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Clinical evaluation of muscle strength in 20-79-years-old obese Japanese.

It is well known that obesity is closely related to non-insulin-dependent diabetes mellitus, hyperlipidemia, hypertension and cardiovascular disease, and the insulin resistance associated with obesity is supposed to play a central role for the development of these diseases. Thus, effective prevention and treatment of obesity need to be explored. In 357 obese (body mass index > or =26.4) subjects, aged 20-79 years, grip and leg strength were determined and compared with age- and sex-matched 1683 nonobese control subjects. Age-dependent alteration of body composition, evaluated by waist-hip ratio and the relative fat mass volume, was also compared. Finally, the relationship between the number of risk factors related to atherosclerosis and muscle strength was evaluated. Grip and leg strength in obese subjects were obviously stronger than controls under the age of 60 in both sexes. However, in the subjects over 60 years old, muscle strength was similar between obese subjects and controls. Weight bearing index (WBI) (leg strength (kg)/body weight (kg)) in obese subjects was remarkably lower than that in controls in all generations. In obese subjects, the waist-hip ratio and relative percentage of fat increased with aging, and obese subjects with multiple risk factors had higher waist-hip ratio and a tendency for lower muscle strength. Reduced WBI was considered to be a fundamental feature of obese subjects, and obese subjects increased fat composition with aging, which may be linked with low muscle strength. Thus, we need to design the most effective protocols to maximize and maintain quantitative and qualitative properties of muscle.

Adult↗

An 18-month follow-up study on vibrotactile sense, muscle strength and symptoms in computer users with and without symptoms.

OBJECTIVES: The aim was to explore whether symptoms, sensory perception and muscle strength among computer users with and without symptoms in forearm or hand had changed after 18 months. METHODS: Twenty-six out of 30 females, experienced computer users, from a baseline study participated in the follow-up. In addition, five control subjects participated. The subjects completed a questionnaire regarding exposure to computer work, prevalence and severity of symptoms, health status and physical activity. Perceived thresholds for vibration were measured twice with 3 h in between on the right hand on four different sites innervated by the radial, median or ulnar nerve. Furthermore, sensory perception was measured on the left hand on two sites innervated by the median and ulnar nerve, respectively. Skin temperature was measured at each site prior to sensory perception measurements. Maximal handgrip strength and maximal pinch-grip strength were measured for both hands. RESULTS: Eighty-three percent of the subjects who had symptoms at baseline still had symptoms and 21% of the subjects who did not have symptoms at baseline experienced symptoms at follow-up. The first and the second sensory perception measurement were highly correlated. Vibrotactile sensory threshold representing the radial nerve was increased since baseline among the subjects who originally had symptoms. At follow-up, the vibrotactile sense for the computer users who reported symptoms in forearm or hand at baseline was deteriorated for the sites representing the median, ulnar and radial nerves compared to the control group. Among the original symptom free subjects with intensive computer work increases in vibrotactile perception thresholds were found for the sites representing the median and ulnar nerves. Handgrip muscle strength remained unchanged for all groups. CONCLUSIONS: The study indicates that sensory dysfunctions as well as symptoms in forearm and hand among computer users to a high degree are persistent. Muscle strength seems to be well maintained.

Adult↗

Evaluation of cervical range of motion and isometric neck muscle strength: reliability and validity.

OBJECTIVE: To examine the test-retest reliability and construct validity of cervical active range of motion and isometric neck muscle strength as measured by the Multi Cervical Rehabilitation Unit (Hanoun Medical Inc., Ontario). DESIGN: A cross-sectional study. SETTING: Institutional practice. SUBJECTS: Twenty-one patients with neck pain and 25 healthy volunteers. METHODS: After a trial-run session, active range of motion (AROM) was measured in the subsequent two sessions, with 2-3 days in between. During each session, three measurements were taken for each direction (flexion, extension, lateral flexions and rotations). The measurement of isometric strength was after a 15-minute break following completion of the measurement of AROM. Three measurements were made for each of the six directions (flexion, extension, lateral flexions, protraction and retraction). The software of the Multi Cervical Rehabilitation Unit automatically recorded and calculated the maximum AROM and isometric strength. RESULTS: There was a good to high level of reliability in the measurement of AROM for both groups of subjects, with intraclass correlation coefficients (ICCs) ranging from 0.81 to 0.96. Results also demonstrated very good to excellent reliability in isometric strength measurement (ICCs ranged from 0.92 to 0.99). Moreover, there was a significant difference in isometric neck muscle strength (p = 0.001) and in AROM (p = 0.034) between the two groups. CONCLUSIONS: The Multi Cervical Rehabilitation Unit was found to be reliable and valid for testing the cervical active range of motion and isometric neck muscle strength for both normal and patient subjects.

