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At least 523 records · Page 29Linked to original sources
PubMed2003

On reducing hand impact force in forward falls: results of a brief intervention in young males.

OBJECTIVE: To test the working hypotheses that after a brief (10 min) intervention, (a) young adults can volitionally reduce fall-related wrist impact forces, and (b) no difference in impact force would exist between intervention and control groups at 3-weeks or 3-months follow-up. BACKGROUND: The wrist is the most commonly fractured site in the body at any age, most often as a result of impact with the ground while arresting a forward fall.Methods. Twenty-nine healthy young male volunteers participated. A 3-month intervention group (n=10) performed five standardized forward falls before and after a 10-min instructional intervention aimed at reducing wrist impact forces during the baseline visit. They, along with a 3-month control group (n=11) who did not receive the intervention, were remeasured in five trials at 3-weeks and 3-months follow-up, without intervening practice. A baseline control group (n=8) performed the five trials, then repeated them at the baseline visit without receiving the intervention. Unilateral body segment kinematics and bilateral hand-ground impact forces were measured and the hypotheses were tested using repeated measures analysis of variance. RESULTS: At the baseline visit, a significant group-by-trial-block interaction was found (P=0.02): the 3-month intervention group reduced their average maximum impact forces by 18% from initial values (P=0.002); the baseline control group did not do so (0.5% increase, P=0.91). The 3-month intervention (20 falls) and control (15 falls) groups did not differ at the 3-month follow-up (P=0.62); however, when the groups were combined their maximum impact force had decreased significantly (8.9%, P=0.04) over that time. CONCLUSIONS: Healthy young males learned in 10 min to significantly reduce wrist impact forces in forward falls, but retention was poor at 3-weeks follow-up. Irrespective of group, however, after the 5 falls at 3-weeks subjects had taught themselves to reduce their impact forces at the 3-months follow-up. RELEVANCE: A brief educational intervention can significantly reduce forward fall-related impact forces in the short term. However, with or without the brief intervention, the experience of performing between 5-10 forward falls 3 weeks apart apparently resulted in decreased impact forces over the next 2 months, thereby reducing the risk of injury in these forward falls.

Accidental Falls↗
PubMed2004

Getting a grip on your feelings: effects of action orientation and external demands on intuitive affect regulation.

The authors propose that volitional action is supported by intuitive affect regulation, defined as flexible, efficient, and nonrepressive control of own affective states. Intuitive affect regulation should be most apparent among action-oriented individuals under demanding conditions. Consistent with this, a demanding context led action-oriented individuals to down-regulate negative affect in self-reports (Study 1), in an affective Simon task (Study 2), and in a face discrimination task (Study 3). In line with the idea that intuitive affect regulation is guided by top-down self-regulation processes, intuitive affect regulation in a face discrimination task was mediated by increases in self-accessibility (Study 3). No parallel effects emerged among action-oriented participants in a nondemanding context or among state-oriented participants.

Adult↗
PubMed2006

"When no means no": can reactance augment the theory of planned behavior?

A longitudinal study examined women's clinic attendance for treatment and follow-up after having received an abnormal cervical screening result. Participants (N = 660) completed questionnaire measures of variables specified by the theory of planned behavior and J. Kuhl's (2000) measure of low volitional control--reactance--prior to receiving up to 3 subsequent appointments during the following 15 months. The theory of planned behavior was capable of predicting persistent attendance and discriminated women who kept all of their scheduled appointments from those who dropped out from treatment. Consideration of reactance enhanced prediction of behavior and discriminated between women who delayed appointment keeping and women who ceased attending.

Adult↗
PubMed2004

Working memory capacity and the antisaccade task: individual differences in voluntary saccade control.

Performance on antisaccade trials requires the inhibition of a prepotent response (i.e., don't look at the flashing cue) and the generation and execution of a correct saccade in the opposite direction. The authors attempted to further specify the role of working memory (WM) span differences in the antisaccade task. They tested high- and low-span individuals on variants of prosaccade and antisaccade trials in which an eye movement is the sole requirement. In 3 experiments, they demonstrated the importance of WM span differences in both suppression of a reflexive saccade and generation of a volitional eye movement. The results support the contention that individual differences in WM span are not exclusively due to differences in inhibition but also reflect differences in directing the focus of attention.

