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Results for “Muscle Strength”

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At least 253 records · Page 14Linked to original sources

PubMed1994

Respiratory muscle strength and hemodynamics in chronic heart failure.

To examine whether respiratory muscle weakness is associated with cardiac function and/or exercise capacity in chronic heart failure (CHF), 23 patients with CHF were evaluated with respiratory muscle strength, pulmonary function tests, cardiac catheterization, and exercise test. The subjects were divided into three groups on their New York Heart Association (NYHA) functional class. Group A consisted of 13 patients with NYHA functional classification class 3 or 4, group B consisted of 10 patients with NYHA classification class 2, and group C consisted of 15 age-matched normal controls. Respiratory muscle strength was assessed with maximal static inspiratory mouth pressure at residual volume level and expiratory mouth pressure at total lung capacity level (PImax, PEmax, respectively). Pulmonary functions in patients with CHF showed almost normal. PImax in group A was significantly less than that in group B or C, although PImax in group B was not significantly different from that in group C. In the patients with CHF, PImax correlated positively with cardiac index and maximal oxygen consumption (r = 0.460 and r = 0.503, p < 0.05, respectively). These findings suggest that inspiratory muscle strength, which was impaired in patients with severe CHF, may be dependent on cardiac function and may be one of the limiting factors on impaired exercise capacity in the patients with CHF.

Aged↗

PubMed2000

Measures of bioavailable serum testosterone and estradiol and their relationships with muscle strength, bone density, and body composition in elderly men.

In the present cross-sectional study of 403 independently living elderly men, we tested the hypothesis that the decreases in bone mass, body composition, and muscle strength with age are related to the fall in circulating endogenous testosterone (T) and estrogen concentrations. We compared various measures of the level of bioactive androgen and estrogen to which tissues are exposed. After exclusion of subjects with severe mobility problems and signs of dementia, 403 healthy men (age, 73-94 yr) were randomly selected from a population-based sample. Total T (TT), free T (FT), estrone (E1), estradiol (E2), and sex hormone-binding globulin (SHBG) were determined by RIA. Levels of non-SHBG-bound T (non-SHBG-T), FT (calc-FT), the TT/SHBG ratio, non-SHBG-bound E2, and free E2 were calculated. Physical characteristics of aging included muscle strength measured using dynamometry, total body bone mineral density (BMD), hip BMD, and body composition, including lean mass and fat mass, measured by dual-energy x-ray absorptiometry. In this population of healthy elderly men, calc-FT, non-SHBG-T, E1, and E2 (total, free, and non-SHBG bound) decreased significantly with age. T (total and non-SHBG-T) was positively related with muscle strength and total body BMD (for non-SHBG-T, respectively, beta = 1.93 +/- 0.52, P < 0.001 and beta = 0.011 +/- 0.002, P < 0.001). An inverse association existed between T and fat mass (beta = -0.53 +/- 0.15, P < 0.001). Non-SHBG-T and calc-FT were more strongly related to muscle strength, BMD, and fat mass than TT and were also significantly related to hip BMD. E1 and E2 were both positively, independently associated with BMD (for E2, beta = 0.21 +/- 0.08, P < 0.01). Non-SHBG-bound E2 was slightly strongly related to BMD than total E2. The positive relation between T and BMD was independent of E2. E1 and E2 were not related with muscle strength or body composition. In summary, bioavailable T, E1, total E2, and bioavailable E2 all decrease with age in healthy old men. In this cross-sectional study in healthy elderly men, non-SHBG-bound T seems to be the best parameter for serum levels of bioactive T, which seems to play a direct role in the various physiological changes that occur during aging. A positive relation with muscle strength and BMD and a negative relation with fat mass was found. In addition, both serum E1 and E2 seem to play a role in the age-related bone loss in elderly men, although the cross-sectional nature of the study precludes a definitive conclusion. Non-SHBG-bound E2 seems to be the best parameter of serum bioactive E2 in describing its positive relation with BMD.

Absorptiometry, Photon↗

PubMed1995

Reproducibility of subjectively graded voluntary isometric muscle strength in unilateral and simultaneous bilateral exertion.