Adult↗

Hormone replacement therapy increases isometric muscle strength of adductor pollicis in post-menopausal women.

A randomized open trial of hormone replacement therapy was used to assess changes in adductor pollicis muscle strength during 6-12 months of treatment with Prempak C 0.625(R) in comparison with an untreated control group. Muscle strength (maximal voluntary force; MVF), muscle cross-sectional area and bone mineral density were measured. Women entering the trial had oestrogen levels below 150 pmol.l-1, confirming their post-menopausal hormonal status. In the treated group, MVF increased by 12.4+/-1.0% (mean+/-S.E.M.) of initial MVF over the duration of treatment, while it declined slightly (2.9+/-0.9%) in the control group. This increase in strength could not be explained by an increase in muscle bulk, there being no significant increase in cross-sectional area during the study. Those subjects who were weakest at enrolment showed the greatest increases in muscle strength after treatment. Bone mineral density in total hip, Ward's triangle and total spine increased in the treated group, in agreement with previous studies. There was no correlation between the individual increases in bone mineral density and those in MVF.

Analysis of Variance↗

The twitch interpolation technique for the estimation of true quadriceps muscle strength.

The aim of this study was to examine the reliability of the twitch interpolation technique when used to estimate the true isometric knee extensor muscle strength. This included an examination of whether submaximal activation causes any bias in the estimation of the true muscle strength and an examination of the precision of the method. Twenty healthy subjects completed three contraction series, in which the subjects were told to perform as if their voluntary strength was 60%, 80% or 100% of that determined by a maximal voluntary contraction (MVC). Electrical muscle stimulations were given at each of five different contraction levels in each series. At torque levels above 25% of MVC the relationship between torque and twitch size could be approximated to be linear. The true muscle strength (TMS) could therefore be estimated using linear regression of the twitch-torque relationship to the torque point of no twitch in each of the three series, termed TMS60, TMS80 and TMS100. The TMS80 was slightly lower (P < 0.01), median 94% (IQ range 87-101%) of the TMS100. The TMS60 was median 99% (IQ range 83-125%) (NS) of TMS100, but a few severe outliers were observed. In conclusion, we found the reliability of the method acceptable for many research purposes, if series with estimated central activation of below 40-50% were excluded. The only moderate precision and the slightly lower estimations in subjects applying submaximal does, however, limit its usefulness.

Adult↗

How is walking speed related to muscle strength? A study of healthy persons and persons with late effects of polio.

OBJECTIVES: To evaluate the relationship between walking speed and muscle strength in the lower extremities in healthy persons and in persons with late effects of polio and to compare the models for these relationships. DESIGN: Retrospective analysis. SETTING: University hospital department. PARTICIPANTS: An urban sample of 144 healthy men and women (age range, 40-79 y) and 234 (146 women, 88 men) subjects with late polio. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Muscle strength in the lower extremities was measured and combined into an index. Walking speed for spontaneous and maximal walking was measured. A nonlinear regression model was developed. RESULTS: Evidence was provided for the nonlinear relationship between walking speed and strength. A specific strength threshold could not be identified. The asymptote of this curve for maximal walking was 2.57 m/s in the healthy group and 2.02 m/s in the subjects with late effects of polio. A high body mass index (>25 kg/m2) lowered the asymptote. CONCLUSIONS: It is important to prevent strength decrease that approaches the critical level where a further reduction affects walking speed more evidently. The difference in the relationship between muscle strength and walking speed for the 2 groups studied may partly depend on biomechanic imbalance between muscle groups.

Adult↗

Effects of nutritional supplementation and resistance training on muscle strength in free living elders. Results of one year follow.

