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PubMed1996

Effects of unilateral concentric-only dynamic constant external resistance training.

The purposes of this investigation were to examine the effects of unilateral concentric-only leg extension dynamic constant external resistance (DCER) training on: (a) concentric DCER strength in the trained and contralateral (untrained) legs, (b) concentric isokinetic peak torque-velocity curves in the trained and contralateral legs, and (c) retention of concentric DCER strength and concentric isokinetic peak torque in the trained and contralateral legs following detraining. Sixteen adult male (mean age +/- SD = 24.0 +/- 4.0 yr) volunteers comprised training (TR, n = 8) and control (CTL, n = 8) groups. The TR group trained the nondominant limb with concentric-only leg extension DCER exercise (3-5 sets of 6 repetitions at 80% of one-repetition maximum load) for eight weeks followed by eight additional weeks of detraining. The CTL group did not train. All subjects were tested pretraining, posttraining and detraining for unilateral concentric-only leg extension DCER strength as well as concentric isokinetic peak torque at 1.05, 2.09, 3.14, 4.19, and 5.24 rad.s-1 in both legs. Mixed factorial ANOVAs, follow-up, and post-hoc analyses indicated that the training resulted in increased DCER strength in both the trained (42%) and contralateral (15%) legs as well as isokinetic peak torque in the trained leg (7-19%) at velocities ranging from 1.05 to 5.24 rad.s-1. There was no cross-training effect, however, for isokinetic peak torque. Furthermore, the training-induced increases in DCER strength and isokinetic peak torque were retained across eight weeks of detraining.

Adult↗
PubMed1987

Cardiovascular adjustments induced by training evaluated during semisupine isotonic exercise and recovery period: an echocardiographic study.

Two groups of subjects were examined: trained athletes (group A) and a sedentary control group (group B). The subjects performed submaximal bicycle exercise in the semisupine position to evaluate the differences between the two groups with regard to cardiovascular response during exercise and recovery and to point out all the changes due to training. During the first part of exercise, cardiac output increased contemporary with heart rate and myocardial contractility as shown by the trend of the ejection fraction, higher in group A, under the same level of total vascular peripheral resistances. Later there was an increase of cardiac output for a further increase of heart rate and cardiac inotropism due to the homeometric mechanism. During recovery the heart rate and peripheral vascular resistance reduction led to an increase of venous return which set up the Frank-Starling mechanism via an increase of left ventricular dimensions. These adjustments were more efficient in group A. During exercise and recovery the heart rate-pressure product was constantly lower in group A with a significant difference to group B. Therefore, trained athletes' myocardium is more efficient than that of the sedentary group because it performs an external work load with a lower oxygen consumption.

Adult↗
PubMed1986

Structural changes in skeletal muscle tissue with heavy-resistance exercise.

Muscle strength, muscle cross-sectional area, fiber size, fiber type distribution, capillarity, and mitochondrial volume were estimated before and after 6 weeks of heavy-resistance exercise. Isokinetic torque production of the knee extensor muscles increased by a total of 17.6%, mainly during the first half of the training period. The cross-sectional area of the vastus lateralis muscle increased by 8.4%, mainly during the second half of the training period. Morphometrically determined fiber size, fiber type distribution, and capillarity from biopsies of vastus lateralis did not change significantly with training. Likewise, the surface densities of inner and outer mitochondrial membranes as well as the volume density of myofibrils remained unchanged. In contrast, the volume density of mitochondria decreased by 9.6%. However, due to the increase in total muscle volume, the calculated absolute volume of mitochondria remained constant, whereas the absolute volume of myofibrils increased by 10%. It is concluded that strength training of short duration in previously untrained young male subjects does not change the ultrastructural composition of mitochondria and that the apparent dilution of mitochondria can quantitatively be accounted for by the increase in myofibrillar volume.

Adenosine Triphosphatases↗
PubMed2000

Distal biceps tendon rupture operated on with the Boyd-Anderson technique: follow-up of 9 patients with isokinetic examination after 1 year.

