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Results for “Muscle Strength”

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At least 739 records · Page 41Linked to original sources

PubMed1992

A comparative study of the muscle strength and mass of the arm flexors and extensors in paraplegic and in non paraplegic basketball players.

OBJECTIVES: to study the changes in the strength of the elbow flexors and extensors in paraplegic subjects, and the agonist/antagonist mass and strength ratio in paraplegic wheelchair users. METHOD: 10 paraplegic wheelchair basketball players were compared with 10 healthy basketball players. The 20 subjects underwent a clinical and dynamometric isokinetic assessment, and a CT scan measurement of the muscle cross-sectional surface area of the flexor and extensor muscles of the elbows. RESULTS: there was an increase in muscle strength in paraplegic subjects. There was no significant difference in the agonist/antagonist ratio between the dominant and non dominant upper limb in paraplegics whereas such a difference was found in healthy subjects. The muscle mass was increased in the paraplegics, but a correlation between muscle mass and strength was only found in the healthy subjects.

Adult↗

PubMed2004

Effect of training on the muscle strength and dynamic balance ability of adults with down syndrome.

The purpose of this study was to evaluate the effect of training on the muscle strength and dynamic balance ability of adults with Down syndrome (DS). Twenty-five adults with DS were separated into 2 groups. Fifteen subjects (mean age, 24.5 years) constituted the experiment group, whereas 10 subjects (mean age, 24.7 years) were in the control group of the study. Parameters measured were peak torque, isokinetic muscle endurance, and dynamic balance ability. All subjects performed a leg strength test on a Cyber II isokinetic dynamometer. In addition, the subjects' dynamic balance ability was measured by means of a balance deck (Lafayette). The experimental group followed a 12-week training program. As the results indicated, the experimental group showed a statistically significant improvement in all measured values when compared with the control group. It is concluded that adults with DS can improve their physical and kinetic abilities with the application of a systematic and well-designed training program.

Adult↗

PubMedDate not supplied

Influence of muscle strength and body weight and composition on regional bone mineral density in healthy women aged 60 years and over.

Although weight, lean mass, fat mass and muscular strength are often found to be intercorrelated, the respective role of each parameter in bone mineral density (BMD) remains unknown in older women. The aim of the present study was to investigate the relationship between body weight and composition and quadriceps strength on femoral neck and lumbar spine BMD in healthy postmenopausal women. The relationship between isokinetic quadriceps strength measured by Biodex and BMD measured by dual energy X-ray absorptiometry was studied in 56 women aged 60-81 (70.5 +/- 6.2) years in multiple regression models adjusted for age, body composition and menopausal treatment. Weight and age were associated with femoral neck BMD (33 and 10% of variance accounted for, respectively) and lumbar spine BMD (23 and 8% of its variance). When body weight and quadriceps strength were excluded from the model, lean mass and age were associated with femoral neck BMD (29 and 14% of variance explained, respectively) and lumbar spine BMD (28 and 11% of variance explained, respectively). When quadriceps strength was entered into the model, it was strongly associated with femoral neck BMD (30% of variance accounted for), in addition to lean mass (9%) and age (7%), whereas it was not associated with lumbar spine BMD. In conclusion, lean mass explains a great part of the strong association between body weight and femoral neck and lumbar spine BMD. Quadriceps strength explains a great part of the association between lean mass and BMD at the femoral neck site but not at the lumbar spine site. These results suggest a site-specific effect of muscular strength on bone and a potential role of the age-related decline of muscle strength in age-related bone loss in postmenopausal women.

Age Factors↗

PubMed2001

Respiratory muscle strength, lung function, and dyspnea in patients with sarcoidosis.

