A strain-gauge dynamometer for the measurement of the strength of isometric contraction.
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Isometric Contraction↗
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Results for “Muscle Strength Dynamometer”
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Upper motor neuron lesions: their effect on muscle performance and appearance in stroke patients with minor motor impairment.
OBJECTIVE: To evaluate muscular performance and appearance in patients with prior stroke who were ambulatory. DESIGN: Nonrandomized study. SETTING: University hospital laboratory. SUBJECTS: Sixteen persons (11 men, 5 women) with minor motor impairments, 6 to 24 months after stroke, were included. As reference, data were used from a population-based sample of 144 men and women. MAIN OUTCOME MEASUREMENTS: Muscle performance was evaluated using a Kin-Com dynamometer in both the affected and the nonaffected leg. Peak isometric strength was measured at a 60 degree angle in both extension and flexion. Maximal isokinetic strength was measured at 60 degrees/sec and at 180 degrees/sec. Endurance was evaluated during isometric and dynamic knee extensions. Muscle biopsies were taken on nine patients and muscle tissue areas were determined with computed tomography. RESULTS: The affected leg was weaker but not different in relative endurance compared with the nonaffected side. The performance of the nonaffected side was somewhat lower than that of a matched reference population. No major difference in fiber composition between the affected and nonaffected legs was noted, except for a lower degree of capillarization in the affected leg. CONCLUSION: In well-functioning stroke patients with good motor performance, further muscle training that includes resistance exercise might be indicated.
Adult↗
DETERMINATION OF THE OPTIMUM SETTING OF AN ADJUSTABLE GRIP DYNAMOMETER.
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Hand Strength↗
Knee extensor and knee flexor strength: cross-sectional area ratios in young and elderly men.
The relationships between isometric and isokinetic-concentric knee extensor and knee flexor strength, and quadriceps and hamstring cross-sectional area (CSA) were determined in young (n = 13, M = 24.5y) and elderly (n = 12, M = 70.7y) men. Quadriceps and hamstring CSA was determined by computed tomography. Knee extensor and flexor strength at 0 degree/s and 120 degree/s was determined on a Kin-Com isokinetic dynamometer. Compared to the young men, elderly men had significantly smaller quadriceps muscles and were weaker (22-32%) in knee flexion and knee extension at both angular velocities. Strength:CSA ratios were similar at 0 degree/s, but elderly men had decreased ratios for both extensors and flexors at 120 degree/s. Correlations of knee extensor and flexor strength with muscle CSA were significant at both velocities in elderly men, but not at either velocity for the knee flexors in young men. The decrease in isometric strength in elderly men can be accounted for by their decrease in muscle CSA, but their decrease in isokinetic-concentric strength was greater than their loss of CSA. Further study is required to determine the reason for this nonproportional loss of isokinetic-concentric strength.
Adult↗
Evaluation of eccentric exercise in treatment of patellar tendinitis.
The purpose of this study was to analyze the effects of a quadriceps femoris muscle eccentric training program on strength gain in patients with patellar tendinitis. The effect of an eight-week eccentric exercise program on quadriceps femoris muscle work was evaluated in four groups of subjects--two groups of "normal" (healthy) subjects and two groups of patients with patellar tendinitis. All four groups participated in a home muscle stretching exercise program, but only two groups--one group of normal subjects (N-A) and one group of subjects with tendinitis (T-A)--received additional eccentric training on an eccentric isokinetic dynamometer. The eccentric quadriceps femoris muscle work ratio (involved limb/uninvolved limb x 100) was used to quantify strength in the N-A and T-A Groups. Pain ratings were recorded for subjects with tendinitis before and after the eight-week experiment and were correlated with the dependent variable using a Spearman rank-order correlation coefficient. The N-A Group performed significantly better than all subjects with tendinitis (p less than .05). Subjects in the T-A Group, however, showed a trend toward increasing eccentric quadriceps femoris muscle work capacity over the eight-week training period. As pain ratings in the T-A Group increased, work ratios decreased. We concluded that eccentric exercise may be an effective treatment for patellar tendinitis, but that knee pain may limit optimal gains in strength.
