Biomedical subjects

Z Dvir

Publications and source records attributed to Z Dvir.

30 records · Page 2Linked to original sources

PubMed1995

Variations in several mechanical parameters associated with elbow flexion during practice under different load criteria.

The purpose of this study was to analyze variations in the accuracy of the moment produced by the elbow flexors during feedback-assisted acquisition of a motor skill. The task consisted of minimizing the error around three criterional levels: 20%, 30%, or 50% of the maximal isokinetic concentric moment of these muscles measured at 90 degrees/sec. Healthy women, aged 22 to 30 years, were divided into three groups (nA = 6, nB = 6, nC = 4) corresponding to the above criteria. They were asked to perform 10 sets of 10 right-elbow flexions per day over a period of three consecutive days. The results indicated a significant difference among the groups mainly in terms of overshooting (Group A) or undershooting (Group C) the criterion. On the other hand, Group B subjects performed optimally as indicated both by a significant convergence to the criterion (30%) and a comparatively small number of repetitions required for achievements. These findings demonstrate the existence of an optimal performance point which is located at about 30% of the maximal isokinetic concentric moment.

Adult↗

PubMed1993

The relationship between short-term antibiotic treatments and fatigue in healthy individuals.

Antibiotic treatment tends sometimes to result in sensations of fatigue and decreased physical performance. The effects of antibiotics were therefore studied in 50 healthy, male trainees, aged 18-25 years, assigned in a random, double-blind fashion to one of the following treatments: tetracycline, ampicillin, trimethoprim/sulphamethoxazole, placebo I and placebo II. Duration of treatment was five times the half-life of each agent and the placebo was matched accordingly. Muscle enzyme activity (serum glutamine oxaloacetate transaminase, lactate dehydrogenase, creatine phosphokinase), maximal aerobic capacity (VO2max), muscle strength (MS), and rating of subjective sensation of fatigue were assessed prior to and upon conclusion of treatment. Compared to pretreatment values, plasma enzymes activity was elevated in all five groups (P < 0.005). No differences in VO2max or in MS were found among the subjects treated with either one of the antibiotics or those given a placebo. A significant difference in VO2max was found between the groups treated for 1 day (antibiotic and placebo) and the groups treated for 3 days (antibiotic and placebo) (P < 0.0001). The rating of subjective sensation was not affected by any of the agents. We concluded that in healthy individuals, a short-term antibiotic treatment had no deleterious effect on aerobic capacity or on muscle strength and was not associated with subjective side effects. The time interval between the two maximal tests could, however, have affected the aerobic capacity. Physiological disturbances associated with a sensation of fatigue following a longer period of antibiotics cannot be excluded.

Adolescent↗

PubMed1993

Quantitative evaluation of stance balance performance in the clinic using a novel measurement device.

This study was undertaken to test the clinical applicability of a novel device for measurement of stance balance performance. Samples were taken from hemiparetic patients (n = 27, age range 60-80) and of three groups of healthy subjects (24 subjects at ages 64-81, 13 at ages 27-50 and 24 aging 20-24 years). Stance was evaluated in six different positions incorporating two perturbing effects: visual deprivation and movements--linear and angular--of the base of support. Three variables were measured: sway and the values of the X and Y coordinates of the Center of Pressure. Concurrent validity of the system was assessed by comparing results with data of other works that tested comparable variables in similar populations and with already well established instrumentation. Repeatability of measurements was checked by performing all tests twice and comparing their results, as well as by calculating test retest reliability. The findings pointed to significant effects of vision and of movement of the base of support on sway, and to a significant difference between sway of hemiparetic patients and healthy subjects. The location of the COP in both the X and Y coordinates was not substantially influenced by the above effects. The agreement of the findings with existent knowledge indicates that the system is credible for measurement of body sway and of the location of the COP in various stance positions.

Adult↗

PubMed1990