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Manual muscle strength testing and dynamometry for bilateral ulnar neuropraxia in a surgeon.

This case study describes a patient who had bilateral neuropraxia of the ulnar nerve following a 5-day bicycle ride across the Swiss Alps. The patient, who was a surgeon, and the referring therapist were uncertain about the diagnosis at the time of referral. The purposes of this case study are to familiarize the hand therapist with "cyclist's palsy" and to illustrate how the recoveries of both nerves were followed using manual muscle strength testing and dynamometry. A form developed for the simultaneous assessment and comparison of the two measurements is presented. Muscle strength is tested and graded as suggested in another article of this issue.

Adult↗

Influence of muscle strength on bone strength during childhood and adolescence.

In connection with the prevention of osteoporosis, paediatrics is challenged with ensuring the optimal formation of the skeletal system with maximal bone strength during childhood and youth. Biomechanical use represents the most important stimulus for activating the skeletal system. The measurement of muscle strength (grip strength) in 97 females aged 3-62 years and 71 males aged 3-61 years showed an age-dependent course. On the whole, males have greater strength with a more pronounced increase after puberty, reaching a peak maximum at 25-30 years. Females show a more moderate increase after puberty. In a pilot study, bone strength (as bone strength index-BSI) was analysed at the distal radius using peripheral quantitative computerized tomography (pQCT). BSI was calculated on the basis of the geometric data of the polar moment of resistance in combination with the cortical bone density. BSI values increase with age and reach a peak maximum at 25-30 years. There was a highly significant correlation between BSI and grip strength (r = 0.87). These relationships are especially interesting for therapeutic concepts differentiating between direct and indirect (via the muscle system) influences on the skeletal system. The non-invasive bone strength analysis in combination with muscle strength offer new perspectives for the evaluation of the functional muscle-bone unit.

Adolescent↗

Colocalization and functional analyses identify GBE1 as a gene linking muscle strength and cardiometabolic fitness.

Handgrip strength is a proxy for muscular fitness, an indicator for general health status, and is associated with cardiometabolic health. The mechanisms connecting handgrip strength to skeletal muscle function are incompletely understood. We applied integrated linkage-disequilibrium-adjusted colocalization analysis of genome-wide association study summary statistics for handgrip strength, combined with expression and splicing quantitative trait loci from skeletal muscle, and identified glycogen branching enzyme 1 (GBE1) as a candidate gene for handgrip strength. CRISPR-interference knockdown of GBE1 in immortalized human skeletal muscle cells (HMCL-7304) demonstrated decreased glycogen content and accumulation of polyglucosan bodies. Knockdown of GBE1 led to increased oxygen consumption rate, oxidative stress, and changes in mitochondrial morphology. Transcriptomic profiling of GBE1 knockdown cells identified upregulation of the human superoxide dismutase 2 and enrichment of pathways related to muscle contraction and oxidative stress responses. These functional genomic analyses prioritize GBE1 as a muscle-relevant candidate gene for handgrip strength and provide mechanistic insights to muscle fitness.NEW & NOTEWORTHY Colocalization of genome-wide association study (GWAS) loci with quantitative trait loci (QTL) in skeletal muscle tissue identified GBE1 as a candidate for handgrip strength. Cellular phenotypes with GBE1 knockdown in immortalized human skeletal muscle cells include decreased glycogen content, accumulation of polyglucosan bodies, changes in mitochondrial function and morphology, and increased expression of reactive oxygen species (ROS) scavengers. Transcriptomic changes suggest a role for GBE1 in muscle contraction and oxidative stress-mediated responses.

Humans↗

Bone mineral density, muscle strength and physical activity. A population-based study of 332 subjects aged 15-42 years.

The aim of this population-based study was to find out whether differences in levels of physical activity have an influence on bone mass quantity and whether quadriceps muscle strength is a reliable determinant of bone mass. Included were 175 men and 157 women, aged 15-42 years. Bone mineral density (BMD) was measured at various sites by dual X-ray absorptiometry (DXA) and single photon absorptiometry (SPA). Muscle strength was assessed using an isokinetic muscle force meter. A questionnaire was used to estimate the level of physical activity. We found a positive correlation between physical activity and BMD for boys at the distal forearm and for girls at the trochanter (age group 15-16 years). Active men (age group 21-42 years) had up to 9% higher BMD levels at the hip than those who were less active. Quadriceps muscle torque was not an independent predictor of BMD. Our data suggest that a higher level of physical activity-within the limits of a "normal life style"-may have a positive effect on BMD in the proximal femur of young adults, which in turn may lessen the subsequent risk of fracture.