Reproduction error of voluntary isometric muscle strength that was graded subjectively by the subject was investigated under unilateral and bilateral conditions. Six kinds of tasks, i.e. elbow flexion, elbow extension, hand grip, second digit abduction, knee extension and leg extension were employed. It was clear that absolute error (AE) increased with increase of exerted muscle strength in both unilateral and bilateral conditions. Mean of AE in each task was 4-5% of maximal muscle strength in the task in unilateral conditions. Algebraic or constant error (CE) decreased with increase of exerted strength. Demands for smaller strength tended to overshoot and larger ones tended to undershoot. In bilateral conditions when the different levels of strength for each limb were required to be exerted, AE on the weaker side tended to be larger than that in unilateral conditions. Thus a possibility that magnitude of AE might be affected by amount of attention was suggested. The subjectively graded criterion strength for a specific required level, when the strength was expressed as relative to the maximal strength, was almost the same in every task within a subject although it was different between subjects. It is suggested that each subject might have an awareness of relative magnitude of exerted strength.

Arm↗

PubMed2002

Six months of hormone replacement therapy does not influence muscle strength in postmenopausal women.

OBJECTIVES: Postmenopausal hormone replacement therapy (HRT) has positive effects on fracture incidence before any effects on bone mineral density can be demonstrated. This has been attributed to increased muscle strength by HRT. This study was designed to evaluate the effect of 6 months of HRT on muscle strength in postmenopausal women. METHODS: Forty postmenopausal women, aged 60-78 were included in the study. They were randomly divided in two groups with 20 women in each group. One group received Menorest 50 microg/24 h (estradiol 4.3 mg) and Gestapuran 2.5 mg (medroxyprogesteron) daily and the other group received placebo treatment. The study was conducted as a double blinded, prospective and placebo controlled trial. Hand grip strength, isokinetic knee flexion and extention, and physical activity were measured before treatment, after 3 and 6 months. Physical activity was estimated using a classification system of physical activity. A JAMAR hydraulic hand dynamometer and a Cybex II dynamometer were used to evaluate muscle strength. RESULTS: Hand grip strength in the right hand, increased significantly in both groups (HRT P<0.001 and placebo P<0.01) and in the left hand in the HRT group (P<0.01). However, there were no differences in muscle strength between the two groups. There was no significant change in isokinetic knee flexion or extension after 6 months in either of the groups. The estimated physical activity increased slightly in the placebo group, but there was no significant difference compared to the treatment group. CONCLUSIONS: Our data suggest that 6 months of HRT does not influence muscle strength in postmenopausal women.

Aged↗

PubMed1998

Comparison of muscle and tendon stiffness, jumping ability, muscle strength and fatigue in the plantar flexors.

An isokinetic dynamometer was used to measure plantar flexion muscle strength at 60 degrees/s and 200 degrees/s in 10 healthy young men (mean age 25 years). Muscle and tendon stiffnesses were determined on the dynamometer by the use of electrical stimulation and passive stretch (200 degrees/s). Differences in jumping heights between squat and counter-movement jumps were calculated from flight times. The number of heel-rises performed until exhaustion, standing on one leg, were counted. Stepwise regression analysis showed that differences in jumping height increased with lower muscle strength and with higher muscle and tendon stiffnesses, indicating that elastic components may be of more importance in persons with lower muscle strength. The number of heel-rises was negatively dependant on tendon stiffness, indicating that increased stiffness may enhance the development of fatigue.

Adult↗

PubMed2003

Reproducibility of grading scales of pelvic muscle strength: standard versus tampon scale.

The purpose of this study was to demonstrate the reproducibility of an objective scale utilizing a tampon to assess pelvic muscle strength and to compare it to a digital evaluation of muscle strength [1]. Thirty women presenting to the office were enrolled in the study. Their pelvic floor muscle strength was separately assessed by both examiners using both scales. The reproducibility of the scales was then analyzed by Cohen's kappa measure of interrater agreement. The tampon scale was found to have a measure of agreement of 0.76 (excellent interrater agreement if >0.75). In contrast, the digital scale was found to have a measure of agreement of 0.68 (fair agreement if 0.40-0.75). Therefore, the tampon scale is an easy and reproducible approach for assessing pelvic floor muscle strength.

Female↗

PubMed2003

Muscle strength in children treated for displaced femoral fractures by external fixation: 31 patients compared with 31 matched controls.

