Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Volition”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 595 records · Page 33Linked to original sources
PubMed1996

The influence of bolus volume and viscosity on anterior lingual force during the oral stage of swallowing.

The influence of bolus volume and viscosity on the distribution of anterior lingual force during the oral stage of swallowing was investigated using a new force transducer technology. The maximum force amplitudes from 5 normal adults were measured simultaneously at the mid-anterior, right, and left lateral tongue margins during 10 volitional swallows of 5-, 10-, and 20-ml volumes of water, applesauce, and pudding. Results indicated significant increases in peak force amplitude as viscosity increased. Volume did not significantly influence maximum lingual force amplitudes. Individual subjects demonstrated consistent patterns of asymmetrical force distribution across the lingual margins tested. The results suggest that bolus-specific properties influence the mechanics of oral stage lingual swallowing. This finding has important clinical implications in the assessment and treatment of dysphagic individuals.

Adult↗
PubMed1986

The effects of high intensity exercise on muscle and plasma levels of alpha-ketoisocaproic acid.

Alpha-ketoisocaproic acid (KIC) is the product of the transamination of the indispensable amino acid leucine, which is the first step in the complete degradation of leucine. To determine the effects of intense exercise on muscle and blood levels of KIC, 7 male volunteers performed cycle exercise to exhaustion. After pedaling at an intensity of 90 W for 3 min, the load was increased by 60 W every 3 min until volitional fatigue. Muscle biopsies were obtained prior to and immediately after exercise and rapidly frozen for later determination of KIC. During exercise, blood lactate levels increased as expected, while plasma KIC levels did not change. Following exercise, plasma KIC levels rose significantly with peak values occurring 15 min after exercise and did not return to pre-exercise values until 60 min after exercise. In contrast, muscle KIC levels increased during exercise from a pre-exercise mean of 49.4 +/- 4.1 mumol X kg-1 wet wt to 78.1 +/- 6.5 mumol X kg-1 after exercise, an average increase of 48% (P less than 0.05). These data indicate that during intense exercise, leucine transamination in muscle may continue at a faster rate than the decarboxylation of KIC. In addition, plasma levels of KIC did not reflect the intracellular accumulation of KIC during exercise, suggesting a delay in the diffusion of KIC from muscle.

Humans↗
PubMed1987

Study of human muscle contraction using electrically evoked twitch responses during passive shortening and lengthening movements.

Electrically evoked twitch properties of the human plantarflexor muscles were measured with the muscles at a constant length (static) and during passive shortening and lengthening. A Kin-Com dynamometer system was used to passively move the ankle joint at 0.52 rad s-1 (30 degrees s-1), as well as to record the twitch responses which were elicited by supramaximal electric shocks applied over the tibial nerve in the popliteal fossa. In the lengthening and shortening conditions, twitches were evoked by triggering the shocks so that the twitch response occurred at a similar angular position for all three conditions. The lengthening twitch peak torque was about twice as large as that recorded for the shortening condition. There was, however, no statistical difference in the twitch time course in these three testing conditions. This twofold increase in the peak twitch torque during lengthening, compared to shortening, is much greater than the torque increase reported during eccentric, as compared to concentric maximal voluntary contractions. These findings suggest that a deactivation process of the contractile system occurs during muscle shortening, while in contrast, during passive lengthening a potentiation mechanism is acting, and that both these mechanisms are independent of volitional muscle activation. The present study is the first to demonstrate the possibility of electrically evoked contractions of human muscles during passive lengthening and shortening. We believe that the use of such evoked contractions may be promising for the study of contractile behaviour of human skeletal muscles during eccentric and concentric conditions.

Adult↗
PubMed1983

Assessment of anaerobic capacity in runners.

