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PubMed1993

Reliability of isokinetic muscle strength testing in 45- to 78-year-old men and women.

The test-retest reliability of isokinetic muscle strength testing was determined in 45- to 78-year-old men (N = 71; mean age = 60.2 years) and women (N = 107; mean age = 60.0 years). The dynamic muscle strength of the knee and elbow extensor (KE, EE) and flexor (KF, EF) muscle groups was measured at slow (60 degrees/sec) and fast (K = 240 degrees/sec; E = 180 degrees/sec) angular velocities using a Cybex II isokinetic dynamometer on two occasions seven to ten days apart. The mean peak torque in the second test was significantly higher (p < 0.001) in all muscle groups and both angular velocities tested in both sexes. The angle at which peak torque occurred did not change from the first to the second test except in the KF of females tested at 60 degrees/sec. Pearson's correlation coefficients (CCs; p < 0.01) in males ranged from .68 to .77 in the knee and from .71 to .84 in the elbow. In females, the CCs (p < 0.01) ranged from .58 to .74 in the knee and from .67 to .78 in the elbow. Thus in a large number of older men and women at least two tests may be necessary to determine isokinetic peak torque.

Adult↗

PubMed1980

Occupational health studies on airport transport workers. II. Muscle strength of airport transport workers.

Airport transport workers do manual work in loading and unloading the cargo space of passenger airplanes. In several types of airplanes the work has to be carried out in narrow spaces and in cramped positions. The present study describes the isometric strength of some muscle groups in 70 airport transport workers. Trunk extensors, trunk flexors, muscles involved in bimanual vertical lifting, elbow extensors, and elbow flexors were measured. A method with fixed positions and strictly isometric contractions was used. The strengths of the different muscle groups correlated with each other and with body weight; those of lifting, trunk flexors and biceps also with stature. The absolute strength of the muscle groups declined with advancing age at rates from 0.3% to 1.5% per year, the relative strength (N/kg body weight) by 0.9%-2.0% per year.

Adult↗

PubMedDate not supplied

Gait analysis and muscle strength in children with congenital pseudarthrosis of the tibia: the effect of treatment.

Twelve patients with healed congenital pseudarthrosis of the tibia underwent gait analysis and muscle strength testing to determine the functional result of treatment. Six children younger than 4 years of age presented with pseudarthroses (early onset), and six children first fractured at older than 4 years of age (delayed onset). Four children with amputations as final treatment for congenital pseudarthrosis were studied for comparison. The early-onset group had undergone an average of 4.2 surgeries and all required transankle fixation. The delayed-onset group had undergone an average of 1.5 surgeries, with one child requiring fixation across the ankle. Lack of ankle push-off and foot drop occurred in the early-onset group. Terminal stance phase ankle power generation was greatly diminished in the early-onset group. Total mechanical work performed by the affected limb, when compared to the uninvolved contralateral limb, was symmetric in delayed-onset patients and reduced by 68% in early-onset patients and by 85% in amputees. Gastrocsoleus strength was reduced by 40%. Gait and muscle strength of patients with "healed" congenital pseudarthrosis of the tibia are markedly disturbed. Early onset of disease, early surgery, and transankle fixation lead to an inefficient gait comparable to that of amputees.

Age of Onset↗

PubMed1980

Decrease of respiratory muscle strength and static lung volumes in obese asthmatics.

Ten obese patients with steroid-dependent bronchial asthma were studied. All were female nonsmokers and all had normal chest roentgenograms. The patients were divided into 2 groups according to their total lung capacity (TLC), i.e., those with decreased TLC (N = 4) and those with normal TLC (n = 6). It was found that patients with low TLC had decreased respiratory muscle strength, as measured by maximal inspiratory esophageal pressure, and that the pressure-volume (P-V) curve of the lung was shifted downward and to the right. There were no differences between the 2 groups in degree of airflow limitation, in per cent increase in body weight, and in duration and dose of steroid therapy. All had normal values of diffusion, corrected for alveolar volume. It is concluded that respiratory muscle strength is an important factor in maintaining normal static lung volumes. The data suggest that the combination of obesity and steroid therapy can cause a decrease in respiratory muscle strength in certain obese patients with bronchial asthma. The change in P-V curve seen in the patients with decreased TLC may be secondary to the decrease in static lung volumes.

