Grip Strength Task Research Articles

Pain interference mediates the association between epigenetic aging and grip strength in middle to older aged males and females with chronic pain.

Chronic pain is one of the leading causes of disability that may accelerate biological aging and reduce physical function. Epigenetic clocks provide an estimate of how the system ages and can predict health outcomes such as physical function. Physical function declines may be attributed to decreases in muscle quality due to disuse that can be measured quickly and noninvasively using grip strength. The purpose of this study was to explore the associations among self-reported pain, grip strength, and epigenetic aging in those with chronic pain. Participants (57.91 ± 8.04 years) completed pain questionnaires, a blood draw and hand grip strength task. We used an epigenetic clock previously associated with knee pain (DNAmGrimAge), and used the subsequent difference of predicted epigenetic age from chronological age (DNAmGrimAge-Difference). Exploratory pathway analyses revealed that pain intensity mediated the association between DNAmGrimAge-difference and handgrip strength in males only (β = -0.1115; CI [-0.2929, -0.0008]) and pain interference mediated the association between DNAmGrimAge-difference and handgrip strength in males β = -0.1401; CI [-0.3400, -0.0222]), and females (β = -0.024; CI [-0.2918, -0.0020]). Chronic knee pain may accelerate epigenetic aging processes that may influence handgrip strength in older age adults. Chronic pain could be a symptom of the aging body thus contributing to declines in musculoskeletal function in later life.

Chronic muscle recordings reveal recovery of forelimb function in spinal injured female rats after cortical epidural stimulation combined with rehabilitation and chondroitinase ABC.

Cervical level spinal cord injury (SCI) can severely impact upper limb muscle function, which is typically assessed in the clinic using electromyography (EMG). Here, we established novel preclinical methodology for EMG assessments of muscle function after SCI in awake freely moving animals. Adult female rats were implanted with EMG recording electrodes in bicep muscles and received bilateral cervical (C7) contusion injuries. Forelimb muscle activity was assessed by recording maximum voluntary contractions during a grip strength task and cortical motor evoked potentials in the biceps. We demonstrate that longitudinal recordings of muscle activity in the same animal are feasible over a chronic post‐injury time course and provide a sensitive method for revealing post‐injury changes in muscle activity. This methodology was utilized to investigate recovery of muscle function after a novel combination therapy. Cervical contused animals received intraspinal injections of a neuroplasticity‐promoting agent (lentiviral‐chondroitinase ABC) plus 11 weeks of cortical epidural electrical stimulation (3 h daily, 5 days/week) and behavioral rehabilitation (15 min daily, 5 days/week). Longitudinal monitoring of voluntary and evoked muscle activity revealed significantly increased muscle activity and upper limb dexterity with the combination treatment, compared to a single treatment or no treatment. Retrograde mapping of motor neurons innervating the biceps showed a predominant distribution across spinal segments C5–C8, indicating that treatment effects were likely due to neuroplastic changes in a mixture of intact and injured motor neurons. Thus, longitudinal assessments of muscle function after SCI correlate with skilled reach and grasp performance and reveal functional benefits of a novel combination therapy.

439 The effect of non-invasive transcutaneous auricular vagus nerve stimulation (taVNS) on hypoxic-ischemic injury in newborn rats

