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Results for “Muscle Strength”

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PubMed1988

Maximal isokinetic muscle strength in patients with primary hyperparathyroidism before and after parathyroid surgery.

Primary hyperparathyroidism (HPT) is associated with symptoms of generalized fatigue and muscle weakness. The purpose of this study was to investigate muscular function in HPT quantitatively and to evaluate the effect of parathyroid surgery in this respect. The maximal isokinetic muscle strength (peak torque) of knee extension and flexion was measured with a Cybex-II dynamometer in 16 patients with primary HPT (mean serum calcium 2.81 +/- 0.14 mmol/l), four of whom had subjective impairment of strength, and in nine control patients submitted to hemithyroidectomy due to atoxic thyroid adenoma. Before surgery there was no significant difference in muscle strength between the two groups, neither was there any consistent relationship between the subjective feeling of muscular weakness and the measured peak torque. Seven months after surgery the HPT patients had increased their muscle strength by 8 per cent (P less than 0.05). The improvement was correlated with the pre-operative serum calcium levels (r = 0.56, P = 0.02) and was particularly seen in patients with pre-operative subjective muscular weakness. Patients with only slightly raised calcium values and without subjective muscular symptoms did not benefit clearly from surgery, compared with the controls. The study demonstrates that HPT patients, especially those with neuromuscular symptoms, can improve their muscle strength after parathyroid surgery.

Adult↗

PubMed2001

Assessing inspiratory muscle strength in patients with neurologic and neuromuscular diseases : comparative evaluation of two noninvasive techniques.

STUDY OBJECTIVES: Static mouth pressure during maximal inspiratory efforts is commonly used to evaluate inspiratory muscle strength. However, maximal inspiratory pressure (MIP) presents some potential limitations likely to be overcome by the measure of mouth pressure during a maximal sniff maneuver in patients with respiratory muscle weakness. The aim of the present study was to assess whether mouth pressure during sniff maneuver (Pmosn) is a better index of inspiratory muscle strength than MIP in patients with neurologic and neuromuscular diseases (NNMD) with and without inspiratory muscle weakness. SUBJECTS AND MEASUREMENTS: Both MIP and Pmosn were measured in 30 patients affected by various types of NNMD and in 41 control subjects. Pmosn was measured with a 5-cm latex balloon-catheter system, the balloon being held in the oral cavity with the lips closed. RESULTS: In control subjects, MIP was either similar (in female subjects) or higher (in male subjects) than Pmosn, the variation coefficients for the two tests being similar both in male subjects (19.3% vs 19.1% for MIP and Pmosn, respectively) and in female subjects (27.5% vs 26.2%, respectively). There was no difference in the Pmosn/MIP ratios observed in the different diseases (one-way analysis of variance, F = 0.29, p = 0.91). In control subjects, a significant inverse relationship between Pmosn/MIP ratio and MIP (r = - 0.66, p < 0.00001) was found, ie, the lower the MIP, the higher the Pmosn/MIP ratio, suggesting an increasing difficulty in performing MIP as MIP values decreased. The majority of patients were between the prediction limits of the regression calculated for control subjects. At variance, patients with Duchenne dystrophy and low MIP were under the prediction limits of the regression calculated for control subjects, indicating a lower-than-expected PMOSN. CONCLUSIONS: In patients with NNMD, irrespective of the etiology, we found the following: (1) Pmosn does not overcome the limitations of MIP measurement; (2) the two maneuvers are not interchangeable, but rather complement one another in the assessment of inspiratory muscle strength; (3) Pmosn may underestimate muscle strength as assessed by MIP in patients with NNMD with inspiratory muscle weakness; and (4) in patients with low MIP, the lower-than-expected Pmosn/MIP ratio confirms inspiratory muscle weakness.

Adult↗

PubMed1999

Once-weekly resistance exercise improves muscle strength and neuromuscular performance in older adults.