17-Hydroxycorticosteroids↗

PubMed1990

Inspiratory muscle strength and respiratory drive in patients with rheumatoid arthritis.

In 15 patients with rheumatoid arthritis (RA) and in 12 age- and sex-matched normal subjects, we evaluated inspiratory muscle strength and respiratory control system. Inspiratory muscle strength was assessed by measuring maximal inspiratory pressure (MIP). Respiratory drive was assessed by evaluating surface electromyographic activity of the diaphragm (EMGd) during both room-air breathing and hypercapnic rebreathing. Compared to the predicted value (mean +/- 1.65 SD), MIP was significantly reduced in nine patients (60%). All told, we noticed a significant inverse relationship in the patients between MIP and duration of steroid therapy (p less than 0.01). During room-air breathing, both EMGd and mouth occlusion pressure (P0.1), expressed both in actual values and as percentage of MIP, were significantly greater in patients than in the normal control group (p less than 0.001 for both). Both EMGd and P0.1 (%MIP) response slopes to CO2 were significantly greater in patients than in the normal control group (p less than 0.01 and p less than 0.001, respectively) and significantly related to the functional stage of disease. During quiet breathing and for a PETCO2 of 60 mm Hg, both EMGd (p less than 0.01 and p less than 0.05, respectively) and P0.1 (%MIP) (p less than 0.01 and p = 0.001, respectively) were inversely related to MIP. These results indicate that RA patients may exhibit inspiratory muscle weakness and increased respiratory drive. Steroid myopathy and rheumatoid myositis could explain the reduction in MIP, whereas neural afferents arising from respiratory muscle, lung, or joint receptors could be involved in the observed increase in neural drive.

Arthritis, Rheumatoid↗

PubMed1995

Comparative effects of plasma exchange and pyridostigmine on respiratory muscle strength and breathing pattern in patients with myasthenia gravis.

BACKGROUND: Pyridostigmine, an acetylcholinesterase antagonist, is useful in improving respiratory function in patients with myasthenia gravis. More recently, plasma exchange has been employed in myasthenia gravis because it acts presumably by removal of circulating antibodies against acetylcholine receptors. Surprisingly, comparative data on the effects of pyridostigmine and plasma exchange on lung volumes, respiratory muscle strength, and ventilatory control system in patients with myasthenia gravis are lacking. METHODS: Nine consecutive patients with grade IIb myasthenia gravis were studied under control conditions and after a therapeutic dose of pyridostigmine. In a second study the patients were re-evaluated a few days after a cycle of plasma exchange, before taking pyridostigmine. In each subject pulmonary volumes, inspiratory (MIP) and expiratory (MEP) muscle force, and respiratory muscle strength, calculated as average MIP and MEP as percentages of their predicted values, were measured. The ventilatory control system was evaluated in terms of volume (tidal volume, VT) and time (inspiratory time, TI, and total time, TTOT) components of the respiratory cycle. Mean inspiratory flow (VT/TI)--that is, the "driving"--and TI/TTOT: that is, the "timing"--components of ventilation were also measured. RESULTS: In each patient treatment relieved weakness and tiredness, and dyspnoea grade was reduced with plasma exchange. Following treatment, vital capacity (VC) increased on average by 9.7% with pyridostigmine and by 14% with plasma exchange, and MIP increased by 18% and 26%, respectively. In addition, with plasma exchange but not with pyridostigmine forced expiratory volume in one second (FEV1) increased by 16% and MEP increased by 24.5%, while functional residual capacity (FRC) decreased a little (6.8%). The change in respiratory muscle strength was related to change in VC (r2 = 0.48). With plasma exchange, VT increased by 18.6% and VT/TI increased by 13.5%, while neither TI nor TI/TTOT changed. CONCLUSIONS: Plasma exchange can be used in patients with myasthenia gravis when symptoms are not adequately controlled by anticholinesterase agents. Plasma exchange increases respiratory muscle force and tidal volume due to changes in "driving" but not "timing" of the respiratory cycle.

