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Results for “Muscle Strength Dynamometer”

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PubMed1992

Prevention of bone loss and muscle atrophy during manned space flight.

This paper reviews the biomedical literature concerning human adaptation to nonterrestrial environments, and focuses on the definition of practical countermeasures necessary for long-term survival on the Moon, Mars and during long-term space missions and exploration. Of particular importance is the development of clinically relevant countermeasures for prevention of pathophysiological changes in the musculoskeletal and cardiopulmonary systems under these conditions. The countermeasures which are proposed are based upon a combination of biomechanical and theoretical analyses. The biomechanical analyses are based upon clinical measurements of human skeletal density changes associated with weight lifting as well as clinical studies of human strength and fitness currently being conducted using an isoinertial trunk dynamometer. The theoretical analysis stems from a mathematical model for bone loss in altered gravity environments that we have begun to develop. These analyses provide guidelines for the development of practical therapeutic treatments (exercise, artificial gravity) designed to minimize musculoskeletal deconditioning associated with less than Earth gravity environments. Our findings suggest that very intensive exercise, which impose high loads on the musculoskeletal system for brief periods, may be more efficient in preserving bone and skeletal muscle conditioning within "safe" limits for longer periods than low intensity activities such as treadmill running and bicycling. A 1/6 to 1/7-g gravitational environment is predicted to be sufficient to preserve bone strength above the fracture risk level. Basic biomedical support of manned space missions, Moon and Mars bases should include routine assessment of skeletal density, muscle strength, cardiac output and total energy expenditure. This information can be used to periodically re-evaluate exercise programs and or artificial gravity requirements for crew members.

Adaptation, Physiological↗

PubMed1983

Effect of isometric and isokinetic muscle training on static strength and dynamic power.

This study investigated whether isokinetic strength training might induce changes in static and dynamic power already achieved as a result of isometric strength training. The subjects were twelve males. The isometric strength and dynamic power of elbow flexors were tested by means of an electric dynamometer and fly-wheel every two weeks. During the first 8 weeks all subjects trained the elbow flexors isometrically at four different positions of elbow joints. This training produced 27-36% gains in isometric strength and 34-46% in power. Thereafter the subjects were divided into two groups: the FG group who trained isokinetically at a fast velocity of 157 degrees . s-1, and the SG group at slow velocity of 73 degrees . s-1. After 6 weeks of training, the FG group produced a significant gain in power with light equivalent masses and the SG group did so with heavy equivalent masses. Neither group showed change in isometric strength.

Adult↗

PubMed2005

Quantification of muscle strength and imbalance in neurogenic pes cavus, compared to health controls, using hand-held dynamometry.

BACKGROUND: Pes cavus foot deformity in neuromuscular disease is thought to be related to an imbalance of musculature around the foot and ankle. The most common cause of neurogenic pes cavus is Charcot-Marie-Tooth (CMT) disease. The aim of this investigation was to objectively quantify muscle strength and imbalance using hand-held dynamometry in patients diagnosed with CMT and pes cavus, compared to healthy controls. METHODS: Muscles responsible for inversion, eversion, plantarflexion, and dorsiflexion of the foot and ankle were measured in 55 subjects (11 CMT patients with a frank pes cavus, and 44 healthy controls with normal feet) using the Nicholas hand-held dynamometer (HHD). Test-retest reliability of the HHD procedure also was determined for each of the four muscle groups in the healthy controls. RESULTS: Test-retest reliability of the HHD procedure was excellent (ICC3,1 = 0.88 to 0.95) and the measurement error was low (SEM = 0.3 to 0.7 kg). Patients with CMT were significantly weaker than normal for all foot and ankle muscle groups tested (p < 0.001). Strength ratios of inversion-to-eversion and plantarflexion-to-dorsiflexion were significantly higher in the patients with CMT and pes cavus compared to individuals with normal foot types (p > 0.01). CONCLUSIONS: Hand-held dynamometry is an objective and reliable instrument to measure muscle strength and imbalance in patients with CMT and a pes cavus foot deformity.

Adult↗

PubMed2006

Shoulder strength profile in elite junior tennis players: horizontal adduction and abduction isokinetic evaluation.