OBJECTIVE: To determine the effect of frequency of resistive training on gain in muscle strength and neuromuscular performance in healthy older adults. DESIGN: A randomized controlled trial with subjects assigned either to high-intensity resistance training 1 (EX1), 2 (EX2), or 3 (EX3) days per week for 24 weeks or to a control group (CO). SETTING: An exercise facility at an academic medical center. SUBJECTS: Forty-six community-dwelling healthy men (n = 29) and women (n = 17) aged 65 to 79 years. INTERVENTION: Progressive resistance training consisting of three sets of eight exercises targeting major muscle groups of the upper and lower body, at 80% of one-repetition maximum (1-RM) for eight repetitions, either 1, 2, or 3 days per week. MEASURES: Dynamic muscle strength (1-RM) using isotonic equipment every 4 weeks, bone mineral density and body composition by dual energy X-ray absorptiometry (DXA), and neuromuscular performance by timed chair rise and 6-meter backward tandem walk. RESULTS: For each of the eight exercises, muscle strength increased in the exercise groups relative to CO (P < .01), with no difference among EX1, EX2 and EX3 groups at any measurement interval. Percent change averaged 3.9 +/- 2.4 (CO), 37.0 +/- 15.2 (EX1), 41.9 +/- 18.2 (EX2), and 39.7 +/- 9.8 (EX3). The time to rise successfully from the chair 5 times decreased significantly (P < .01) at 24 weeks, whereas improvement in the 6-meter backward tandem walk approached significance (P = .10) in the three exercise groups compared with CO. Changes in chair rise ability were correlated to percent changes in quadriceps strength (r = -0.40, P < .01) and lean mass (r = -0.40, P < .01). CONCLUSIONS: A program of once or twice weekly resistance exercise achieves muscle strength gains similar to 3 days per week training in older adults and is associated with improved neuromuscular performance. Such improvement could potentially reduce the risk of falls and fracture in older adults.

Absorptiometry, Photon↗

PubMed2004

Delta-4-androstene-3,17-dione binds androgen receptor, promotes myogenesis in vitro, and increases serum testosterone levels, fat-free mass, and muscle strength in hypogonadal men.

Previous studies of Delta 4-androstene-3,17-dione (4-androstenedione) administration in men have not demonstrated sustained increments in testosterone levels, fat-free mass (FFM), and muscle strength, and failure to demonstrate androstenedione's androgenic/anabolic effects has stifled efforts to regulate its sales. To determine whether 4-androstenedione has androgenic/anabolic properties, we evaluated its association with androgen receptor (AR) and its effects on myogenesis in vitro. Additionally, we studied the effects of a high dose of 4-androstenedione on testosterone levels, FFM, and muscle strength in hypogonadal men. We determined the dissociation constant (K(d)) for 4-androstenedione using fluorescence anisotropy measurement of competitive displacement of fluorescent androgen from AR ligand-binding domain. AR nuclear translocation and myogenic activity of androstenedione were evaluated in mesenchymal, pluripotent C3H10T1/2 cells, in which androgens stimulate myogenesis through an AR pathway. We determined effects of a high dose of androstenedione (500 mg thrice daily) given for 12 wk on FFM, muscle strength, and hormone levels in nine healthy, hypogonadal men. 4-Androstenedione competitively displaced fluorescent androgen from AR ligand-binding domain with a lower affinity than dihydrotestosterone (K(d), 648 +/- 21 and 10 +/- 0.4 nm, respectively). In C3H10T1/2 cells, 4-androstenedione caused nuclear translocation of AR and stimulated myogenesis, as indicated by a dose-dependent increase in myosin heavy chain II+ myotube area and up-regulation of MyoD protein. Stimulatory effects of 4-androstenedione on myosin heavy chain II+ myotubes and myogenic determination factor expression were attenuated by bicalutamide, an AR antagonist. Administration of 1500 mg 4-androstenedione daily to hypogonadal men significantly increased serum androstenedione, total and free testosterone, estradiol, and estrone levels and suppressed SHBG and high-density lipoprotein cholesterol levels. 4-androstenedione administration was associated with significant gains in FFM (+1.7 +/- 0.5 kg; P = 0.012) and muscle strength in bench press (+4.3 +/- 3.1 kg; P = 0.006) and leg press exercises (+18.8 +/- 17.3 kg; P = 0.045). 4-androstenedione is an androgen that binds AR, induces AR nuclear translocation, and promotes myogenesis in vitro, with substantially lower potency than dihydrotestosterone. 4-androstenedione administration in high doses to hypogonadal men increases testosterone levels, FFM, and muscle strength, although at the dose tested, the anabolic effects in hypogonadal men are likely because of its conversion to testosterone.