Adult↗
Stretch-shortening cycle during plantar flexion in young and elderly women and men.
The stretch-shortening cycle (SSC) is a combination of eccentric and concentric muscle actions. The purpose of the study was to compare the SSC of four different groups comprising a total of 29 women and 30 men, divided according to sex and age (i.e. 20-40 years and 70-85 years). A KIN-COM dynamometer was used for strength measurements of the plantar flexion of the right foot. An electromyogram (EMG) from the gastrocnemius muscle was recorded simultaneously. Maximal voluntary concentric muscle actions at 120 degrees.s-1 and 240 degrees.s-1 with and without prior eccentric muscle actions were performed. Average torque values of the range of motion between 90 degrees and 99 degrees of the ankle joint were extracted. All four groups were significantly stronger at 120 degrees.s-1 than at 240 degrees.s-1 for pure concentric actions. The average torque values of the concentric phases in the SSC movement were significantly higher than the torque values for pure concentric actions in all four groups and at both velocities. The EMG was significantly lower or unchanged in the SSC movement compared to a pure concentric action in all groups. A larger percentage increase in torque with prior eccentric action was found in young women compared to young men at both velocities. Our results suggested that the enhanced performance was even more marked when a concentric action was preceded by an eccentric action in the young women than in the young men, probably due to better utilization of elastic forces, but we could not demonstrate any age-related differences in enhanced performance with SSC.
Adolescent↗
Maximum grip strength is not related to bone mineral density of the proximal femur in older adults.
In the past decade there have been numerous publications reporting a significant and direct relationship between handgrip strength and bone mineral density (BMD) of the proximal femur in older adults. The present report challenges the appropriateness of the methods, and thus the conclusions used in these studies. Specifically, these studies failed to control for the concomitant influence of body weight on both BMD and muscle strength. In the present study, maximum handgrip strength was measured using a conventional hand-held hydraulic dynamometer. Bone mineral density of the proximal femur was measured using dual-energy X-ray absorptiometry (DXA). Using allometric scaling, the influence of body weight on the value of maximum handgrip strength was removed for the data of the women. A small, but significant relationship between BMD of the proximal femur and maximum handgrip strength was found that accounted for about 6% of the total variation. The relationship between BMD of the proximal femur and unscaled maximum handgrip strength was not significant for the men. The findings diminish the confidence in a protective effect of skeletal muscle on some nonadjacent skeletal structures and suggest that these relationships may benefit from being revisited. The results highlight the utility of allometric scaling in analyses in which the relationship between a physiological variable and a body dimension variable can be nonlinearly and simultaneously influenced by other body dimension variables that are not considered in the analysis and therefore are statistically uncontrolled.
Absorptiometry, Photon↗
Normative values for isometric muscle force measurements obtained with hand-held dynamometers.
BACKGROUND AND PURPOSE: The extent of a patient's impairment can be established by comparing measurements of that patient's performance with normative values obtained from apparently unimpaired individuals. Only a few studies have described normative values for muscle strength measured by hand-held dynamometry. The purpose of this study of older adults, therefore, was to obtain normative values of maximum voluntary isometric force using hand-held dynamometers. SUBJECTS: One hundred fifty-six asymptomatic adults (77 men, 70 women) participated in this study. The subjects' mean age was 64.4 years (SD=8.3, range=50-79). The male subjects' mean age was 64.5 years (SD=8.4, range=50-79), and the female subjects' mean age was 64.3 years (SD=8.2, range=50-79). METHODS: Gender, age, dominant side, height, weight, and activity level were recorded. Eight upper-extremity movements (shoulder flexion, extension, abduction, and medial and lateral rotation; elbow flexion and extension; and wrist extension) and five lower-extremity movements (hip flexion and abduction, knee flexion and extension, and ankle dorsiflexion) were resisted by one of three experienced testers using a strain-gauge hand-held dynamometer. RESULTS: Gender, age, and weight were identified as independent predictors of force for all muscle actions on both the dominant and nondominant sides. These variables were used, therefore, to create regression equations and normative values for the force of each muscle action. CONCLUSION AND DISCUSSION: The reference values provided may allow clinicians who follow the described testing protocol to estimate the severity of force-generating impairments in patients aged 50 to 79 years.