Adult↗
PubMed1994

Intersyllabic movement timing in the fluent speech of stutterers with different disfluency levels.

The goal of this study was to identify possible differences in movement timing in the fluent speech of adult stutterers who show varying levels of speech disfluency. Strain gauge recordings of lip and jaw movements and electroglottographic recordings of laryngeal vibration were obtained in 31 subjects as they repeated simple speech utterances. Measures of the duration and variability of intersyllablic articulatory events were analyzed in relation to speech disfluency level and history of speech treatment. As expected, movement durations were longer in subjects who had been through speech treatment. No significant associations were observed between timing durations and disfluency level. However, more disfluent subjects tended to show reduced variability in timing durations, an effect that was independent of speech treatment. This finding is interpreted in relation to previous observations on control systems that show instability and disfunction in association with reduced output variability. When disfluency level was measured during physiologic testing, duration interacted with speech treatment, with more disfluent subjects in the treatment group showing increased durations in their fluent speech. This effect is attributed to volitional control intended to facilitate speech fluency.

Adult↗
PubMed1999

Cortical potentials related to decision-making: comparison of two types of go/no-go decision.

The S1-S2 go/no-go reaction time task has been frequently used to assess volitional inhibition. In this study our aim was to compare the ERPs elicited by S1 and S2 by using a modified S1-S2 paradigm which involved a two-stage go/no-go decision. The go and the no-go S1 ERPs did not differ substantially, and both displayed a prominent negativity with peaks at 260 ms (S1N260) and at 330 ms (S1N330) post-S1. The S1N260 was similar to the N2 from no-go S2 trials. Since after all three types of stimuli, movement is not required and is inappropriate, this negativity may represent the correlate of the voluntary decision to suppress movement. Later, the S1 ERPs were dominated by frontal negativity (S1N330), probably reflecting further processes related to response preparation, while the S2 ERPs displayed a large central and parietal positivity (P3), probably reflecting the processes of evaluation of response accuracy.

Adult↗
PubMed2000

Comorbid fibromyalgia accounts for reduced fecundity in women with myofascial face pain.

OBJECTIVE: This study examined factors related to reduced fecundity among women with myofascial face pain (MFP) arising from hypotheses concerning the role of neurohormonal factors in MFP and associated conditions. DESIGN: Fecundity rates among 162 MFP cases and 173 demographically equivalent acquaintance female controls were compared. OUTCOME MEASURES: Fecundity indicators and factors underlying differential fecundity rates were investigated. RESULTS: It was determined that female cases with MFP had significantly fewer children and were more likely to have never been pregnant. Although women with MFP were more likely than controls to indicate that volitional factors related to their health discouraged them from any or additional pregnancies, these factors did not account for lower rates of fecundity. MFP cases also did not differ from controls on self-reported indicators of infertility. Moreover, we show that reduced fecundity was restricted to the subgroup of MFP cases who reported a history of fibromyalgia. CONCLUSIONS: Reduced fecundity in women with MFP is restricted to those who self-report a history of fibromyalgia. Possible mechanisms for reduced fecundity in fibromyalgia are discussed. These findings highlight the need to screen for widespread pain among women with regional myofascial pain syndromes.

Adolescent↗
PubMed2001

Biomimetic finger control by filtering of distributed forelimb pressures.

A linear filter was developed for decoding finger commands from volitional pressures distributed within the residual forelimb. Filter parameters were based on dynamic pressures recorded from the residual limb within its socket, during specific finger commands. A matrix of signal features was derived from eight-dimensional (8-D) pressure vectors, and its pseudoinverse comprised the filter parameters. Results with amputees showed that the filter could discriminate specific finger flexion commands, suggesting that pressure vector decoding (PVD) can provide them with biomimetic finger control.

Adult↗
PubMed2005

Just get out the door! Importance of walking outside the home for maintaining mobility: findings from the women's health and aging study.