OBJECTIVES/GOALS: Neonatal hypoxic-ischemic encephalopathy (HIE) is an acute neurologic syndrome where decreased blood flow and oxygen to the brain causes acute and chronic brain dysfunction. The only proven neuroprotective intervention for HIE is hypothermia treatment started within 6 hours of birth and 50% of survivors have long-term deficits. METHODS/STUDY POPULATION: Pre-clinical adult stroke studies demonstrated that vagus nerve stimulation (VNS) has anti-inflammatory effects and attenuates brain damage. Transcutaneous auricular VNS (taVNS) is safe and feasible in infants and may improve the motor skill of bottle feeding. We hypothesize that a combined hypothermia-taVNS treatment shortly after HIE birth will have neuroprotective effects, improve motor function, attenuate infarct volume inflammation compared to hypothermia alone. The HIE model includes ligation of the right common carotid artery in postnatal day 7 (P7) rats followed by 90min hypoxia (8% oxygen) and 2hr hypothermia. taVNS or sham taVNS was administered using a bipolar electrode placed on the auricular concha region for 30min, [30sec trains, 0.5msec duration, 20Hz frequency, followed by 4.5min breaks] RESULTS/ANTICIPATED RESULTS: Experimental groups include +HIE/+taVNS, +HIE/-taVNS, and -HIE/-taVNS. To assess motor function, grasping reflex and forelimb grip strength tasks were assessed prior to surgery through P10. Infarct volume was assessed at 72h after injury by staining coronal sections with cresyl-violet. Thirty-four rat pups underwent surgery with an 8.82% mortality rate. taVNS was well tolerated by the P7 rats when delivered below perceptual threshold (0.4-1.1mA). There was no difference in elementary motor function or infarct volume between any group. DISCUSSION/SIGNIFICANCE: Future studies will include 2.5hr hypoxia for a more severe brain injury and a -HIE/+taVNS control group. These initial pre-clinical studies in neonates are important in determining whether taVNS may translate as a treatment to improve outcomes after neonatal HIE.

The diabetes drug semaglutide reduces infarct size, inflammation, and apoptosis, and normalizes neurogenesis in a rat model of stroke

Stroke is a condition with few medical treatments available. Semaglutide, a novel Glucagon-like peptide-1 (GLP-1) analogue, has been brought to the market as a treatment for diabetes. We tested the protective effects of semaglutide against middle cerebral artery occlusion injury in rats. Animals were treated with 10 nmol/kg bw ip. starting 2 h after surgery and every second day for either 1, 7, 14 or 21 days. Semaglutide-treated animals showed significantly reduced scores of neurological impairments in several motor and grip strength tasks. The cerebral infarction size was also reduced, and the loss of neurons in the hippocampal areas CA1, CA3 and the dentate gyrus was much reduced. Chronic inflammation as seen in levels of activated microglia and in the activity of the p38 MAPK – MKK – c-Jun- NF-κB p65 inflammation signaling pathway was reduced. In addition, improved growth factor signaling as shown in levels of activated ERK1 and IRS-1, and a reduction in the apoptosis signaling pathway C-raf, ERK2, Bcl-2/BAX and Caspase-3 was observed. Neurogenesis had also been normalized by the drug treatment as seen in increased neurogenesis (DCX-positive cells) in the dentate gyrus and a normalization of biomarkers for neurogenesis. In conclusion, semaglutide is a promising candidate for re-purposing as a stroke treatment.

Laterality, spatial abilities, and accident proneness

Although handedness as a measure of cerebral specialization has been linked to accident proneness, more direct measures of laterality are rarely considered. The present study aimed to fill that gap in the existing research. In addition, individual difference factors in accident proneness were further examined with the inclusion of mental rotation and navigation abilities measures. One hundred and forty participants were asked to complete the Mental Rotations Test, the Santa Barbara Sense of Direction scale, the Greyscales task, the Fused Dichotic Word Test, the Waterloo Handedness Questionnaire, and a grip strength task before answering questions related to number of accidents in five areas. Results indicated that handedness scores, absolute visual laterality score, absolute response time on the auditory laterality index, and navigation ability were significant predictors of the total number of accidents. Results are discussed with respect to cerebral hemispheric specialization and risk-taking attitudes and behavior.

Physiological and behavioural indices of hostility: An extension of the capacity model to include exposure to affective stress and right lateralized motor stress

Right hemisphere functional cerebral systems have reliably been associated with sympathetic nervous system arousal and the perception of negative affective events. The goal of the current research was to provide additional support for the capacity model of hostility by examining changes attributable to functional cerebral systems within the right hemisphere using a dual concurrent task paradigm. To incorporate exposure to negative affective and right-lateralized motor stress using this approach, high and low hostile individuals completed a series of grip-strength tasks before and after hearing a recording of angry infant vocalizations. Results supported the capacity model in that high hostile individuals were unable to maintain regulatory control over right hemisphere activation as indicated through increased motor perseveration in the pre- and post-affective stress conditions, heightened systolic blood pressure (SBP) upon exposure to negative emotional sounds, and increased heart rate (HR) following stress. Conversely, low hostile individuals showed improved regulatory control over these regions as evidenced by reduced motor perseveration in the pre- and post-affective stress conditions, maintenance of SBP and reductions in HR following stress. The current data support the capacity model and extend its scope to include exposure to affective and right-lateralized motor stress.

