Handgrip Device Research Articles

Quantitative assessment of hand motor function in cervical spinal disorder patients using target tracking tests.

Cervical spondylotic myelopathy (CSM) is a chronic spinal disorder in the neck region. Its prevalence is growing rapidly in developed nations, creating a need for an objective assessment tool. This article introduces a system for quantifying hand motor function using a handgrip device and target tracking test. In those with CSM, hand motor impairment often interferes with essential daily activities. The analytic method applied machine learning techniques to investigate the efficacy of the system in (1) detecting the presence of impairments in hand motor function, (2) estimating the perceived motor deficits of CSM patients using the Oswestry Disability Index (ODI), and (3) detecting changes in physical condition after surgery, all of which were performed while ensuring test-retest reliability. The results based on a pilot data set collected from 30 patients with CSM and 30 nondisabled control subjects produced a c-statistic of 0.89 for the detection of impairments, Pearson r of 0.76 with p < 0.001 for the estimation of ODI, and a c-statistic of 0.82 for responsiveness. These results validate the use of the presented system as a means to provide objective and accurate assessment of the level of impairment and surgical outcomes.

Binding space and time through action.

Space and time are intimately coupled dimensions in the human brain. Several lines of evidence suggest that space and time are processed by a shared analogue magnitude system. It has been proposed that actions are instrumental in establishing this shared magnitude system. Here we provide evidence in support of this hypothesis, by showing that the interaction between space and time is enhanced when magnitude information is acquired through action. Participants observed increases or decreases in the height of a visual bar (spatial magnitude) while judging whether a simultaneously presented sequence of acoustic tones had accelerated or decelerated (temporal magnitude). In one condition (Action), participants directly controlled the changes in bar height with a hand grip device, whereas in the other (No Action), changes in bar height were externally controlled but matched the spatial/temporal profile of the Action condition. The sign of changes in bar height biased the perceived rate of the tone sequences, where increases in bar height produced apparent increases in tone rate. This effect was amplified when the visual bar was actively controlled in the Action condition, and the strength of the interaction was scaled by the magnitude of the action. Subsequent experiments ruled out that this was simply explained by attentional factors, and additionally showed that a monotonic mapping is also required between grip force and bar height in order to bias the perception of the tones. These data provide support for an instrumental role of action in interfacing spatial and temporal quantities in the brain.

Comparison of two isometric handgrip protocols on sympathetic arousal in women

Isometric handgrip is commonly used in stress research because the task reliably increases sympathetic arousal. Various handgrip protocols have been used; they vary in handgrip strength, duration of grip, and the number of cycles of handgrip and rest. However, most protocols require the calibration of a maximum voluntary contraction (MVC) prior to the handgrip task, which is not always convenient (i.e., in a functional magnetic resonance imaging study). Here, we wanted to test whether two handgrip protocols with different strength, duration and cycle protocols would reliably elicit sympathetic arousal in the absence of calibrating an MVC. Sixty-two healthy naturally cycling women and women on hormonal contraception participated in one of the two isometric handgrip protocols using a hand therapy ball of medium resistance. Women completed one of the following handgrip protocols: 1) 30% of a perceived maximum voluntary contraction for 3min or 2) 3cycles of maximum voluntary contraction for 18s with a one minute rest in between. All handgrip blocks were counterbalanced with a control condition. Sympathetic arousal was measured throughout the session via pupil diameter changes and salivary alpha-amylase. Results indicate that in the absence of calibrating an MVC, the handgrip tasks elicited different changes in sympathetic arousal. Pupil dilation responses increased significantly in the handgrip versus control blocks only in participants in the 18-s protocol. Additionally, more participants exhibited a salivary alpha-amylase response to the handgrip block in the 18-s condition compared to the 3-min condition. Thus, these results suggest that neuroimaging and behavioral studies with isometric handgrip should be able to successfully induce sympathetic nervous activity with the 18-s paradigm, regardless of the handgrip device and the ability to calibrate an MVC.

A Prediction Model for Functional Outcomes in Spinal Cord Disorder Patients Using Gaussian Process Regression.