Adult↗

PubMed1996

Lack of variation in muscle strength with menstrual status in healthy women aged 45-54 years: data from a national survey.

Isometric handgrip, quadriceps muscle strength and leg extensor power were assessed as part of a large representative survey of adult men and women in England. The gender ratios for these muscle strength measurements did not differ across age groups, which ranged from 25 to 65 years. Data from a subsample of women who were aged between 45 and 54 years and free of major health problems or current gynaecological problems (n = 299) and were analysed to see if there were differences in the muscle measurements according to reported menstrual status. Analysis of variance was used to compare four subgroups of women as follows: those who were still menstruating regularly (n = 89), those who had stopped altogether (n = 92), those who were irregular (n = 33) and those on hormone replacement therapy (n = 15). No significant differences were found between these subgroups in any of the three muscle measurements, body mass, fat-free mass (derived from four skinfolds), body mass index, or customary activity levels. There was a significant age difference of 2 years between two subgroups. After having controlled for this, using analysis of covariance, the outcome was not changed. These women were also compared with men in the same age range; the women had about 60% of the strength of the men and a highly significant difference remained after controlling for fat-free mass in all subgroups. No evidence was found for an ergogenic effect of the high oestrogen status conferred by natural menstruation or hormone replacement therapy.

Analysis of Variance↗

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↗

PubMed2003

Reduced muscle strength in abduction of the index finger: an important clinical sign in hand-arm vibration syndrome.

Muscle strength in extrinsic and intrinsic hand muscle was assessed in 21 patients with hand-arm vibration syndrome. Twenty-one age-matched healthy workers served as controls. Grip and pinch strength was significantly reduced in the vibration-exposed group (18%; p = 0.006 and 18% p = 0.007, respectively) as well as strength of palmar abduction of the thumb (28%; p < 0.0001) and radial abduction of the index finger (37%; p < 0.0001) while abduction strength in the little finger was not significantly reduced (7%). We postulate that the reduced manipulative skill and impaired dexterity of the hand, which often is associated with vibration syndrome, is not only of sensorineural origin but may also be an effect of reduced intrinsic muscle strength. Reduced strength in abduction of the index finger is an important indicator of intrinsic muscular dysfunction in subjects who use hand-held vibrating tools.

Analysis of Variance↗

PubMed2002

Effect of inspiratory muscle strength training on inspiratory motor drive and RREP early peak components.

This study investigated the effect of inspiratory muscle strength training (IMST) on inspiratory motor drive [mouth occlusion pressure at 0.1 s (P(0.1))] and respiratory-related evoked potentials (RREP). It was hypothesized that, if IMST increased inspiratory muscle strength, inspiratory motor drive would decrease. If motor drive were related to the RREP, it was further hypothesized that an IMST-related decrease in drive would change RREP latency and/or amplitude. Twenty-three subjects received IMST at 75% of their maximal inspiratory pressure (Pi(max)) with the use of a pressure threshold valve. IMST consisted of four sets of six breaths daily for 4 wk. P(0.1) and the RREP were recorded before and after IMST. Posttraining, Pi(max) increased significantly by 36.0 +/- 2.7%. P(0.1) decreased significantly by 21.9 +/- 5.2%. The increase in Pi(max) was significantly correlated to the decrease in P(0.1). RREP peaks P(1a), N(f), P(1), and N(1) were identified pre- and post-IMST, and there was no difference in either amplitude or latency for those peaks. These results demonstrate that high-intensity IMST significantly increased Pi(max), decreased P(0.1), but did not change the RREP.

Adult↗

PubMed2004

Muscle strength as a predictor of long-term survival in severe congestive heart failure.

