Objective recording of muscle strength.
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Humans↗
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Load moment, muscle strength and level of muscular activity during internal rotation training of the shoulder.
Existing studies of shoulder joint loading, muscle strength and muscular activity do not, from the point of view of clinical application, adequately cover these factors, knowledge of which is important for the design of optimal exercises for training shoulder impairments. In the present study, exercises using a weight-and-pulley device have been analysed in order to map the resistance moments of force in relation to the muscular strength capacity of shoulder internal rotators , and to map the activation of these muscles in response to the resistance from the device. The relationships established in the study provide a basis for optimising various types of shoulder training exercises. For example, an angle of 40 degrees between frontal plane and shoulder-pulley line has been found to give the best adaptation of resistance to strength. The study also demonstrates the possibility of using a pulley apparatus for shoulder inward rotator muscle training.
Adult↗
The effects of nutritional status and hyperinflation on respiratory muscle strength in children and young adults.
Malnutrition and hyperinflation may both lead to respiratory muscle weakness. To assess separately the effects of chronic hyperinflation and malnutrition on respiratory muscle strength (RMS), 22 subjects with cystic fibrosis (CF) with both hyperinflation and malnutrition were compared to 10 asthmatic patients, a group with hyperinflation without malnutrition, 9 subjects with anorexia nervosa (AN), a group with malnutrition without lung disease, and 14(6 males and 8 females) control subjects with neither compromise. Nutritional status was assessed by body mass percentile (BMP) and percentage ideal weight (PIWT). RMS was diminished in the AN and CF groups (PImax 90 +/- 27, 88 +/- 31 versus 124 +/- 40 cm H2O, p less than 0.05; PEmax 87 +/- 12, 93 +/- 39 versus 121 +/- 32 cm H2O, p less than 0.05), but no difference was found when the AN group was compared with only the female controls. The decrease in PImax in the CF group was primarily due to the mechanical disadvantage placed on the diaphragm by their marked hyperinflation, a mean RV/TLC ratio of 50 +/- 23%. As older CF subjects had previously been shown to have decreased RMS when malnourished, a CF subgroup in the same age range as the controls was evaluated. RMS in this group did not differ from controls despite the presence of malnutrition and hyperinflation. RMS is mildly influenced by nutritional status as assessed by BMP and PIWT but not to any degree of clinical significance.
Adolescent↗
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↗
Muscle strength in obese elderly women: effect of recreational physical activity in a cross-sectional study.
BACKGROUND: Muscle strength (MS) may be impaired in obese persons, and this impairment may be a consequence of both obesity and low physical fitness. OBJECTIVE: We investigated whether MS differed between obese [body mass index (BMI; in kg/m2 > 29], normal-weight (BMI = 24-29), and lean (BMI < 24) elderly subjects and compared the MS of sedentary and active subjects according to their BMI group. DESIGN: The study included 215 obese [ (+/- SD) age: 80.0 +/- 3.5 y; BMI: 31.9 +/- 2.6], 630 normal-weight (age: 80.2 +/- 3.7 y; BMI: 26.3 +/- 1.4), and 598 lean (age: 80.7 +/- 3.5 y; BMI: 21.6 +/- 1.8) women with good functional ability. A cross-sectional design was used. Anthropometric measures (weight, height); measures of appendicular skeletal muscle mass (by dual-energy X-ray absorptiometry), isometric knee and elbow extension (by statergometer), and isometric handgrip strength (by dynamometer); and data on health status and self-reported recreational physical activity (RPA: walking, gymnastics, cycling, swimming, gardening) were collected. RESULTS: Absolute (unadjusted) MS was higher in obese than in lean women (P < 0.01), except for handgrip strength (P > 0.05). When adjusted for age, height, RPA, pain, depression, and appendicular skeletal muscle mass, MS did not differ significantly between obese, normal-weight, and lean subjects, except for knee extension (significant interaction effect with RPA; P = 0.01). With increasing BMI, lower limb strength did not change in the sedentary women but increased in active (> or = 1 h/wk in > or = 1 RPA for > or = 1 mo) women. All adjusted MS measures in active participants were significantly higher (P < 0.001) than those in their sedentary peers. CONCLUSION: The adjusted MS of elderly women is not associated with obesity but is higher in active subjects than in sedentary ones, especially in the lower limbs of obese subjects.