A new method for assessment of anaerobic capacity is presented. It consists of two treadmill runs at 22 km X h-1 and 7.5% slope, the first one being interrupted after 40 s (submax. test), the second continuing until volitional exhaustion (max. test). Measured variables are the increase in arterial lactate concentration over the pre-exercise value in the submax. test (delta L40), the maximal arterial lactate level in the max. test (Lmax), and time to exhaustion (tmax). Fifty-five male runners of high competitive level were examined with this procedure, including 400-m runners of differing performance capacity (400 m A and B/C), middle-distance (MD), long-distance (LD), and marathon runners (M). Eleven physical education students served as controls (C). tmax was 88.3 +/- 11.0, 85.2 +/- 11.4, 83.1 +/- 12.7, 63.1 +/- 11.4, 43.7 +/- 7.5, and 50.7 +/- 5.0 s for 400 m A, 400 m B/C, MD, LD, M, and C. The corresponding values for Lmax were 17.47 +/- 1.68, 17.52 +/- 2.03, 16.27 +/- 2.18, 13.44 +/- 2.13, 10.13 +/- 2.68, and 15.54 +/- 1.43 mmol X 1(-1) and for delta L40 5.93 +/- 1.10, 7.13 +/- 1.55, 6.39 +/- 0.89, 6.68 +/- 1.18, 8.19 +/- 1.37, and 10.76 +/- 1.62 mmol X 1(-1). The differences in delta L40, most likely reflecting differences in high energy phosphate utilization, suggest that excellent performance in any running event is associated with increased alactacid anaerobic capacity.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Inhibition of brain dopa-decarboxylase by RO 4-4602 infused ICV blocks alcohol drinking induced in rats by cyanamide.

Following the stereotaxic implantation of chronic cannulae for intracerebroventricular (ICV) infusion, rats were given an alcohol preference test to establish their preferred concentration in comparison with water. After alcohol was removed, 15 mg/kg cyanamide was then injected subcutaneously for 4 days in order to maximize volitional intake of single solutions of alcohol, which in these animals ranged from 7 to 15%. The L-dopa-decarboxylase inhibitor benserazide (Ro 4-4602) injected subcutaneously twice daily in doses of 50-100 mg/kg failed to alter the rats' alcohol consumption either in terms of g/kg or proportional values. However, when given ICV twice daily in concentrations of 10 ng-2.0 micrograms per 5.0 microliters volume, benserazide attenuated the rats' alcohol drinking significantly. This reduction occurred in a dose-dependent manner in terms of both absolute and proportional intakes of alcohol. Pre-treatment of the animals with 1.0 microgram benserazide given ICV, when alcohol was removed from the test situation, did not abolish the subsequent ingestion of alcohol but its peripheral administration (50 mg/kg) enhanced drinking. These results suggest that the interference with the metabolic pathway of dopamine or serotonin synthesis, possibly through the mechanism of reduced formation of aldehyde adducts in the brain, markedly alters the pattern of voluntary drinking in the rat. Alternatively, benserazide could act by its central inhibition of aldehyde dehydrogenase, which in turn would concomitantly elevate levels of acetaldehyde and thereby reduce alcohol drinking.

Alcohol Drinking↗
PubMed1984

Fluphenazine-induced acute and tardive dyskinesias in monkeys.

Five Cebus apella monkeys were treated with biweekly injections of fluphenazine enanthate (0.1-3.2 mg/kg IM). Three of these completed 1 full year of treatment, one injured its leg after 6 months of treatment and was killed, and another died of unknown causes after 9 months of treatment. All monkeys displayed abnormal movements corresponding to the early appearing extrapyramidal symptoms of neuroleptic-treated patients. These consisted initially of slowing or absence of volitional movement, trembling of the hands, trembling of the entire body, and general drowsy behavior. As treatment progressed, a variety of abnormal postures and movements appeared after each injection that were not exacerbated by drug withdrawal and, as tested at the end of the year, could be abolished or prevented with benztropine mesylate (0.2-0.5 mg/kg IM). The three monkeys that completed 1 year of treatment with fluphenazine were then withdrawn from the drug. After withdrawal, all three developed movements similar in appearance to those of patients with tardive dyskinesia (TD). Reinstitution of fluphenazine treatment, as tested in one monkey, abolished all movements resembling TD.

Animals↗
PubMed1994

Coincidental changes in ventilation and electromyographic activity during consecutive incremental exercise tests.