AIMS: The objective of the study was to test the relationship between isolated muscle strength and outcome, and its significance in the context of other exercise variables. METHODS AND RESULTS: 122 consecutive patients (LVEF 21+/-7%) were enrolled in the study. Isokinetic strength testing of the knee extensor and flexor muscles were performed. A subset of 51 patients underwent additional upright bicycle testing with gas exchange analysis. The outcome up to 60 months was defined by event-free survival (group A, n=59) or death (group B, n=34). Patients who had been transplanted were excluded from further analysis. The peak strength of the quadriceps muscle was comparable in both groups (N.S.). In contrast, the index (value adjusted for weight) did reveal significant differences (P<0.04), similar to the peak torque of the knee flexor muscle (P<0.04), whose index was even more significant with regard to differences (P<0.01). Multivariate analysis including muscle strength variables, pVO2 and workload into one model show that the flexor strength index is the only independent variable (x2=9 P<0.003). A cut-off point of 68 Nm x 100/kg in the strength index of the flexor muscles was used to establish a significant difference between groups with regard to outcome (P<0.01). Thus, the isokinetic strength of the knee flexor muscles is related to outcome. Moreover, this parameter is superior to variables such as peakVO2 and workload.

Aged↗

PubMed1999

[Skeletal muscle strength following orthotopic heart transplantation].

AIM OF THE STUDY: Strength measurement of thigh muscles of patients after orthotopic heart transplantation (HTX) with a sedentary lifestyle, entering a cardiac rehabilitation program. DESIGN: Cross-sectional study; values are compared to patients with chronic heart failure (CHF) and healthy controls. METHODS: Isometric and isokinetic peak torque of knee extensor and flexor muscles measured on a Cybex 6000. Twenty minutes' muscle fatigue test of knee extensor muscles. Test of motor tasks of daily living. RESULTS: HTX group: n = 18, age 59 +/- 7 years, body mass index (BMI) 29 +/- 5, months after HTX 46 +/- 36 months; CHI group: n = 24, age 55 +/- 8 years, BMI 25 +/- 4, months after CHF 19 +/- 16 months; control group: n = 10, age 55 +/- 6 years, BMI 26 +/- 5. The HTX group differed significantly (p < 0.05) from the CHI group. Peak torque of knee extensor muscles: HTX: 120.3 +/- 8.4; CHI: 127.8 +/- 8.0 Nm; controls: 158.3 +/- 5.5 (ANOVA p < 0.05); peak torque of knee flexor muscles: HTX 65.6 +/- 5.9 Nm; CHI 70.1 +/- 6.2 Nm; controls 84.4 +/- 3.1 Nm(ANOVA p < 0.01). Peak torque of knee extensor muscles related to body weight: HTX: 137.4 +/- 10.0 Nm%, CHI: 162.6 +/- 9.3 Nm%, control group 202.8 +/- 5.7 Nm% (ANOVA p < 0.01). Muscle fatigue test of knee extensor muscles: isometric maximal strength (maximal voluntary contraction, MCV; HTX vs. CHI): 331.6 +/- 14.7 N vs. 335.5 +/- 18.6 N (n.s.), MVC after 5 minutes 296.3 +/- 15.7 N vs. 288.4 +/- 16.7 N; MVC after 10 minutes: 283.5 +/- 15.7 N vs. 282.5 +/- 17.7 N; MVC after 15 minutes 275.7 +/- 13.7 N vs. 280.6 +/- 21.6 N. No significant differences between groups were observed. All values were significantly lower than those of healthy controls (406.2 N; 385.9 N; 373.7 N and 369.6 N). There was a significant decline in MVC after 5 minutes compared to initial values (p < 0.01), in both patients groups but not in the control group. No further decline in MVC was observed beyond the 5th minute of the fatigue test (p > 0.05). CONCLUSION: Peak torque related to body weight and muscle endurance of knee extensor muscles of sedentary patients after orthotopic HTX do not significantly differ from those of comparable patients with CHF but do differ from those of healthy controls. Specific training of muscle strength is needed for patients even several years after orthotopic heart transplantation.

Aged↗

PubMed1997

The influence of muscle group location and race on the relationship between muscle strength and power.