Aged↗
Variation of neck muscle strength along the human cervical spine.
The aim of this study was to describe and explain the variation of neck muscle strength along the cervical spine. A three-dimensional model of the head-neck complex was developed to test the hypothesis that the moment-generating capacity of the neck musculature is lower in the upper cervical spine than in the lower cervical spine. The model calculations suggest that the neck muscles can protect the lower cervical spine from injury during extension and lateral bending. The maximum flexor moment developed in the lower cervical spine was 2 times higher than that developed in the upper spine. The model also predicted that the neck musculature is 30% stronger in the lower cervical spine during lateral bending. Peak compressive forces (up to 3 times body weight) were higher in the lower cervical spine. These results are consistent with the clinical finding that extension loading of the neck often leads to injuries in the upper cervical spine. Analysis of the model results showed that neck flexor strength was greater in the lower cervical spine because of the relatively large size of the sternocleidomastoid muscle. The hyoid muscles developed significant flexor moments about the joints of the upper cervical spine, as these muscles had relatively large flexor moment arms; however, this effect was offset by the action of the sternocleidomastoid, which exerted a large extensor moment in the upper spine. Lateral bending strength of the neck muscles was governed by geometry (i.e., moment arms) rather than by muscle size.
Journal Article↗
Does a muscle strength index provide complementary information to traditional disease activity variables in patients with rheumatoid arthritis?
OBJECTIVE: To develop a muscle strength index (MSI) and determine whether it provides complementary information to traditional disease activity variables in patients with rheumatoid arthritis (RA). METHODS: The MSI was developed on the basis of practical and empirical aspects and statistical considerations. Intra and interobserver reliability was assessed on the data from 3 observers on 2 strength measurements in each of 10 patients. The association of the MSI with variables of disease activity and severity was assessed in univariate analysis. The contribution of the MSI in the explanation of physician's global disease activity after accounting for the effect of traditional measures of disease activity was assessed in multiple linear regression models. RESULTS: Eight strength measurements (extension and flexion of knee and elbow joints) obtained with a hand held pull gauge were aggregated into the MSI as the mean of the standardized scores. In 65 patients with RA, the MSI had a high internal consistency (Cronbach's alpha 0.95) and intra and interobserver reliability (Pearson correlation coefficient 0.94 each). The MSI correlated moderately with traditional measures of disease activity and strongly with physical functional disability and radiological damage. In contrast to grip strength, the MSI explained additional variation of physician's global assessment of disease activity if added to variables of pooled activity indices. CONCLUSION: The MSI is a reliable and valid measure of disease activity and severity and may improve the content validity of pooled disease activity indices.
Adult↗
Decreased neck muscle strength is highly associated with pain in cervical dystonia patients treated with botulinum toxin injections.
OBJECTIVES: To compare the isometric neck muscle strength of cervical dystonia patients treated with botulinum toxin injections with that of healthy control subjects and to evaluate the association between neck strength, neck pain, and disability in these patients. DESIGN: Clinical cross-sectional study. SETTING: Outpatient rehabilitation and neurology clinics in a Finnish hospital. PARTICIPANTS: Twenty-three patients with cervical dystonia with botulinum toxin-treated neck muscles and 23 healthy control subjects. INTERVENTIONS: Not applicable. Main outcome measures Isometric neck strength was measured by a special neck strength measurement system. Disability was measured by the Neck Disability Index, and pain and symptoms of cervical dystonia by a visual analog scale. RESULTS: Isometric neck strength in all directions measured was significantly lower (25%-44%) in the cervical dystonia patients than in the healthy controls. Neck pain levels reported during the strength tests (r range, -.36 to -.70) and neck pain experienced during the preceding week (r range, -.52 to -.63) were inversely associated with isometric strength results. The difference between sides in rotation strength was 35% in the patient group (P<.001), whereas no significant difference between sides was found in the healthy controls. Fifty-one percent of the patients reported moderate or severe disability. Pain, stiffness, and incorrect position of the head were the most prominent symptoms. CONCLUSIONS: Cervical dystonia patients with botulinum toxin-treated neck muscles showed significantly lower maximal neck strength than healthy controls. The patients also had a statistically significant difference between sides in neck rotation strength. Thus, strength measures may be useful to detect disturbance in the function of the neck muscles.