Predicting the functional outcomes of spinal cord disorder patients after medical treatments, such as a surgical operation, has always been of great interest. Accurate posttreatment prediction is especially beneficial for clinicians, patients, care givers, and therapists. This paper introduces a prediction method for postoperative functional outcomes by a novel use of Gaussian process regression. The proposed method specifically considers the restricted value range of the target variables by modeling the Gaussian process based on a truncated Normal distribution, which significantly improves the prediction results. The prediction has been made in assistance with target tracking examinations using a highly portable and inexpensive handgrip device, which greatly contributes to the prediction performance. The proposed method has been validated through a dataset collected from a clinical cohort pilot involving 15 patients with cervical spinal cord disorder. The results show that the proposed method can accurately predict postoperative functional outcomes, Oswestry disability index and target tracking scores, based on the patient's preoperative information with a mean absolute error of 0.079 and 0.014 (out of 1.0), respectively.

Utilization of a novel digital measurement tool for quantitative assessment of upper extremity motor dexterity: a controlled pilot study.

BackgroundThe current methods of assessing motor function rely primarily on the clinician’s judgment of the patient’s physical examination and the patient’s self-administered surveys. Recently, computerized handgrip tools have been designed as an objective method to quantify upper-extremity motor function. This pilot study explores the use of the MediSens handgrip as a potential clinical tool for objectively assessing the motor function of the hand.MethodsEleven patients with cervical spondylotic myelopathy (CSM) were followed for three months. Eighteen age-matched healthy participants were followed for two months. The neuromotor function and the patient-perceived motor function of these patients were assessed with the MediSens device and the Oswestry Disability Index respectively. The MediSens device utilized a target tracking test to investigate the neuromotor capacity of the participants. The mean absolute error (MAE) between the target curve and the curve tracing achieved by the participants was used as the assessment metric. The patients’ adjusted MediSens MAE scores were then compared to the controls. The CSM patients were further classified as either “functional” or “nonfunctional” in order to validate the system’s responsiveness. Finally, the correlation between the MediSens MAE score and the ODI score was investigated.ResultsThe control participants had lower MediSens MAE scores of 8.09%±1.60%, while the cervical spinal disorder patients had greater MediSens MAE scores of 11.24%±6.29%. Following surgery, the functional CSM patients had an average MediSens MAE score of 7.13%±1.60%, while the nonfunctional CSM patients had an average score of 12.41%±6.32%. The MediSens MAE and the ODI scores showed a statistically significant correlation (r=-0.341, p<1.14×10-5). A Bland-Altman plot was then used to validate the agreement between the two scores. Furthermore, the percentage improvement of the the two scores after receiving the surgical intervention showed a significant correlation (r=-0.723, p<0.04).ConclusionsThe MediSens handgrip device is capable of identifying patients with impaired motor function of the hand. The MediSens handgrip scores correlate with the ODI scores and may serve as an objective alternative for assessing motor function of the hand.Electronic supplementary materialThe online version of this article (doi:10.1186/1743-0003-11-121) contains supplementary material, which is available to authorized users.

A randomized study to assess two different techniques of aspiration while performing transabdominal chorionic villus sampling

The technique used to perform transabdominal chorionic villus sampling (CVS) is not standardized, but aspiration of villi is generally obtained by discontinuous vacuum created in a syringe, manually or by a hand-grip device. We evaluated the feasibility of a new method of performing CVS which employs a 4-mL Vacutainer connected to the needle, producing a continuous negative pressure. Two hundred pregnant women, whose gestational age ranged from 10 + 2 to 16 + 2 (mean, 12 + 1) weeks, entered the randomized study, which was powered to detect with 90% probability the absence of any difference in the size of chorionic samples obtained by using a 20-mL syringe with the vacuum obtained by a hand-grip device (Group 1) or by a vacutainer (Group 2). Four operators with different levels of experience performed all the procedures, which were done transabdominally using a freehand technique with a 20-gauge needle under ultrasound guidance. Maternal age, body mass index, gestational age and the way the needle was inserted within the chorion were similar in the two groups. The median amount of villi sampled was 20 mg, with no differences between the two groups. The rate of fetal loss was 1.7%. All losses occurred in women of Group 1 who had only one needle insertion. A second needle insertion was required more frequently while using the vacutainer. This new technique for performing transabdominal CVS uses a readily available device and is as effective as traditional sampling systems to aspirate villi. It has the advantage of being a one-operator procedure.