We operated on 9 patients for distal biceps tendon rupture using the Boyd-Anderson technique. All patients were re-examined after at least 1 year using a questionnaire, radiographs, motion measurements and isokinetic testing. 2 patients had temporary radial nerve dysfunction and 7 patients had diminished forearm rotation. Elbow flexion strength was reduced by median 13% and supination strength by 19%. We think the Boyd-Anderson technique can be recommended, but slightly reduced strength and forearm rotation must be expected.

Adult↗
PubMedDate not supplied

Longitudinal changes in isokinetic leg strength in 10-14-year-olds.

This study used multilevel regression modelling to longitudinally investigate the influences of age, sex, body size, skinfold thicknesses and maturity on the development of isokinetic knee extension and flexion on eight occasions over a 4-year period. Forty-one subjects (20 boys and 21 girls) were measured and 295 isokinetic leg strength tests and associated measures were successfully completed. Subjects were aged 10.0 +/- 0.3 years at the onset of the study. Stature, body mass, triceps and subscapular skinfold thicknesses, and sexual maturation (according to pubic hair development) were assessed at each test occasion. Isokinetic concentric knee extension and flexion of the dominant leg were determined to elicit maximal peak extension (PET) and flexion torque (PFT). Statistical significance was accepted at p < 0.05. Multilevel regression modelling indicated that stature and mass were significant predictors of both PET and PFT. Age and maturity were non-significant explanatory variables once stature and mass had been accounted for. Skinfold thickness exerted a significant negative effect independent of mass and stature on PFT but not PET. At test occasion 8, cross-sectional areas (CSAs) of the knee extensors (ExCSA) and flexors (FlexCSA) were determined using magnetic resonance imaging on 23 boys and 14 girls and examined as predictors of isokinetic leg strength. There were no significant sex-related differences in PET or PFT. Pearson product moment correlation coefficients indicated a significant relationship between ExCSA and PET and FlexCSA and PFT for both boys and girls. Analysis of covariance (ANCOVA) demonstrated that ExCSA and FlexCSA were significant explanatory variables for PET and PFT, respectively, but became non-significant once stature and mass had been introduced into the analysis. To conclude, there were no significant sex differences in PET or PFT between the ages of 10 and 14 years and the development of PET and PFT could be accounted for by the increase in stature and mass. Age, maturity and thigh muscle CSA were all non-explanatory variables in the production of PET and PFT once body size had been controlled for.

Adolescent↗
PubMed2002

Forward-dynamics simulation of anterior cruciate ligament forces developed during isokinetic dynamometry.

A mathematical (computer) model was developed and used to study the mechanics of the human knee during extension exercises employing an isokinetic dynamometer. All parts of the body were fixed to ground, except for the right shank and foot, which were free to move in the parasagittal plane. A linkage attached the dynamometer to the shank; tibiofemoral articulation consisted of single-point contact, allowing both sliding and rolling to occur. Physiologically based representations of ligaments and muscles imparted forces to the shank. A forward dynamics simulation was performed to calculate the forces developed in the knee for isokinetic speeds ranging from 0 (isometric exercise) to 300 degrees /s. Simulations were conducted for a constant-speed phase during isokinetic knee extension exercise. It was assumed for the duration of each simulated exercise that the quadriceps were fully activated and the other muscles were fully deactivated. The force in the anterior cruciate ligament was found to be governed by the force-velocity properties of the quadriceps; the model predicts that 300 deg/sec isokinetic exercise can reduce the force transmitted to the ACL by almost a factor of two compared with that present during isometric knee extension.

Anterior Cruciate Ligament↗
PubMed1999

The effects of strength training on strength and health-related quality of life in older adult women.

The short-term effects of an accessible exercise intervention on the strength and health-related quality of life (HRQOL) among older adult women were evaluated. We conducted an 8-week resistance training intervention utilizing elastic bands in 62 community-dwelling women with a mean age of 68 years. Participants were randomly assigned to either an exercise or a control group. Pre- and postintervention assessments included strength tests and HRQOL. Results revealed significant increases in three major muscles compared to the control group. However, there were no significant changes on either mental or physical health functioning. The elastic bands provide older adult women with an inexpensive, practical exercise program that effectively increases strength within 8 weeks but may have little effect on self-reported HRQOL.