BACKGROUND: Sarcoidosis is a systemic granulomatous disorder that is estimated to involve the skeletal muscles in up to 50% of patients. There is little information on the relationship among respiratory muscle strength, lung volumes, and the degree of dyspnea in patients with sarcoidosis. DESIGN AND PATIENTS: Lung function and maximal respiratory muscle force generation were measured in 36 patients with sarcoidosis (24 patients with pulmonary parenchymal infiltration) and 25 control subjects free of cardiorespiratory disease. Dyspnea in the sarcoidosis patients was quantitated by a score based on an activity tolerance assessment scale (ranging from rest to climbing hills or stairs). SETTING: Outpatient clinics of two teaching hospitals. RESULTS: Mean FVC, maximal voluntary ventilation, total lung capacity (TLC), functional residual capacity, residual volume (RV), and diffusing capacity of the lung for carbon monoxide (DLCO) were all at least 16% less than corresponding control values (in all cases, p < 0.001), while maximal inspiratory mouth pressure (PImax) and maximal expiratory mouth pressure (PEmax) were 37% and 39% less, respectively, than control values (both at p < 0.0001). PImax and PEmax declined with increasing dyspnea in a more graded, steady manner than did spirometric and DLCO values. For all measurements, however, the lowest mean values were found in patients with the most severe level of dyspnea. Strong inverse relationships were observed between PEmax and PImax with dyspnea level (p < 0.0001 and p < 0.01, respectively). Both PImax and PEmax correlated best with absolute values of FVC, while only PEmax correlated with RV (absolute and percent predicted) and percent predicted values of TLC. CONCLUSIONS: Maximal respiratory pressures correlate more closely with dyspnea level than lung volumes and DLCO. Since dyspnea is the most common presentation in early to moderately advanced sarcoidosis, respiratory pressures may be a more reliable index of functional work capacity and reflection of activities of daily living than standard tests of lung function.

Adult↗

PubMed1995

Bone density in young women is associated with body weight and muscle strength but not dietary intakes.

Potential determinants of bone mineral density (BMD) were studied cross-sectionally in 115 healthy, sexually mature Caucasian women aged 18 years. Bone mineral density (Hologic QDR1000W) of the lumbar spine, proximal femur (five sites), and distal tibia and fibula; fasting blood and urine calcium biochemistry; serum sex hormone levels (follicular phase); nutrient intakes; aerobic fitness; trunk muscle strength; and habitual activity levels were measured. The effects of heredity were considered by measuring the BMD of 107 of the subjects' mothers. Simple and stepwise regression analysis were used to identify significant determinants of BMD at each of the regions studied. The analysis indicated that significant bivariate correlations exist between BMD at all sites and body weight (r = 0.23-0.47, p < or = 0.01), lean body weight (r = 0.34-0.46), trunk strength (r = 0.27-0.47), physical activity score (r = 0.20-0.25), and aerobic fitness (r = 0.29-0.45). Dietary calcium intake correlated significantly with BMD at the trochanter site only (r = 0.19), and none of the biochemical or hormonal indices measured correlated consistently with BMD at any site. Significant correlations between the BMD of mothers and daughters ranged from r = 0.43 at lumbar spine to r = 0.34 at the intertrochanteric site. Paired t-tests showed the daughters had significantly (p < 0.03) lower BMD than their mothers at the lumbar spine (98 +/- 12% [mean +/- SD]) and significantly higher (p < 0.002) BMD at the femoral neck, trochanter, and total hip sites (110 +/- 16%, 108 +/- 17%, 103 +/- 14%, respectively). When stepwise regression analysis included weight-corrected strength of the trunk flexor muscles (Corr Flex), weight-corrected aerobic fitness (Corr VO2max), physical activity score, and body weight, body weight was the only significant determinant of BMD at all sites. Corr Flex made significant contributions at all sites except the femoral neck, while Corr VO2max made additional contribution at the femoral neck, trochanter, total hip, and shaft of femur sites. These variables accounted for 13-27% of the variance in BMD. The addition of mother's BMD to these independent variables, in stepwise regression analysis, improved the prediction to 18-31% of the variance.

Absorptiometry, Photon↗

PubMed1995

Software compensation for lung volume in assessment of inspiratory muscle strength and endurance.