In a prospective study (1993-2000), we measured the isokinetic strength of the quadriceps and hamstring muscles in 31 children aged 5-17 years, on average, 3 (1.5-5) years after treatment for a displaced femoral fracture by external fixation and early mobilization. A group of age-, sex- and weight-matched children without previous injury were used as controls. The hop-index test was used to assess the patient's confidence in the injured limb and was similar in the fractured and unfractured legs as well as in the patients and controls. We measured the peak torque output at 2 angular velocities (60 degrees/s and 180 degrees/s) in the hamstring and quadriceps muscles, using Cybex testing equipment. Torque to body weight ratios were used to compare muscle strength in patients and controls. We found no differences in muscle strength between patients and controls or in the distribution of which leg was stronger, equal or weaker in the patients or controls at any test speed. External fixation and early mobilization seem to prevent residual muscle weakness, which occurs with traction or a cast for femoral fractures in children.

Adolescent↗

PubMed2004

Genetic variation in the human vitamin D receptor is associated with muscle strength, fat mass and body weight in Swedish women.

OBJECTIVE: Bone mineral density (BMD) is under strong genetic control and a number of candidate genes have been associated with BMD. Both muscle strength and body weight are considered to be important predictors of BMD but far less is known about the genes affecting muscle strength and fat mass. The purpose of this study was to investigate the poly adenosine (A) repeat and the BsmI SNP in the vitamin D receptor (VDR) in relation to muscle strength and body composition in healthy women. DESIGN: A population-based study of 175 healthy women aged 20-39 years was used. METHODS: The polymorphic regions in the VDR gene (the poly A repeat and the BsmI SNP) were amplified by PCR. Body mass measurements (fat mass, lean mass, body weight and body mass index) and muscle strength (quadriceps, hamstring and grip strength) were evaluated. RESULTS: Individuals with shorter poly A repeat, ss and/or absence of the linked BsmI restriction site (BB) have higher hamstring strength (ss vs LL, P=0.02), body weight (ss vs LL, P=0.049) and fat mass (ss vs LL, P=0.04) compared with women with a longer poly A repeat (LL) and/or the presence of the linked BsmI restriction site (bb). CONCLUSIONS: Genetic variation in the VDR is correlated with muscle strength, fat mass and body weight in premenopausal women. Further functional studies on the poly A microsatellite are needed to elucidate whether this is the functionally relevant locus or if the polymorphism is in linkage disequilibrium with a functional variant in a closely situated gene further downstream of the VDR 3'UTR.

Absorptiometry, Photon↗

PubMed1995

Relationship between respiratory muscle strength and lean body mass in men with COPD.

It has been suggested that low body weight may be associated with decreased respiratory muscle function in COPD, but the precise mechanism is not known. Since body compositional change inevitably accompanies body weight change, we decided to study the possible relationship between respiratory muscle strength and body composition in patients with COPD. We studied respiratory muscle strength, pulmonary function, and body composition in 24 Japanese male patients with COPD. Patients were divided into two groups according to their body weight (group A, body weight lower than 80% of ideal body weight vs group B, 80% or more) and a comparison was made together with age-matched controls (group C). Maximal inspiratory mouth pressure (PImax) and maximal expiratory mouth pressure (PEmax) were measured by a previously reported method. Body compositional analysis was performed using dual energy x-ray absorptiometry (DXA; Norland XR26). It showed significantly lower fat body mass (FAT), FAT/body weight%, and lean body mass (LEAN) in group A than those in group B. The PImax in group A was significantly lower than that in group B and C (44.2 +/- 13.8, 76.4 +/- 29.9, and 88.6 +/- 18.1 cm H2O, respectively). PEmax in group A was also significantly lower than that in group B and group C (61.9 +/- 20.1, 86.7 +/- 26.8, and 90.4 +/- 17.6 cm H2O, respectively). Both PImax and PEmax were significantly correlated with LEAN (r = 0.656, r = 0.591, p < 0.01, respectively) in patients with COPD. These results show that respiratory muscle strength is closely associated with body weight and lean body mass in patients with COPD. The present approach to compare respiratory muscle strength with lean body mass should be useful for studying the mechanism of respiratory muscle weakness in patients with COPD.