Aged↗
PubMed1988

Effects of heavy-resistance triceps surae muscle training on strength and muscularity of men and women.

The purpose of this study was to determine selected functional and structural effects of heavy-resistance training on the triceps surae muscles of men and women. We pretested 28 men and 28 women for triceps surae muscle isotonic strength and muscularity after five practice sessions that familiarized them with the study equipment. Triceps surae muscle isotonic strength was determined using a 1-repetition maximum seated heel raise. Muscularity involved the measurement of relaxed lower leg circumference and net circumference and ultrasonically determined triceps surae muscle thickness. Twenty-eight subjects (14 men, 14 women) were selected randomly after pretesting to participate in 24 sessions of standardized weight training primarily involving the triceps surae muscles, and the remaining subjects (14 men, 14 women) served as nontraining controls. After eight weeks of training, triceps surae muscle isotonic strength had increased significantly (p less than .001) for both men and women in the Treatment Group when compared with the Control Group. No other dependent variables changed significantly. We concluded that eight weeks of heavy-resistance training involving the triceps surae muscles elicits similar significant increases in isotonic muscle strength in both men and women without concurrent increases in muscularity.

Adult↗
PubMed1989

Back support mechanisms during manual lifting.

The ability of individuals to lift heavy loads without injury to the vertebral elements has led to the formulation of several explanations of this phenomenon. In this article, the existing literature on lifting is reviewed and mechanisms of back support during lifting are described. These mechanisms include the intra-abdominal pressure mechanism, the thoracolumbar fascia mechanism, and combinations of these mechanisms with the use of the erector spinae, multifidus, and psoas muscles. Physical therapists are often responsible for teaching patients and workers "proper" lifting techniques; however, controversy exists concerning the proper lift. Although lifting with the lower back in flexion and lifting in extension have been proposed, there are indications for each depending on individual circumstances. Lifting instructions for workers without low back injuries should be distinguished from instructions for patients with low back pain. General rules for lifting include: plan the lift, avoid twisting, keep the load close to the body, and bend at the knees.

Back↗
PubMed1994

Endurance training in patients with multiple sclerosis: five case studies.

BACKGROUND AND PURPOSE: The purpose of this report is to describe how patients with multiple sclerosis increased the isokinetic peak torque of their knee flexors and perceived well-being after an endurance training program. SUBJECTS AND METHODS: Five patients trained for 4 to 6 weeks using an endurance program for the lower extremities. Before and after training, the subjects performed 50 repeated maximum knee flexions, with simultaneous recording of surface electromyographic activity of two knee flexors, on 3 separate days using an isokinetic dynamometer. Throughout the tests, the subjects rated their perception of peripheral muscle fatigue. Visual analog scales (VAS) were used to rate different aspects of well-being. RESULTS: Both the perception of peripheral fatigue and the different VAS ratings had changed positively after training. Three patients achieved higher peak torque levels throughout the posttraining endurance test. CONCLUSION AND DISCUSSION: Based on these positive results, the authors conclude that more comprehensive studies of exercise prescription in patients with multiple sclerosis are desirable.

Activities of Daily Living↗
PubMed2002

Thera-Band Tubing.

Explore the source record for details and available documents.

Durable Medical Equipment↗
PubMed2006

Two simple, reliable and valid tests of proximal muscle function, and their application to the management of idiopathic inflammatory myositis.