3T3 Cells↗

PubMed2004

Trunk muscle strength, cross-sectional area, and density in patients with chronic low back pain randomized to lumbar fusion or cognitive intervention and exercises.

STUDY DESIGN: A randomized study. OBJECTIVES: To compare muscle strength, cross-sectional area, and density of the back muscles in two categories of patients with chronic low back pain, randomized to either lumbar fusion or cognitive intervention and exercises. SUMMARY OF BACKGROUND DATA: In two clinical trials, patients with chronic low back pain plus disc degeneration and postlaminectomy syndrome, respectively, were randomized to either lumbar fusion or cognitive intervention and exercises. We have previously reported that results for the primary outcome were similar at the 1-year follow-up examination. METHODS: As the treatment alternatives and test procedures were identical, the two trials were merged into one. A total of 124 patients 25 to 60 years of age were included. Muscle strength, measured by isokinetic test device and by the Biering-Sørensen Test, was measured in 112 patients, and the cross-sectional area and density of the back muscles were measured in 61 patients at the inclusion and at the 1-year follow-up examination. RESULTS: The exercise group performed significantly better in muscle strength than did the lumbar fusion group, with the mean difference at 184 Nm (95% confidence interval, 64-303 Nm; P = 0.003) and for the Biering-Sørensen Test 21 seconds (95% confidence interval, 6-36 seconds; P = 0.006). The density at L3-L4 decreased in the lumbar fusion group but remained unchanged in the exercise group. The mean difference was 5.3 HU (95% confidence interval, 1.1-9.5 HU; P = 0.01). The cross-sectional area was unchanged in both groups. CONCLUSIONS: Patients with chronic low back pain who followed cognitive intervention and exercise programs improved significantly in muscle strength compared with patients who underwent lumbar fusion. In the lumbar fusion group, density decreased significantly at L3-L4 compared with the exercise group.

Adult↗

PubMed1984

Clinical assessment of trunk flexor muscle strength in healthy girls 3 to 7 years of age.

We developed a clinical method for assessing trunk flexor muscle strength in healthy children that can be applied to assist physical therapists in determining strength accurately in pediatric patients. In this study, we assessed trunk flexor muscle strength in 75 healthy girls 3 to 7 years of age. Muscle strength was graded on a scale of 0 to 5 using modified, manual muscle testing methods. These methods attempted to minimize the amount of hip flexor muscle activity during trunk flexion and allow more isolated action of the abdominal trunk flexor muscles. The frequency of Normal (Grade 5) strength first appeared to predominate at age 5 years with the majority of children demonstrating Normal (Grade 5) strength by age 7 years. Regression analysis illustrated a positive linear relationship (beta = .37, p less than .001) between mean muscle grade and age group. We discuss muscle cross-sectional area, muscle-fiber diameter, muscle-cell number, maturation of the central nervous system, and changes in body proportions with age as possible contributing factors to the results of this study.

Abdominal Muscles↗

PubMed2005

Quantitative trait loci for human muscle strength: linkage analysis of myostatin pathway genes.