Absorptiometry, Photon↗

PubMed2000

Skeletal muscle mass and muscle strength in relation to lower-extremity performance in older men and women.

OBJECTIVE: Low muscle strength is associated with poorer physical function, but limited empirical evidence is available to prove the relationship between muscle mass and physical function. We tested the hypothesis that persons with lower muscle mass or muscle strength have poorer lower-extremity performance (LEP). DESIGN: A cross-sectional, population-based study. PARTICIPANTS: A cohort of 449 men and women aged 65 years and older living in Amsterdam and its surroundings participating in the second examination (1995-1996) of the Longitudinal Aging Study Amsterdam. MEASUREMENTS: Leg skeletal muscle mass was measured using dual-energy X-ray absorptiometry (DXA). Grip strength was used as an indicator of muscle strength. Timed functional performance tests, including walking and repeated chair stands, were used to assess LEP. RESULTS: After adjustment for body height and age, leg muscle mass was positively associated with LEP in men (regression coefficient 0.178 [95% confidence interval 0.013-0.343], P = .035). In women an inverse association was observed, which became positive after additional adjustment for body mass index (BMI) (0.202 [-0.001-0.405], P = .052). Grip strength was positively associated with LEP in men and women. After additional adjustment for behavioral, physiological, and psychological variables, the associations between leg muscle mass and LEP disappeared, whereas grip strength remained to be independently associated with LEP in men (0.079 [0.042-0.116], P = .0001), with a tendency in women (0.046 [-0.009-0.101], P = .11). Results were similar when quartiles of leg muscle mass or grip strength were used. CONCLUSIONS: These results suggest that low muscle strength, but not low muscle mass, is associated with poor physical function in older men and women. However, prospective studies are needed to investigate the association between loss of muscle mass and physical function.

Absorptiometry, Photon↗

PubMed2005

Effect of exercise training on peak aerobic power, left ventricular morphology, and muscle strength in healthy older women.

The effect that aerobic (AT) and/or strength training (ST) has on altering peak aerobic power (VO2peak), muscle strength, left ventricular (LV) morphology, and diastolic filling in healthy older women is not known. We assessed the effects of 12 weeks of AT, ST, combined aerobic and strength training (COMT), or no training (NT) on VO2peak, muscle strength, LV morphology, and diastolic filling in 31 healthy women (68 +/- 4 years). Relative VO2peak was significantly greater after 12 weeks of AT, ST, or COMT. Upper and lower extremity strength were significantly higher after 12 weeks of ST or COMT with no change after AT or NT. LV morphology and diastolic filling were not altered after 12 weeks of AT, ST, COMT, or NT. Twelve weeks of ST or COMT are as effective as 12 weeks of AT for increasing relative VO2peak, however, ST and COMT are more effective than AT for improving overall muscle strength.

Age Factors↗

PubMedDate not supplied

[The usefulness of vaginal cones as a method of measuring perineal muscle strength. The RECOVA Group. REeducación COnos VAginales].

OBJECTIVE: To determine the utility of vaginal cones for the measurement of perineal muscle strength. METHODS: A study was conducted on 134 women (mean age 31.8 years) to determine the correlation between a clinical test for measuring perineal muscle strength and the number of vaginal cones retained by the patients. RESULTS: A correlation was found between the clinical test for measuring perineal muscle strength and the number of vaginal cones retained in 90% of the cases. This correlation increased to 96% in patients that had undergone rehabilitation of the perineal muscles with vaginal cones for a period of three months. CONCLUSION: Our results show that vaginal cones permit objective measurement of perineal muscle strength.

Adult↗

PubMed1980

Isometric and isokinetic quadriceps muscle strength in 70-year-old men and women.

Isometric and isokinetic muscle strength during right knee-extension and maximal extension velocity were measured in forty men and thirty-two women, regarded as representative for the healthy seventy-year-old urban population. Muscle strength in women was on average 56 percent of that in the men. Equations for calculation of normal values from the individual's body height and weight are given. The maximal extension velocity of knee-extension was similar in both sexes. The subjects were classified with regard to previous occupational and leisure-time physical activity. An inverse correlation was found between muscle strength and previous occupational physical activity in the men.