Aged↗
Arthroscopically assisted ACL reconstruction. Is a drain necessary?
We report on the results of a prospective randomised controlled trial to evaluate the use of an intra-articular drain following arthroscopically assisted ACL reconstruction using patellar tendon autograft. Forty-nine patients were recruited for the trial and randomised into receiving or not receiving a drain following surgery. An independent observer who was blinded for the use of the drain assessed the knees for swelling, range of movement (ROM) and pain at 2, 4 and 6 weeks postoperatively. Muscle strength was assessed at 12 weeks following surgery using the KIN COM III isometric dynamometer. We found that the knees that were drained following surgery initially had less swelling and a better ROM. However, at 4 weeks this difference had disappeared. At 3 and 6 months, there was no functional difference between the two groups. We recommend that no drain be used following ACL reconstruction as removal of the drain is uncomfortable and carries theoretical and avoidable risks.
Adolescent↗
Relationship between estrogen use and musculoskeletal function in postmenopausal women.
OBJECTIVES: The purpose of this study was to examine the relationship between estrogen use and muscle strength, bone mineral density (BMD), and body composition variables in postmenopausal women. Forty healthy, untrained women participated in this study. Subjects (53-65 years) were > or =5 years postmenopausal and were categorized into either estrogen replacement therapy (ERT n=20) or non-estrogen replacement therapy (Non-ERT n=20) groups. METHODS: Muscular strength was measured by 1-RM testing using Cybex isotonic weight machines. Handgrip strength was measured using a handgrip dynamometer. Diagnostic Ultrasound was used to determine cross-sectional areas of the biceps brachii and rectus femoris muscle groups. BMD of the lumbar spine, proximal femur, and total body was assessed by Dual Energy X-Ray Absorptiometry (Lunar DPX-IQ). Body composition variables were obtained from the total body scan. Serum osteocalcin was measured as an indicator of bone remodeling. RESULTS: There were no significant differences (P>0.05) for isotonic muscular strength, muscle cross-sectional areas, handgrip strength, or percent fat between ERT and Non-ERT groups. ERT had significantly higher (P<0.05) BMD for the total body, femoral neck and Ward's Area. There were moderate positive relationships between lean body mass and the hip sites (r=0.61-0.70, P<0.05). Regression analyses determined that lean body mass was the strongest predictor of the hip BMD sites. Estrogen use also was a significant predictor for the femoral neck and Ward's Area sites. CONCLUSION: Women taking estrogen exhibited similar muscular strength, muscle size, and body composition as their estrogen-deficient counterparts. Estrogen use was also associated with higher BMD for the total body and hip sites. Generally, body composition, specifically lean body mass, influenced hip BMD more than muscular strength or estrogen use.
Body Composition↗
Physical and physiological factors associated with success in professional alpine skiing.
Scientific data on the physiological profile of world class skiers are sparse. During the last decade the Austria Ski Team was the most successful in the world. It was the objective of this study to describe the physical and physiological characteristics of World Cup (WC) skiers. Twenty female and 28 male members of the Austrian WC Ski Team were examined pre- and post-seasonally from 1997 to 2000. Physical parameters such as age, height, body mass, body mass index, percent body fat and thigh circumference were recorded from each athlete. The physiological variables investigated consisted in the aerobic power and in the muscle strength of the lower limbs. Racing performance was defined by the WC ranking position. The athlete's aerobic performance capacity was assessed by maximal exercise testing on a bicycle ergometer, and the isokinetic muscle strength of the knee extensor and flexor muscles by the use of a computer-interfaced dynamometer. From 1997 to 2000 about half (48 %; n = 106) of all alpine WC racing events (n = 221) were won by the athletes investigated. The typical world class skier is in the mid-twenties (25.2 y [female]; 27.6 y [male]). The mean values for height were 1.66 m (female) vs. 1.81 m (male), for body mass 65.1 kg (female) vs. 87 kg (male) and for the percentage of body fat 24.5 % (female) vs. 15.8 % (male). The maximum power output was 4.3 +/- 0.4 (female ) and 4.7 +/- 0.4 W/kg (male), the corresponding values for VO(2)max were 55 +/- 3.5 (female) and 60 +/- 4.7 ml/kg/min (male). The maximal values for peak torque and work for knee extension amounted to 206 +/- 21 (female) and 334 +/- 43 Nm (male), and 2690 +/- 364 (female) and 4414 +/- 629 J (male), respectively. In both sexes there were neither significant laterality nor dysbalance. The hamstring/quadriceps ratios were between 0.57 - 0.60. Among all physical and physiological variables, only the aerobic power in males was found to be strongly correlated (r = 0.947; p = 0.001 for W (max); r = 0.964; p < 0.001 for VO(2)max) to racing performance. The study proves the practical experience that success in professional alpine skiing is not related to single physiological variables. Two main factors, however, are crucial, i. e. high levels of aerobic power and muscle strength.