Botulinum Toxins, Type A↗
CTG-repeat length in distal and proximal leg muscles of symptomatic and non-symptomatic patients with myotonic dystrophy: relation to muscle strength and degree of histopathological abnormalities.
Myotonic dystrophy (DM) is an autosomal dominant, multisystemic disorder with a variable phenotypic expression including muscle weakness and myotonia. The muscle wasting is most marked in distal limbs and in facial and neck muscles, although proximal limb muscles become affected as the disease progresses. The CTG-trinucleotide-repeat expansion associated with myotonic dystrophy is usually larger in muscle tissue than in leukocytes. It is unclear whether the repeat length itself bears any relation to the differences in the degree of weakness and atrophy between different muscles. We therefore analysed CTG-repeat lengths in blood and in proximal (m. vastus lateralis) and distal (m. tibialis anterior) muscles of patients with DM (n = 4) and non-symptomatic carriers of the mutant DM allele (n = 2) using conventional Southern blot hybridization. Muscle strength and histopathological abnormalities were evaluated for each muscle. In patients with clinical symptoms, the degree of paresis and morphological abnormalities was markedly more pronounced in m. tibialis anterior than in m. vastus lateralis. In these individuals, the CTG-repeat length was larger in muscles than in leukocytes, whereas in the two non-symptomatic carriers no difference could be detected. Furthermore, there was no clear difference in the repeat length between the two muscles in any of the patients. In conclusion, the selective muscular weakness and atrophy in DM do not seem to be related to differences in CTG-repeat length between different muscles.
Adult↗
Respiratory muscle strength training: treatment and response duration in a patient with early idiopathic Parkinson's disease.
The outcome of a 20 week expiratory muscle strength training program (EMST) is documented in a patient with early idiopathic Parkinson's disease. A pressure threshold device was utilized and training occurred in the home setting. The training was intensive with a physiologically challenging load specific to the expiratory muscles, adjusted weekly based on the participant's performance. Results indicated that strength, as indexed by the generation of maximum expiratory pressure (MEP), increased by 50% in the first 4 weeks of training, consistent with the average strength increase obtained in previous research. Strength increases continued beyond the traditional 4 weeks of training with a final improvement in MEP of 158% from baseline over the 20 weeks. When the EMST was discontinued for a period of 4 weeks, the participant's MEP decreased by 16% from the 20 week endpoint measurement. The strength training pattern of the expiratory muscles observed in this study was similar to the pattern previously reported for limb muscles.
Breathing Exercises↗
Anthropometric, muscle strength, and spinal mobility characteristics as predictors in the rating of acceptable loads in parcel sorting.
The rating of acceptable load (RAL) attained with a standard test (RALSt) and a wrk-simulating test (RALW) for postal parcel sorting was related to anthropometric, muscle strength, and spinal mobility characteristics of 18 male sorters. The subjects comprised a subsample of 103 experienced male sorters who carried out the RAL tests at postal sorting centres. The dynamic hand-grip endurance correlated significantly (p = 0.036) to the RALSt results. Correspondingly, there was a significant correlation (p = 0.044) between the ratio of maximal isometric strength of trunk extension to body weight and the RALW. The dynamic hand-grip endurance predicted 26% of the variation in the RALSt; in the RALW the maximal isometric strength of trunk flexion to body weight ratio predicted 24%. The subjects who rated heavier weights for RALSt tended to have a better trunk mobility. The dynamic endurance of hand-grip muscles, trunk strength, and spinal flexibility seemed to be the most powerful predictors for the psychophysically assessed 'acceptable loads' in experienced workers performing manual materials handling tasks.
Adult↗
Effects of treatment on airway dynamics and respiratory muscle strength in Parkinson's disease.