OBJECTIVE: To establish normative data for muscle performance during isokinetic horizontal abduction and adduction of the shoulder in elite junior tennis players. METHODS: Thirty six tennis players were evaluated (23 male, 13 female; mean age 14 years (range 12-18)). An isokinetic dynamometer was used to test the shoulder horizontal abductors and adductors at 60 and 180 degrees/s. Absolute and relative peak torque (PT and PT/BW), total work (TW), endurance ratio (ER), and the ratio of the peak torque between horizontal abductors and adductors (HAB/HAD ratio) were recorded. Data were compared for the dominant and non-dominant shoulders, horizontal abductor and adductor muscles, and between players grouped according to age. RESULTS: The dominant shoulder was significantly (p<0.05) stronger than the non-dominant shoulder in all variables except ER and HAB/HAD ratio. The abductors were significantly (p<0.05) weaker than the adductors in all subjects. The type of backhand (one handed or two handed) did not influence the strength of the shoulder horizontal abductors on the dominant side. The number of years of tennis practice had an effect on muscle strength as evaluated by absolute data (PT and TW) but not relative measurements (PT/BW and TW/BW). CONCLUSION: The findings confirm that horizontal abduction and adduction are stronger in the dominant shoulder of junior tennis players. The clinical relevance of these findings is not established, and more studies are needed to compare tennis players with athletes from other sports and non-athletes.

Adolescent↗

PubMed2003

A comparison of 3 hand-held dynamometers used to measure hip abduction strength.

Quantification of strength with hand-held dynamometers is commonplace. Hand-held dynamometers offer ease of use; however, previous investigations have shown much variability between repeated measures using the same dynamometer. Even less is known regarding the degree of variability between various dynamometers. Therefore, the intent of this investigation was to compare measures of hip abduction strength recorded with 3 different but commonly used hand-held dynamometers, specifically the Microfet 2 Load Cell, Jamar Hand-Held, and Dial Push-Pull Gauge. Maximal isometric hip abduction strength was recorded in 10 women (27.6 +/- 6.2 years) over 3 consecutive days using a different device each day. A significant difference in recorded force was noted between the devices (p < 0.001) as the Microfet showed significantly less force than the others. This was supported by intraclass correlation coefficients (ICCs) ranging from 0.277 to 0.688. These data suggest that consideration must be given to using the same dynamometer when quantifying strength over repeated sessions.

Adult↗

PubMed2005

Validation of an abdominal muscle strength test with dynamometry.

Adequate abdominal strength prevents work- and sports-related injuries and stabilizes the spine for athletic activities. The double-leg-lowering maneuver (DLLM) is a popular test to assess abdominal strength because of its simplicity; however, its validity and reliability have not been studied thoroughly. To determine the validity and reliability of the DLLM, 4 examiners evaluated 28 subjects. The validity of the DLLM was evaluated with the Nicholas Hand-Held Dynamometer (NHHD) as the gold standard. The DLLM scores were compared to themselves for reliability and to NHHD scores for validity. Reliability for the DLLM was very high (r = 0.932). Validity of the DLLM was low (r = -0.338 to -0.446). The DLLM is reliable, but it has low validity to assess abdominal strength. The DLLM may be a useful tool to assess pelvic tilt motor control for spine stability, but it is not suitable for assessing muscle strength.

Abdominal Muscles↗

PubMed1996

Effects of strength and endurance training on isometric muscle strength and walking speed in elderly women.

The separate effects of 18 weeks of intensive strength and endurance training on isometric knee extension (KE) and flexion (KF) strength and walking speed were studied in 76- to 78- year-old women. Maximal voluntary isometric force for both KE and KF was measured in a sitting position on a custom-made dynamometer chair at a knee angle of 60 degrees from full extension. Maximal walking speed was measured over a distance of 10 m. The endurance-trained women increased KE torque and KE torque/body mass after the first 9 weeks of training when compared with the controls. when comparing the baseline, 9 week and 18 week measurements within the groups separately, both the endurance- and strength-training groups increased KE torque, KE torque/body mass and walking speed. Individual changes in KE torque/body mass before and after 18 weeks of training averaged 19.1% in the strength group, 30.9% in the endurance group and 2.0% in the controls. This study indicates that in elderly women the effects of physical training on muscle strength and walking speed occur after endurance as well as strength training. The considerable interindividual variation in change of muscle performance is also worth noticing.

Aged↗

PubMed1989

The relationship between muscle strength and sprint kinematics in elite sprinters.

Twenty-three elite sprinters, 9 females and 14 males, were filmed while performing a maximal sprint. Age, height, weight, and personal best 100 m time were also determined for each sprinter. Several kinematic variables were calculated for each athlete from the filmed sprint, including stride length, stride frequency, horizontal and vertical velocity of the CG, and the angular kinematics of the limbs. A Kin/Com isokinetic dynamometer was used to determine lower limb peak and average torque values. Correlation coefficients were calculated between each of the kinematic variables and each of the strength variables. Stepwise multiple regression analysis was also carried out for each set of kinematic and strength variables, to determine the best predictors of sprinting speed. Significant relationships were noted between sprinting times for the 100 m and peak torque scores (N.m/kg) for males for fast concentric knee extension and slow eccentric dorsiflexion, and for females for concentric dorsiflexion at both speeds, and slow eccentric dorsiflexion.