Altered behavior in experimental cortical dysplasia

Developmental delay and cognitive impairment are common comorbidities in people with epilepsy associated with malformations of cortical development (MCDs). We studied cognition and behavior in an animal model of diffuse cortical dysplasia (CD), in utero irradiation, using a battery of behavioral tests for neuromuscular and cognitive function. Fetal rats were exposed to 2.25 Gy external radiation on embryonic day 17 (E17). At 1 month of age they were tested using an open field task, a grip strength task, a grid walk task, inhibitory avoidance, an object recognition task, and the Morris water maze task. Rats with CD showed reduced nonlocomotor activity in the open field task and impaired motor coordination for grid walking but normal grip strength. They showed a reduced tendency to recognize novel objects and reduced retention in an inhibitory avoidance task. Water maze testing showed that learning and memory were impaired in irradiated rats for both cue discrimination and spatially oriented tasks. These results demonstrate significant deficits in cortex- and hippocampus-dependent cognitive functions associated with the diffuse abnormalities of cortical and hippocampal development that have been documented in this model. This study documents multimodal cognitive deficits associated with CD and can serve as the foundation for future investigations into the mechanisms of and possible therapeutic interventions for this problem.

The AUSCAN subscales, AIMS-2 hand/finger subscale, and FIOHA were not unidimensional scales

Objectives Evaluate the internal construct validity of the Australian/Canadian (AUSCAN) index for hand osteoarthritis (HOA) and identify the physical function instrument with best performance. Study Design and Setting AUSCAN, AIMS-2 (Arthritis Impact Measurement Scale 2), and Functional Index of HOA (FIHOA) were self-completed by 209 HOA patients (mean [standard deviation] age 61.6 [5.7] years) at baseline and 128 at follow-up. Rasch analysis was performed. Results AUSCAN pain, physical function, and stiffness subscales comprised three constructs. AUSCAN scale performance was improved after removal of “Pain at rest” from the pain scale and division of physical function into two scales of high precision and grip strength tasks. AIMS-2 hand/finger subscale and FIHOA were improved after removal of one and two items, respectively and collapse of two AIMS-2 response categories. AUSCAN physical function scale showed better targeting to the sample and higher person reliability compared with FIHOA and especially AIMS-2 because of less “severe” items concerning grip strength tasks as opposed to precision tasks. Conclusion The AUSCAN subscales, AIMS-2 hand/finger scale, and FIHOA were not unidimensional. However, deletion of misfitting items improved scale performance. The revised AUSCAN physical function and FIHOA scales are preferable for measurement of grip strength and precision tasks, respectively.

Neuronavigation Increases the Physiologic and Behavioral Effects of Low-Frequency rTMS of Primary Motor Cortex in Healthy Subjects

Low-frequency repetitive transcranial magnetic stimulation (rTMS) can exert local and inter-hemispheric neuromodulatory effects on cortical excitability. These physiologic effects can translate into changes in motor behavior, and may offer valuable therapeutic interventions in recovery from stroke. Neuronavigated TMS can maximize accurate and consistent targeting of a given cortical region, but is a lot more involved that conventional TMS. We aimed to assess whether neuronavigation enhances the physiologic and behavioral effects of low-frequency rTMS. Ten healthy subjects underwent two experimental sessions during which they received 1600 pulses of either navigated or non-navigated 1 Hz rTMS at 90% of the resting motor threshold (RMT) intensity over the motor cortical representation for left first dorsal interosseous (FDI) muscle. We compared the effects of navigated and non-navigated rTMS on motor-evoked potentials (MEPs) to single-pulse TMS, intracortical inhibition (ICI) and intracortical facilitation (ICF) by paired-pulse TMS, and performance in various behavioral tasks (index finger tapping, simple reaction time and grip strength tasks). Following navigated rTMS, the amplitude of MEPs elicited from the contralateral (unstimulated) motor cortex was significantly increased, and was associated with an increase in ICF and a trend to decrease in ICI. In contrast, non-navigated rTMS elicited nonsignificant changes, most prominently ipsilateral to rTMS. Behaviorally, navigated rTMS significantly improved reaction time RT and pinch force with the hand ipsilateral to stimulation. Non-navigated rTMS lead to similar behavioral trends, although the effects did not reach significance. In summary, navigated rTMS leads to more robust modulation of the contralateral (unstimulated) hemisphere resulting in physiologic and behavioral effects. Our findings highlight the spatial specificity of inter-hemispheric TMS effects, illustrate the superiority of navigated rTMS for certain applications, and have implications for therapeutic applications of rTMS.