Absorptiometry, Photon↗

Weight loss, muscle strength, and angiotensin-converting enzyme inhibitors in older adults with congestive heart failure or hypertension.

OBJECTIVES: To determine whether angiotensin-converting enzyme (ACE) inhibitor use may be associated with weight maintenance and sustained muscle strength (measured by grip strength) in older adults. DESIGN: Data from the Cardiovascular Health Study (CHS), a community-based prospective cohort study of 5,888 older adults, were used. SETTING: Subjects were recruited from four U.S. sites beginning in 1989; this analysis included data through 2001. PARTICIPANTS: CHS participants with congestive heart failure (CHF) or treated hypertension. MEASUREMENTS: The exposure, current ACE inhibitor use, was ascertained by medication inventory at annual clinic visits; the outcomes were weight change and grip-strength change during the following year. Multivariate linear regression was used, accounting for correlations between observations on the same participant over time. RESULTS: The average annual weight change was -0.38 kg in 2,834 participants (14,443 person-years) with treated hypertension and -0.62 kg in 342 participants (980 person-years) with CHF. ACE inhibitor use was associated with less annual weight loss after adjustment for potential confounders: a difference of 0.17 kg (95% confidence interval (CI)=0.05-0.29) in those with treated hypertension and 0.29 kg (95% CI=-0.25-0.83) in those with CHF. There was no evidence of association between ACE inhibitor use and grip-strength change. CONCLUSION: ACE inhibitor use may be associated with weight maintenance, but not maintenance of muscle strength, in older adults with treated hypertension.

Aged↗

Prediction of maximal back muscle strength from indices of body mass and fat-free body mass.

OBJECTIVES: The purpose of this study was to examine, in healthy volunteers, the relationship between back extensor muscle strength and body size. METHODS: The maximal voluntary isometric back extensor strength of 456 volunteers, aged 18-42 yr and with no history of low back pain, was measured in a standing, slightly flexed forward posture. This was then correlated with two indices of body size: body mass and fat-free body mass. RESULTS: Significant linear relationships were observed between back muscle strength and each of the two indices of body size. There was a gender difference in both the slope and the intercept of the regression equations describing the relationships. There was no independent influence of age within the range studied. CONCLUSION: It was possible to establish predictive equations for back extensor strength based on body size which could be used to quantify strength 'deficits', for instance in patients with low back pain, and to prescribe submaximal target forces for use in endurance training and testing.

Adult↗

Control of ventilation, respiratory muscle strength, and granulomatous involvement of skeletal muscle in patients with sarcoidosis.

Granulomatous involvement of skeletal muscle occurs in 50 to 80 percent of patients with sarcoidosis. How this may affect respiratory muscle function in sarcoidosis is not known. To attempt to answer this question, we compared respiratory function and muscle force generation, and control of ventilation in 12 untreated patients with 12 healthy, nonsmoking subjects. While seated, room air breathing, measurements included expiratory reserve volume (ERV), components of breathing pattern, and occlusion pressure at 1 s (P0.1). Three of nine patients who consented to muscle biopsy demonstrated granulomatous involvement on histologic examination, and Pmax values less than the group mean; however, some patients without muscle granulomas also demonstrated low Pmax values. Breathing pattern in the sarcoid patients was rapid and shallow, but not related to the degree of radiographic infiltration or respiratory elastance. Mean inspiratory flow (VT/TI), minute ventilation, and P0.1 were, in general, greater than in the control subjects, indicating an increase in central drive. There was a significant inverse correlation between FVC and P0.1, and a weak inverse relationship between ERV and P0.1. With no significant difference between group "effective impedances" (P0.1/(VT/TI)), findings indicate that in the sarcoidosis group, decreased muscle force generation was compensated for by an increase in central drive. Granulomatous infiltration may be one of many factors contributing to respiratory muscle weakness in sarcoidosis.