Adolescent↗

PubMed1988

Make tests and break tests of elbow flexor muscle strength.

The purposes of this investigation were 1) to compare the forces produced by the elbow flexor muscles during make tests and break tests and 2) to determine the reliability of each of the test procedures. I used a hand-held dynamometer to perform two make tests and two break tests on 27 young women. The forces produced by the elbow flexor muscles during break tests were significantly larger than (p less than .001), albeit correlated with (r greater than .80), the forces produced during make tests. Each testing procedure was reliable (r = .909 for make tests; r = .922 for break tests). On the basis of reliability, one type of testing cannot be considered clearly superior to the other.

Adult↗

PubMed2001

Polymorphic variation in the human myostatin (GDF-8) gene and association with strength measures in the Women's Health and Aging Study II cohort.

OBJECTIVES: To determine whether polymorphic variation in the myostatin gene differentially influences the maintenance of muscle strength in older adults, and to find supportive evidence in a cohort of older women. DESIGN: Correlation study of polymorphic variation in a cohort of older women. SETTING: Representatively sampled older female population living in the eastern half of Baltimore, Maryland. PARTICIPANTS: Participants were 286 women, age 70 to 79. Of these, 81.1% were Caucasian, 18.8% were African American, and 0.2% were Asian or Hispanic. MEASUREMENTS: Overall strength was measured with a dynamometer and defined as the sum of the strongest measures of hip, knee, and grip strength on the dominant side. RESULTS: We identified or confirmed six myostatin polymorphic variants in the Women's Health and Aging Study II population. Of the polymorphisms, K153R is the most common, with an allele frequency of 0.19 in African Americans. Unadjusted mean strength by genotype suggested lower muscle strength in those African-American women with the R genotype compared with those with the K genotype (K/K: 72.50 +/- 13.9 kg (n = 39) vs K/R: 67.14 +/- 11.4 kg (n = 13) vs R/R: 63.1 +/- 11.3 kg (n = 3)). After adjustment for race in a linear regression model, the R genotype remained associated with lower strength levels (P = .04). Statistical significance decreased when body mass index and race were both added to the model (P = .09). CONCLUSIONS: Recognizing that small sample size in the study of genes of modest effect are unlikely to yield significant differences, these data suggest an association of the R153 allele with lower strength in high-functioning older women, which should be studied further in a larger cohort.

Aged↗

PubMed2005

Factors related to spinal mobility in patients with postmenopausal osteoporosis.

Quality of life in patients with spinal osteoporosis is impaired by the decline of spinal mobility. However, the factors related to the spinal mobility in these patients are still unclear. We evaluated the possible factors affecting spinal mobility in patients with postmenopausal osteoporosis. A total of 128 postmenopausal women with osteoporosis aged over 50 years (mean, 70 years) were included in this study. The thoracic and lumbar kyphosis angles and range of motion (ROM) of the total spine were measured in the upright position and at maximum flexion/extension with a computer-assisted device. The paravertebral muscle thicknesses (PVMT) of thoracic and lumbar spine in the upright position were measured using an ultrasound unit. The number of vertebral fractures was evaluated with radiographs of the spine. Isometric back extensor strength (BES) was evaluated with a strain-gauge dynamometer. Correlations between these variables were then analyzed. Age (r=-0.412), lumbar kyphosis angle (r=-0.284), BES (r=0.369), PVMT at the lumbar spine (r=0.227) and the number of vertebral fractures (r=-0.260) showed significant correlations with total spinal ROM (P<0.05). However, no significant correlations were observed between the total spinal ROM and PVMT at the thoracic spine (r=-0.069) or thoracic kyphosis angle (r=-0.138). Multiple regression analysis revealed that the BES was the most significant contributor to the total spinal ROM. The present study suggests a possible association between BES and spinal mobility in patients with postmenopausal osteoporosis.

Aged↗

PubMedDate not supplied

Isokinetic and isometric strength in osteoarthrosis of the knee. A comparative study with healthy women.