To investigate how treatment can affect airway dynamics and respiratory muscle strength in Parkinson's disease (PD), we assessed maximum effort inspiratory and expiratory mouth pressures (MIP and MEP), oscillatory impedance, and maximum expiratory and inspiratory flow-volume curves (MEFV and MIFV) in 10 patients (8 male and 2 female; mean age 51 +/- 5.3 yr, SD) after temporary interruption of antiparkinsonian therapy (off) and during continuous subcutaneous infusion of a direct stimulant of dopamine receptors, apomorphine (on). Treatment improved neurologic scores (off 25 +/- 5, on 9 +/- 5, modified Webster scale, p < 0.001), MEP (off 45 +/- 25, on 63 +/- 29 cm H2O, p = 0.003), and peak inspiratory flow (PIF; off 3.83 +/- 1.6, on 4.37 +/- 1.7 L/s, p = 0.028). Maximum inspiratory pressure was very low off treatment (-25 +/- 16 cm H2O) and improved moderately with apomorphine (-33 +/- 17 cm H2O) (p = 0.064). Total respiratory resistance during tidal breathing was normal in 9 patients both off and on treatment despite, in some cases, dramatic changes in MEFV and MIFV curves. These results suggest that abnormalities of the flow-volume curves may be due to problems in the rapid activation and coordination of contraction of upper airways and chest wall muscles during forced maneuvers, which is improved by apomorphine treatment.
Adult↗
Early changes in isokinetic lower limb muscle strength in recovering geriatric subjects on the basis of nutritional status.
BACKGROUND: In older people, the decrease in muscle mass and strength has a bad effect on functional status. Malnutrition and lack of physical activity exacerbate this phenomenon. OBJECTIVE: The main purpose of this study was to estimate isokinetic lower limb muscle strength in recovering older subjects on the basis of nutritional status. DESIGN: Twenty-eight elderly subjects hospitalized for an acute event (85.8 +/- 6 years), including 16 malnourished, were enrolled in this study when clinically stable (T0). Re-assessment at one-month was performed in nine after oral supplementation and conventional physiotherapy (T1). The Maximal Peak Torque (MPT) of the ankle plantar flexors was estimated in concentric mode at 30 and 60 degrees /s. The MPT of the knee flexors and extensors was evaluated in the same mode at 30 degrees /s, 60 degrees /s and 120 degrees /s. All patients underwent a nutritional examination with anthropometric measures, dietary intake survey, biochemical indexes and determination of the medial gastrocnemius volume by magnetic resonance imaging. RESULTS: At T0, whatever the muscle group tested (except at 120 degrees /s for the knee), the MPT appeared significantly lower in the malnourished group. At T1, the increase in MPT (plantar flexors) in malnourished patients was greater at 60 degrees /s (+23.8 %) than at 30 degrees /s (+14.8 %). Correlations between MPT and nutritional parameters were observed in the malnourished group only at T1 and in the normal-nourished group. CONCLUSION: Isokinetic assessment seems to be a pertinent method to estimate lower limb muscle strength in older and frail subjects. Early modifications in strength were observed in malnourished patients who received oral supplementation and physiotherapy.
Aged, 80 and over↗
Effects of musculoskeletal work load and muscle strength on strain at work in women and men aged 44 to 58 years.
The effects of musculoskeletal work load and muscle strength on strain at work were analysed among 60 women and 69 men (mean age 52 +/- 3.4) in municipal jobs in Finland. The musculoskeletal work load was determined by analysing the jobs by a job description method. The maximal isometric hand grip strength was assessed with a manometer, trunk flexion and trunk extension strength with a dynamometer, and dynamic trunk flexion endurance strength with a sit-up test. Heart rate was registered continuously and ratings of perceived exertion were determined 4 times during the work shift. The results revealed that high musculoskeletal work load was systematically and significantly related to high strain at work in both sexes. A high mean heart rate related to an individual's range in women was an interaction effect of high work load and low hand grip strength or low trunk flexion strength. Among men, both high mean and maximal heart rates in relation to the heart rate range was due to the interaction effects of high work load and low trunk extension strength. The interaction of work load and strength was not systematically related to the ratings of perceived exertion during work. It was concluded that the musculoskeletal work load exerted the main effects on the cardiorespiratory and perceived strains at work. The interaction effects of work load and strength on strain depended on the sex and the muscle group in the studied work load level of elderly municipal employees.
Female↗
[Measurement of central respiratory drive and inspiratory muscles strength in patients with uremia].
