Grip Endurance Research Articles

Low-volume muscular endurance and strength training during 3-week forearm immobilization was effective in preventing functional deterioration

PurposeThe purpose of this study was to determine whether endurance and strength hand grip exercises during 3-week upper limb immobilization preserve muscle oxidative capacity, endurance performance and strength.MethodsTen healthy adult men underwent non-dominant forearm immobilization by plaster cast for 21 days. Five healthy adult subjects were designated as the immobilization (IMM) group and five were designated as the immobilization + training (IMM+TRN) group. Grip strength, forearm circumference, dynamic handgrip endurance and muscle oxygenation response were measured before and after the 21 day immobilization period. Using near-infrared spectroscopy (NIRS), muscle oxygen consumption recovery (VO2mus) was recorded after a submaximal exercise and the recovery time constant (TcVO2mus) was calculated. Reactive hyperemic oxygenation recovery was evaluated after 5 minutes ischemia. Two training programs were performed by the IMM+TRN group twice a week. One exercise involved a handgrip exercise at 30% maximum voluntary contraction (MVC) at a rate of 1 repetition per 1 second until exhaustion (about 60 seconds). The other involved a handgrip exercise at 70% MVC for 2 seconds with a 2 second rest interval, repeated 10 times (40 seconds).ResultsThere was a significant group-by-time interaction between the IMM and IMM+TRN groups in the TcVO2mus (p = 0.032, F = 6.711). A significant group-by-time interaction was observed between the IMM and IMM+TRN groups in the MVC (p = 0.001, F = 30.415) and in grip endurance (p = 0.014, F = 9.791). No significant group-by-time interaction was seen in forearm circumference and reactive hyperemic oxygenation response either in IMM or IMM+TRN group.ConclusionThe training programs during immobilization period used in this experiment were effective in preventing a decline in muscle oxidative function, endurance and strength.

Validity and Reliability of the adapted Spring Balance as a Hand-Grip Dynamometer

Reliable and valid evaluation of hand strength is important for determining the effectiveness of treatment strategies. Muscular grip strength is objectively measured by various types of dynamometers but some instruments are costly, time-consuming to use, or have questionable reliability. The various dynamometers that proved satisfactory over the years are expensive and scarce. Most physiotherapy departments in the developing countries and particularly Nigeria cannot boast of any of these dynamometers. This led us to develop the adapted spring balance (ASB) as a grip dynamometer. For any tool to be of great value in clinical assessment it must be valid and reliable. This study was therefore carried out to examine the validity and reliability of the new instrument (the ASB). Grip strength and endurance testings were conducted on forty (40) apparently healthy subjects (aged 22.38 ± 2.18 years) using both the ASB and the Jamar dynamometers. The data were analyzed for concurrent validity and test-retest reliability using the Pearson's product moment correlation method. The scores on the ASB correlated well with those obtained on the Jamar (grip strength, r = 0.766; grip endurance, r = 0.626) and it was found to have high test-retest reliability (grip strength, r = 0.808; grip endurance, r = 0.711). Linear regression equations were derived to enable the physiotherapist convert the ASB readings to approximate Jamar readings. This becomes very useful where there is the need to compare a patient's performance with standard norms. The results of this study indicate that clinicians can use the ASB dynamometer knowing that it is valid and reliable. The Journal of Medicine in the Tropics Vol. 9 (1) 2007: pp. 11-20

Myostatin DNA vaccine increases skeletal muscle mass and endurance in mice

Myostatin is a transforming growth factor-beta family member that acts as a negative regulator of skeletal muscle growth. In mice, genetic disruption of the myostatin gene leads to a marked increase in body weight and muscle mass. Similarly, pharmacological interference with myostatin in vivo in mdx knockout mice results in a functional improvement of the dystrophic phenotype. Consequently, myostatin is an important therapeutic target for treatment of diseases associated with muscle wasting. To construct a therapeutic DNA vaccine against myostatin, we coupled the foreign, immunodominant T-helper epitope of tetanus toxin to the N terminus of myostatin, and BALB/c mice were immunized with the recombinant vector. Sera from vaccinated mice showed the presence of specific antibodies against the recombinant protein. In addition, body weight, muscle mass, and grip endurance of vaccinated mice were significantly increased. Our study provides a novel, pharmacological strategy for treatment of diseases associated with muscle wasting.