Gender Differences in Brachial Blood Flow during Fatiguing Intermittent Handgrip

Females have been reported to have greater resistance to skeletal muscle fatigue than males. Blood flow, which plays an important role in supplying oxygen and nutrients to working muscles, may play an important role in the mechanisms of gender difference. We hypothesized that females would have greater conduit artery blood flow supplying working muscles than males during intermittent maximal handgrip exercise. Healthy adult (22-31 yr old) males (N = 8) and females (N = 8), lying in a supine position, repeated static maximal voluntary contractions (MVC) with a handgrip device in an intermittent pattern. Mean brachial arterial blood flow (MBABF) was continuously monitored using Doppler ultrasonography during the 5-s muscle-relaxation phase, when intramuscular pressure does not impede measurement of muscle blood flow during the 4-min exercise period, and continuously during the 10-min recovery period. Vascular conductance (VC) was calculated from the MBABF normalized by forearm volume and mean blood pressure (MBP). Females achieved higher relative muscle force (%MVC) than males throughout both the exercise and the recovery periods (P < 0.05); females tended to exhibit smaller declines in muscle force (i.e., less fatigue). Exercise-induced increases in MBABF normalized to forearm volume were greater in females compared with males during the relaxation phases (P < 0.05), during which females also exhibited greater VC than males (P < 0.05). Our findings suggest that the normalized MBABF and VC in females, who experience less muscle fatigue, are greater during intermittent maximal voluntary handgrip exercise.

Effects of catastrophizing on pain perception and pain modulation

The multidimensional experience of pain is thought to be partially influenced by the pain modulation system as well as by individual psychological components. Recent studies demonstrated possible common neural network mediating both domains. The present study examined the relationships between pain perception, pain modulation, and catastrophizing in healthy subjects. Forty-eight participants (29 females and 19 males) completed the pain catastrophizing scale (PCS) and underwent psychophysical tests in order to evaluate the modulation of pain, using the diffuse noxious inhibitory control (DNIC) paradigm. Contact heat pain (47.0 degrees C applied for 1 min), which was used as the "test" stimulation, was applied before and after a physical effort that induces pain (repeated squeezing of a hand grip device), which was used as a "conditioning" stimulus. Numeric pain scale intensities (NPS, 0-10) were evaluated four times during each of two separate consecutive runs of heat stimulation. Results showed a significant positive correlation of PCS with heat pain (r = 0.48, p < 0.0005) and with muscle pain (r = 0.31, p = 0.03). In addition, significant negative correlations were found between PCS and DNIC effect (r = -0.34, p = 0.02). Moreover, once catastrophizing was entered into the regression analysis, the previously significant effect of gender was no longer found. In conclusion, individuals with high catastrophizing levels demonstrated higher pain intensities and lower effects of DNIC indicating that catastrophizing might have a significant impact on pain perception via an association with pain modulation.

DEVELOPMENT OF A SIMPLE INDEX OF STRENGTH AND ENDURANCE PERFORMANCE IN POWER GRIP ASSESSMENT

1789 Our purpose was to develop a method whereby muscular strength and endurance in power grip assessment could be easily quantified. Healthy workers from different occupations (74 males, 34.8±10.4 yrs; 74 females, 33.5±9.5 yrs) repetitively squeezed-released a commercially available static hand grip device for 60 s trials at 36 cycles/min. Analog force output records for each subject provided 18 cycles for analysis. Initial strength(IS) and final strength (FS) were calculated as the peak force means for cycles 1-3 and 16-18, respectively. Endurance was defined by the strength decrement index (SDI), where SDI = [(IS-FS/IS) x 100], and IS was used as the measure of strength. A linear scale was used to transform IS and SDI mean scores, with individual strength and endurance performance scores (SEPS) calculated by summing transformed IS and SDI mean scores. Ninety-six percent of the sample (n = 142) scored within an acceptable test range defined as the combined sample mean ± 2 sd for SEPS. FS was the best predictor of SEPS for each gender. Linear regression equations for SEPS were: SEPS (males) = 3.112 + 0.062 (FS) (s.e.e. =0.717); SEPS (females) = 2.504 + 0.106 (FS)(s.e.e. = 0.641). These results suggest that 1) SEPS provides a simple method for quantifying power grip strength and endurance performance, and 2) SEPS may have practical implications for occupational health care professionals who routinely administer power grip assessments. TableTable