Dynamic stability of the knee joint depends on the appropriate strength ratio of quadriceps and hamstring muscles. The purpose of this investigation was to determine the maximum peak torque (MPT) and MPT ratios of hamstrings to quadriceps (H/Q) muscles in patients with knee osteoarthritis (OA). Two groups of patients were included in the study. The first group consisted of 30 patients (Group A) with the clinical and radiologic findings of knee OA. The second group consisted of 30 patients (Group B) exhibiting knee joint pain without roentgenologic findings of knee OA. The findings of two patient groups were compared with each other and also with 30 healthy subjects (Group C). Isokinetic (at 60 degrees/s and at 180 degrees/s) and isometric (at 30 degrees and at 60 degrees of knee flexion) tests were performed by the rate-limiting isokinetic dynamometer system. Isokinetic and isometric MPT loss of knee flexors and extensors was found in both patient groups with respect to controls, but MPT ratios of H/Q muscles did not show a statistically significant difference compared with the control group. This may be related to the equal strength loss of knee flexors and knee extensors in patients with knee OA. It is concluded that strengthening exercises of hamstring muscles is as important as quadriceps strengthening in rehabilitation of knee OA.

Adult↗

PubMed1991

Thigh muscle function after partial tear of the medial ligament compartment of the knee.

The purpose of the study was to assess the isokinetic and isometric strength and power profile of the knees of 48 patients who had a previous second-degree sprain (partial tear) of the medial ligament compartment, the most common knee ligament injury in sports. The CYBEX II isokinetic dynamometer was used in the measurements. On an average of 8 yr after the injury, the mean strength deficit of the injured knees was minimal: 4 +/- 5% (range 0-28%) in extension and 2 +/- 4% (0-20%) in flexion. The average strength score (max. 100 points) was 90 +/- 11 (56-100), representing an excellent classification. In hamstrings, the relative strength deficit increased significantly with a higher speed of isokinetic movement (P less than 0.05). Compared with the strength parameters (peak torques), the other functional parameters of the injured knees (total work, average power, and peak torque acceleration energy) showed some but not significantly greater deficits (hamstrings 9-11%, quadriceps 6-8%). In conclusion, the general thigh muscle function in knees with old second-degree sprain of the medial ligament compartment appears good and acceptable, but the strength deficits are systematically greater in higher speeds of isokinetic movement. Therefore, rehabilitation utilizing high speed extension and flexion exercises is recommended.

Adolescent↗

PubMed1997

Gender differences in effects of 20 days horizontal bed rest on muscle strength in young subjects.

Gender differences in the effect of 20 days bed rest (BR) on muscle strength were evaluated in voluntary 11 male and 7 female students. Maximum Isometric Voluntary Contractions (MVC) of 4 right arm muscles (RAM), 5 right leg muscles (RLM), and 2 body trunk muscles were measured with an isometric dynamometer, respectively. Muscle masses (MM) of right arm and leg and body trunk were determined by dual energy X-ray absorptiometry, respectively. The maximum cross sectional area (CSAmax) of right m. quadriceps femoris was measured by magnetic resonance imaging. Elbow flexion MVC in males and all MVC of RLM except knee flexion in both males and females were decreased (p<0.05), but elbow extension MVC in females was increased (p<0.05), while all of other MVC only tended to decrease. However, the decrements in leg MVC were not correlated to the leg MM, and also the decrement in knee extension was not correlated to the CSAmax of m. quadriceps. The reduction of MVC of antigravity muscles might be caused not only by a decrease in MM but also by other factors. The greater decrements of leg MVC during BR were the higher initial level in males, but the inverse was observed in females. However, this discrepancy between males and females cannot be explained in the present study.

Adolescent↗

PubMed1996

Total and regional bone mass in female soccer players.

This cross-sectional study investigated bone mass in female athletes participating in an impact-loading sport (soccer), and evaluated whether any changes in bone mass could be related to the type of weight-bearing loading and muscle strength. The group of soccer players consisted of 16 second-division female players (age 20.9 +/- 2.2 years) training for about 6 hours/week. The reference group consisted of 13 nonactive females (age 25.0 +/- 2.4 years) not participating in any kind of regular or organized sport activity. The groups were matched according to weight and height. Areal bone mineral density (BMD) was measured in total body, head, lumbar spine, femoral neck, Ward's triangle, trochanter, the whole femur and humerus, and in specific sites in femur diaphysis, distal femur, proximal tibia, and tibia diaphysis using dual X-ray absorptiometry. Isokinetic concentric peak torque of the quadriceps and hamstring muscles was measured using an isokinetic dynamometer. The soccer players had significantly (P < 0.05-0.01) higher BMD in the lumbar spine (10.7%), femoral neck (13.7%), Ward's triangle (19.6%), nondominant femur and humerus (8.2 and 8.0%, respectively), distal femur (12.6%), and proximal tibia (12.0%) compared with the nonactive women. There was no significant difference in muscle strength of the thigh between the two groups. In the nonactive group, muscle strength in the quadriceps and especially hamstrings, was correlated to BMD of the adjacent bones (whole femur, hip sites) and also to distant sites (humerus). In the soccer group, there were no correlations between muscle strength and BMD of the adjacent and distant bones. Soccer playing and training appears to have a beneficial effect on bone mass in young females, and it seems that there is a site-specific skeletal response to the type of loading subjected to each BMD site. Muscle strength in the thigh is not related to bone mass in female soccer players.