Estimating upper limb discomfort level due to intermittent isometric pronation torque with various combinations of elbow angles, forearm rotation angles, force and frequency with upper arm at 90° abduction

Industrial jobs involving upper arm abduction have a strong association with musculoskeletal disorders and injury. But there is still paucity of data on the different risk factors that are responsible for the genesis of such disorders or injuries. The current laboratory study is an attempt in that direction. Thirty-six right-handed male university students participated in a full factorial model of three forearm rotation angles (60% prone and supine and neutral range of motion), three elbow angles (45°, 90° and 135°), two exertion frequencies (10 and 20/min) and two levels of pronation torque (10% and 20% MVC). Discomfort rating after each five-minute treatment was recorded on a visual analogue scale. Repeated measures ANCOVA with grip endurance time as a covariate indicated that forearm rotation angle ( p=0.001), elbow flexion angle ( p=0.016), MVC torque ( p=0.001) and frequency ( p=0.049) were significant. Grip endurance time was not significant ( p=0.74). EMG activity of the Pronator Teres (PT) and the Extensor Carpi Radialis Brevis (ECRB) revealed that both muscles were affected by forearm rotation and level of MVC torque. A supplementary experiment in which MVC pronation torque at different articulations was measured showed that some of the increased discomfort appeared to be due to increased relative MVC at some of the extreme articulations. The findings indicated that, with the upper arm in abduction, an elbow angle of 45° and forearm prone, are a posture vulnerable to injury and should be avoided. Grip endurance time as a covariate warrants further investigation. Relevance to industry There is still a paucity of data on risk factors for musculoskeletal disorders for upper arm articulations typical of industrial jobs, especially postures involving upper arm abduction. Industrial jobs involving upper arm abduction have a strong association with injury as operators must often maintain static upper arm abduction while performing tasks for long durations. This study presents discomfort and pronation torque MVC data at different upper arm articulations to identify and control high-risk tasks in industry well before they develop into Musculoskeletal Disorders, especially at the design stage when using biomechanical models.

Oral Administration of Memantine Prolongs Survival in a Transgenic Mouse Model of Amyotrophic Lateral Sclerosis

Background and purposeN-methyl-D-aspartate (NMDA)-mediated neurotoxicity and oxidative stress have been implicated in the etiology of amyotrophic lateral sclerosis (ALS). Memantine is a low-affinity, noncompetitive NMDA receptor antagonist that may protect against motor neuron degeneration.MethodsThirty transgenic mice expressing the G93A SOD1 mutation were randomly divided into control, low-dose memantine (30 mg/kg/day), and high-dose memantine (90 mg/kg/day) groups, with memantine supplied daily with drinking water beginning at 75 days of age. Body weight, survival, and behavioral performances including a rotarod test, paw grip endurance, and hindlimb extension reflex were assessed in the control and memantine-diet groups.ResultsClinical symptoms were evident in the G93A transgenic mice by 11 weeks of age. Memantine was tolerated well. Compared to control, mice treated with memantine performed better in the rotarod test and hindlimb extension reflex. Moreover, low-dose memantine treatment significantly prolonged the survival of the transgenic mice relative to control mice (141 vs 134 days, p<0.05).ConclusionsThese findings suggest that memantine, even when administered at the time of symptom onset, has beneficial effects on patients with ALS.