OBJECTIVES: To determine the association between volitional walking behavior and change in walking ability and lower extremity function over 1 year in functionally limited older women. DESIGN: Longitudinal cohort study. SETTING: Data were collected in participant's homes in Baltimore, Maryland. PARTICIPANTS: One thousand two cognitively intact community-resident female Medicare beneficiaries aged 65 and older enrolled in the Women's Health and Aging Study. MEASUREMENTS: Reported walking behavior and change in reported walking difficulty, usual and rapid gait speed, and lower extremity physical performance score over 1 year. RESULTS: Of 800 functionally limited women who could walk unassisted at baseline and were alive and contacted 1 year later, 226 (28%) walked regularly, at least eight blocks per week. These women exhibited better health and functioning than nonwalkers (e.g., lower prevalence of depressive and fatigue symptoms and cardiovascular disease and higher mean ankle-arm index, forced expiratory volume in the first second, and gait speed). One year later, independent of initial functional status, social-psychological and behavioral factors, and health conditions, walkers were 1.8 times (95% confidence interval=1.2-2.7; P=.002) more likely to maintain reported walking ability and showed less decline in customary walking speed (0.009 m/s vs -0.070 m/s; P=.001) and functional performance score (-0.17 vs -0.73; P=.01) than women who walked less than eight blocks. CONCLUSION: The strength, consistency, and specificity of the association between walking behavior and maintenance of mobility provide strong evidence that even a small amount of regular walking can confer short-term protection from further mobility loss in functionally limited women. The observation that most women capable of walking at least eight blocks per week were not doing so indicates the need to get more women "out the door" and to encourage those who walk a little to walk a little more.

Aged↗
PubMed1980

Anticipation and fusimotor activity in preparation for a voluntary contraction.

1. Multi-unit and single-unit recordings were made of muscle spindle afferent activity from the pretibial muscles of human subjects who were initially relaxed. The muscles were subjected to a stretching perturbation of 1 s duration, occurring irregularly, on average once every 5 s. In test sequences, an auditory or visual warning was provided 1 . 06 s before some of the perturbations. Subjects were required to oppose every perturbation by contracting the receptor-bearing muscle as rapidly as possible. 2. Following the warning all subjects sometimes tensed the receptor-bearing muscle unintentionally in preparation for the perturbation. In these contractions, the discharge of a spindle ending accelerated only if the contraction strength exceeded the ending's threshold for activation, established in control voluntary contractions performed under isometric conditions. 3. When the receptor-bearing muscle did not contract in the interval between warning and perturbation, there was no detectable change in the multi-unit recordings of spindle activity or in recordings from twelve of thirteen single spindle afferents. The thirteenth spindle afferent discharged prior to the perturbation in the absence of detectable e.m.g. in response to (only) three of twenty-three warning stimuli. However, this ending had been so responsive during isometric voluntary contractions that a contraction level at which it did not respond could not be established, and it is suggested that the findings with this ending resulted from its low threshold rather than from selective activation of the fusimotor system. 4. When subjects were warned of the perturbations, the dynamic response of spindle endings to the perturbations was not increased in size or altered in latency. 5. The motor response to perturbations without warning generally contained only long-latency (volitional) e.m.g. activity occurring 107--200 ms after the onset of the perturbation. When a warning was given, short-latency (reflex) e.m.g. activity was also recorded, beginning 46--76 ms after the onset of the perturbation. 6. It is concluded that anticipation of the need to contract a muscle does not result in selective activation of fusimotor neurones in preparation for the contraction. The change in stretch reflex gain that occurs as a result of 'anticipation' occurs through a central process which does not involve the fusimotor system.

Acoustic Stimulation↗
PubMed1991

Regularly scheduled voluntary exercise synchronizes the mouse circadian clock.

Circadian rhythm entrainment has long been thought to depend exclusively on periodic cues in the external environment. However, evidence now suggests that appropriately timed vigorous activity may also phase shift the circadian clock. Previously it was not known whether levels of exercise/activity associated with spontaneous behavior provided sufficient feedback to phase shift or synchronize circadian rhythms. The present study investigated this issue by monitoring the sleep-wake, drinking, and wheel-running circadian rhythms of mice (Mus musculus) during unrestricted access to running wheels and when free wheel rotation was limited to either 12- or 6-h intervals with a fixed period of 24 h. Wheel rotation was controlled remotely. Mice spontaneously ran in wheels during scheduled access, and free-running sleep-wake and drinking circadian rhythms became entrained to scheduled exercise in 11 of 15 animals. However, steady-state entrainment was achieved only when exercise commenced several hours into the subjective night. The temporal placement of running during entrainment was related (r = 0.7003, P less than 0.02) to free-running period before entrainment. Mice with a free-running period less than 23.0 h did not entrain but exhibited relative coordination between free-running variables and the wheel availability schedule. Thus the circadian timekeeping system responds to temporal feedback arising from the timing of volitional exercise/activity, suggesting that the biological clock not only is responsive to periodic geophysical events in the external environment but also derives physiological feedback from the spontaneous activity behaviors of the organism.