Adult↗

Three-dimensional computed tomography imaging evidence of regeneration of the semitendinosus tendon harvested for anterior cruciate ligament reconstruction: a comparison with hamstring muscle strength.

OBJECTIVE: The purpose of this study was to evaluate the regeneration of semitendinosus tendons harvested for anterior cruciate ligament (ACL) reconstruction using 3-dimensional (3D) computed tomography (CT) imaging and to compare the degree of regeneration with hamstring strength. METHODS: Twenty-nine patients who underwent ACL reconstruction using ipsilateral autogenous semitendinosus tendons were examined before surgery and 6 and 12 months after surgery by 3D CT imaging. The types of regenerated tendons and the proximal shift of the muscle-tendon junction were evaluated. RESULTS: The types of regenerated semitendinosus tendons varied from case to case. There was a positive correlation between the peak torque ratio of the hamstring muscle strength and the proximal shift of the muscle-tendon junction 6 months after surgery. The proximal shift did not affect the peak torque ratio 12 months after surgery, however. CONCLUSIONS: A proximal shift of the muscle-tendon junction may help to explain the individual differences in early postoperative hamstring muscle strength recovery.

Adolescent↗

[Exercise increases muscle strength and probably prevents hip fractures].

No hypothesis-testing studies (blinded, randomized, controlled, prospective) with fracture as endpoint have been published so far. Instead we have to rely on observational cohort and case-control studies, from which available data imply that physical activity reduces the risk of hip fracture in women and perhaps also in men. This could be the case, but repeated sampling bias could present the same outcome. Whether or not exercise reduces the number of vertebral fractures and other fragility fractures is less often evaluated. Fracture rate seems not to be reduced with cessation of exercise. The evidence that exercise modifies the risk of falling is compelling. Exercise is associated with improved muscle strength, coordination and balance. Exercise increases muscle strength even in octogenarians by 20-200 per cent, but these benefits are lost if activity is reduced. Exercise reduces the risk of falling and perhaps also the number of falls. Whether or not the number of injurious falls is reduced by exercise is even more hotly debated.

Accidental Falls↗

The assessment of levator muscle strength: a validation of three ultrasound techniques.

Levator ani muscle function is traditionally evaluated by palpation or perioneometry. Recently, three different techniques of performing this task by translabial ultrasound have been described. The authors intended to validate these new methods by correlating results with assessments performed by perineometry and palpation. One hundred consecutive women were evaluated prospectively by a physiotherapist and a gynecologist. The physiotherapist undertook an assessment by palpation (Oxford grading) and perineometry (Peritron). The gynecologist performed translabial ultrasound. Both were blinded against each other's results. Correlations between ultrasound and palpation were between 0.52 and 0.62, with displacement of the bladder neck agreeing most closely with palpation. As regards perineometry, correlations were 0.38 to 0.52, and again bladder neck displacement agreed best with the physiotherapeutic assessment. All correlations were highly significant. It appears that the assessment of levator function by ultrasound correlates strongly with vaginal palpation of muscle strength and perineometry.

Adolescent↗

Nature of age-related changes in muscle strength of the extremities of women.

Age-related changes in the muscle strength of the extremities of 123 women (20-79 years) were measured using a hand-held dynamometer. The isometric strength of three upper- and three lower-extremity muscle actions declined across ages. The magnitudes of strength decreases were a function of both the action and side tested. The earlier and steeper strength declines in actions of functional importance, e.g., knee extension, should alert those working with aging women of the potential importance of strengthening such muscle actions.

Adult↗

Respiratory muscle strength during continuous ambulatory peritoneal dialysis (CAPD).