Adult↗

PubMed2000

High-intensity dynamic human muscle performance enhanced by a metabolic intervention.

PURPOSE: The purpose of this study was to quantify the effects of a metabolic treatment on human muscle dynamic performance (strength, work, and fatigue) measured under conditions of acute, exhaustive high-intensity anaerobic isokinetic exercise. METHODS: Unilateral prefatigue and postfatigue peak torque and work values were measured in the quadriceps femoris of 13 subjects using a computer-controlled isokinetic dynamometer, over a 23-d interval. The two experimental treatments were: 1) a glycine and L-arginine salt of alpha-ketoisocaproic acid calcium ("GAKIC"); and 2) isocaloric sucrose (control). Based on a randomized double-blind cross-over repeated measures design, measurements were made before and during an exhaustive anaerobic fatigue protocol to calculate a Fatigue Resistance Index (FRI = [peri-exhaustion torque]\[baseline peak torque]), as well as total work. RESULTS: The FRI and total work for each of the exhaustion sets measured at 0, 5, and 15 min after oral GAKIC treatment were greater than values obtained for isocaloric control treatment (P < 0.02). GAKIC treatment increased the mean resistance to fatigue (FRI) up to 28% over isocaloric control. Overall gain in total muscle work attributable to GAKIC was 10.5 +/- 0.8% greater than control, sustained for at least 15 min. After 24 h, both GAKIC and control concentric forces returned to the same absolute values (P > 0.05): mean FRI = 0.42 +/- 0.05 and mean total work = 4600 +/- 280 J. There were no significant differences attributable to random order of testing. CONCLUSIONS: Compared with isocaloric carbohydrate, oral GAKIC treatment increased muscle torque and work sustained during intense acute anaerobic dynamic exercise; additionally, it increased overall muscle performance by delaying muscle fatigue during the early phases of anaerobic dynamic exercise.

Adult↗

PubMed2000

Reexamining the sarcopenia hypothesis. Muscle mass versus muscle strength. Health, Aging, and Body Composition Study Research Group.

The association of muscle mass and muscle strength with lower-extremity performance, as measured by timed repeated chair stands, was investigated using preliminary data from 3,075 Black and White participants (70-79 years old) in the Health, Aging, and Body Composition Study. Leg muscle mass (LM) was measured by dual-energy X-ray absorptiometry (Hologic QDR 4500). The maximal isokinetic torque of the leg extensors (LS) was measured at 60 degrees/s using a Kin-Com isokinetic dynamometer. Men were stronger, had greater LM, and better performance than women. As expected, low LS was associated with poorer performance after adjusting for race, study site, and body fat. Low LM was associated with poorer performance in men and women, with a potential threshold effect in women only. When LS and LM were modeled simultaneously, only LS remained independently associated with performance. In conclusion, muscle strength, but not muscle mass, is independently associated with lower-extremity performance.

Absorptiometry, Photon↗

PubMed2005

Effects of long-term tennis playing on the muscle-bone relationship in the dominant and nondominant forearms.

The relationship between muscle strength and bone mineral density illustrates the positive effect of mechanical loading on bone. But local and systemic factors may affect both muscle and bone tissues. This study investigated the effects of long-term tennis playing on the relationship between lean tissue mass and bone mineral content in the forearms, taking the body dimensions into account. Fifty-two tennis players (age 24.2 +/- 5.8 yrs, 16.2 +/- 6.1 yrs of practice) were recruited. Lean tissue mass (LTM), bone area, bone mineral content (BMC), and bone mineral density were measured at the forearms from a DXA whole-body scan. Grip strength was assessed with a dynamometer. A marked side-to-side difference (p < 0.0001) was found in favor of the dominant forearm in all parameters. Bone area and BMC correlated with grip strength on both sides (r = 0.81-0.84, p < 0.0001). The correlations were still significant after adjusting for whole-body BMC, body height, or forearm length. This result reinforced the putative role of the muscles in the mechanical loading on bones. In addition, forearm BMC adjusted to LTM or grip strength was higher on the dominant side, suggesting that tennis playing exerts a direct effect on bone.

Absorptiometry, Photon↗