Adult↗
Pre-operative oral carbohydrate loading in colorectal surgery: a randomized controlled trial.
OBJECTIVE: Surgery induces a catabolic response with stress hormone release and insulin resistance. The aim of this study was to assess the effect of pre-operative carbohydrate administration on grip strength, gastrointestinal function and hospital stay following elective colorectal surgery. METHODS: Thirty-six patients undergoing elective colonic resection were randomized into one of three groups. Group 1 were fasted; Group 2 were given pre-operative oral water, Group 3 received equivalent volumes of a Maltodextrin drink. Time to first flatus, first bowel movement and hospital stay were recorded. Muscle strength was measured pre-operatively, and on alternate days thereafter until discharge using a grip strength dynamometer. RESULTS: Patients in the carbohydrate group had a median postoperative hospital stay of 7.5 days compared with 13 days in the water group (P > 0.01) and 10 days in the fasted group (P = 0.06). The median time postsurgery to first flatus was 3 days for both the fasted and water groups compared with 1.5 days in the carbohydrate group (P = 0.13). First bowel movement occurred on day 3 in the carbohydrate group, day 4 in the fasting group and day 5 in the water group. The fasted group showed a significant reduction in postoperative grip strength (P < 0.05) with a median drop of 10% at discharge. Neither the water nor the carbohydrate groups showed significant reductions in muscle strength. CONCLUSION: We found that pre-operative administration of oral carbohydrate leads to a significantly reduced postoperative hospital stay, and a trend towards earlier return of gut function when compared with fasting or supplementary water.
Administration, Oral↗
Strength and muscle quality in a well-functioning cohort of older adults: the Health, Aging and Body Composition Study.
OBJECTIVES: To determine whether lower lean mass and higher fat mass have independent effects on the loss of strength and muscle quality in older adults and might explain part of the effect of age. DESIGN: Single-episode, cross-sectional analyses of a cohort of subjects in the Health, Aging and Body Composition (Health ABC) Study. SETTING: Ambulatory clinic and research laboratory. PARTICIPANTS: Two thousand six hundred twenty-three men and women aged 70 to 79 from the Health ABC Study. MEASUREMENTS: Upper and lower extremity strength was measured using isokinetic (knee extension) and isometric (grip strength) dynamometers. Body composition (lean mass and fat mass) was determined by measuring lean mass of upper and lower extremities and the total body by dual-energy x-ray absorptiometry. Muscle quality was ascertained by taking the ratio of strength to muscle mass for both upper and lower extremities. RESULTS: Upper and lower extremity strength and muscle quality decreased as age increased. Most of the explained variance in strength was due to differences in muscle mass, but, in those at the extremes of body fat and lower leg muscle quality, the association with body fat was independent of the effect of age. Although blacks had greater muscle strength and mass than whites, leg muscle quality tended to be lower in blacks than in whites. Upper extremity strength adjusted for lean mass and muscle quality were also associated inversely and independently with age, body fat, and black race. CONCLUSION: In this older cohort, lower strength with older age was predominantly due to a lower muscle mass. Age and body fat also had significant inverse associations with strength and muscle quality. Both preservation of lean mass and prevention of gain in fat may be important in maintaining strength and muscle quality in old age.
Age Factors↗
Effects of a home program on strength, walking speed, and function after total hip replacement.