These experiments examined the effect of metabolic acidosis, induced as a result of dynamic exercise, on ventilation, lactate concentration and electromyographic activity. Seven subjects performed two consecutive incremental exercise tests until volitional exhaustion was achieved. The two tests were identical and were separated by a 7-min period of light exercise. During the tests, ventilation, mixed expired oxygen and carbon dioxide, arterialized venous blood and electromyographic activity from the vastus lateralis was sampled. The results showed that the ventilation and electromyographic measurements followed a similar time course during both tests, although ventilation during the initial 6 min of the second test was significantly greater than the values recorded during the first test. In addition, throughout the first test lactate concentration increased with time, and pH, bicarbonate concentration and partial pressure of carbon dioxide decreased. In contrast, during the second test, lactate concentration decreased, and pH and bicarbonate concentration increased; during a period of time when ventilation and electromyographic activity were increasing. These findings have led us to conclude that changes in ventilation and electromyographic activity observed during incremental exercise are not related to changes in blood lactate concentration. It is suggested that such a conclusion supports the hypothesis that the changes in ventilation are mediated by an increase in neural activity originating from the subthalamic motor region or exercising limbs, induced in response to the need to progressively recruit fast twitch muscle fibres as exercise work rate is increased and as individual muscle fibres begin to fatigue.

Adult↗
PubMed1994

The ventilation, lactate and electromyographic thresholds during incremental exercise tests in normoxia, hypoxia and hyperoxia.

These experiments examined the effect of hypoxia and hyperoxia on ventilation, lactate concentration and electromyographic activity during an incremental exercise test in order to determine if coincident chances in ventilation and electromyographic activity occur during an incremental exercise test, despite an enhancement or reduction of peripheral chemoreceptor activity. In addition, these experiments were completed to determine if electromyographic activity and ventilation are enhanced or reduced in response to the inspiration of oxygen-depleted and oxygen-enriched air, respectively. Seven subjects performed three incremental exercise tests, until volitional exhaustion was achieved, while inspiring air with a fractional concentration of oxygen of either 66%, 21% or 17%. In addition, another single subject completed two tests while inspiring air with a fractional concentration of either 17% or 21%. During the tests, ventilation, mixed expired oxygen and carbon dioxide, arterialized venous blood and the electromyographic activity from the vastus lateralis were sampled. From these values ventilation, electromyographic and lactate thresholds were detected during normoxia, hypoxia and hyperoxia. The results showed that although ventilation and lactate concentration were significantly less during hyperoxia as compared to normoxia or hypoxia, the carbon dioxide production values were not significantly different between the normoxic, hypoxic and hyperoxic conditions. For a particular condition, the time, carbon dioxide production and oxygen consumption values that corresponded to the ventilation and electromyographic thresholds were not significantly different, but the values corresponding to the lactate threshold were significantly less than those for the electromyographic and ventilation thresholds. Comparisons between the three conditions showed that the time, carbon dioxide production and oxygen consumption values corresponding to each of these thresholds were not significantly difficult.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Slow upward drift of VO2 during constant-load cycling in untrained subjects.

The oxygen uptake kinetics during constant-load exercise when sitting on a bicycle ergometer were determined in 7 untrained subjects by measuring breath-by-breath VO2 during continuous exercise to volitional exhaustion (mean endurance time = 1160 +/- 172 s) at a pedal frequency of 70 revolutions.min-1. The power output, averaging 189.5 W, was set at 82.5% of that eliciting the individual VO2max during a 5 min incremental exercise test. Throughout the exercise period, the VO2 kinetics could be appropriately described by a two-component exponential equation of the form: VO2(t) = Ya[1 - exp(-kat)] + Yb[1 - exp(-kbt)] where VO2 is net oxygen consumption and t the time from work onset. VO2 measured at the end of exercise was close to VO2max (98% VO2max) and the mean values of Ya, ka, Yb and kb amounted to 1195 ml O2.min-1, 0.034 s-1, 1562 ml O2.min-1, and 0.005 s-1 respectively. The initial rate of increase in VO2 predicted from the above equation is slower than that calculated, for the same work intensity, on the basis of the data obtained by Morton (1985) in trained subjects. For t greater than 480 s, however, the two models yield substantially equal results.

Bicycling↗
PubMed1987

Effects on physical performance of intrinsic sympathomimetic activity (ISA) during selective beta 1-blockade.

In 15 healthy, not specifically trained volunteers (age: 26.6 +/- 2.7 years) single equipotent doses of a selective beta 1-blocker with intrinsic sympathomimetic activity (ISA) (200 mg Epanolol-Visacor; V) and of a selective beta 1-blocker without ISA (100 mg Metoprolol; M) were compared with placebo (P) with respect to their influence upon physical performance capacity and metabolism in a random, double blind, cross-over experimental setting. The subjects underwent three step by step incremental treadmill tests and three treadmill endurance tests until volitional exhaustion. Maximum running speed and maximum oxygen uptake were used as measures of maximum performance capacity. Running speed and oxygen uptake related to individual anaerobic threshold, and running time and running distance in the endurance tests were used as measures of endurance capacity. Both maximum and endurance performances were reduced significantly by beta-blockade. No relevant differences were discerned between V and M. The uniform reduction in exercise heart rate with both beta-blockers demonstrated the application of equipotent doses. At rest, heart rate was significantly higher under V than under M. Carbohydrate metabolism was unaffected, both beta-blockers showing equal inhibition of lipolysis during exercise. We conclude that intrinsic sympathomimetic activity has no influence upon physical performance and metabolism during selective beta 1-blockade.