THE EFFECTS OF TRAINING ON FOREARM VASCULAR CONDUCTANCE IN ELDERLY AND YOUNG MEN AND WOMEN 73

Young adults experience increases in maximal forearm vascular conductance(FVC) after a training program of dynamic hand gripping exercise (Sinoway et al., J. Appl. Physiol., 62:1987). Whether healthy, elderly subjects undergo similar peripheral adaptations to exercise training in their forearms is uncertain. Therefore, the purpose of this study was to evaluate the effects of dynamic hand grip training on maximal vasodilation of the nondominant(NDOM) forearms in 8 elderly (67±2yrs; mean±S.E.) and 9 young(23±1 yrs) men and women. Submaximal and maximal oxygen uptake(VO2) tests were done on elderly and young subjects, respectively. Maximal forearm blood flow (FBF) was measured by strain gauge plethysmography following 10 min of arterial occlusion coupled with one min ischemic handgrip exercise on both the dominant (DOM) and NDOM forearms. After testing, all subjects trained their NDOM forearm using a weighted handgrip device. Subjects trained for 8 wks, 3x/wk. Exercise durations and intensities were increased until they could exercise for 30 min at 30% of their maximal voluntary contraction. Submaximal and maximal VO2 did not change(p>0.05) over the 8 wks in the elderly (16.6±1.7 vs 17.4±1.7 ml·kg-1·min-1) or young(36.1±3.2 vs 36.5±2.6 ml·kg·-1min-1). Strength significantly increased(p≤0.05) in the NDOM arm for both the young (63.6±9.6 vs 74.1±8.6 kg) and elderly (48.9±12.2 vs 64.1±11.6 kg). There were no arm by age by time interactions for resting and maximal FBF and mean arterial pressure. The 8 wks of training did not alter resting FVC for the NDOM forearm in the young (0.0471±0.0068 vs 0.0465±0.0071 units) and elderly (0.0358±0.0061 vs 0.0364±0.0067 units). Maximal FVC for the NDOM forearm was also not different between the young(0.3279±0.0370 vs 0.2244±0.0402 units) and elderly(0.2434±0.0489 vs 0.2019±0.0321 units) or altered by the training program. These data suggest that 8 wks of dynamic handgrip training can elicit increases in strength without altering vascular conductance in the young or the elderly.

ACTIVATION AND BEHAVIOR. I. RELATIONSHIP BETWEEN PHYSIOLOGICAL "INDICANTS" OF ACTIVATION AND PERFORMANCE DURING MEMORIZATION OF NONSENSE SYLLABLES USING DIFFERING INDUCED TENSION CONDITIONS.

This is the first of a series of studies oriented toward determining what physiological variables constitute the most reliable and valid indices of activation level; what is the minimal number of variables required to estimate accurately general activation level as well as patterns of activation, taking into account the activity of both the autonomic and somatic nervous systems; and how each variable relates to performance under specified conditions. The primary purpose of this study was to ascertain how four different “indicants” of activation level relate to one another and to verbal performance under different induced tension conditions. Sixteen Ss memorized 16 5-syllable lists of 3-letter nonsense syllables under 16 conditions in a single experimental session, using a balanced Latin square to control for order effects. The conditions were generated by various combinations of three independent variables: (1) mode of syllable presentation (visual vs auditory); (2) method of inducing tension (lifting weights vs squeezing hand dynamometer); and (3) amount of induced tension (5, 10, 15, and 20 lbs.). Each trial was 2 min. long, being followed by 2 min. of rest. Orderly within- and between-trial changes were noted in skin conductance, heart rate, and neck and forearm flexor tension level, but the changes varied, respectively, among the four variables from decreasing to increasing functions. This gradual transition was explained in terms of the relative degree of control the autonomic and somatic nervous systems exerted on each of the variables. The decreasing functions probably reflect a gradual reduction in the degree of anxiety or apprehensiveness experienced by Ss; the increasing functions probably reflect an increase in the amount of muscular effort exerted by Ss in order to maintain a specified amount of force on a hand grip device. Increasing amounts of induced tension caused performance to deteriorate and caused heart rate and forearm flexor tension level to increase. The manner in which the syllables were presented and method of inducing tension significantly affected performance but not the physiological variables.