OBJECTIVE: This study investigated the influence of muscle group location and racial background on the relationship between measures of muscle strength and power. It was hypothesized that both African American (AA) and Caucasian American (CA) males would exhibit similar strength-power relationships, but these relationships would be dependent upon muscle group location. EXPERIMENTAL DESIGN: A cross-sectional, comparative design was used. SETTING: The Human Performance Laboratory at the U. of Oklahoma. SUBJECTS: Normal, healthy college-aged AA (n = 14) and CA (n = 15) males volunteered for this study. MEASURES: Upper and lower body strength (IRM) was assessed using a Smithpress bench press and Polaris leg press, and upper and lower body power was measured with a piezoresistive accelerometer. RESULTS: When comparing power between upper and lower body muscle groups, both AA and CA groups exhibited similar relationships (r = 0.68 and r = 0.61, respectively), however, the relationship between upper and lower body strength was relatively stronger for the AA group (r = 0.65 vs r = 0.42). When evaluating the strength-power relationship within a given muscle group, i.e., upper or lower body, there were no racial differences, but the relationship between strength and power did differ with respect to muscle group location. CONCLUSIONS: There were stronger relationships between measures of muscular strength and power for the lower limbs when compared to the upper body indicating the importance of muscle group location rather than racial ethnicity as a confounding factor that can affect neuromuscular force production. This information is important when attempting to characterize neuromuscular function relative to specific skills or motor sport performance, thus emphasizing the principle of specificity.

Acceleration↗

PubMed2002

Evaluation of methods for normalizing muscle strength in elite and young athletes.

BACKGROUND: The following equation has been most often used in order to present recorded muscle strength (F) normalised for various measures of body size (such as body mass m) Fnor = F x m(-b). Since previous studies have provided inconsistent results, the purpose of the present one was to assess the value of the exponential parameter b (b-value) that (a) provides both the normalised strength independent of body mass and (b) demonstrates the highest possible correlation between the normalised strength and standard tests of movement performance. METHODS: Thirteen groups of male and female athletes of both different age and different sport specialisation were tested for maximal isometric force of various leg muscle groups, as well as for vertical and standing long jump. RESULTS: The data obtained on most of the experimental groups suggested that the b-value close to the theoretically predicted b=0.67, but also different from b=0 and b=1, should be used for calculation of the normalised strength independent of body mass. Although the strength normalised using b=0.67 and b=1 demonstrated higher correlation with jumping performance than the non-normalised strength (i.e., b=0), the data also suggested that b>1 could provide the highest prediction of movement performance. CONCLUSIONS: Muscle strength should be calculated as force per kg(2/3) rather than as absolute force or force calculated per kg of body mass in order to assess strength independent of body size in routine testing of muscle function. However, different and probably task specific normalisation methods could be required in order to predict performance of various movement tasks by assessed muscle strength.

Adolescent↗

PubMed2000

Muscle strength, functional mobility and vitamin D in older women.

Vitamin D deficiency may lead to loss of type II muscle fibres, and thereby to atrophy of proximal muscles with an increased risk of falling and bone fractures. The aim of the study was to determine if six months of vitamin D treatment (0.5 microg alphacalcidol) could positively influence values for muscle strength and functional mobility in vitamin D-deficient older women. Twenty-seven women entered the study which took place at a teaching hospital outpatient department. Ten vitamin D-deficient (serum 25(OH)D3 <20 nmol/L) older (>70 years) women and 13 age-matched female subjects with normal vitamin D levels (serum 25(OH)D3 >30 nmol/L) completed the study. Preand post-treatment data were obtained for isometric knee extensor strength, handgrip strength and functional mobility (walking distance over 2 minutes and the timed i'Up & Go" test). Six months of treatment with alphacalcidol led to significant improvements (compared to the controls) in values of isometric knee extensor strength (left leg: 14.6% +/- 5.7%. p=0.03; right leg: 11.5% +/- 5.0%, p=0.02) (mean +/- SEM). The achievements in the timed "Up & Go" test and 2-minute walking test did not improve in the alphacalcidol group compared to the controls after 6 months. However, within the vitamin D-deficient group, 6 months of alphacalcidol treatment led to a significant increase in the walking distance over 2 minutes (increase from 137.6 +/- 12.6 to 151.3 +/- 11.2 meters, p=0.03). The controls, with normal vitamin D levels, did not exhibit improvements in performance of any of the tests over a period of 6 months. Summarized, alphacalcidol seems to improve muscle strength and walking distance over 2 minutes in vitamin D-deficient older women.