BACKGROUND: To increase the sensitivity of measurements of maximal inspiratory pressure (MIP) as a test of inspiratory muscle strength and endurance, software was developed to correct for variation in lung volume. METHODS: Using a body plethysmograph to determine absolute lung volume during each manoeuvre, values for MIP were expressed as a percentage of the pressure "expected" from the unfatigued MIP/lung volume relation in each subject. RESULTS: The method reduced the variance in peak and average pressure during a series of 18 MIP manoeuvres of 10 seconds duration separated by rest intervals of 10 seconds. CONCLUSIONS: The correlation between average pressure and contraction number was improved significantly by the MIP/lung volume correction. This simple correction has many applications in measurements of the MIP.

Adult↗

PubMed2005

Muscle strength, volume and activation following 12-month resistance training in 70-year-old males.

In elderly males muscle plantar flexor maximal voluntary contraction (MVC) torque normalised to muscle volume (MVC/VOL) is reduced compared to young males as a result of incomplete muscle activation in the elderly. The aim of the present study was to determine the influence of a 12-month resistance training programme on muscle volume, strength, MVC/VOL, agonist activation and antagonist coactivation of the plantarfexors in elderly males. Thirteen elderly males aged 70 years and over (range 70-82 years), completed a 12-month whole body resistance-training programme (TRN), training three times a week. Another eight males (range 18-30 years), who maintained their habitual physical activity for the same 12-month period as the TRN group acted as controls (CTRL). Isometric plantarflexor maximal voluntary contraction (MVC) torque increased in the TRN group by 20% (P < 0.01), from 113.1 +/- 22.0 Nm to 141.5 +/- 19.2 Nm. Triceps surae volume (TS VOL) assessed using MRI, increased by 12%, from 796.3 +/- 78.9 cm(3) to 916.8 +/- 144.4 cm(3) . PF activation, measured using supramaximal double twitch interpolation, increased from 83.6+/-11.0% pre training, to 92.1 +/- 7.6% post training (P < 0.05). Dorsiflexion MVC and antagonist coactivation (assessed using surface electromyography) did not change with training. Plantarflexor MVC torque normalized for triceps surae muscle volume (MVC/VOL) was 142.6 +/- 32.4 kN m(-2) before training and 157.0 +/- 27.9 kN m(-2) after training (a non-significant increase of 8%). No significant change in any measurement was observed in the CTRL group. This study has shown that the gain in muscle strength in response to long-term (12-month) training in older men is mostly accounted for by an increased muscle volume and activation.

Aged↗

PubMed2004

Assessment of muscle strength and motor fatigue with a knee dynamometer in subjects with multiple sclerosis: a new fatigue index.

OBJECTIVE: To measure muscle strength and motor fatigue with a knee dynamometer and to assess the intra-rater reliability of measurements for maximal isometric extensor and flexor torques and the reliability of a new fatigue index (FI) in patients with mild to moderate multiple sclerosis (MS). DESIGN: Repeated assessments with one-week intervals. SETTING: The Masku Neurological Rehabilitation Centre, Masku, and the Social Insurance Institution, Research Department, Turku, Finland. SUBJECTS: Twenty-eight MS patients. OUTCOME MEASURES: Maximal isometric torque during 5 s and fatigue of knee flexors and extensors during isometric contractions of 30 s were assessed. A new FI was established and compared with the two previously used indices (FI1 and FI2). All three indices are based on the calculated area under the force versus time curve (AUFC), with FI1 using the 30-s recording time in its entirety and F2 omitting the initial 5 s in the calculation. In the new fatigue index (FI3), the time point of maximum (TPM) torque achieved by the subject is used as the starting point in the calculation. The patient's subjective fatigue was measured by Fatigue Severity Scale (FSS). RESULTS: The intraclass correlation coefficient (ICC) was 0.97 in maximal isometric torque measurements. FI3 showed good intra-rater reliability (ICC =0.68-0.86). None of the fatigue indices correlated with FSS. CONCLUSIONS: Maximal isometric torque and motor fatigue of knee flexor and extensor muscles can be reliably measured using a knee dynamometer in MS patients. The new FI proved to be a reliable model for MS patients.