The Effects of Self-Set versus Assigned Goals on Exercisers’ Self-Efficacy for an Unfamiliar Task

This experiment compared the effects of self-set versus assigned goals on exercisers’ (N = 50, M age = 23.6) self-efficacy to perform a novel grip-strength task. After their first task attempt, all participants received the same bogus performance feedback. Participants in the self-set condition then set their own goal for their second attempt, whereas those in the assigned condition were given the goal of squeezing 3 more pounds. The assigned condition reported higher task-self efficacy (M = 58.7) than the self-set condition (M = 42.4) prior to their second task attempt (p = .02). These findings suggest that goals assigned by an authority figure can increase self-confidence in beginner exercisers.

Improvement Strategies in Free-Throw Shooting and Grip-Strength Tasks

Participants performed a free-throw shooting task and a grip-strength task before and after imagery, nonspecific arousal, or no instructions. Imagery improved performance in the free-throw shooting task, which is assumed to have more cognitive components than the grip-strength task. Imagery did not improve performance in the grip-strength task, which is assumed to have fewer cognitive components than the free-throw task. Nonspecific arousal, on the other hand, improved performance in the grip-strength task but not in the free-throw shooting task. Athletic experience, confidence levels, and gender were correlated with actual performance levels in both tasks, but not with improvement. Results are discussed within the transfer-appropriate processing framework.

The development and evaluation of an ergonomic glove

The primary intent of this study was to determine if a hand glove could be designed on a criterion of selective protection. Force distribution patterns on the palmar side of hand were obtained from various studies to develop zones of hand that needed protection. A new design for gloves was developed based on the principle of selective protection, where protective material is introduced in varying levels over different parts of the glove, in order to provide protection where it is most needed, and at the same time preserve the desirable dexterity and strength capabilities of the barehand, optimizing the trade-off between protection and performance. Two pairs of prototype gloves incorporating different levels of protection were fabricated and tested using a battery of performance tests and an algometer test for pressure sensitivity. The test battery comprising four dexterity tasks and a maximal voluntary grip strength task was used to assess a number of glove conditions, including the two prototype gloves developed. The results indicate that the performance of the prototype gloves are comparable, and that the performance times for the double glove and the two prototype gloves tested were not significantly different. For the grip strength, the two prototype gloves were better than the double glove. The assembly task performance for the prototype II (laminar glove) was significantly lower than that of the other glove types tested. It appears that gloves of variable thickness can be developed to afford adequate protection at zones of most need. Glove manufacturers are recommended to use an ergonomic approach in the design of gloves. Such an approach, besides protecting the safety objective of gloves, could enhance productivity considerably.

Comparison of intrastriatal injections of quinolinic acid and 3-nitropropionic acid for use in animal models of Huntington's disease