OBJECTIVE: To develop objective, isotonic, reliable and valid tests of upper (UL) and lower (LL) limb proximal muscle function for use in the management of idiopathic inflammatory myositis (IIM). METHODS: The '1 kg arm lift' test was devised to assess UL function and the '30 s chair stand' test was used for LL function. The tests were performed in 30 control subjects to determine short (24 h) and long (2 week) interval test-retest reliability. Thirty-two patients with IIM were assessed over a period of 2 yr. RESULTS: In the control group both tests showed excellent test-retest reliability; Spearman correlation >0.8 for both tests over both time intervals. Twenty-four of the 32 IIM patients remained in remission over a mean period of 20.7 months throughout which scores varied by <5 for the '1 kg arm lift' test and <3 for the '30 s chair stand' test from each patient's mean score. Eight patients relapsed with scores falling by >5 for the '1 kg arm lift' test and by >3 for the '30 s chair stand' test from the mean remission score in each case. Both UL and LL scores correlated inversely with serum creatinine kinase. CONCLUSION: Two isotonic tests of proximal muscle function are described. They exhibit excellent test-retest reliability and demonstrate construct validity in IIM. Both tests are responsive to changes in disease activity, offer physiological and practical advantages over existing tests of muscle function and are suitable for use in clinical practice.

Adult↗
PubMed1988

Comparative effects of halothane, enflurane, and isoflurane at equipotent anesthetic concentrations on isolated ventricular myocardium of the ferret. II. Relaxation.

The effects of halothane, enflurane, and isoflurane on myocardial relaxation were compared in papillary muscles of the right ventricle of adult male ferrets at 30 degrees C. The sensitivity of cardiac relaxation to the loading conditions was determined by examining the time course of relaxation before, during, and after exposure to incremental concentrations of halothane (n = 9 muscles), enflurane (n = 9 muscles), and isoflurane (n = 9 muscles) in steps of 0.25 MAC up to 1.5 MAC of halothane and of enflurane and up to 2.0 MAC of isoflurane. Load sensitivity of relaxation was quantified by comparing force and time coordinates at the onset of the isometric relaxation phase in several afterloaded isotonic twitch contractions with relaxation of the isometric twitch. Load sensitivity of relaxation, which is of particular benefit during early rapid filling of the heart, was decreased in a dose-dependent reversible fashion by halothane, enflurane, and, to a lesser extent, by isoflurane. These anesthetics abbreviated isometric relaxation, yet prolonged the time course of muscle lengthening which is suggestive of an impairment of calcium uptake by the sarcoplasmic reticulum and of a decrease in calcium sensitivity of the contractile proteins.

Anesthetics↗
PubMed1996

Role of the endocardial endothelium in the negative inotropic effects of thiopental.

BACKGROUND: Myocardial function is regulated by endocardial endothelium (EE). Several studies have demonstrated the involvement of vascular endothelium in regulating the vasoactive effects of anesthetic agents. Because vascular endothelium and EE form a contiguous layer, it was postulated that EE might also be involved in regulating the inotropic effects of anesthetics. The effects of thiopental on isolated feline papillary muscle with and without EE were examined. METHODS: The study was performed on isolated cat papillary muscles (n = 48). The effects of increasing doses of thiopental (1.5, 3, 6, 9, 12, and 24 micrograms/ml) on isometric and isotonic muscle contraction parameters were evaluated in three protocols under different experimental conditions. In the first protocol, the effects of thiopental were studied in the muscles with an intact EE (group A, n = 8) and muscles in which the EE was selectively damaged by a 1-s immersion in 0.5% Triton X-100 (group B, n = 8). In the second protocol, cumulative concentration responses for thiopental were obtained in muscles with (group C, n = 8) and without (group D, n = 8) EE, pretreated with 10(-3) M of the blocking NG-nitro-L-arginine methyl ester (L-NAME). In the third protocol, the same cumulative concentration responses were obtained for thiopental in muscles with (group E, n = 8) and without (group F, n = 8) EE after pretreatment with 5 x 10(-4) M L-arginine. RESULTS: In the presence of an intact EE, thiopental induced a dose-dependent decrease in myocardial function. With the EE removed, low doses of thiopental (1.5 to 6 micrograms/ml) no longer altered myocardial function. Pretreatment of the muscles with L-NAME inhibited the negative inotropic effects of low doses of thiopental and mimicked the response obtained after EE was removed. Pretreatment with L-arginine slightly accentuated the negative inotropic effects of low doses of thiopental. CONCLUSIONS: The negative inotropic actions of small doses of thiopental depend on the presence of an intact EE. Pretreatment of the muscles with L-NAME inhibited the negative inotropic effects of low doses of thiopental, suggesting possible involvement of the nitric oxide pathway.