Adult↗

PubMed1988

Muscle strength and its development. New perspectives.

Skeletal muscle undergoes substantial adaptation when it is subjected to a strength training regimen. At one extreme, these effects are manifested as profound morphological changes, such as those exemplified by bodybuilders. However, it is possible to increase strength without any change in muscle size. This dissociation underscores the notion that strength is not solely a property of muscle but rather it is a property of the motor system. The nervous system seems to be of paramount importance for the expression and development of strength. Indeed, it is probable that increases in strength can be achieved without morphological changes in muscle but not without neural adaptations. This review focuses on the role of the nervous system in the development of strength. In the strength literature, 3 topics exemplify the importance of the nervous system in strength development. These 3 topics are considered in detail in the review: electromyostimulation, cross-training effects, and EMG-force relationships. Evidence is presented from several different paradigms emphasising the significant contribution of neural mechanisms to the gains in strength with short term training. Although little is known about the specific neural mechanisms associated with strength training adaptations, the literature emphasises that the measure of human performance known as strength can be influenced by a variety of neurophysiological processes.

Electric Stimulation↗

PubMed2001

Measuring knee extensor muscle strength.

OBJECTIVE: To compare manual muscle test with hand-held dynamometer measurements of knee extension strength. A secondary analysis of measurements (n = 256 knees) from 128 acute rehabilitation patients was performed. DESIGN: Knee extensor muscle testing was conducted according to the technique of Hislop and Montgomery; 0 to 5 grades were converted to an expanded 0 to 12 scale. Dynamometry was used to measure the isometric knee extension force with 'gravity eliminated.' RESULTS: Manual muscle test and dynamometer measures were highly correlated (r = 0.768; P < 0.001); the correlation was higher when the quadratic nature of the relationship was taken into account (R = 0.887; P < 0.001). Although the dynamometer forces that were associated with different manual muscle test grades differed overall (F = 67.736; P < 0.001), the forces associated with some of the higher grades did not differ statistically. CONCLUSIONS: These findings reinforce the convergent construct validity of the manual muscle test and dynamometry measurements but challenge the discriminant construct validity of manual muscle testing. An alternative manual muscle testing grading scheme is suggested that provides for discriminant validity and retains convergent validity.

Adult↗

PubMed1991

The interrelationship between physical exercise, muscle strength and body adiposity in a healthy elderly population.

OBJECTIVE: To determine the relationship between habitual physical exercise and body adiposity in a healthy elderly population. RESEARCH DESIGN AND METHODS: Physical exercise was measured by a questionnaire previously adapted for use with the healthy elderly. The level of exercise was converted into calories expended over the previous 14 days and was divided into tertiles. Body adiposity was measured at six sites by anthropometry, and overall percent body fat was measured by bioelectric impedence. PARTICIPANTS AND SETTING: Two hundred and thirteen healthy ambulatory subjects over the age of 60 (116 females and 97 males) were recruited from a large retirement community in Southern Arizona. The mean age of the subjects was 70.0 years. RESULTS: Percent body fat was similar in men with different levels of physical activity (27.9% for lowest tertile of activity, 28.1% for middle tertile of activity, and 28.5% for highest tertile of activity). The corresponding values of percent fat in women was 38.0%, 36.0%, and 37%, respectively. There was a statistically significant increase in muscle strength measured in five muscle groups with a hand-held dynamometer with increasing levels of activity. CONCLUSIONS: These data indicate that level of physical exercise, over the range of 0 to 1,528 Kcal/day, does not predict body adiposity in the healthy elderly population. To decrease body fat without a change in dietary habits would require a more intensive exercise regimen than currently being undertaken by most healthy elderly people.

Aged↗

PubMed2004

Muscle strength in type 2 diabetes.

