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PubMed1992

Oral magnesium supplementation improves metabolic variables and muscle strength in alcoholics.

Magnesium deficiency is common among chronic alcoholics, but the knowledge of oral magnesium supplementation to this group is limited. We, therefore, randomized 49 chronic alcoholics, moderate to heavy drinkers for at least 10 years to receive oral magnesium or placebo treatment for 6 weeks according to a double-blind protocol. Effects on metabolic variables and muscle strength were analyzed. Significant reduction of aspartate-aminotransferase (ASAT), alanine-aminotransferase (ALAT) and gamma-glutamyl-transpeptidase (GGT) were seen after magnesium, whereas no change was observed with placebo. Bilirubin decreased in both groups. Serum Na, Ca, and P increased significantly during magnesium therapy compared with no statistically significant change in the placebo group. Serum K and Mg increased slightly after magnesium supplementation and decreased in the placebo group, resulting in a significant difference between the two groups at the end of the study. Muscle strength increased significantly during magnesium treatment, contrasting to no change with placebo. Blood pressure, heart rate, hematological variables, serum lipids (cholesterol, HDL, TG), glucose tolerance, and creatinine were unchanged in the two groups after treatment. Alcohol consumption was similar before and during the trial and does not explain the differences between the two groups The results shows that short-term oral magnesium therapy may improve liver cell function, electrolyte status, and muscle strength in chronic alcoholics.

Administration, Oral↗

PubMed1992

Spinal mobility and trunk muscle strength in 15-year-old schoolchildren with and without low-back pain.

From a population of 1,503 schoolchildren, 38 15-year-old children suffering from low-back pain and 38 asymptomatic controls were selected for testing of spinal mobility and trunk muscle strength. The asymptomatic controls were matched by age, sex, and school class. In the group with recurrent or continual low-back pain (17 boys and 21 girls), the boys were over 4 cm taller than those in the control group. In both sexes sagittal mobility was decreased in lumbar extension and straight leg raising, and increased in lumbar flexion. Endurance strength in the abdominal and back muscles was decreased compared to the control pupils, who reported no back pain at all in the questionnaire collected 1 year before the testing procedure. The pupils reporting sciatica (n = 7) at some time, in addition to recurrent low-back pain, had decreased lumbar flexion and side bending compared to those with recurrent low-back pain (n = 31) without sciatica. The results of the study indicated that in this growing-age population there was a subgroup with recurrent low-back pain having a different spinal mobility pattern as well as decreased trunk muscle strength.

Adolescent↗

PubMed1992

Trunk-muscle strength during concentric and eccentric contraction: a comparison between healthy subjects and patients with chronic low-back pain.

The physical evaluation and exercise program of trunk muscles in patients with chronic low-back pain (CLBP) is still controversial. Many studies have been performed in the isometric and/or concentric contraction mode. Few data, however, have been reported on trunk-muscle strength during eccentric contraction, which plays a significant role in functional activities. To evaluate whether trunk-muscle strength on eccentric contraction could be applicable to the assessment and exercise of the patients with CLBP, trunk strength was measured in 20 healthy men and 16 healthy women, as well as 15 male and 10 female patients with CLBP. Maximum voluntary concentric and eccentric strength was measured during attempted flexion and extension in a seated position. In the healthy subjects, the maximum torque of extensors was greater than that of the flexors during both concentric and eccentric contraction (p less than 0.05). In flexors and extensors, maximum torque exerted on the eccentric contraction was always greater than that on the concentric contraction (p less than 0.05). Although strength was likely to be weaker in the patients with CLBP than in the healthy subjects, there were no statistical differences between the two groups. In terms of the flexor/extensor ratio of maximum torque, there were also no statistical significances between the two groups in either contraction mode. In the flexors, correlation coefficient (r) between concentric and eccentric torque was 0.84 for the healthy subjects and 0.48 for the CLBP subjects (p less than 0.05). In the extensors, the coefficient was 0.90 for the healthy patients and 0.71 for the CLBP patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1977

Voluntary isometric muscle strength of patients undergoing rehabilitation following fractures of the lower limb.

Isometric muscle strength was measured in 32 servicemen recovering from fractures of the lower limb. At the time when patients were admitted for rehabilitation there were marked reductions of strength in the injured limb of muscles acting at the hip, knee and ankle joints. Marked improvement of strength occurred during rehabilitation, but there were still significant differences between the limbs at the time of discharge from the rehabilitation unit.

Ankle Joint↗

PubMed2026

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↗

PubMed1992

Training can improve muscle strength and endurance in 78- to 84-yr-old men.