1. 1. The present study compared the effects of acute intrastriatal administration of quinolinic acid (QA) and 3-nitropropionic acid (3-NP), two neurotoxins used in animal models of Huntington's disease (HD), on the following behavioral and histological measures: (1) open field activity levels; (2) performance on balance beam and grip strength tasks; (3) acquisition of a radial-arm-water-maze (RAWM) task; (4) size of striatum and lateral ventricles; (5) amount of cytochrome oxidase (CYO) labeling; and (6) counts of Nissl-stained neurons and NADPH-diaphorase-labeled neurons in the striatum. 2. 2. Rats were given bilateral intrastriatal injections of either 200 nmol QA, 750 nmol 3-NP, or phosphate buffered saline (PBS) two weeks prior to behavioral testing and four weeks prior to histological processing. 3. 3. The behavioral results indicated that both QA and 3-NP injections caused an increase in activity levels at two weeks postlesion, but only the QA rats showed hyperactivity at four weeks postlesion. Both QA and 3-NP rats showed significant impairment in the balance beam task, but only 3-NP rats differed significantly on the grip-strength task. Both toxins caused learning impairments in the RAWM task, with 3-NP rats being more severely impaired. 4. 4. The neuroanatomical results indicated that both QA and 3-NP produced significant striatal atrophy and ventricular dilation, as well as a reduction in CYO staining and loss of Nissl-stained neurons, but only the 3-NP lesions created necrotic cavities in the striatum. However, the QA treatments resulted in significant loss of NADPH-diaphorase neurons in regions peripheral to the site of injection. 5. 5. In general, these results suggest that QA treatments produce milder behavioral and neuroanatomical effects that mimic some of the earlier symptoms of HD, while 3-NP produced more severe effects which mimic both the later symptoms and the juvenile onset of HD.

Development of a post-offer screening tool for patient support services.

The purpose of our project was to develop a post-offer screening tool that demonstrates interrater reliability, predictive validity, and face validity and that accurately represents the physical demands of the patient support services (lifting team) job at our health care facility. The screening tool, which consists of 11 static and dynamic tasks, was developed, using the 13 incumbent staff members of the patient support services department, to determine whether the criteria established for each task matched the physical abilities of at least 80% of the total group tested. Test-retest design was used for this study. Intraclass correlation coefficients and the Kappa statistic were used to calculate interrater reliability. Face validity was determined through the Job Similarity Questionnaire completed by all subjects. Subjects did not meet criteria established for the static knee pull and the knuckle-to-elbow lift tasks, resulting in modification of these two criteria. Interrater reliability ranged from .22 for the maximum static pull wall task to .94 for the left-hand grip strength task. Face validity ranged from 53.9% to 92.4%. Although face validity of the Job Similarity Questionnaire represented a wide range, we believe that the results were homogeneous enough to continue with the screening tool unchanged, except for lowering the expected outcome on two tasks. Interrater reliability was established for 75% of the tasks. The lack of variation of data for the other 25% prevented statistical analysis of those tasks but confirmed that all members met the physical criteria.

Motor dysfunction in a photothrombotic focal ischaemia model

The study of behavioural deficits resulting from cerebral infarction in animal models of stroke has in the past taken second place to histological assessment. This is particularly true of the photothrombotic lesion model. Most tests currently used to measure motor deficits use a scoring system to quantify parameters such as beam walking. The present study set out to characterise a simple and objective assessment for motor impairment in the photothrombotic cortical lesion model. Rats were assessed on a number of motor function tests, i.e. gross locomotor activity, rotarod, and grip strength. After the establishment of stable baselines, cortical photothrombotic lesions were induced, after which the animals were re-tested for a further 18 days. The presence of cortical photothrombotic lesions significantly impaired the rats' performance on the rotarod and grip-strength tests. The deficit observed with the grip-strength task appeared 24 h postsurgery, but was much reduced by day 18 postsurgery. The rotarod test revealed an effect that took longer to establish, but which was more persistent. Gross locomotor activity was not affected. These data suggest that bilateral photothrombotic lesions of the prefrontal cortex produce deficits that can be detected by rotarod and grip-strength tasks.