Aged↗

PubMed1997

Isometric muscle strength of Chinese young males in Taiwan.

This paper represents the results of an anthropometric measurement of the isometric muscle strength of Chinese young males in Taiwan aged from 16 to 20 years. The study uses a sample of 120 male students and measures four types of muscle strength: (1) right arm strength in exerting pull, push, adduction, abduction, lift, and press directions with five elbow angles (60, 90, 120, 150 and 180 degrees) in seated posture; (2) grip strength of both hands; (3) backlift strength: and (4) chest expanding strength. The obtained data are analysed and listed. Comparisons are made between the results of this study and those from domestic and foreign studies available in the literature. In general, their pattern is similar, but values obtained in this study are relatively smaller than those obtained in western countries.

Adolescent↗

PubMed2004

Relationship of leg muscle strength and knee function in the early period after anterior cruciate ligament reconstruction.

The purpose of this descriptive study was to assess the relationship between knee function and the strength testing performance of various leg muscles in the early period after anterior cruciate ligament reconstruction (ACLR). Twenty-four patients who had recent ACLR (seven females and 17 males, mean age=27 years) were tested for leg muscle strength and knee function 2 weeks after surgery. The concentric peak torques of the hip and knee extensors and knee flexors were measured at 210 degrees s(-1). In addition, the latter two muscle groups were measured at 60 degrees s(-1), and also isometrically (at a knee angle of 60 degrees). Knee function was assessed using a three-dimensional motion analysis system combined with a force platform. This system determined knee joint angles, torques and powers during level walking, stair ascent and stair descent. Pearson's correlation coefficients were calculated to assess the relationships between the injured knee function variables and the injured/uninjured strength ratios. The correlation coefficients ranged (in absolute value) from 0.03 to 0.81, and were generally higher for the stair tasks compared with level walking, and highest for the knee extensors (as compared with the knee flexors and hip extensors), and the strength test velocity appears much less important than the muscle group tested. These results contribute evidence indicating the importance of knee extensor strength to knee function in the early period after ACLR.

Adult↗

PubMed1994

Breathing pattern, ventilatory drive and respiratory muscle strength in patients with chronic heart failure.

The purpose of this study was to evaluate whether chronic heart failure (CHF) may induce changes in breathing pattern and ventilatory neural drive. We studied 45 male inpatients with CHF, (25 patients in NYHA class II, 20 in class III) and 22 sex-matched post myocardial infarction patients without left ventricular dysfunction who served as controls. CHF patients underwent right heart catheterization and assessment of cardiac output by thermodilution technique. Patients and controls underwent evaluation of left ventricular ejection fraction by 2D echocardiography, spirometry, diffusion capacity, blood gases, breathing pattern, mouth occlusion pressure and respiratory muscle strength determination. Results of CHF patients were compared to controls and evaluated for differences according to the degree in severity of functional impairment. CHF patients showed a slight reduction in lung volumes and in diffusion capacity. In CHF neural drive, as assessed by mouth occlusion pressure (P0.1), was significantly increased in comparison to controls (P0.1 = 1.86 (0.7) and 1.4 (0.6) cmH2O in CHF and controls respectively). Analysis of breathing pattern showed only a slight yet significant increase in respiratory frequency while respiratory muscle strength, as assessed by measurement of maximal inspiratory and expiratory pressures (MIP and MEP respectively) was slightly reduced (MIP = 79(27) and 104(28); MEP = 111(32) and 142(33) cmH2O respectively). Observed changes were more relevant in patients with advanced NYHA functional classes whereas no relationship among indices of cardiac and respiratory function was found. We conclude that chronic heart failure induces changes in neural ventilatory drive and respiratory muscle strength related to the severity of the disease.

Cardiac Output↗