Transient caloric restriction in early adulthood hastens disease endpoint in male, but not female, Cu/Zn‐SOD mutant G93A mice

Long-term caloric restriction (CR) prolongs the lifespan in healthy insects, rodents, and nonhuman primates. We previously reported that long-term CR improves motor performance but hastens clinical onset of disease in an animal model of amyotrophic lateral sclerosis (G93A mice). G93A mice overexpress the mutant human Cu/Zn-SOD gene and show progressive lower motor neuron weakness and increased oxidative stress. To study short-term (15 days) CR in the same animal model, we investigated the effect of transient caloric restriction (TCR) on paw grip endurance, clinical onset, disease progression (time from clinical onset to endpoint), and lifespan. Starting at age 40 days, 32 separately caged G93A mice were randomly divided into two groups: ad libitum (AL, n = 17; 10 females, 7 males) and TCR (n = 15; 6 females, 9 males) with a diet equal to 60% of AL. When the TCR mice lost 30% of their weight they were offered food AL until endpoint, otherwise all TCR mice were provided food AL from age 55 days until endpoint (i.e., range of TCR = 13-15 days). Paw grip endurance started to decrease significantly at age 96 days compared with baseline values for all the groups. TCR males reached clinical onset 5 days sooner than TCR females. Disease progression was 8 days faster in TCR mice than AL mice and 6 days faster in male mice than female mice. The probability of survival was significantly different between the groups, with the TCR males having a faster rate of reaching endpoint than TCR females, AL males, and AL females. We conclude that TCR hastens clinical onset of disease and shortens the lifespan in male, but not female, G93A mice. Moreover, TCR hastens progress of disease but has no effect on paw grip endurance. The female sex is protective against the detrimental effects of short-term CR in G93A mice. Assuming we can extrapolate these results to humans, short-term CR should be avoided in patients with amyotrophic lateral sclerosis, especially men.

Physiological correlates of cancer-related fatigue in advanced non-small cell lung cancer (NSCLC) patients

8525 Background: Fatigue is a debilitating consequence of lung cancer and its treatments. The etiology of fatigue is unclear, and our current knowledge does not point to logical interventions. In this study, global fatigue score was assessed using the Brief Fatigue Inventory (BFI). A symptom questionnaire, as well as muscular and cardiorespiratory function, were assessed as potential contributors to the global fatigue score. Methods: Participants were evaluated by a physical therapist within the McGill Cancer Nutrition and Rehabilitation Program. Performance-based measures of physical function [upper limb strength and endurance (Jamar dynamometry), lower limb strength (30sec chair rise), cardiorespiratory function (2 minute walk -2MW)] and a symptom questionnaire [Edmonton Symptom Assessment Scale (ESAS)] were conducted at one point in time. Results: Eighty patients (43M:37F, mean age 68 ± 12 ) participated in the study. Forty-seven percent were actively receiving treatment at the time of assessment. On the BFI, 56% had moderate or severe fatigue and 88% indicated fatigue had interfered with their functioning during the past 24 hours. Global fatigue scores were unrelated to hand grip strength or endurance measurements but were significantly correlated with chair rise performance (R= -0.31, p&lt;0.05), 2MW (R= -0.31, p&lt;0.05), ESAS rating of pain (R=0.47, p&lt;0.01), overall ESAS rating of breathlessness (R= 0.59, p&lt;0.01), and ESAS rating of strength (R=0.58, p&lt;0.01). Multivariate regression analysis suggested the best model for global fatigue scores incorporates chair rise performance, 2MW performance, ESAS rating of strength and ESAS rating of shortness of breath (adjusted R sq = 0.68, p&lt;0.01). Conclusions: Fatigue is prevalent and impacts on the function of advanced NSCLC patients. Several key factors contribute to this fatigue, with muscular and cardiorespiratory restrictions playing an important role. Such findings may have clinical implications in the recommendations of rest and exercise to best manage fatigue. No significant financial relationships to disclose.