Ergonomic Glove: Design and Evaluation

A new design for gloves was developed based on the principle of selective protection, where protective material is introduced in varying levels over different parts of the glove, in order to provide protection where it is most needed, and at the same time preserve the desirable dexterity and strength capabilities of the barehand, optimizing the trade-off between protection and performance. The pattern for selective protection was arrived at based on existing research, and two pairs of gloves incorporating different levels of protection have been prototyped and are currently being tested using a battery of performance tests and an Algometer test for pressure sensitivity. A battery of tests was developed to evaluate a new glove design which used the principle of selective levels of protection over different parts of the hand, in order to maximize protection, and minimize loss of dexterity. The test battery comprised of four dexterity tasks and a maximal voluntary grip strength task. The battery assessed the performance of 5 hand conditions, barehand, single glove (one layer), double glove (two layers), and two prototype gloves, one with one layer of protection (contour glove) and the other with four layers of protection over selected parts of the hand (laminar glove). The evaluation compared the performance of the prototype gloves developed with respect to the performance with the double layer glove and the single layer glove. The results indicated that the performance of the prototype gloves was comparable, and that the performance times for the double glove and the two prototype gloves tested were not significantly different. For the test of grip strength, the two prototype gloves tested enabled better performance than the double glove. The assembly task performance for the prototype II (laminar glove) was significantly lower than that of the other glove types tested

The Measurement of Handedness by Preference and Performance Tests

Hand preference and hand proficiency were compared on 50 male subjects (30 self-classified left-handers and 20 self-classified right-handers) according to their responses to a 20 item questionnaire and their performances on a handwriting and a grip-strength task. Performance differences between the two sides for each group were not related to overall preference assessments but were positively associated with hand preferences on corresponding questionnaire items. Distributions of the performance differences between the two sides for the right- and left-handers were well separated for handwriting but completely overlapped for grip strength. Significant correlations between the performances on each side were recorded on both tasks. The results stress the importance of using the same criteria in making preference vs. performance comparisons and highlight the need to recognize and control the influence of previous training or experience.

The postweaning housing environment determines expression of learning deficit associated with neonatal monosodium glutamate (M.S.G.)

Perinatal M.S.G. treatment causes a syndrome characterized by damage to the hypothalamic arcuate nucleus, other circumventricular areas, parts of the visual system and the dentate gyrus of the hippocampus. The resulting hormonal dysfunction may be responsible for developmental anomalies of organ systems, obesity, and alterations in sensory/motor performance. We have shown that some behavioral indicators of M.S.G. toxicity in rats can be masked by rearing them in enriched housing conditions. Here, we evaluated the impact of six housing conditions on M.S.G.-induced alterations of organ systems and behavior. Perinatal M.S.G. treatment reduced adrenal, heart and testes weights, as well as total white blood cell (WBC) counts, and increased tail flick latencies. These measures were unaffected by the housing condition. M.S.G.-induced reductions in body weight, grip strength, water maze and dominance task performance varied as a function of housing. Deficits in water maze performance were most evident following social and isolated single-cage housing. We propose that deficits in water maze performance following perinatal M.S.G. may be attributable to hippocampal damage that can be alleviated by rearing the rats in stimulating environments.

Skill, strength, handedness, and fatigue.

Thirty male subjects, 20 of whom were self-classified left-handers and 10 right-handers, were tested on a grip-strength task and a handwriting task with each hand, both under normal conditions and in a situation of induced experimental fatigue. On the basis of questionnaire scores, the left-handers were sub-divided into two groups comprising the 10 most left-handed and the 10 least left-handed subjects. The test of grip strength showed a small but significant deterioration in performance of both hands from fatigue. With the handwriting task, a similar significantly adverse effect of fatigue was recorded for all groups as well as a large significant difference in performance between the preferred and nonpreferred hands under normal conditions, which decreased under fatigue. An explanation of these differential effects is discussed in terms of the greater efficiency of the preferred hand in the highly developed skill of handwriting.

Effects of Experimenter Expectancy Set and Experimenter Sex upon Grip Strength and Hand Steadiness Scores

Abstract The purpose of this study was to determine the effects of the expectancy set of the experimenter, the main effects of the sex of the experimenter, and the interaction effects of the sex of the experimenter and the sex of the subject upon performance of a grip strength task and a hand steadiness task. The subjects were 48 undergraduate males and 48 undergraduate females. Eight graduate males and 8 graduate females served as the experimenters. Each group of 6 subjects and 1 experimenter was randomly assigned to treatment. Half of the experimenters received information as to the performance they should expect from their subjects. The other 8 remained naive regarding expected performance outcomes. Results indicated that the male experimenters with the expectancy set obtained results in accordance with their expectations on the grip strength task. Female experimenters obtained results in direct opposition to their expectations on the same task. No significant experimenter expectancy effects were found...