This study reports the results of a multipoint linkage study that aims to unravel the genetic basis of muscle strength and muscle mass in humans. Myostatin (GDF8) is known to be a strong inhibitor of muscle growth in animals. However, studies examining human myostatin polymorphisms are rare and are limited to the GDF8 gene itself. Here, the contribution to isometric and concentric knee strength of nine key proteins involved in the myostatin pathway is studied in a nonparametric multipoint linkage analysis by means of a variance components and regression method. A sample of 367 healthy young male siblings was phenotyped on an isokinetic dynamometer and genotyped for markers of the myostatin pathway genes. Three of the loci were found significantly linked with a quantitative trait locus (QTL) for knee muscle strength. First, D13S1303 showed replication of an explorative single-point linkage study with a maximum LOD score of 2.7 (P = 0.0002). Second, maximum LOD scores of 3.4 (P = 0.00004) and 3.3 (P = 0.00005) were observed for markers D12S1042 and D12S85, respectively, at 12q12-14. Finally, marker D12S78 showed an LOD score of 2.7 at 12q22-23. We conclude that several genes involved in the myostatin pathway, but not the myostatin gene itself, are important QTLs for human muscle strength. An additional set of valuable candidate genes that were not part of the myostatin pathway was found in the chromosome 12 and 13 genomic regions.

Adolescent↗

PubMed2004

Training-induced changes in muscle CSA, muscle strength, EMG, and rate of force development in elderly subjects after long-term unilateral disuse.

The ability to develop muscle force rapidly may be a very important factor to prevent a fall and to perform other tasks of daily life. However, information is still lacking on the range of training-induced neuromuscular adaptations in elderly humans recovering from a period of disuse. Therefore, the present study examined the effect of three types of training regimes after unilateral prolonged disuse and subsequent hip-replacement surgery on maximal muscle strength, rapid muscle force [rate of force development (RFD)], muscle activation, and muscle size. Thirty-six subjects (60-86 yr) were randomized to a 12-wk rehabilitation program consisting of either 1) strength training (3 times/wk for 12 wk), 2) electrical muscle stimulation (1 h/day for 12 wk), or 3) standard rehabilitation (1 h/day for 12 wk). The nonoperated side did not receive any intervention and thereby served as a within-subject control. Thirty subjects completed the trial. In the strength-training group, significant increases were observed in maximal isometric muscle strength (24%, P < 0.01), contractile RFD (26-45%, P < 0.05), and contractile impulse (27-32%, P < 0.05). No significant changes were seen in the two other training groups or in the nontrained legs of all three groups. Mean electromyogram signal amplitude of vastus lateralis was larger in the strength-training than in the standard-rehabilitation group at 5 and 12 wk (P < 0.05). In contrast to traditional physiotherapy and electrical stimulation, strength training increased muscle mass, maximal isometric strength, RFD, and muscle activation in elderly men and women recovering from long-term muscle disuse and subsequent hip surgery. The improvement in both muscle mass and neural function is likely to have important functional implications for elderly individuals.

Aged↗

PubMed1997

Muscle strength in rheumatoid elbow: quantitative measurement and comparison to Larsen's X-ray grade.

Accurate assessment of elbow function is important to determine the total ability of the arm. The purpose of this study was to clarify the relationship between isometric muscle strength of the elbows of patients with rheumatoid arthritis (RA) and Larsen's X-ray evaluation. Fifty-six elbows of 45 RA patients aged 47 to 77 years (mean age, 63 years) were tested. Muscle strength was measured with an isometric torque-cell dynamometer. Test-retest reliability of the dynamometer was proven by measuring 12 elbows of 6 healthy young men. In RA patients, elbow flexion and extension strength decreased in proportion to increases in the severity of Larsen's grades from Grade 1 to 4. However, Grade 5 elbows had greater muscle strength than those in Grade 4. Forearm pronation and supination strength also decreased in proportion to increases in the severity of Larsen's grades from Grade 1 to 5. This quantitative study made it clear that the muscle strength of RA patients' elbows almost completely correlates to X-ray finding according to the grade of Larsen's evaluation based on X-rays. With regard to muscle strength of postoperative elbows, both flexion strength and supination strength after total elbow replacement (TER) were about two times greater than before TER, and after synovectomy it was as great as those in non-operative RA patients of Grade 2.

Adult↗

PubMed2002

Muscle strength following direct injection of doxorubicin into rabbit sternocleidomastoid muscle in situ.