Aged↗

PubMed2006

Identifying offline muscle strength profiles sufficient for short-duration FES-LCE exercise: a PAC learning model approach.

UNLABELLED: Functional electrical stimulation-induced leg cycle ergometry (FES-LCE) provides therapeutic exercise for persons with spinal cord injury (SCI). However, there exists no systematic approach to predict whether an individual has sufficient thigh muscle strength necessary for FES-LCE exercise. OBJECTIVE: To develop and test a Probably Approximately Correct (PAC) learning model as a predictor of thigh muscle strengths sufficient for short-duration FES-LCE exercise and compare the model's performance with other well-known statistical methods. METHODS: Six healthy male individuals with SCI, having age (32.0 +/- 12.5 years), height (1.8 +/- 0.04 m), and weight (79.12 +/- 10.76 kg), participated in static and dynamic experiments. During static experiments, absolute crank torque measurements were used to estimate thigh muscle strengths in response to maximum FES intensities of 70 mA, 105 mA, and 140 mA at fixed crank positions on an FES-LCE. During dynamic experiments, changes in power output measurements were used to classify rider performance as 'Fatigue' or 'No Fatigue' during short-duration FES-LCE at maximum stimulation intensities of 70 mA, 105 mA, and 140 mA and flywheel resistance levels of 0/8th, 1/8th, and 2/8th kilopounds. A Probably Approximately Correct (PAC) learning model was developed to classify static offline muscle strength observations with online rider performances. PAC's discriminatory power was compared with logistic regression (LR), Fisher's linear discriminant analysis (LDA), and an artificial neural network (ANN) model. RESULTS: PAC and ANN learning models correctly identified 100% of the training examples. PAC's average performance on the validation set was 93.1%. The ANN and LR performed comparable with 92.8% and 93.1% accuracy, respectively. The LDA method faired well on the validation set at 89.9%. CONCLUSIONS: PAC performed well in identifying muscle strengths associated with the online performance criterion. Although PAC did not perform best during cross-validation, this model has many advantages over the other methods. PAC can adapt to changes in classification schemes and is more amenable to theoretical analyses than the other methods. PAC learning has an intuitive design and may be a practical choice for classifying muscle strength profiles with well-defined performance criteria.

Adult↗

PubMed1995

Muscle strength and body composition: associations with bone density in older subjects.

This study investigated the relationship between isokinetic muscle strength and bone density (SPA and DPA) in men and women aged 45-77 yr. Regression models were adjusted for age, weight, smoking status, and calcium supplementation. Elbow extensors (but not flexors) peak torque was correlated with radial density in men (partial r = 0.26, P < 0.05) and women (partial r = 0.24, P < 0.05). Knee flexor (but not extensor) peak torque in women was significantly correlated with spine density (partial r = 0.28, P < 0.05), and muscle mass was significantly correlated with Ward's triangle density (partial r = 0.35, P < 0.05). No associations between knee flexor or extensor muscle strength and spine or femur bone density were observed in men. Fat-free mass (FFM, hydrodensitometry) was associated with all bone density sites in males and females (partial r = 0.30-0.55; P < 0.05). These results demonstrate that 1) significant associations observed between elbow extensor strength and radial bone density in men and women may reflect loading along the longitudinal axis of the radius associated with elbow extensor activity; and 2) significant associations exist between knee flexor muscle strength and lumbar density in women only. Additionally, the associations between FFM and bone density do not necessarily reflect associations between isokinetic muscle strength and bone density.

Aged↗

PubMed2004

Role of sensory input and muscle strength in maintenance of balance, gait, and posture in Parkinson's disease: a pilot study.