OBJECTIVE: To investigate the changes of central respiratory drive and inspiratory muscles function in patients with uremia. METHODS: We performed the measurement of forced vital capacity (FVC), maximal voluntary ventilation (MBC), forced expiratory volume in one second (FEV1), peak expiratory flow (PEF), maximal midexpiratory flow (MMEF), expiratory flow of 25 per cent of FVC (V25), lung carbon monoxide diffusing capacity (DLco), maximal inspiratory mouth pressure (MIP) and airway occlusion pressure (P0.1) in 25 patients with uremia and 20 normal subjects. RESULTS: In patients with uremia, the FVC, MBC, FEV1, PEF, MMEF and V25 which reflect the lung ventilatory function and the DLco which reflects the lung diffusing function were significantly lower than those in normal subjects. The patients' MIP which reflects inspiratory muscles strength was significantly lower and their P0.1 which reflects the central respiratory drive was significantly higher, compared with the normal subjects'. CONCLUSION: Our findings suggest that on the basis of the disorder of ventilation and diffusing function of the lungs, the inspiratory muscles function of the patients with uremia is significantly decreased and the central respiratory drive of the patients is increased.
Aged↗
Balance, muscle strength, and fear of falling in older adults.
This study examined balance ability, lower-extremity muscle strength, fear of falling and their inter-relationships in 40 community-dwelling older adults (>65 years). Subjects who self-identified either as being fearful of falling or not (no concern) were screened to exclude those with known risk factors for falling. Limits of stability, maximal isometric strength, gait speed, and fear of falling were contrasted between groups (27 control subjects, 13 fearful subjects). Those fearful of falling demonstrated smaller center of pressure (COP) excursions in anterior, left, and right directions (p<.0001) and used a smaller percentage of their base of support during maximal weight shifting in combined anterior-posterior and right-left directions (p<.001) compared to the control group. Strength did not differ between groups, but was associated with the ability to shift the COP in the anterior-posterior direction (p<.05). Fear of falling also related to weight shifting ability (p<.017). Seniors fearful of falling demonstrated limitations in balance ability and balance confidence that could not be explained by muscle weakness.
Aged↗
Inspiratory muscle strength and endurance during hyperinflation and histamine induced bronchoconstriction.
BACKGROUND: This study investigated whether the inspiratory muscles are susceptible to fatigue during acute airway narrowing because of increased airway resistance and hyperinflation. METHODS: Asthmatic subjects performed up to four series (on separate days) of 18 maximal static inspiratory efforts of 10 seconds' duration with 10 second rest intervals (50% duty cycle; total duration six minutes): at functional residual capacity (FRC) (control); after histamine induced bronchoconstriction, which decreased forced expiratory volume in one second (FEV1) to a mean of 55% (SD 11%) of the initial value; at a voluntarily increased lung volume (initial volume held at 140% control); and after inhalation of histamine at a voluntarily increased lung volume. RESULTS: For the group of subjects the mean (SD) maximal inspiratory pressure (MIP) in the control experiments was 114 (22) cmH2O and the initial volume was 3.5 (1.2) 1. After histamine inhalation the initial lung volume for contractions increased to 118% (5%) of the control volume. In the high lung volume experiments initial volumes were 140% (12%) of the control (volume without histamine) and 140% (15%) (with histamine). The relation between MIP and initial absolute lung volume was determined for each subject before fatigue developed. When the inspiratory pressures for each contraction in the endurance test were normalised to the pressure expected for that lung volume, no significant differences were found between the four experimental conditions for MIP, or between pressures sustained over the 18 contractions. CONCLUSIONS: Histamine induced bronchoconstriction and hyperinflation had no detectable effect on inspiratory muscle strength or endurance in these asthmatic subjects.
Adult↗
Trunk muscle strength during constant velocity movements.
A new apparatus has been designed for standardized measurements of the strength of human trunk muscles utilizing the isokinetic (constant movement velocity) technique (Cybex). It is possible to measure the produced torque during maximal voluntary isometric and isokinetic contractions in the whole range of motion during flexion, extension and lateral flexion of the trunk. Effects of gravity are eliminated since the movements are performed in the horizontal plane. Torque can be measured around different centres of rotation of the body. With this experimental set-up the strength of the trunk muscles has been characterized in a group of 14 normal male subjects (18-31 yrs). The torque produced by the trunk muscles varied with movement velocity and trunk position in the arc of motion. Peak torque occurred in a position where the muscles involved were stretched. The strength of the trunk extensors exceeded that of the flexors, but the degree (ratio) varied with trunk position. The relative contribution of the hip muscles to the total torque produced with the centre of rotation at the hip joint was larger for flexors than for extensors and varied with velocity and position. It is concluded that the present technique is useful to characterize the human trunk muscles.
Adolescent↗