The Physiology of Rock Climbing

In general, elite climbers have been characterised as small in stature, with low percentage body fat and body mass. Currently, there are mixed conclusions surrounding body mass and composition, potentially because of variable subject ability, method of assessment and calculation. Muscular strength and endurance in rock climbers have been primarily measured on the forearm, hand and fingers via dynamometry. When absolute hand strength was assessed, there was little difference between climbers and the general population. When expressed in relation to body mass, elite-level climbers scored significantly higher, highlighting the potential importance of low body mass. Rock climbing is characterised by repeated bouts of isometric contractions. Hand grip endurance has been measured by both repeated isometric contractions and sustained contractions, at a percentage of maximum voluntary contraction. Exercise times to fatigue during repeated isometric contractions have been found to be significantly better in climbers when compared with sedentary individuals. However, during sustained contractions until exhaustion, climbers did not differ from the normal population, emphasising the importance of the ability to perform repeated isometric forearm contractions without fatigue becoming detrimental to performance. A decrease in handgrip strength and endurance has been related to an increase in blood lactate, with lactate levels increasing with the angle of climbing. Active recovery has been shown to provide a better rate of recovery and allows the body to return to its pre-exercised state quicker. It could be suggested that an increased ability to tolerate and remove lactic acid during climbing may be beneficial. Because of increased demand placed upon the upper body during climbing of increased difficulty, possessing greater strength and endurance in the arms and shoulders could be advantageous. Flexibility has not been identified as a necessary determinant of climbing success, although climbing-specific flexibility could be valuable to climbing performance. As the difficulty of climbing increases, so does oxygen uptake (VO(2)), energy expenditure and heart rate per metre of climb, with a disproportionate rise in heart rate compared with VO(2). It was suggested that these may be due to a metaboreflex causing a sympathetically mediated pressor response. In addition, climbers had an attenuated blood pressure response to isometric handgrip exercises when compared with non-climbers, potentially because of reduced metabolite build-up causing less stimulation of the muscle metaboreflex. Training has been emphasised as an important component in climbing success, although there is little literature reviewing the influence of specific training components upon climbing performance. In summary, it appears that success in climbing is not related to individual physiological variables but is the result of a complex interaction of physiological and psychological factors.

Task-based standards for lifeboat crew: Avoiding ageism

The current retirement age for Royal National Lifeboat Institution (RNLI) Inshore lifeboat (ILB) and All-weather lifeboat (ALB) crew is 45 and 55 years respectively. Forthcoming European legislation on ageism has led various groups, including the RNLI, to explore the option of replacing a mandatory retirement age with a task-related fitness standard. Such a standard ensures that the employee is physically capable of performing the most demanding critical tasks, irrespective of age or gender. This paper describes the approach and final fitness requirements of a project designed to replace age-related retirement with a task-related fitness test for the 5000 lifeboat crew of the RNLI. The final fitness test is a combination of work evaluation in the field and physical strength tests of the back, triceps, and grip endurance.

Grip strength and endurance: Influences of anthropometric variation, hand dominance, and gender

Studies of grip strength typically examine maximum force during a single repetition, but this type of exertion is relatively rare in the workplace, where tasks frequently involve repeated forceful dynamic grasping or prolonged static holding. This study examined grip strength and endurance in three experiments: single-repetition, 10-repetition, and 30-second static hold. The relationships between anthropometric variation and grip performance were assessed for 51 individuals, aged 18–33. Measurements of the forearm and hand were found to be better predictors of grip strength than were height and weight. The ability to predict strength was most accurate for the single-repetition, and then declined with increasing duration of the experiment. Compared to univariate measurements, multivariate analysis (principal components) slightly improved the ability to predict absolute grip force. In contrast to strength, anthropometric variation was completely unassociated with relative grip endurance (percent change in force production). While larger males produced greater average grip force than did females, no significant differences existed between the genders in measures of relative endurance. The dominant hand was significantly stronger than the opposite hand, but also fatigued more rapidly. This trend was more pronounced in females than in males. Relevance to industry Grip strength and relative endurance may both contribute to the risk of work-related accidents and cumulative musculoskeletal injury. Because grip force and endurance are unrelated, ergonomists should consider which factor is most important and appropriate for their design and research goals.