Nine men, 78-84 yr of age, participated in a dynamometer training program 2-3 times/wk, totaling 25 sessions, using voluntary maximal isometric, concentric, and eccentric right knee-extension actions (30 and 180 degrees/s). Measurements of muscle strength with a Kin-Com dynamometer and simultaneous electromyograms (EMG) were performed of both sides before and after the training period. Muscle biopsies were taken from the right vastus lateralis muscle. The total quadriceps cross-sectional area was measured with computerized tomography. Training led to an increase in maximal torque for concentric (10% at 30 degrees/s) and eccentric (13-19%) actions in the trained leg. The EMG activity increased at maximal eccentric activities. The total cross-sectional quadriceps area of the trained leg increased by 3%, but no changes were recorded in muscle fiber areas in these subjects, who already had large mean fiber areas (5.15 microns 2 x 10(3)). The fatigue index measured from 50 consecutive concentric contractions at 180 degrees/s decreased and the citrate synthase activity increased in all but one subject. The results demonstrate that increased neural activation accompanies an increase in muscle strength at least during eccentric action in already rather active elderly men and that muscle endurance may also be improved with training.

Aged↗

PubMed2026

Effects of exercise on muscle strength and characteristics in rheumatic diseases and sarcopenia: Protocol for the Care for Muscle (C4M) Study.

OBJECTIVE: Muscle weakness is prevalent in rheumatoid arthritis (RA), osteoarthritis (OA) and sarcopenia (SARC). Endurance exercises may improve mitochondrial function and oxidative capacity, while strength exercises are thought to stimulate myofibrillar protein synthesis. This study aims to compare the effects of strength and endurance exercise and explore the association between muscle characteristics and exercise outcomes in patients with RA, OA and SARC. We hypothesize that responses to endurance and strength exercises in patients with muscle weakness are influenced by intramuscular pathology including muscle morphology, mitochondrial function, and systemic inflammation, based on their disease pathology, potentially requiring personalized training schedules. METHODS: This two-arm, parallel-group exploratory trial will enroll 69 patients (23 RA, 23 OA, 23 SARC), randomized to endurance (n = 35) or muscle strength exercises (n = 34), using minimization to balance disease type and gender. The 8-week intervention includes two supervised sessions per week using a controlled cable pulley device (Reforter™) and fitness equipment, plus one weekly home-based session. The primary outcome is isokinetic muscle strength (peak torque), measured with the Biodex system®. Secondary outcomes include muscle morphology, mitochondrial function, systemic inflammation and muscle endurance (by Biodex and 6 Minute Walk test). Muscle morphology will be assessed via 3D ultrasound imaging of the vastus lateralis. Mitochondrial function will be analyzed using high-resolution respirometry on muscle biopsies. Systemic inflammation will be measured using multiplex assays or ELISA on serum samples. DISCUSSION: This study will explore differential responses to muscle endurance and muscle strength exercises in patients with RA, OA, and SARC, offering novel insights into the molecular mechanisms of muscle weakness. The findings may help identify potential mechanisms underlying variability in exercise response and provide effect size estimates to guide future confirmatory studies and more targeted exercise interventions. TRIAL REGISTRATION: ClinicalTrials.gov NCT06480643 (date of registration28-06-24).

Humans↗

PubMed1992

Salbutamol, a beta 2-adrenoceptor agonist, increases skeletal muscle strength in young men.

1. beta 2-Adrenoceptor agonists have been shown to increase rapidly lean body mass and reverse muscle wasting in several animal models of human illness. However, no published information is available for humans. In the present study, we investigated the effects of a slow-release preparation of salbutamol or a placebo on skeletal muscle functional capacity in 12 healthy men. The strength of different muscle groups was measured on two occasions before and after 14 and 21 days of treatment. 2. No significant changes in muscle strength were observed with placebo during the trial. In contrast, the strength of both quadriceps muscles increased significantly (12 +/- 3%) after 14 days on salbutamol, and remained elevated at 21 days. Whereas the strength of the hamstring muscles of the dominant leg significantly increased after 21 days on salbutamol (22 +/- 6%), the strength of the non-dominant hamstring muscles returned to baseline values. 3. There was no significant change in the grip strength of either hand in these subjects during the trial. The maximal static inspiratory mouth pressure increased significantly (7 +/- 2%) after 14 days on salbutamol, and increased further after 21 days (15 +/- 4%); the expiratory mouth pressure remained constant. No significant changes in body weight, skinfold thickness, lean body mass or limb circumferences were measured in either group. 4. These data demonstrate that short-term administration of salbutamol increases voluntary muscle strength in man. However, the magnitude and duration of this effect vary between muscle groups. This study implies that the beta 2-adrenoceptor agonists may be of therapeutic potential in altering skeletal muscle function in humans.

Adult↗

PubMed1992

Muscle strength according to level of physical exercise and educational background in middle-aged women in Finland.

The aim of this study was to examine the role of socio-economic status and the practice of physical exercise in explaining variation in muscle strength in 50 to 60-year-old women. Consequently, four study groups combining education and physical activity were formed: (1) university education, physically active; (2) university education, sedentary; (3) vocational or lower level of education, physically active; (4) vocational or lower level of education, sedentary. Maximal isometric strength of hand grip, arm flexion, body flexion and extension as well as dynamic power of the abdominal muscles were measured in 112 women. The results of the maximal isometric strength measurements were standardised by body mass index. The means of the maximal isometric strength results and sit-up tests were compared between the groups using two-way analysis of variance. The physically active women performed better than the sedentary in both the isometric and dynamic tests. Greater muscle strength was also found among the more highly educated compared with the less educated. The less educated sedentary women showed the poorest performance in the strength tests.