Anesthetics, Intravenous↗
PubMedDate not supplied

Detection of a "faked" strength task effort in volunteers using a computerized exercise testing system.

The objective of this study was to develop an experimental method to separate a "faked" strength effort from a "best" effort in volunteers. Thirty-four pain-free volunteers (18 males, 16 females) performed a shoulder press and pull-down on an isokinetic computerized exercise testing system (CETS), giving a best effort followed by a faked effort. Two months later, a randomly selected subgroup (6 males) repeated the experiment to test the predictive validity of the derived variables. In the statistical analysis, best efforts were first compared with fake efforts by paired ttest for 80 CETS variables for males and females separately. Variables showing a strong difference between the best and faked effort were then selected for further analysis. In the second step of the analysis, the method of multiple correlations (r2 method) was used to reduce the number of redundant CETS variables to five in both the male and female groups. In the third step, a stepwise discriminant analysis was used to select predictor variables for the male and female groups. For the variables selected by the discriminant analysis for both males and females, sensitivities and specificities were calculated. Finally, the developed discriminant formula was used in the predictive validity part of the study to determine the sensitivities and specificities of the developed method. The discriminant analysis selected the following CETS variables for male and female groups, respectively: duty cycle down, work weight/down, peak value up (males); and average power up, 40% repetition down, duty cycle up (females). For males, using their three variables, the discriminant function classified 77.14% of the efforts correctly with 88.9% sensitivity and 64.7% specificity. For females, using their three variables, the discriminant function classified 90.63% of the efforts correctly with 100% sensitivity and 81.3% specificity. In the predictive validity group, the discriminant function classified 75% of the efforts correctly with 83.3% sensitivity and 66.7% specificity. This pilot study indicates that the method developed here may be useful in the experimental study for the discrimination between faked and best efforts on this isokinetic CETS machine. Future studies using this method will need to involve a larger number of volunteers.

Adult↗
PubMed1992

Lumbar iEMG during isotonic exercise: chronic low back pain patients versus controls.

Two studies investigated the use of lumbar integrated electromyography (iEMG) during flexion-extension exercises of the lumbar spine. The first study compared the iEMG fatigue slopes of 12 pain-free controls during a standardized isotonic workout with a heavy weight and a light weight. Results indicated that the slopes of the iEMG across flexion-extension repetition was negative in both conditions, with the heavy weight producing significantly steeper fatigue slopes. In the second study, iEMG was compared from 16 chronic low back pain (CLBP) patients and 12 asymptomatic controls during isotonic exercise. Integrated EMG was recorded during 18 lumbar extension-flexion cycles (3 min) at a standard pace. Each subject exercised at a weight equal to 60% of his maximum isometric torque produced at the most extended position. Results indicated significantly less iEMG was produced by the CLBP group during both concentric and eccentric exertion. For both groups, eccentric exertion produced significantly less iEMG than concentric exertion. The groups showed significantly different iEMG fatigue slopes, with the control group showing declining iEMG by repetition, while the CLBP group showed flatter, slightly increasing iEMG. This occurred for both eccentric and concentric comparisons. A muscle deficiency model of CLBP is supported and results suggest the importance of endurance factors in addition to strength in rehabilitation efforts. Results also suggest the possibility of using this methodology for detecting insincere efforts in lumbar spine assessment.

Adult↗
PubMedDate not supplied

Mechanical performance of exertubing for isotonic hand exercise.

The purpose of this study was to determine the mechanical performance of hollow latex rubber tubes used for hand rehabilitation. The results of this investigation provide load extension profiles of each tube that document the forces required to elongate the tube to a specific length. By relating these mechanical performance tests to quantitative measures of hand strength, an individualized exercise prescription can be designed for rehabilitation of the injured hand.

Burns↗