Direct intramuscular injection of doxorubicin results in permanent myofiber loss. A previous phase I trial demonstrated that such injections could successfully treat blepharospasm and hemifacial spasm. Our previous in vitro study demonstrated that doxorubicin resulted in a dose-dependent reduction in isometric force generation in sternocleidomastoid muscle in rabbits. This present study examined alterations in force generation in these treated muscles in situ, i.e., with the blood and nerve supply intact. Two months after a single doxorubicin injection, functional changes in peak twitch, tetanic force generation, and fatigue rate were assessed in control and doxorubicin-treated sternocleidomastoid muscles in rabbits. Peak force measurements were reduced in the treated muscles. These reductions in muscle strength were significantly greater at tetanic peak amplitudes. Fatigue rate was not altered by doxorubicin treatment of the sternocleidomastoid muscles. These findings support the potential clinical use of doxorubicin chemomyectomy for the treatment of patients with cervical dystonia.

Animals↗

PubMed2003

Short-term recovery of limb muscle strength after acute stroke.

OBJECTIVES: To document, by using norm-referenced strength measures, the recovery of limb muscle strength of patients undergoing stroke rehabilitation and to examine the relation between comorbidities and the recovery of strength after stroke. DESIGN: Retrospective analysis of data from a consecutive convenience sample of patients examined clinically between 1994 and 1997. SETTING: Acute inpatient rehabilitation unit. PARTICIPANTS: Fifty patients with stroke who were able to follow commands and were examined during acute rehabilitation by a single examiner (AWA). INTERVENTIONS: Stroke rehabilitation emphasizing early movement, exercise with resistance, and daily functional activities. MAIN OUTCOME MEASURE: The strength at discharge of 7 muscle actions (shoulder abduction, elbow flexion, elbow extension, wrist extension, hip flexion, knee extension, ankle dorsiflexion) measured bilaterally with a hand-held dynamometer and compared with norm-referenced values. RESULTS: Differences in strength between admission and discharge were significant for all muscle actions on the weaker side and for 4 of the 7 muscle actions on the stronger side. At discharge, the bilateral strength of all muscle actions was weaker than predicted by data from healthy individuals of comparable age, sex, and weight (F>17.000, P<.001). Strength did not differ between subjects who did and did not have a previous stroke or comorbidities. CONCLUSIONS: Subjects undergoing inpatient rehabilitation soon after stroke experienced an increase in limb muscle strength bilaterally. This increase was not influenced by previous stroke or comorbidities.

Adult↗

PubMed2002

Relation between use of angiotensin-converting enzyme inhibitors and muscle strength and physical function in older women: an observational study.

BACKGROUND: Angiotensin-converting enzyme (ACE) inhibitors prevent decline in physical function in patients with congestive heart failure (CHF). We aimed to see whether ACE inhibitors also prevent reduction in physical performance and in muscle strength in older women who do not have CHF. METHODS: We assessed 3-year rates of decline in both knee extensor muscle strength and walking speed in 641 women with hypertension who had participated in the Women's Health and Aging Study. Women were stratified into four groups according to type and duration of antihypertensive drug treatment. 61 had used ACE inhibitors continuously, 133 intermittently, 146 never, and 301 had used other hypertensive drugs either continuously or intermittently. FINDINGS: Participants who had taken ACE inhibitors continuously had a lower mean 3-year decline in muscle strength of -1.0 kg (SE 1.1) compared with -3.7 (0.5) kg in continuous/intermittent users of other antihypertensive drugs (p=0.016) and with -3.9 kg in those who had never used antihypertensives (p=0.026). Muscle strength fell by 3.0 kg in 3 years in both continuous and intermittent users of ACE inhibitors (p=0.096). Mean 3-year decline in walking speed in continuous ACE inhibitor users was -1.7 cm/s compared with -13.6 cm/s in intermittent users of ACE inhibitors (p=0.015), -15.7 cm/s in continuous/intermittent users of other antihypertensive drugs (p=0.002), and -17.9 cm/s in never users of antihypertensive drugs (p=0.001). INTERPRETATION: ACE inhibitor treatment may halt or slow decline in muscle strength in elderly women with hypertension and without CHF.

Aged↗

PubMed1971

Back muscle strength, lifting, and stooped working postures.

