renewable diesel blends effectively reduced PM emissions, mainly due to reduction in elemental carbon emissions (EC), however no readily apparent reductions in organic carbon (OC) emissions were observed. When compared to CARB ULSD, soy- and animal-based biodiesel blends showed statistically significant increases in nitrogen oxides (NOx) emissions for 50% or higher biodiesel blends. The 20% blends of the biodiesels showed no statistically significant effect on NOx emissions on any cycle. In contrast, renewable diesel slightly decreased NOx emissions and the degree of reduction was statistically significant for 50% or higher blends over the UDDS cycle, but not at the 20% blends. The highway cruise cycles did not show a statistically strong NOx emission trend with increasing blend level of renewable diesel. Biodiesel and renewable fuel impacts on two greenhouse gases, CO2 and N2O emissions were of lower magnitude when compared to other regulated pollutants emissions, showing a change in their emissions within approximately ±3% from the CARB ULSD.
•Effect of biodiesels (BD) and renewable diesel (RD) on regulated emissions (RE) was investigated on a chassis dynamometer.•BD showed higher degree of emission reductions for PM, THC, and CO than RD.•BD showed significant increases in NOx emissions for 50% or higher blends.•BD and RD impacts on CO2 and N2O emissions were of lower magnitude relative to other RE.
RESUMEN: El objetivo del siguiente estudio fue determinar y comparar los valores de composición corporal, parámetros bioeléctricos y fuerza de prensión manual de escaladores chilenos federados y ...recreativos. Participaron voluntariamente 13 escaladores chilenos, de los cuales 4 eran federados (25,75 ± 2,87 años) y 9 recreativos (22,33 ± 1,41 años). La composición corporal se evaluó por medio de un impedanciómetro bioeléctrico octopolar multifrecuencia, mientras que la fuerza de prensión manual se determinó con un dinamómetro manual. Si bien no hubo diferencias en las variables de composición corporal entre ambos grupos, el ángulo de fase del tronco fue superior en los federados en comparación a los recreativos (p = 0,011 95 % IC = 1,10; 5,20). Respecto a la fuerza de prensión manual, la fuerza relativa fue superior para los federados (p = 0,025 95 % IC = 0,10; 0,22), mientras que la diferencia de la fuerza entre la mano dominante y no dominante fue mayor para los recreativos (p = 0,012 95 % IC = 1,60; 10,05). Este es uno de los primeros estudios que explora las diferencias entre escaladores chilenos federados y recreativos. Los resultados sugieren una diferenciación a nivel de ángulo de fase y fuerza de prensión manual, lo cual debería corroborarse con futuros estudios.
Pelvic floor disorders are caused by weakening or damage to the tissues lining the bottom of the abdominal cavity. These disorders affect nearly 1 in every 4 women in the United States and symptoms ...that drastically diminish a patient's quality of life. Vaginal closure force is a good measure of pelvic health, but current vaginal dynamometers were not designed for the rigors of hospital reprocessing, often failing due to sensor degradation through repeated sterilization processes. In order to obtain measurements of vaginal closure force in a large study, we designed a vaginal dynamometer that utilizes a removable intra-abdominal sensor already in production for the study. The sensor's existing data acquisition system was modified to transmit to a tablet allowing the user to view data in real-time. The new speculum design allowed a single sensor to measure vaginal closure force before being used to collect intra-abdominal pressure data in the same study visit. The measurements taken with the new speculum were similar to measurements taken with a previously reported vaginal dynamometer.