Motor function in type 2 diabetes is largely unknown. In 36 type 2 diabetic patients and in 36 control subjects matched for sex, age, weight, height, and physical activity, strength of flexors and extensors at elbow, wrist, knee, and ankle was assessed at isokinetic dynamometry. The degree of neuropathy was determined by clinical scores, nerve conduction studies, and quantitative sensory testing. Eventually, all results were summed to obtain a neuropathy rank-sum score (NRSS). The degree of nephropathy and retinal condition were also evaluated. Diabetic patients had a 17 and 14% reduction of strength of ankle flexors (P < 0.02) and ankle extensors (P < 0.03), respectively. At the knee, strength of extensors and flexors was reduced by 7% (NS) and 14% (P < 0.05), respectively. At the elbow and wrist, muscle strength was preserved. The NRSS was related to the strength at the ankle (r = -0.45, P < 0.01) and knee (r = -0.42, P < 0.02). Following multiple regression analysis, the NRSS but not the degree of nephropathy or retinopathy was related to strength at the ankle and knee. In conclusion, type 2 diabetic patients may have muscle weakness at the ankle and knee related to presence and severity of peripheral neuropathy.

Aged↗

PubMed1998

Three dimensional measurements of pelvic tilt in trans-tibial amputations: the effects of pelvic tilt on trunk muscles strength and characteristics of gait.

The aim of this study was to determine the degree of pelvic tilt in the three dimensions, the trunk muscle strength and effects on gait in trans-tibial amputated patients. This study comprised of 22 unilateral trans-tibial amputated patients who were seen at the authors' Prosthetics and Orthotics Laboratory for the purpose of prosthetic provision. Measurements were made using plurimeter and caliper and gait observations were made by video camera. In the sagittal and horizontal planes respectively the pelvic tilt was measured to be 12 degrees and 5.73 degrees, and such measurements in relation to the trunk extensor and flexor muscles were shown to be statistically significant (p < 0.05). On the contrary, the same could not be said for frontal plane measurements. In addition, in 9 cases excessive knee flexion was noted during the stance phase having a direct influence on the pelvic tilt (p < 0.05).

Adolescent↗

PubMed1999

Sarcopenia and decreased muscle strength in the elderly woman: resistance training as a safe and effective intervention.

A principle component of age-related weakness and frailty in women is sarcopenia. This decrease in skeletal muscle mass is a progressive syndrome that will affect the quality of life for elderly women by decreasing the ability to perform many activities of daily living. Strength training is known to be an effective means of increasing muscular strength and size in many populations, and can be utilized successfully to significantly improve muscle strength, muscle mass and functional mobility in elderly women up to the age of 96 years. Such exercise can minimize the syndrome of physical frailty due to decreased muscle mass and strength. Any rehabilitation or exercise program for the elderly woman would benefit from the inclusion of such a training regime.

Activities of Daily Living↗

PubMed2003

Muscle strength testing: evaluation of tests of explosive force production.

The purpose of the study was to evaluate four tests of explosive force production (EFP). Specifically, the main aims of the study were to assess the reliability of different EFP tests, to examine their relationship with maximum muscle strength, and to explore the relationship between EFP tests and functional movement performance. After an extensive preliminary familiarization with the tasks, subjects ( n=26) were tested on maximum explosive strength of the elbow extensor and flexor muscle, as well as on rapid elbow extension and flexion movements performed in both an oscillatory and a discrete fashion. In addition to maximum force ( F(max)), four different EFP tests were assessed from the recorded force-time curves: the time interval elapsed between achieving 30% and 70% of F(max) ( F(30-70%)), the maximum rate of force development (RFD), the same value normalized with respect to F(max) (RFD/ F(max)), and the force exerted 100 ms after the contraction initiation ( F(100 ms)). Excluding F(30--70%), all remaining EFP tests revealed either good or fair reliability (intraclass correlation coefficients being within 0.8-1 and 0.6-0.8 intervals, respectively) which was also comparable with the reliability of F(max). RFD and F(100 ms) demonstrated a positive relationship with F(max), but not T(30-70%) and RFD/ F(max). Stronger elbow flexor muscles also demonstrated higher values of RFD and F(100 ms) than weaker elbow extensor muscles, while no difference was observed between either T(30-70%) or RFD/ F(max) recorded from two muscles. Despite the simplicity of the tested movement tasks, the relationship observed between the EFP tests and the peak movement velocity remained moderate and partly insignificant. It was concluded that most of the EFP tests could be reliable for assessing neuromuscular function in their muscle-force- (or, indirectly, muscle size) dependent (such as RFD and F(100 ms)), or muscle-force-independent ( T(30-70%) and RFD/ F(max)) forms. However, their "external validity" when applied to assess the ability to perform rapid movements could be questioned.