PURPOSE: To assess the effects of a one year nutritional supplementation and resistance training program on muscle strength and walking capacity in the elderly. MATERIAL AND METHODS: Elderly subjects from two outpatient clinics received a nutritional supplement, that provided 400 Kcal, 15 g/protein and 50% of vitamin DRVs per day. Half the subjects receiving and not receiving the supplement were randomly assigned to a resistance exercise training program with two sessions per week. Every six months, body composition using DEXA, limb muscle strength, maximal inspiratory and expiratory pressures and walking capacity were assessed. RESULTS: One hundred forty nine subjects were considered eligible and 101 (31 supplemented and trained, 28 supplemented, 16 trained and 26 without supplementation nor training) completed the year of follow up. Overall compliance with the supplement was 48 22 % and trained subjects attended 56 21% of programmed sessions. No changes in fat free mass were observed in any of the groups, but fat mass increased from 22.5 7.3 to 23.2 7.3 kg in all groups (p < 0.001). Upper and lower limb strength and walking capacity increased significantly in trained subjects whether supplemented or not. Maximal inspiratory pressure and right hand grip strength increased only in the supplemented and trained group. CONCLUSIONS: Resistance training improved muscle strength and walking capacity.

Aged↗

Muscle strength changes as measured by dynamometry following functional rehabilitation in individuals with spinal cord injury.

OBJECTIVE: To objectively quantify muscle strength changes over the course of functional rehabilitation and up to 15 months postdischarge in individuals with spinal cord injury (SCI). METHOD: Hand-held dynamometry was used to evaluate the strength of six muscle groups in 31 individuals after acute SCI (tetraplegia, n = 13, paraplegia, n = 18). Assessment was performed by a single research therapist at admittance and discharge from functional rehabilitation and 3 months and 15 months after discharge. RESULTS: There were significant increases of mean strength values for all muscle groups between admittance and discharge in individuals with parapalegia (median value between 13% and 22%) and tetraplegia (median value between 33% and 83%). Three months after discharge, only individuals with tetraplegia continued to significantly improve their mean strength for four muscle groups (elbow flexors-extensors and shoulder flexors-extensors). One year later, elbow flexors were significantly improved in both paraplegic and tetraplegic persons, while shoulder extensors showed significant gains only in individuals with paraplegia. Study results showed a large variability in the individual profiles of upper limb strength recovery, particularly in tetraplegic individuals. Although some individuals showed strength gains exceeding 200%, some strength decreases were noted. CONCLUSION: Recovery of muscle strength in individuals with tetraplegia over individuals with parapalegia continues for a longer period since it depends initially on recovery of muscle innervation. This study quantified strength improvements during rehabilitation and clearly showed that these gains can be maintained or even increased when the person returns to community living.

Activities of Daily Living↗

Innervation and properties of the rat FDSBQ muscle: an animal model to evaluate voluntary muscle strength after incomplete spinal cord injury.

Muscles innervated from spinal segments close to the site of a human spinal cord injury are often under voluntary control but are weak because they are partially paralyzed and partially denervated. Our objective was to develop an animal model of this clinical condition to evaluate strategies to improve voluntary muscle strength. To do so, we examined the spinal and peripheral innervation of the flexor digitorum superficialis brevis quinti (FDSBQ) muscle of the rat foot, characterized the muscle and motor unit properties, and located the FDSBQ motoneurons. Retrograde labeled motoneurons were in L4 to L6 spinal cord. Unilateral stimulation of L4 to S1 ventral roots and recording of evoked force showed that FDSBQ motor axons exited via two ventral roots (L5 and L6 or L6 and S1) in 38% of rats and via one ventral root in 62% of rats. FDSBQ motor axons traveled via two peripheral nerves, the lateral plantar (76% of axons) and sural nerves (24%). Each ventral root contributed motor axons to each nerve branch. Thus, by combining conduction block of one peripheral nerve to induce partial muscle paralysis and ventral root section to induce partial denervation, it is possible to produce in one rat muscle the consequences of many human cervical spinal cord injuries. FDSBQ muscles and motor units were mainly fast-twitch, fatigable, and composed of fast-type muscle fibers. The narrow range of motor unit forces (1-13 mN), the low mean twitch force (5.1 +/- 0.3 mN), and the large number of motoneurons (31 +/- 4) suggest that rat FDSBQ muscle is a good model of distal human musculature which is frequently influenced by spinal cord injury. We conclude that the FDSBQ muscle and its innervation provide a useful animal model in which to study the consequences of many spinal cord injuries which spare some descending inputs but also induce substantial motoneuron death near the lesion.