Adrenergic beta-Antagonists↗
PubMedDate not supplied

Cardiopulmonary performance during exercise in patients with repaired tetralogy of Fallot with absent pulmonary valve.

In patients with tetralogy of Fallot and absent pulmonary valve, the dilated pulmonary arteries sometimes result in bronchial compression and pulmonary symptoms due to airway obstruction, recurrent pulmonary infection, and development of bronchiectasis. After complete intracardiac repair, residual pulmonary disease may be expected to result in impaired cardiopulmonary performance during exercise. To assess this hypothesis, nine patients with tetralogy of Fallot and absent pulmonary valve underwent exercise testing and were compared to 38 patients with tetralogy of Fallot repaired using a transannular patch. All patients were exercised to maximum volition using a 1 minute incremental treadmill protocol with monitoring of pulmonary functions and expired gases. Maximal heart rate, maximal oxygen consumption, oxygen consumption at anaerobic threshold, and maximal respiratory exchange ratio were similar for the two groups. There was no significant difference for ventilation and gas exchange parameters at rest or at maximal exercise, and values for both groups were below the predicted normal for healthy subjects. Breathing reserve, however, did tend to be somewhat lower in the group with tetralogy of Fallot with absent pulmonary valve. In summary, despite significant preoperative symptoms, cardiopulmonary performance during exercise in patients with tetralogy of Fallot and absent pulmonary valve is similar to patients with tetralogy of Fallot repaired with a transannular patch.

Adolescent↗
PubMed1979

Target training: a technique for assessing self-regulation of skin temperature.

The determination of the achievement of self-regulation of hand temperature can be difficult, even with adequate baseline and control procedures. Although bidirectional training is often mentioned as a technique for thorough learning and for a convincing demonstration of temperature control, patients are sometimes unwilling or unable to lower hand temperature volitionally. This case report describes a patient who, due to failure at lowering her hand temperature, developed the target training method to convince herself of her self-regulation skill. The method may be useful in both clinical and research settings.

Adult↗
PubMed1989

Hand temperature norms for headache, hypertension, and irritable bowel syndrome.

Hand temperature norms are presented for 221 headache patients (migraine, mixed, and tension), 105 hypertensives, 45 irritable bowel syndrome patients, and 56 normal controls under conditions of resting baseline, self-relaxation, volitional handwarming, mental arithmetic, and cold pressor. The two vascular headache groups (migraine and mixed) had significantly lower hand temperatures across conditions.

Adult↗
PubMed1975

The influence of varying oxygen tensions in inspired gas on 133Xenon muscle clearance and fatigue levels during sustained and dynamic conctractions.

Isometric and isotonic endurance levels of both elbow flexors and knee extensors were tested during inspired gas mixtures of ca. 10%, 21% or 100% oxygen in nitrogen. The four work loads were set a 25, 50, 60 and 70% of maximal volitional isometric strength (IS). The isotonic exercise routine was carried out using weight lifting techniques of 20 repetitions per min from 75 degrees to 105 degrees of elbow flexion and knee extensions respectively. Prior to, during, and after the endurance experiments 133Xe clearance was monitored by light weight scintillation counters. A depot of 0.1 to 0.2 ml of isotonic saline containing 50 to 150 muCi of the isotope was used as an intramuscular tracer. The exercise clearance values varied inversely to the test load during isometric exercise. Isotonic exercise for both elbow flexors and knee extensors showed increasing clearance values up to 60% IS. Above this level a decrease in total clearance was recorded. Oxygen tension had no statistical effect on the clearance values. However, the relatively large scatter of the 133Xe clearance method, and an inhomogenous perfusion of skeletal muscle may have masked any anticipated effect of the various O2 tensions. Variations due to the raised intramuscular pressure appeared to be much more dominant than the hypothezised variation due to the 3 set oxygen tensions.