Adult↗

PubMed1976

Ventilatory muscle strength and endurance training.

We studied respiratory mechanics in young volunteers before and after 5-wk training programs limited to the ventilatory muscles. Four strength trainers (S) performed repeated static maximum inspiratory and expiratory maneuvers against obstructed airways. Four endurance trainers (E) performed voluntary normocarbic hyperpnea to exhaustion. Subjects spent 30-45 min each day in these exercises, 5 days a week. Four control subjects (C) did no training. We attempted to minimize the effect of learning. S increased pressure maximums by about 55%, but vital capacity and total lung capacity by only about 4%. Initially all subjects could sustain hyperpnea at about 81% of their control 15-s maximum voluntary ventilation (MVV) for 15 min; E increased this to about 96% and increased their MVV by 14% as well. No other statistically significant changes were recognized in any group. We conclude that ventilatory muscle strength or endurance can be specifically increased by appropriate ventilatory muscle training programs.

Adult↗

PubMedDate not supplied

Gait analysis and muscle strength in children with surgically treated clubfeet.

Twenty-three children who had unilateral surgery for idiopathic clubfeet underwent gait analysis and isokinetic muscle-strength testing at an average of 10 years after surgical release. Ankle sagittal-plane kinematics were disturbed in 20 clubfeet. Fifteen children had an internal foot-progression angle. Genu valgum and knee hyperextension were common. Plantarflexion power was decreased by 23% on the side of surgery (p = 0.00005). Quadriceps weakness (defined as a decrease in strength >10% of the nonoperated-on limb's strength) was seen in nine of 22 operated-on limbs and hamstring weakness in eight of 22. Gastrocsoleus weakness exceeded 10% in 16 of 21 clubfeet. Average weakness of the gastrocsoleus was 27% (p < 0.05). Ten-year analysis of children treated with clubfoot releases revealed disturbances in ankle motion and strength. Loss of plantarflexion power and gastrocsoleus strength can be predicted by Achilles tendon lengthening. Knee kinematic abnormalities and weakness also were seen. These abnormalities produce functional difficulties in gait and may lead to degenerative changes later.

Child, Preschool↗

PubMed2005

Effects of eccentric exercise training on cortical bone and muscle strength in the estrogen-deficient mouse.

The purpose of this study was to determine whether eccentrically biased exercise training could attenuate changes in muscle and bone function associated with estrogen deficiency in the mouse model. Four groups of ICR mice were used: control (Con), sham ovariectomized (Sham), ovariectomized (OVX), and ovariectomized + high-force resistance training (OVX+Train). All groups except Con were implanted with a nerve cuff surrounding the peroneal nerve to stimulate the left ankle dorsiflexors. Training consisted of 30 stimulated eccentric contractions of the left ankle dorsiflexors at approximately 150% of peak isometric torque every third day for 8 wk. After the training period, groups were not significantly different with regard to peak torque or muscle size. However, the tibial midshaft of the trained leg in the OVX+Train mice exhibited greater stiffness (+15%) than that in the untrained OVX mice, which could not be explained by changes in cross-sectional geometry of the tibia. Scaling of bone mechanical properties to muscle strength were not altered by ovariectomy or training. These data indicate that eccentric exercise training in adult mice can significantly increase bone stiffness, despite the absence of ovarian hormones.

Animals↗