Animals↗

Muscle strength after successful total knee replacement: a 6- to 13-year followup.

This study investigated the long term results of muscle strength of the knee joint after total knee replacement. Isokinetic testings of 120 degrees and 180 degrees per second and isometric testings at 30 degrees and 60 degrees knee flexion were studied on 1 healthy group and 3 groups of patients 6 to 13 years after total knee arthroplasty with prosthesis designs of total condylar, low contact stress meniscal bearing, or low contact stress rotating platform. The total condylar and low contact stress rotating platform prostheses were designed for use with a cut posterior cruciate ligament, whereas the low contact stress with meniscal bearing type was designed for use with a retained posterior cruciate ligament The muscle strength ratios of hamstring to quadriceps were compared among the prosthetic designs and there were no statistical differences among patient groups. Whether the posterior cruciate ligament was cut or retained did not affect the relative muscle strength of the quadriceps and hamstring. All hamstring to quadriceps ratios from the isokinetic testings of these 3 prostheses design groups were greater than those of the healthy group, but were quite close to those of patients with cut anterior cruciate ligaments or with lower levels of daily activity. The hamstring to quadriceps ratios after successful total knee replacement were not the same as those of the healthy group even after long term (6-13 years) functional adaptation.

Aged↗

Lack of association between estrogen receptor genotypes and bone mineral density, fracture history, or muscle strength in elderly women.

The PvuII polymorphism of the estrogen receptor (ESR) gene and its relation to bone mineral density (BMD), fracture history, and muscle strength was studied in 313 postmenopausal (76 +/- 5 years) women of Caucasian origin, of whom 142 had suffered from a fragility fracture after the age of 50 years (14 with fracture of the hip, 38 of the spine, 45 of the wrist, and 85 of other bones). The ESR genotype distribution was similar in women with and without a history of fragility fracture (PP 21%, Pp 43%, pp 36% compared with PP 18%, Pp 47%, pp 35%). We did not find a correlation between the ESR genotypes and BMD at the lumbar spine, the femoral neck, or the proximal forearm. No association was found with grip or quadriceps strength. We further evaluated the relationship between the vitamin D receptor (VDR) and ESR haplotypes and BMD in a random subgroup of 270 elderly women. No differences were found in women with the BBpp versus the bbPP haplotype in the femoral neck (mean difference +/- SD, in Bbpp compared with bbPP groups: -0.05 +/- 0.15 g/cm2), the spine (0.01 +/- 0.13 g/cm2), or the forearm (0.04 +/- 0.08 g/cm2). The significant association of quadriceps strength with VDR genotypes (25% lower in BB compared with bb genotype, p < 0.05) was not influenced by ESR haplotypes. We conclude that in elderly Caucasian women the PvuII ESR polymorphism is not associated with osteoporosis, fracture history, nor muscle strength and does not influence the association of bone density and muscle strength with polymorphism of the VDR.

Aged↗

Respiratory muscle strength and gas exchange in neuromuscular diseases: comparison with chronic pulmonary emphysema and idiopathic pulmonary fibrosis.

To examine whether or not the respiratory muscle weakness is correlated with decrease in arterial oxygen tension (PaO2), respiratory muscle and pulmonary functions in 14 patients with neuromuscular diseases (NMD) were studied and compared with those of 12 patients with chronic pulmonary emphysema (CPE) and 15 patients with idiopathic pulmonary fibrosis (IPF). Respiratory muscle strength was assessed by maximal static inspiratory and expiratory mouth pressure at three lung volumes (RV, FRC and TLC). Although mean pulmonary functions in NMD showed virtually normal function, respiratory muscle strength was significantly less than the corresponding values in CPE and IPF. In NMD, maximal inspiratory mouth pressure at RV level (PImax) correlated positively with %TLC and %VC (r = 0.652 and r = 0.536, respectively). Moreover, PImax was significantly correlated with PaO2 (r = 0.561), but not with PaCO2. Maximal expiratory mouth pressure at TLC (PEmax) correlated positively with %TLC and %VC. In CPE and IPF, respiratory muscle strength had no correlation with PaO2 and PaCO2. These findings suggest that inspiratory muscle dysfunction in NMD may be one of the factors responsible for determination of the level of hypoxemia and lung volume.