McGrath, R, FitzSimmons, S, Andrew, S, Black, K, Bradley, A, Christensen, BK, Collins, K, Klawitter, L, Kieser, J, Langford, M, Orr, M, and Hackney, KJ. Prevalence and trends of weakness among ...middle-aged and older adults in the United States. J Strength Cond Res 37(12): 2484-2490, 2023-Muscle weakness, which is often determined with low handgrip strength (HGS), is associated with several adverse health conditions; however, the prevalence and trends of weakness in the United States is not well-understood. We sought to estimate the prevalence and trends of weakness in Americans aged at least 50 years. The total unweighted analytic sample included 22,895 Americans from the 2006-2016 waves of the Health and Retirement Study. Handgrip strength was measured with a handgrip dynamometer. Men with weakness were below at least one of the absolute or normalized (body mass, body mass index) cut points: <35.5 kg, <0.45 kg/kg, <1.05 kg/kg/m 2 . The presence of any weakness in women was also identified as being below one of the absolute or normalized HGS cut points: <20.0 kg, <0.34 kg/kg, or <0.79 kg/kg/m 2 . There was an increasing trend in the prevalence of any weakness over time ( p < 0.001). The prevalence of weakness was 45.1% (95% confidence interval CI: 44.0-46.0) in the 2006-2008 waves and 52.6% (CI: 51.5-53.7) in the 2014-2016 waves. Weakness prevalence was higher for older (≥65 years) Americans (64.2%; CI: 62.8-65.5) compared with middle-aged (50-64 years) Americans (42.2%; CI: 40.6-43.8) in the 2014-2016 waves. Moreover, the prevalence of weakness in the 2014-2016 waves was generally higher in women (54.5%; CI: 53.1-55.9) than in men (50.4%; CI: 48.7-52.0). Differences existed in weakness prevalence across races and ethnicities. The findings from our investigation suggest that the prevalence of weakness is overall pronounced and increasing in Americans. Efforts for mitigating and better operationalizing weakness will elevate in importance as our older American population grows.
Abstract
Handedness is an individual’s preference to use one hand performing activities such as cutting with a knife or writing. Handedness is divided into two, right-handed and left-handed. ...Handedness can be influenced by genetics, prenatal development, and parenting. This study aims to analyse the categorization of handedness based on self-confessed, 10 daily uni-manual activities and hand strength performance. This study was conducted for 1 month by visiting a crowd of more than two people and providing a consent sheet following the questionnaire, personal data questionnaire including sex and age, 10 daily activity questionnaires and power grip questionnaires accompanied by power grip measurements using a dynamometer. A total of 610 individuals were assessed. The study showed that handedness could be determined by assessing self-confessed, 10 daily uni-manual activities with addition of hand strength performance. The older a person was the stronger the power grip value, those with a right-handed preference had a greater right handgrip value. Age was found did not affect handedness.
ABSTRACT
Introduction
This study compared voluntary activation during isometric, concentric, and eccentric maximal knee extensions at different joint angles.
Methods
Fifteen participants performed ...isometric, concentric, and eccentric protocols (9 contractions each). For each protocol, the central activation ratio (CAR) was randomly measured at 50°, 75°, or 100° of knee joint angle (0° = full knee extension) using superimposed supramaximal paired nerve stimulations during contractions.
Results
CAR increased between 50° and 100° during isometric (93.6 ± 3.1 vs. 98.5 ± 1.4%), concentric (92.4 ± 5.4 vs. 99.2 ± 1.2%), and eccentric (93.0 ± 3.5 vs. 96.6 ± 3.8%) contractions. CAR was lower during eccentric than both isometric and concentric contractions at 75° and 100°, but similar between contraction types at 50°.
Conclusions
The ability to activate muscle maximally is impaired during eccentric contractions compared with other contraction types at 75° and 100°, but not at 50°. Muscle Nerve 56: 750–758, 2017
PURPOSEThis study aimed to compare hip abductor muscle strength between individuals with symptomatic, unilateral gluteal tendinopathy (GT), and asymptomatic controls.
METHODSFifty individuals with GT ...age between 35 and 70 yr and 50 sex- and age-comparable controls were recruited from the community. Maximal isometric strength (torque normalized to body mass) of the hip abductors was recorded in the supine position using an instrumented manual muscle tester. A two-way mixed ANCOVA, with covariates of self-reported pain during testing and pain limiting maximum effort, was used to compare hip abductor strength of the symptomatic and asymptomatic hip between GT and control individuals. Data were expressed as mean and SD, with the pairwise comparisons expressed as mean differences and 95% confidence intervals.
RESULTSIndividuals with GT demonstrated significantly lower hip abductor torque of both their symptomatic and asymptomatic hip than healthy controls (both P < 0.05), with mean strength deficits of 0.35 N·m·kg (32%) on the symptomatic hip and 0.25 N·m·kg (23%) on the asymptomatic hip. In individuals with GT, the symptomatic hip was significantly weaker than the asymptomatic hip with a mean strength deficit of 0.09 N·m·kg (11%) (P < 0.05).
CONCLUSIONSPeople with unilateral GT demonstrate significant weakness of the hip abductor muscles bilaterally when compared with healthy controls. Although it is not clear whether hip weakness precedes GT or is a consequence of the condition, the findings provide a basis to consider hip abductor muscle weakness in the treatment plan for management of GT.
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