When lifting loads and working in a forward stooped position, the muscles of the back rather than the ligaments and bony structures of the spine should overcome the gravitational forces. Formulae, based on measurements of back muscle strength, for prediction of maximal loads to be lifted, and for the ability to sustain work in a stooped position, have been worked out and tested in practical situations. From tests with 50 male and female subjects the simplest prediction formulae for maximum loads were: max. load = 1.10 x isometric back muscle strength for men; and max. load = 0.95 x isometric back muscle strength - 8 kg for women. Some standard values for maximum lifts and permissible single and repeated lifts have been calculated for men and women separately and are given in Table 1. From tests with 65 rehabilitees it was found that the maximum isometric strength of the back muscles measured at shoulder height should exceed 2/3 of the body weight, if fatigue and/or pain in the back muscles is to be avoided during work in a standing stooped position.

Journal Article↗

PubMed1999

[Peripheral muscle strength in stable COPD patients: correlation with respiratory function variables and quality of life].

The aim of this study was to assess peripheral muscle strength in patients with chronic obstructive pulmonary disease (COPD) using a simple test and to look for correlation with function variables, physiological strength variables and quality of life parameters. Twenty-three COPD patients with moderate to severe air-flow limitation (FEV1 = 39 +/- 12%) in stable phase but displaying inability to carry out daily tasks were enrolled. Peripheral muscle strength was assessed in all patients by measuring the maximum load in a single repetition of five simple upper and lower extremity exercises performed at a multi-gymnastics station. Results were compared to respiratory function variables (FVC, FEV1, FEV1/FVC and gasometry), to results of an exercise test on a cycle ergometer with monitoring of respiratory gases (VEmax, VO2max and Wmax), to endurance (minutes) to dyspnea (Mahler's scale) and to quality of life (Chronic Respiratory Disease Questionnaire-CRDQ). No relation between functional parameters and endurance in minutes was found. Minute ventilation (VE) proved to be significantly related to oxygen intake (VO) and maximum work in the stress test. Dyspnea on Mahler's scale was unrelated, but fatigue variables and emotional function variables on the CRDQ were related. We conclude that peripheral muscle strength is unrelated to level of flow limitation or exercise tolerance in COPD patients. Peripheral muscle strength is related, however, to maximum work load and some aspects of quality of life.

Aged↗

PubMed1999

Relationship between shoulder muscle strength and functional independence measure (FIM) score among C6 tetraplegics.

The degree of disability varies widely among C6 tetraplegic patients in comparison with that at other neurological levels. Shoulder muscle strength is thought to be one factor that affects functional outcome. The aim of this study was to examine the relationship between shoulder muscle strength and the Functional Independence Measure (FIM) motor score among 14 complete C6 tetraplegic patients. The FIM motor score and American Spinal Injury Association (ASIA) motor score of these patients were assessed upon discharge. We evaluated muscle strength of bilateral scapular abduction and upward rotation, shoulder vertical adduction and shoulder extension by manual muscle testing (MMT). The total shoulder strength score was calculated from the summation of those six MMT scores. The relationships among ASIA motor score, total shoulder strength score and FIM motor score were analyzed. The total shoulder strength score was significantly correlated with the FIM motor score and the score of the transfer item in the FIM. In the transfer item of the FIM, the total shoulder strength score showed a statistically significant difference between the Independent and Dependent Group. Shoulder muscle strength appears to be an important factor in the functional abilities of those with C6 complete tetraplegia. Functional variation depends on the strength of shoulder muscles, especially among C6 tetraplegics.

Activities of Daily Living↗

PubMed2006

Whole-body vibration training compared with resistance training: effect on spasticity, muscle strength and motor performance in adults with cerebral palsy.

