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Biomedical subjects

A Wit

Publications and source records attributed to A Wit.

8 recordsLinked to original sources
PubMed2000

A longitudinal study of informational interventions to save energy in an office building.

Informational interventions were employed to promote two behaviors relevant for efficient heating of individual offices in a large office building. In two successive winter seasons, interventions were applied during 4-week periods. Short-term effects were assessed weekly, and long-term effects were assessed 1 year after each of the two intervention periods. Improvements were observed in each intervention period, with partial behavior maintenance 1 year later. The changes observed in the individual offices across conditions are suggestive of the program's capacity to correct relapses in earlier proenvironmental behavior.

Behavior Therapy↗
PubMed1995

The effectiveness of a pendulum swing for the development of leg strength and counter-movement jump performance.

Various training devices have been developed to facilitate 'plyometric' training, one such device being the 'pendulum swing'. To assess the effectiveness of the pendulum swing, the results of a 3 week training programme using a combination of pendulum swing and weight-training exercises were compared to those of a weight-training programme. Subjects were assigned to one of two groups (n = 9) for weight-training only or for combined pendulum and weight-training. Both groups performed the same number of exercise repetitions. Measurements of isometric knee and hip extension-flexion, 1-RM squat weight, maximum jump height and power for a counter-movement jump were taken pre-training, 2 days after the end of the programme and 2 weeks after the end of the programme. The data were analysed using two-way MANOVA and MANCOVA techniques. Both methods showed significant (P < 0.05) increases in knee and hip extension strength. Hip and knee flexion strength increased only for the weight-trained group. Counter-movement jump height increased for both groups (weight-trained, P < 0.05; combined, P < 0.01). Maximum power increased only for the combined group (P < 0.05). When the pre-training scores were used as a covariate, the weight-trained group showed a greater increase in hip flexion and extension strength and knee flexion strength than the combined training group (P < 0.05). The combined group showed the greatest increase in knee extensor strength. It is concluded that the pendulum system induces a training effect which could be used to supplement weight-training for improving vertical jump performance.

Adult↗
PubMed1994

Forearm tremor in relation to selected physiological and body dimensional variables.

Interrelationships between forearm tremor and a number of body dimensional, muscle structure, muscular strength and training background variables were studied among 13 male students with athletic backgrounds. The subjects performed isometric dominant upper extremity elbow flexions with a 90 degrees joint angle and with the forearm held in a horizontal position. A freely hanging mass was attached via a strain gauge transducer, a metal chain and cuff to the forearm. An accelerometer attached to the cuff measured the vertical component of tremor. The power spectrum density function was calculated for a tremor acceleration signal and a bandwidth of 7-20 Hz was analysed in more detail. The right M. vastus lateralis was biopsed in order to determine the muscle fiber composition. Arm mass and muscle fiber composition were found to correlate statistically significantly with the tremor frequency characteristics. In the further analyses arm mass was found to be the only variable explaining the tremor frequency characteristics; the effects of the muscle structure variables were minor when the effects of arm mass was controlled in partial correlation analyses. Interindividual differences in motor unit firing properties were presumed to explain the dependence found between arm mass and tremor frequency.

Acceleration↗
PubMed1992

Investigation of an experimental weight-training programme.

The aim of this study was to compare the effects of conventional weight-training (control) with an experimental programme. The training programme consisted of 12 sessions, 3 a week for 4 weeks. The experimental group (n = 12) performed sets of forearm flexion with a barbell until a 20% decline in maximal force was noted. The controls (n = 11) trained according to established weight-training principles. Isometric tests were performed on both the right and left forearm flexors and during forearm flexion with a barbell: the tests were continued for a 3-week post-experimental period. The subjects were matched on all tests at the start of the experiment. Larger reductions in muscle torque within the training sessions were noted among the experimental subjects--19.8 +/- 2.0, 16.9 +/- 1.9 and 18.0 +/- 1.8% for right, left and combined elbow flexion respectively, compared to 11.8 +/- 2.7, 14.9 +/- 4.1 and 13.4 +/- 3.1% for the controls. The volume of training (number of lifts) was 30.4% higher for the experimental subjects. Muscle strength increased in both groups (P less than 0.05). The controls improved by 12.7 +/- 6.9, 24.9 +/- 22.1, 18.3 +/- 12.3 and 30.3 +/- 11.1% for right, left, combined isometric strength and the barbell test respectively. These did not differ significantly from the corresponding results for the experimental group--7.6 +/- 8.8, 17.0 +/- 12.4, 11.8 +/- 9.3 and 29.1 +/- 10.6% (P greater than 0.05). Neither the decrease in force during a single training session nor the volume of training were related to the training effect expressed as an increase in muscle force (P greater than 0.05). The effectiveness of the conventional programme in producing similar improvements in muscle strength to the experimental programme suggests that a high volume of training is unnecessary for strength gains.

Fatigue↗
PubMedDate not supplied

Relationships between muscular strength and the level of energy sources in the muscle.

Relationships between muscular strength and the level of energy sources in the muscle. Acta Physiol. Pol., 1978, 29 (2): 139--151. An attempt was made to establish a relationship between the post-excercise changes in the level of anaerobic energy sources and changes in the muscular strength. The gastrocnemius muscle of Wistar rats was examined. The muscle strength was measured by the resistance tensometry. In muscle specimens ATP, CP and glycogen contents were determined. It was demonstrated that changes in the post-excersise muscle response to electric stimulus have a phasic character resembling the overcompensation curve. The percent changes in the content of anaerobic energy sources in the muscle after contractions varying in duration suggests also overcompensation the muscle content of these substances. The parallelity between the time of appearance of peak overcompensation phase in the muscle strength and in the post-exercise level of musclar ATP, CP and glycogen contents suggest a casual relationship between these changes.

Adenosine Triphosphate↗
PubMedDate not supplied

Forearm tremor during three different isometric loadings.

Forearm tremor was studied during a spring (stiffness 1090 N.m-1), a rigid isometric and a "dynamic" isometric (carrying a freely hanging mass) loading at the level of 50% of maximal isometric voluntary contraction. Thirteen physical education students ranging in age between 20 and 28 years flexed their dominant forearm isometrically towards the vertical direction (90 degree elbow angle) against the three different loads on three test occasions seated on a dynamometer which measured the force at the wrist together with vertical tremor (accelerometer). A power spectrum density function was established for the tremor (acceleration) between 1.0 and 19.9 Hz. A bandwidth of 6.9-19.9 Hz was subsequently analyzed in more detail including the determination of peak power (PMAX), peak power frequency (FMAX), mean power frequency (MPF), and average power (PAVER) as well as proposition (%) of the whole spectrum occupied by the selected bandwidth. The FMAX, MPF and band percentage variables had the best reproducibility (Cronbach's Alpha 0.85-0.95), while for the PMAX and PAVER the coefficients were lower but still satisfactory (0.69-0.89). The coefficients were rather similar for all three loading conditions. In the spring loading the spectrum components inside the analyzed frequency band occupied almost 90% of the whole spectrum, FMAX was more clearly distinguished from the rest of the spectrum, and tremor amplitude was higher and tremor frequency lower than in the rigid isometric and "dynamic" loadings. The respective tremor amplitude and frequency characteristics showed statistically significant correlations between the rigid isometric and "dynamic" loading conditions.(ABSTRACT TRUNCATED AT 250 WORDS)

Acceleration↗