Body Height↗

PubMed1979

Muscle strength and speed of movement in relation to age and muscle morphology.

Maximum values for isometric strength, dynamic strength, and speed of movement (MEV) in the quadriceps muscle were measured in 114 male subjects who were between 11 and 70 yr. Biopsy samples were taken from the quadriceps muscle in 51 of the subjects (22-65 yr. old). Isometric and dynamic strength increased up to the third decade, remained almost constant to the fifth decade, and then decreased with increasing age. However, no measurable external atrophy of the quadriceps muscle, explaining the decline in strength, could be seen in old age. Histochemical changes in the muscle tissue such as decreased proportion of type II fibers and a selective atrophy of type II fibers, were seen with increasing age. The strength decline in old age was also observed to correlate significantly with the type II fiber area. Multiple regression analyses indicated, however, that mechanisms other than the type II fiber atrophy might be responsible for the decline in strength performance during aging. The implications of these findings are discussed.

Adolescent↗

PubMed1976

Postoperative restoration of muscle strength after intramedullary nailing of fractures of the femoral shaft.

The maximal isometric muscle strength of hip abduction, knee extension and knee flexion was measured in 23 patients operated on for femur diaphyseal fractures and fitted with a stable intramedullary Küntscher nail after reaming of the medullary cavity. The trauma, the immobilization and the surgery influenced the musculature of the operated as well as the intact leg. The muscle power recovered in a couple of years, but even after 2-6 years a significantly reduced power was found in the knee extensors, and a probably significant reduction in the power of the knee flexors in the operated leg when the two legs were compared. Malrotation of the fracture seemed to adversely affect the recovery of muscle power.

Adolescent↗

PubMed1992

Differential muscle strength decline in osteoarthritis of the knee. A developing hypothesis.

The ratio of quadriceps to hamstrings muscle strength (Q/H ratio) is important for the stability of the knee and for protection from excessive stress. The purpose of this study was to explore whether the Q/H ratio is altered in patients with osteoarthritis (OA). Subjects were 43 patients with physician-diagnosed OA of the knee (mean age, 65.61 years; SD, 12.74). Isometric knee flexor and extensor strength was measured with a hand-held dynamometer. Both muscle groups were weak, with relatively greater weakness in the quadriceps muscles. The mean Q/H ratio of 1.43 (SD, 0.39) was below ratios reported for young healthy adults (2.0). The low Q/H ratio might be caused by the inability to correct the measurement for gravity, but a liberal estimate of gravity correction raised the ratio only to 1.71 (SD, 0.47). The low Q/H ratio was probably not caused by physiologic changes due to aging, because the correlation between the ratio and age was low (-0.04). Since the correlation of the Q/H ratio with the usual level of pain (measured by a visual analogue scale) was negative (-0.26), the low ratio might be explained by reflex inhibition due to pain associated with disease.

Adult↗

PubMed1992

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↗

PubMed1992

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↗

PubMed1992

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

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

Adult↗

PubMed1976

Ventilatory muscle strength and endurance training.

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

Adult↗

PubMed1992

Mechanical ankle stabilisation due to the use of orthotic devices and peroneal muscle strength. An experimental investigation.

The mechanical stabilising effect of different orthotic devices and artificially applied muscular strength to the peroneal muscles is tested in cadaveric ankle joints and in vivo. Both orthotic devices as well as muscular strengths of 150 N applied to the peroneal muscles can produce a significant reduction in mechanical ankle instability. However, none of these methods alone can stabilise the ankle joint in such way to completely normalise the talar tilt and anterior drawer sign that is found in stable ankle joints. In contrast to that, clinical results in the treatment of sprained ankles with the application of an orthosis, additional muscular strengthening is the best treatment to achieve a sufficient mechanical ankle stability during the period of ligament healing. Additional factors influencing the mechanical ankle stability are supposed.

Ankle Joint↗

PubMed1977

Muscle strength and fiber composition in athletes and sedentary men.

Members of Swedish national teams in track and field events (sprinting and jumping), downhill skiing, race walking, orienteering, and a group of sedentary men were studied to examine the relationship between muslce fiber characteristics in needle biopsy samples form m. vastus lateralis and muscle strength measured as peak torque during isokinectic knee extensions. In comparison with the sedentary group the following differences were found: a) percentage fast twitch fibers was lower in the endurance athetes, b) fast to slow twitch muscle fiber area ratio was higher in the track athletes, c)track athletes and downhill skier attained higher peak torque values at all angular velocities examined. The track athletes had, however, higher torque values at the fastest angular velocity as compared to the downhill skiers, whereas there was no differnce under isometric conditions. The proportion of fast twitch fibers was related to torque produced, especially at high motion velocity. The training also appeared to affect the force-velocity relationship.

Adult↗