OBJECTIVE: To assess the efficacy of a home exercise program in increasing hip muscle strength, walking speed, and function in patients more than 1.5 years after total hip replacement (THR). DESIGN: Randomized controlled trial. SETTING: Kinesiology laboratory. PARTICIPANTS: Fifty-three patients with unilateral THR were randomly assigned to the training (n=26) and control (n=27) groups. Patients in the training group were further divided into exercise-high (n=13) and exercise-low (n=13) compliance groups according to their practice ratio (high, > or =50%). INTERVENTION: The training group underwent a 12-week home program that included hip flexion range of motion exercises for both hip joints; strengthening exercises for bilateral hip flexors, extensors, and abductors; and a 30-minute walk every day. The control group did not receive any training. MAIN OUTCOME MEASURES: Strength of bilateral hip muscles, free and fast walking speeds while walking over 3 different terrains, and functional performance were assessed by using a dynamometer, videotape analysis, and the functional activity part of the Harris Hip Score, respectively, before and after the 12-week period. RESULTS: Subjects in the exercise-high compliance group showed significantly (P <.05) greater improvement in muscle strength for the operated hip, fast walking speed, and functional score than those in the exercise-low compliance and control groups. CONCLUSIONS: The designed home program was effective in improving hip muscle strength, walking speed, and function in patients after THR who practiced the program at least 3 times a week, but adherence to this home program may be a problem.
Analysis of Variance↗
Isokinetic muscle performance after anterior cruciate ligament surgery. Long-term results and outcome predicting factors after primary surgery and late-phase reconstruction.
The purpose of this study was to evaluate the long-term isokinetic muscle performance after ACL surgery and to analyze by a multiple stepwise regression which factors (if any) predict the overall outcome. The study subjects were 119 patients who had a complete rupture of the ACL and had been treated surgically at the Tampere University Hospital between 1981 and 1990. They were divided into the acute group (N = 62) and into the chronic group (N = 57) according to the time delay between the injury and the ACL surgery. The isokinetic strength measurements of the quadriceps and hamstring muscles were performed on average 4 years after the operation using Cybex II and Cybex 6000 dynamometers (Lumex Inc., Ronkokoma, NY, USA). The peak torques were determined at speeds of 60 and 180 degrees/s and the peak work at speed of 180 degrees/s. The measurements revealed that after the ACL surgery there was still a considerable thigh muscle strength deficit especially in extension of the injured extremity, the average extension strength deficit ranging from 9 to 20%. The extension strength deficit was significantly more prominent in the chronic (18-20%) than in the acute group (9-15%). The extension strength deficit was significantly greater ar the slower (15-20%) than higher (9-18%) speed of the isokinetic movement. In both the acute and chronic groups, a multiple stepwise regression analysis indicated that patellofemoral pain and flexion deficit of the knee were the factors that most frequently and significantly associated with the strength deficits. At the higher speed of the isokinetic movement, these two factors accounted 20% and 21% for the variation seen in the quadriceps strength deficit of the acute group and the chronic group. No correlation could be found between age, sex, height, weight, body mass index, length of the follow-up time, injury type, athletic activity level, immobilization method, knee stability, and the isokinetic muscular performance.
Acute Disease↗
Reliability of simple portable tests of physical performance in older people after hip fracture.
OBJECTIVE: To investigate the test-retest reliability of measures of strength, balance, gait and functional performance when used with older people following hip fracture. SUBJECTS: Thirty people (16 hospital inpatients and 14 community dwellers). DESIGN: Subjects underwent two assessments: one day apart for the hospital inpatients and one week apart for the community dwellers. MEASUREMENT: Strength (dynamometer, sphygmomanometer, spring balance, lateral step-up ability), balance (sway-meter, Functional Reach Test, single leg stance time, Step Test), gait (timed 6-m walk with steps taken, base of support and step length), and functional performance (PPME total score and timed supine-to-sit and sit-to-stand) were measured. RESULTS: Eleven of the 14 continuously scaled measurement tools achieved excellent reliability (intraclass correlation coefficient (ICC) > 0.75) for one or more tests. A hand-held dynamometer was found to be the tool with the highest test-retest reliability for measuring hip muscle strength (ICC (3,1) 0.86 for affected hip abduction). For measurement of knee extension strength, a spring balance (ICC (3,1) 0.94 affected leg) was the most reliable. For testing balance, the Step Test (ICC (3,1) 0.94 for stepping with affected leg) and Functional Reach Test (ICC (3,1) 0.89) had the highest test-retest reliability. The ICC (3,1) values were 0.97 for walking velocity (comfortable pace) and 0.96 for the total score of the Physical Performance and Mobility Examination. CONCLUSION: The test-retest reliability of a number of simple measures of physical performance is excellent when used with this population.