OBJECTIVE: The aim of this study was to evaluate the effect on spasticity, muscle strength and motor performance after 8 weeks of whole-body vibration training compared with resistance training in adults with cerebral palsy. METHODS: Fourteen persons with spastic diplegia (21-41 years) were randomized to intervention with either whole-body vibration training (n=7) or resistance training (n=7). Pre- and post-training measures of spasticity using the modified Ashworth scale, muscle strength using isokinetic dynamometry, walking ability using Six-Minute Walk Test, balance using Timed Up and Go test and gross motor performance using Gross Motor Function Measure were performed. RESULTS: Spasticity decreased in knee extensors in the whole-body vibration group. Muscle strength increased in the resistance training group at the velocity 30 degrees /s and in both groups at 90 degrees /s. Six-Minute Walk Test and Timed Up and Go test did not change significantly. Gross Motor Function Measure increased in the whole-body vibration group. CONCLUSION: These data suggest that an 8-week intervention of whole-body vibration training or resistance training can increase muscle strength, without negative effect on spasticity, in adults with cerebral palsy.

Adult↗

PubMed1995

Quantitative measurement of muscle strength in the mouse.

We have designed a special dynamometer for measuring mouse forelimb muscle strength and endurance. The device exploits a mouse's tendency to grasp a horizontal metal bar while suspended by its tail. A threshold value for the magnitude and duration of force that the mouse can exert is obtained by first allowing the animal to grasp the bar and then applying a steadily increasing downward force to the opposite end of a cable to which the mouse attaches. The bar is attached to a force transducer and pen recorder to produce a permanent record of the force produced by the mouse. Test results show that this dynamometer provides quantitative measurements of muscle strength and endurance in the mouse. Comparisons between experimental groups of normal and wobbler mice, a model for lower motor neuron disease, show that both the force exerted by the animals (muscle strength), and the duration of the pull (endurance), can be quantified and statistically analyzed. This technique can be used as an assay for quantitating the effects of in vivo drug treatments on murine neuromuscular disorders.

Animals↗

PubMed2000

Relationships between physical activity, physical fitness, muscle strength and nutritional state in 5- to 11-year-old children.

The purpose of the present study was to assess different aspects of physical activity and fitness in order to develop a basis for sport programmes for overweight and obese children. Eighty-eight prepubertal children (49 boys, 39 girls, 4.8-11.4 years old, 61% obese, 14% overweight and 25% normal weight) were examined. Body composition was assessed by combined use of anthropometrics and bioelectrical impedance analysis. Resting energy expenditure (REE) and total energy expenditure (TEE) were measured by indirect calorimetry (IC) and individually calibrated 24-h heart rate (HR) monitoring, respectively. Activity-related energy expenditure (AEE) and physical activity level (PAL) were calculated from TEE and REE. Fitness [assessed by O2-pulse, respiratory exchange ratio (RER) at submaximal work intensities] was determined by ergometry. The maximal isometric muscle strength of the legs (m. quadriceps, Fa max, m. ischiocruralis, Fb max) was measured by computer tensiometry. Children were grouped according to their nutritional state, AEE, O2-pulse and muscle strength. When compared with normal weight children, obese and overweight children had increased fat mass (FM), fat-free mass (FFM), waist-to-hip ratio and REE, but no group differences were observed for TEE, AEE, and PAL. Obese and overweight children spent more hours per day watching TV. After correction for body weight and FFM, no group differences in REE were observed, but normal weight children had a higher O2-pulse than overweight and obese children. By contrast, RER was increased in the latter group. The fittest group had the lowest body weight, BMI, FM and FFM. Children with a low O2-pulse spent more hours per day watching TV. Grouping children according to their degree of muscle strength, younger children (4-7.5 years) did not show group differences in nutritional state, energy expenditure, physical activity and fitness. However, in the group of 7.6- to 11-year-old children, those with the greatest muscle strength and FFM had reduced BMI, skin folds, FM and FFM. FM correlated inversely with O2-pulse, but was not associated with TEE, AEE, PAL or muscle strength. By contrast TV consumption was positively associated with FM. To summarize, overweight and obese children were less fit and watched more TV than their normal weight counterparts. FM did not correspond to TEE, AEE or PAL. Muscle strength was not associated with FM in young children, but was inversely associated with FM in older children. Our cross-sectional data are consistent with the idea that increased fitness and reduced physical inactivity may prevent children from being overweight.

Body Composition↗