Adult↗

Gender- and height-related limits of muscle strength in world weightlifting champions.

To assess factors that limit human muscle strength and growth, we examined the relationship between performance and body dimensions in the world weightlifting champions of 1993-1997. Weight lifted varied almost exactly with height squared (Ht(2.16)), suggesting that muscle mass scaled almost exactly with height cubed (Ht(3.16)) and that muscle cross-sectional area was closely correlated with body height, possibly because height and the numbers of muscle fibers in cross section are determined by a common factor during maturation. Further height limitations of muscle strength were shown by only one male champion >/=183 cm and no female champions >/=175 cm. The ratio of weight lifted to mean body cross-sectional area was approximately constant for body-weight classes </=83 kg for men and </=64 kg for women and decreased abruptly for higher weight classes. These findings suggest a nearly constant fraction of body mass devoted to muscle in lighter lifters and a lesser fraction in heavier lifters. Analysis also suggests that contractile tissue comprises approximately 30% less body mass in female champions.

Body Height↗

Proprioception and Muscle Strength in Subjects With a History of Ankle Sprains and Chronic Instability.

OBJECTIVE: To examine if patients with chronic ankle instability or a history of ankle sprains without chronic instability have worse proprioception or less invertor and evertor muscle strength. DESIGN AND SETTING: We assessed proprioception and muscle strength on the Biodex isokinetic dynamometer in the laboratory of the Department of Sports Medicine, University Hospital Ghent. SUBJECTS: Subjects included 87 physical education students (44 men, 43 women, age = 18.33 +/- 1.25 years, mass = 66.09 +/- 8.11 kg, height = 174.11 +/- 8.57 cm) at the University of Ghent in Belgium. Their ankles were divided into 4 groups: a symptom-free control group, subjects with chronic ankle instability, subjects who had sustained an ankle sprain in the last 2 years without instability, and subjects who sustained an ankle sprain 3 to 5 years earlier without instability. MEASUREMENTS: Active and passive joint-position sense was assessed at the ankle, and isokinetic peak torque was determined for concentric and eccentric eversion and inversion movements at the ankle. RESULTS: Statistical analysis indicated significantly less accurate active position sense for the instability group compared with the control group at a position close to maximal inversion. The instability group also showed a significantly lower relative eversion muscle strength (% body weight). No significant differences were observed between the control group and the groups with past sprains without instability. CONCLUSIONS: We suggest that the possible cause of chronic ankle instability is a combination of diminished proprioception and evertor muscle weakness. Therefore, we emphasize proprioception and strength training in the rehabilitation program for ankle instability.

Journal Article↗

Maximum isometric trunk muscle strength and activity at trunk axial rotation during sitting.

This study was performed to provide information relating to the twisted posture being characteristic of the driver of an agricultural tractor working in the field. The relationship of trunk axial strength and muscle activity to trunk twisting angle of prerotation was determined and quantified. Differences between tractor drivers and office workers, and between the two directions of twisting action were also studied. Nine male tractor drivers and nine male office workers performed isometric maximum efforts at about -40, -20, 0, 20 and 40 degrees of pre-set trunk twisting angles in both the clockwise and counterclockwise directions. Exerted torque, true angle of prerotation and muscle activity from left and right side of each of obliquus externus, rectus abdominis and erector spinae were measured simultaneously. The results showed that the subjects could exert the greatest torques when being prerotated in the opposite direction and the lowest torques when being prerotated in the same direction to the direction of exertion. The exerted torques were within the range of 65-145 Nm. There were large differences in obliquus externus and erector spinae activity due to the twisting direction. There were also changes in muscle activity from obliquus externus and rectus abdominis due to prerotation angle. The results raised questions concerning the involvement of the passive tissues and the use of deeper muscles during trunk axial rotation, which should be further investigated.