OBJECTIVE: The purpose of this study was to simultaneously evaluate multiple components of disequilibrium in patients with idiopathic Parkinson's disease (PD) in ON and OFF states and healthy age- and sex-matched controls on tests of balance, gait, and dynamometry. DESIGN: Thirty subjects with Parkinson's disease and 30 controls were matched for age and sex. Isokinetic and balance laboratories of a clinical research center were used for assessment. Performance results for static and dynamic balance by dynamic posturography for sensory organization tests (SOT), limits of stability, clinical gait assessment, and dynamometric assessment for the trunk, hip, and ankle at different speeds for concentric muscle strength were obtained. Tests were done both in ON and OFF state in Parkinson's disease patients and results compared. RESULTS: Between OFF state and controls, a significant difference was observed for SOT-2 (proprioception, P < 0.005), SOT-6 (conflicting vision, P < 0.001), and SOT-4 (eyes open with sway support, P < 0.038), and there was less use of ankle strategy in SOT-3 (sway vision, P < 0.04). No significant difference was observed for vestibular function (SOT-5). Significant difference was also observed (P < 0.001) for all variables in limits of stability except for reaction time and for muscle strength of trunk, hip, and ankle (P < 0.001) between OFF state and controls. After antiparkinsonian medications, significant improvement was observed for gait velocity (P < 0.002), muscle strength (P < 0.001), and strategy score in SOT-3 between OFF and ON states. A positive correlation was observed between muscle strength (ankle, hip, and trunk) and gait velocity (ON state r = 0.37, OFF state r = 0.56) and movement velocity (ON state r = 0.39). A positive correlation was also seen between ankle strength and gait velocity in both ON (r = 0.393) and OFF states (r = 0.397) and between ankle strength and ankle strategy in all SOTs except SOT-3 in the OFF state. CONCLUSIONS: The quantitative reduction of muscle strength in the spine, hip, and ankle, along with impaired proprioception, visual sense, and smaller base of support, were the main causes for postural instability in Parkinson's disease patients. A correlation was seen between muscle strength, static and dynamic balance, and gait in both ON and OFF states. In contrast to the previous studies, the present study showed that medications improved the muscle strength, gait speed, and use of ankle strategy but did not worsen proprioceptive sense.

Adult↗

PubMed1999

Quadriceps muscle strength and dynamic stability in elderly persons.

Several measures of dynamic stability during two functional activities correlated to quadriceps femoris muscle strength. A total of 34 disabled elders (aged 60-88) living in the Boston area consented to maximum isometric quadriceps muscle strength testing, chair rise and gait analysis. During chair rise, quadriceps strength significantly correlated with maximum upper body vertical linear momentum, r=0.53, P<0.005, anterior posterior linear momentum, r=0. 38, P<0.05, and the time to complete the chair rise, r=-0.48, P<0.05, n=29. Stride length and gait velocity correlated (r=0.56, P<0.001 and r=0.51, P<0.002, n=34) with quadriceps muscle strength. The maximum range of whole body anteroposterior (A/P) linear momentum during gait also correlated with quadriceps strength (r=0.47, P=0. 004, n=31). Dynamic stability during chair rise and gait, at preferred speed, correlates directly with quadriceps femoris muscle strength in functionally limited elderly individuals. In our sample, elders performed one of three movement strategies to arise from a chair, and quadriceps strength did not statistically differ between the chair rise strategy groups. However, persons with the greatest quadriceps strength values were more stable regardless of which chair rise strategy they performed. Our data indicate that clinicians should not suggest that patients use compensatory momentum inducing locomotor strategies unless the patient has sufficient strength to control these induced forces.

Age Factors↗

PubMedDate not supplied

Significance of the single-legged hop test to the anterior cruciate ligament-reconstructed knee in relation to muscle strength and anterior laxity.

We investigated the significance of the single-legged hop test to the anterior cruciate ligament-reconstructed knee as it specifically relates to knee muscle strength recovery and residual anterior laxity. The hop test was conducted on 107 patients with unilateral anterior cruciate ligament-reconstructed knees (78 semitendinosus tendon autografts and 29 bone-patellar tendon-bone autografts). Patients were tested an average of 2 years after surgery. Correlation coefficient analyses determined whether the relationship between knee muscle strength recovery and the hop test was invariant across all levels of residual anterior laxity and whether the relationship between residual anterior laxity and the hop test was invariant across levels of quadriceps muscle strength recovery. Furthermore, we examined the effect of graft harvest site on the hop index. Positive correlations were found between the hop index and muscle strength index at all levels of residual anterior laxity (P < 0.05), but these correlation coefficients were relatively low. There were no apparent correlations between the hop index and residual anterior laxity at all levels of quadriceps muscle strength recovery. There was no significant difference in the average hop index between the semitendinosus tendon autograft group and the bone-patellar tendon-bone autograft group.

Adolescent↗