Aged↗
Quantitative trait loci for human muscle strength: linkage analysis of myostatin pathway genes.
This study reports the results of a multipoint linkage study that aims to unravel the genetic basis of muscle strength and muscle mass in humans. Myostatin (GDF8) is known to be a strong inhibitor of muscle growth in animals. However, studies examining human myostatin polymorphisms are rare and are limited to the GDF8 gene itself. Here, the contribution to isometric and concentric knee strength of nine key proteins involved in the myostatin pathway is studied in a nonparametric multipoint linkage analysis by means of a variance components and regression method. A sample of 367 healthy young male siblings was phenotyped on an isokinetic dynamometer and genotyped for markers of the myostatin pathway genes. Three of the loci were found significantly linked with a quantitative trait locus (QTL) for knee muscle strength. First, D13S1303 showed replication of an explorative single-point linkage study with a maximum LOD score of 2.7 (P = 0.0002). Second, maximum LOD scores of 3.4 (P = 0.00004) and 3.3 (P = 0.00005) were observed for markers D12S1042 and D12S85, respectively, at 12q12-14. Finally, marker D12S78 showed an LOD score of 2.7 at 12q22-23. We conclude that several genes involved in the myostatin pathway, but not the myostatin gene itself, are important QTLs for human muscle strength. An additional set of valuable candidate genes that were not part of the myostatin pathway was found in the chromosome 12 and 13 genomic regions.
Adolescent↗
Assessment of isokinetic muscle strength in women who are obese.
STUDY DESIGN: Cross-sectional study of isokinetic trunk and knee muscle strength in women who are obese. OBJECTIVE: To provide reference values, to identify variables that affect peripheral muscle strength, and to provide recommendations for isokinetic testing of trunk and knee muscles in women who are obese and morbidly obese. BACKGROUND: The assessment of peripheral muscle strength is useful for the quantification of possible loss of strength, for exercise prescription, and for the evaluation of the effect of training programs in obese individuals. METHODS AND MEASURES: Isokinetic trunk and leg muscle strength was assessed in 241 women who were obese (18-65 years, body mass index (BMI) > or = 30 kg/m2). Trunk flexion and extension peak torque (PT) was measured using the Cybex TEF dynamometer; trunk rotation (TR) PT was measured using the Cybex TORSO dynamometer; and knee flexion/extension (KFE) PT was measured using the Cybex 350 dynamometer. Body composition was assessed using the bioelectrical impedance method; physical activity was assessed using the Baecke questionnaire; and peak VO2 was assessed using an incremental exercise capacity test on a bicycle ergometer. To identify variables related to muscle strength, Pearson correlations were computed and a stepwise multiple regression analysis was performed. RESULTS: Pearson correlation coefficients of all strength measurements at 60 degrees/s revealed low-to-moderate negative associations with age and positive associations with mass, height, fat free mass (FFM), and peak VO2 (P < 0.05), except for gravity-uncorrected trunk extension strength, which was not related to mass. The sports index of the Baecke questionnaire was associated with TR PT (r = 0.20, P < 0.01) and KFE PT (r = 0.18, P < 0.05). CONCLUSION: The weight of the trunk accounts largely for the measured trunk extensor and flexor strength in women who are obese. Contributing variables of isokinetic trunk flexion and extension strength in women who are obese are age, height, and FFM; whereas sports activities and aerobic fitness are contributing factors for trunk rotational and knee extension strength. Recommendations for measuring isokinetic muscle strength in individuals who are obese are provided.
Adult↗