Abdominal Muscles↗

Relationship between motor FIM and muscle strength in lower cervical-level spinal cord injuries.

STUDY DESIGN: Retrospective analysis. OBJECTIVES: The objectives of this research were to, in subjects with lower cervical spinal cord injury (SCI), examine the relationship between strength of muscle groups as measured by the manual muscle test (MMT) and function (reflected as burden of care) as measured by individual functional independence measure (FIM) motor tasks, and investigate the extent to which MMT scores explain the variance of the motor FIM scores. SETTING: Acute rehabilitation hospitals, Boston, MA, USA. METHODS: Retrospective pilot study of 20 in-patients, age 18-62 years, with an SCI between C5 and C7. Discharge demographic variables, MMT and motor FIM scores were analyzed. Descriptive statistics, Spearman's rank correlation coefficients, stepwise regressions were performed. RESULTS: MMT scores for elbow flexion followed by shoulder flexion and wrist extension correlated with the greatest number of FIM tasks. MMT scores explained some part of the variance in the eight of 12 motor FIM tasks. In six of eight tasks, one key muscle explained a large portion of the variance. CONCLUSION: Key muscles relative to FIM tasks can be identified. These findings may help focus therapeutic interventions aimed at achievement in these tasks.

Activities of Daily Living↗

HRT and exercise: effects on bone density, muscle strength and lipid metabolism. A placebo controlled 2-year prospective trial on two estrogen-progestin regimens in healthy postmenopausal women.

OBJECTIVES: To evaluate the effect of 1- or 3-monthly sequential combinations of estradiol valerate (E2V) and medroxyprogesterone acetate (MPA) on menopausal symptoms, bone density, muscle strength and lipid metabolism in postmenopausal women. METHODS: Changes in bone mineral density (BMD), isometric muscle strength, serum lipids and climacteric symptoms were evaluated in 78 women, 49-55 years of age, with a spontaneous menopause 0.5-3 years earlier. Treatment group I received 2 mg E2V tablets for 11 days, followed by 2 mg E2V + 10 mg MPA for 10 days and placebo for an additional 7 days; treatment group II received 2 mg E2V for 70 days, 2 mg E2V + 20 mg MPA for 14 days, and placebo for 7 days. The placebo group received placebo continuously for 24 months. Each group was further randomised to exercise and non-exercise subgroups. RESULTS: Both hormone regimens significantly reduced menopausal symptoms, and prevented equally well the decrease of BMD both in the lumbar spine and proximal femur. A positive effect of exercise on BMD was observed in the placebo group. No synergistic effect of exercise and estrogen on BMD could be shown. Both hormone regimens increased the isometric strength of back extensor muscles. Serum total and LDL cholesterol decreased during the first year with both estrogen regimens. CONCLUSIONS: Estrogen-progestin regimens were equally effective in the control of menopausal symptoms and preventing bone loss, increasing muscle strength and lowering serum cholesterol.

Bone Density↗

Muscle strength impairments and gait performance deficits in kidney transplantation candidates.

The purposes of this study of patients referred for renal transplant were to describe muscle strength impairments and deficits in gait performance and to establish the relationship between them. Twenty-six patients were tested. Muscle strength measurements included grip, elbow flexion, and shoulder abduction in the upper extremities, and ankle dorsiflexion, knee extension, hip abduction, and timed sit-to-stands in the lower extremities. Gait performance (level ground and stair) was quantified using ordinal scales and speed. Compared with healthy control subjects, patients demonstrated impairments in muscle strength and deficits in gait performance. Patients with diabetes demonstrated greater impairments and deficits than patients without diabetes. Patients with an active fistula demonstrated better grip strength in their upper extremity without the fistula. Gait performance was correlated significantly with lower extremity strength, with knee extension strength and weight providing the best prediction of gait speed (R2 = 0.478 to 0.617). The results of this study suggest that patients referred for renal transplantation possess both strength impairments and deficits in gait performance, the latter being related to the former. The clinician wishing to efficiently monitor strength impairments among patients referred for transplantation can obtain a reasonable indication of them from dynamometric grip and knee extension strength measurements.

Adult↗