Adult↗
PubMed1984

Effects of previous exercise on the ventilatory determination of the aerobic threshold.

To study the effects of previous submaximal exercise on the ventilatory determination of the Aerobic Threshold (AeT), 16 men were subjected to three maximal exercise tests (standard test = ST, retest = RT, and test with previous exercise = TPE ) on a cycle ergometer. The protocol for the three tests consisted of 3 min pedalling against 25 W, followed by increments of 25 W every minute until volitional fatigue. TPE was preceded by 10 min cycling at a power output corresponding to the AeT as determined in ST, followed by a recovery period pedalling against 25 W until VO2 returned to values consistent with the initial VO2 response to 25 W. AeT was determined from the gas exchange curves (ventilatory equivalent for O2, fraction of expired O2, excess of VCO2, ventilation, and respiratory gas exchange ratio) printed every 30 s. The results showed good ST X RT reliability (r = 0.89). TPE showed significantly higher AeT values (2.548 +/- 0.44 1 X min-1) when compared with ST (2.049 +/- 0.331 X min-1) and RT (2.083 +/- 0.30 1 X min-1). There were no significant differences for the sub-threshold respiratory gas exchange ratios among the trials. The sub-threshold VO2 response showed significantly higher values for TPE at power outputs above 50 W. It was concluded that the performance of previous exercise can increase the value for the ventilatory determination of the AeT due to a faster sub-threshold VO2 response.

Adult↗
PubMed1984

Janet's Obsessions and Psychasthenia: a synopsis.

Pierre Janet's Lés Obsessions et la Psychasthénie, Vol. 1 (1903) still stands as the most authoritative work on obsessional and related disorders yet written, but it remains unavailable to an English readership. This article presents an English synopsis of the French original. Janet considers the central problem to be a special mental state which he terms psychasthenia, entailing low psychological tension and an impotence of adaptation to reality. Especially affected are the reality functions of attention, volition, and present-related emotion. Their failure leads through diversion of mental energy to the forced agitations, i.e., mental manias, ruminations, tics, phobias, and anxiety. Obsessions are a late and variable development, when present they symbolize the underlying mental state of incompleteness. The full significance of Janet's contribution may have yet to be established by developments in the neurosciences.

Asthenia↗
PubMed1976

Medical care as a commodity: an exploration of the shipping behavior of patients.

A 10% household sample of high- and low-income census tracts was interviewed to assess the extent of doctor shopping. In 632 households studied, 53% of high socioeconomic status and 51% of low socioeconomic status families had shopped for or changed doctors of their own volition. During the previous year, 4% of each socioeconomic group had consulted more than one doctor without referral for the same episode of illness. Shoppers could be distinguished from non-shoppers--shoppers were younger, were better informed about medical specialties, were less self-reliant, more hypochondriacal, expressed less hostility towarn physicians, and had less positive attitudes toward the medical care system. The differences between shoppers and non-shoppers were generally similar for both high and low socioeconomic status groups. In addition, 52% of the families studied had been forced to change doctors because of circumstances beyond their control, i.e., the patient moved or the doctor moved, retired, or died.

Adult↗
PubMed1996

Effects of task instructions and oscillation frequency on bimanual coordination.

Increases in the oscillation frequency of bimanual movements produce a switch from an antiphase (180 degrees relative phase) to an in-phase (0 degrees relative phase) coordination pattern. This finding is observed when subjects are instructed not to intervene when they feel themselves slipping out of the anti-phase pattern. The question addressed in this study concerned how performance would be affected if subjects were instructed to try to maintain the pattern at all times. This issue was addressed using two separate groups of subjects: one group was given the "do not intervene" instructions, the other group was told to try to stay with the pattern at all times. Forearm rotations were tested in 15 s trials, paced by an auditory metronome set at 1.0, 1.5, 2.0, 2.5, and 3.0 Hz. Frequency distributions of the point estimates of relative phase were analyzed. The Do not Intervene group replicated previous findings, as indicated by the development of a bimodal histogram of relative phase distributions with increases in oscillation frequency. However, a very different pattern of findings emerged with increases in oscillation frequency for the group told to stay with the anti-phase pattern. Rather than a bimodal distribution being developed, the data maintained 180 degrees as its central tendency--no secondary distribution developed around 0 degrees relative phase. These data suggest that volitional control can override the inherent dynamical tendencies of the motor system.

Adult↗