The purpose of this study was to investigate the effect of chronic renal failure (CRF) and continuous ambulatory peritoneal dialysis (CAPD) on respiratory muscle function. Global respiratory muscle strength was assessed by measuring mouth pressures during maximum static inspiration (PIMAX) near residual volume (RV) and expiration (PEMAX) near total lung capacity (TLC), in 26 patients. Maximum pressures, spirometry and lung volumes were measured before dialysis, 4 h after the administration of 2 l of dialysate into the peritoneal cavity, and just after the next drainage. In addition, biochemical indices (urea, creatinine, sodium, potassium, calcium and phosphorus) and haematological indices (haemoglobin (Hb) and haematocrit (Hct)) were measured once before the treatment. The results showed that mean PIMAX and PEMAX were normal, with a very wide range between patients, before CAPD. However, seven patients (27%) showed a PIMAX of < 75% predicted (pred) and eight (31%) a PEMAX < 75% pred. Maximal pressures decreased significantly during CAPD and increased again after the drainage of fluid. Similarly, lung volumes were within the normal range before and decreased significantly during CAPD. The forced expiratory volume in one second to forced vital capacity (FEV1/FVC) ratio did not change. We conclude that respiratory muscle strength was preserved in the majority of the patients with chronic renal failure treated with CAPD. During CAPD, lung volumes and respiratory muscle function were decreased, demonstrating an effect of the abdominal cavity on the mechanics of the respiratory system. However, the decrease in the maximum pressures was less than 20%, indicating that CAPD is a safe procedure in patients without pre-existing pulmonary disease or uraemic pulmonary complications.(ABSTRACT TRUNCATED AT 250 WORDS)

Humans↗

Lung function, hypoxic and hypercapnic ventilatory responses, and respiratory muscle strength in normal subjects taking oral theophylline.

Methylxanthines are known to be respiratory stimulants and are thought by some to augment hypercapnic and hypoxic ventilatory drive and improve respiratory muscle strength. Hypoxic and hypercapnic ventilatory responses were measured in 10 normal subjects before, during, and after administration of theophylline for three and a half days. Pulmonary function, carbon dioxide production, and mouth pressures during maximal static inspiratory and expiratory efforts were also measured. The mean (SD) serum theophylline concentration was 13.8 (3.2) mg/l. Lung volumes and flow rates did not change significantly with theophylline. The mean (SD) values for maximum static inspiratory pressure were 152 (27), 161 (25), and 160 (24) cm H2O, respectively before, during, and after theophylline. Neither these values nor peak expiratory pressure measurements were significantly changed. The slopes of the hypercapnic ventilatory responses were 2.9 (0.9), 3.3 (1.2), and 3.3 (1.4) l/min/mm Hg carbon dioxide tension (PCO2) respectively before, during, and after theophylline administration. The respective values for the slopes of the hypoxic response were -1.4 (0.9), -1.3 (0.8), and -1.1 (0.9) l/min/1% oxyhaemoglobin saturation. None of these values changed significantly with theophylline. Theophylline, however, increased carbon dioxide production (200 to 236 ml/min) and alveolar ventilation (4.7 to 5.7 l/min) significantly, with a concomitant fall of end tidal PCO2 (35.5 to 32.9 mm Hg). It is concluded that in man oral theophylline at therapeutic blood concentrations increases carbon dioxide production and ventilation without changing pulmonary function, respiratory muscle strength, or the hypoxic or hypercapnic ventilatory response significantly.

Adult↗

Evaluation of muscle strength in patients with spinal muscular atrophy.

The first aim of this study was to evaluate the muscular strength in order to document the strength scores for patients with spinal muscular atrophy (SMA). The second aim was to analyze the differences in average strength score among the musculatures at various body parts. Twenty-five patients with type II SMA (mean age of 13.7 +/- 7.0 years) and 15 patients with type III SMA (mean age of 13.7 +/- 8.2 years) were enrolled to undergo a muscle strength evaluation using the method of manual muscle testing. For each patient, the strength of 71 muscle groups were graded using a numerical ordinal scale to obtain individual muscle group scores, average scores of the arms, legs, the musculatures around the limbs' joints, the arm flexors and extensors, and leg flexors and extensors. The data were analyzed using a statistic model of multivariate analysis of variance and paired t-test. All data were administrated respectively for type II and type III SMA. The results showed that in both types of patients, the trunk muscles and the musculatures around the hips possessed lower strength scores, whereas elbow flexors, wrist flexors and extensors, finger flexors, and diaphragms exhibited relatively higher strength scores. In type II SMA the average scores of the musculatures of the left side arms was lower than those of the right side at the joints of scapulas, elbows and wrists. Our data also showed the arm flexor scores were higher than the arm extensor scores in both types, whereas significant higher score of the leg flexor in comparison to the leg extensor was only found in the patients with type II SMA. The profiles of muscle strength and strength differences over various body parts in the patients with type II SMA as well as the type III SMA were obtained from this study.

Adolescent↗