Deterioration of Muscle Function after 21-Day Forearm Immobilization

Although it is well known that immobilization causes muscle atrophy, most immobilization models have examined lower limbs, and little is known about the forearm. The purpose of this study was to determine whether forearm immobilization produces changes in muscle morphology and function. Six healthy males (age: 21.5 +/- 1.4, mean +/- SD) participated in this study. The nondominant arm was immobilized with a cast (CAST) for 21 d, and the dominant arm was measured as the control (CONT). The forearm cross-sectional area (CSA) and circumference were measured as muscle morphology. Maximum grip strength, forearm muscle oxidative capacity, and dynamic grip endurance were measured as muscle function. Magnetic resonance (MR) imaging was used to measure CSA, and 31phosphorus MR spectroscopy was used to measure time constant (Tc) for phosphocreatine (PCr) recovery after submaximal exercise (PCr-Tc). Grip endurance was expressed by the number of handgrip contractions at 30% maximum grip strength load. All measurements were taken before and after the immobilization. After the 21-d forearm immobilization, no changes were seen for each measurement in CONT. CSA and the circumference showed no significant changes in CAST. However, maximum grip strength decreased by 18% (P < 0.05), PCr-Tc was prolonged by 45% (P < 0.05), and the grip endurance at the absolute load was reduced by 19% (P < 0.05) for CAST. In this model, 21-d forearm immobilization caused no significant changes in forearm muscle morphology, but the muscle function showed remarkable deterioration ranging from 18 to 45%.

Assessing disease onset and progression in the SOD1 mouse model of ALS

SOD1 transgenic mice are the most widely used animal model of amyotrophic lateral sclerosis (ALS). In addition to providing valuable insights into the pathogenesis of ALS, these animals are used intensively in many laboratories as an in vivo model for investigating novel therapeutic interventions towards this devastating motorneuron disease. Such pre-clinical studies require objective and reliable quantification of the clinical phenotype of individual mice, most importantly of the neuromuscular abnormalities. Here we compare four parameters of the clinical phenotype: motor signs, body weight, rotarod performance and paw grip endurance for their usefulness in monitoring the SOD1 mouse model. We found that paw grip endurance is a sensitive and inexpensive alternative to the widely used rotarod test.

Assessing hand grip endurance with repetitive maximal isometric contractions

The purpose of this study was to identify a method for measuring hand grip endurance in patients with hand injury as well as in healthy subjects. Twenty hand-injured patients and 60 healthy subjects participated in the study. Each subject performed two sets of maximal repetitive isometric contractions on the Grippit instrument for 180 seconds, with a contraction time of 2.5 seconds and a rest time of 1 second. Reliability data were high for initial grip force and for absolute and relative endurance values at 90 seconds (r range, 0.73 to 0.97, p < 0.001). Relative endurance at 180 seconds, though, showed weaker reproducibility (r = 0.54, p < 0.01). A measuring period of 90 seconds instead of 180 seconds is suggested, because of the results of test-retest reliability. The method allows endurance to be described in relative force values (as a percentage) as well as in absolute force values (Newtons).

Physiological and anthropometric determinants of sport climbing performance

Objective—To identify the physiological and anthropometric determinants of sport climbing performance. Methods—Forty four climbers (24 men, 20 women) of various skill levels (self reported rating 5.6–5.13c on the Yosemite decimal...

Isometric grip endurance of healthy elderly men and women.

Grip endurance is one of the important prerequisites for good performance of the upper extremity and hence it is important to evaluate it correctly. However, we know little about normal grip endurance, especially for elderly people. The main objective of this study was to examine the age-related changes in grip isometric endurance of healthy community-dwelling elderly people. Two-hundred and eighty-six subjects aged between 60 and 90, were randomly selected from the electoral list of the city of Sherbrooke, Quebec, Canada. Grip relative isometric endurance was evaluated using the Jamar dynamometer. Isometric grip endurance was estimated by the number of seconds a subject could sustain 50% of his/her maximal voluntary grip strength. Contrary to other upper extremity sensorimotor parameters, no grip isometric endurance difference was found with age, in spite of a slight tendency towards a decrease. The women tended to have better scores than the men and endurance of dominant hand is better than the non-dominant. The stability with age could be explained by muscle fiber composition modifications.

Hyperthyroid Myopathy and the Response to Treatment

Hyperthyroidism is accompanied by significant dysfunction of both proximal and distal skeletal muscles. The purpose of this study was to quantitate the degree of muscle weakness in newly diagnosed patients with Graves' disease and to assess the response to treatment. Ten patients were prospectively studied with objective measures of strength and endurance of proximal and distal muscles while hyperthyroid (stage I), after 2 weeks of propranolol (stage II), and about 6 months later when euthyroid (stage III). Propranolol treatment for 2 weeks resulted in a subjective decrease in weakness, which was accompanied by a statistically significant improvement in grip strength (P less than 0.01), shoulder strength (P less than 0.02), and grip endurance (P less than 0.01) but not shoulder endurance. Muscle function further improved and attained control levels when the patients were chemically and clinically euthyroid. In contrast, a control group subjected to the same muscle testing protocol before and after 1 week of propranolol treatment showed no improvement in grip, shoulder strength, or shoulder endurance but had decreased grip endurance (P less than 0.01) and increased subjective weakness. These results confirm that muscle weakness commonly is associated with hyperthyroidism and can be quantitatively profound. In contrast to the effects of beta-blockade in normal controls, propranolol partially improves muscle weakness in thyrotoxic patients. We conclude that thyroid hormone and catecholamines in concert mediate the muscle dysfunction of hyperthyroidism.

The Effects of Gloves on Maximum Holding Time

Considerable work is now done while wearing gloves on tasks that require that considerable grip forces be exerted and maintained for extended times. The primary objective of this research was to evaluate the effects of two common working gloves on the time a person can exert a constant grip force as a function of that persons maximum grip force. A simple endurance experiment was conducted to verify that the same relationship between holding time and grip force (as a percentage of maximum grip force under the same conditions) is valid for grip with gloves as is present in other muscular exertions. Subjects were first evaluated for maximum grip force on a standard hand dynamometer with bare hands and while wearing each of the gloves. They then participated in trials to evaluate grip endurance at 20, 40, 60, 80, and 100% of the maximum grip for each condition (bare hand, a leather glove, and a cotton glove). Analysis of variance was used to evaluate the data gathered to determine if the holding time differed for bare hand or glove conditions. This analysis showed no differences between the conditions. This study shows that the effect of a glove on endurance can be predicted by the effect of that glove on the maximum grip force that can be exerted. This will be of value to those persons who design or evaluate work tasks where gloves are required.

Strength Testing After Jaw Repositioning With a Mandibular Orthopedic Appliance.

In brief More athletes are using mandibular orthopedic repositioning appliances (MORAs), and many have claimed they cause surprising performance improvements. However, most research on this subject has suffered from serious design problems. In this double-blind experiment, control, experimental, and placebo groups of college students were tested for left and right maximal grip strength and endurance, maximal quadriceps and hamstring dynamic strength, and maximal quadriceps and hamstring static strength. Statistical analysis of the results showed that the devices did not increase the strength of the muscle groups measured or the muscular endurance of the hand.

Prediction of muscular endurance (work performance) from individual differences in initial and post training increments in static strength.

Forty college men were given tests for static strength and strength endurance prior to an isotonic strength training program. Experimental results indicate that individual differences in static strength are a poor criterion in the prediction of muscular endurance. Following an increase in static strength resulting from isotonic strength training pre-training static strength and post-training strength increments are not indicative of an individual's performance in a hand grip endurance activity.

Effect of Actively Increased Muscle Temperature on Local Muscular Endurance

Abstract The effect of actively warming the forearm musculature on dynamic grip endurance was investigated by comparing the performance of the left and right hands, with or without warming-up, on a spring-loaded grip ergometer. There were 21 male subjects, aged 19 to 23. Warming-up consisted of 9 min. of four hand and wrist exercises conducted in 30-sec. bouts, at a rate of one repetition per sec., with 15-sec. intervals between bouts. This warm-up was shown to lead to temperature increases of between 1.6 C and 2.6 C in the flexor digitorum sublimis muscles of five subjects. Warming-up had no effect on grip endurance.