Animals↗
PubMed2005

Anxiety reduction through detachment: subjective, physiological, and neural effects.

The ability to volitionally regulate emotions helps to adapt behavior to changing environmental demands and can alleviate subjective distress. We show that a cognitive strategy of detachment attenuates subjective and physiological measures of anticipatory anxiety for pain and reduces reactivity to receipt of pain itself. Using functional magnetic resonance imaging, we locate the potential site and source of this modulation of anticipatory anxiety in the medial prefrontal/anterior cingulate and anterolateral prefrontal cortex, respectively.

Adaptation, Psychological↗
PubMed2006

Impact of impaired inspiratory muscle strength on dyspnea and walking capacity in sarcoidosis.

BACKGROUND: Dyspnea and fatigue are frequent but poorly understood symptoms in sarcoidosis patients. This study was aimed at assessing the clinical impact of inspiratory muscle impairment on dyspnea and exercise tolerance. This is the first study using nonvolitional tests that are independent of the patient's cooperation and motivation in addition to volitional tests of inspiratory muscle strength in patients with sarcoidosis. METHODS: Peak maximal inspiratory mouth pressure (Pimaxpeak), maximal inspiratory pressure sustained for 1.0 s (Pimax1.0), twitch mouth pressure (TwPmo), lung function test results, blood gas measurements, 6-min walking distance (6MWD), and Borg dyspnea scale (BDS) scores were assessed in 24 male sarcoidosis patients and 24 healthy male control subjects matched for age and body mass index. RESULTS: Mean (+/- SD) Pimaxpeak (95.2 +/- 25.3% vs 124.6 +/- 23.4% predicted, respectively; p < 0.001) and Pimax1.0 (85.6 +/- 31.4% vs 125.8 +/- 26.8% predicted, respectively; p < 0.001) were lower in sarcoidosis patients compared to control subjects. TwPmo tended to be lower in sarcoidosis patients, and there were three patients who had TwPmo values of < 1.0 kPa, which is a strong indicator of inspiratory muscle weakness. The mean 6MWD was 582 +/- 97 m in sarcoidosis patients and 638 +/- 65 in control subjects (p = 0.025). The mean BDS score was higher in sarcoidosis patients (3.3 +/- 1.7 vs 0.2 +/- 0.5, respectively; p < 0.001). Compared to maximal inspiratory pressure, lung function parameters, and blood gas levels, TwPmo was the strongest predictor for 6MWD (r = 0.663; p = 0.003) and BDS score (r = 0.575; p = 0.012) in sarcoidosis patients following multiple linear regression analysis. CONCLUSIONS: Impairment of inspiratory muscle strength occurs in sarcoidosis patients, and has been suggested to be an important factor causing dyspnea and reduced walking capacity, but this is only reliably detectable when using nonvolitional tests of inspiratory muscle strength.

Adult↗
PubMed1999

Initial report on the limited value of hypoglossal nerve transfer to treat brachial plexus root avulsions.

OBJECT: Hypoglossal nerve (12th cranial nerve) transfer was performed to treat the sequelae of brachial plexus root avulsion in 12 adults and two infants, and the patients were followed to assess the effectiveness of the surgery. METHODS: The 12th cranial nerve was transected at the base of the tongue, and a sural nerve graft was used to bridge the gap between the donor (12th) and recipient nerves: C-5 spinal, axillary, suprascapular, or musculocutaneous nerve. The mean graft length in adult patients was 15.75 +/- 5.5 cm (+/- standard deviation, median 14.5 cm) and in the two infants the graft lengths were 7 and 8 cm, respectively. After a mean postoperative interval of 1138 +/- 254 days, electromyographic examination of the target muscles showed tongue movement-related activity in all patients. Muscle force strength measured according to the Medical Research Council's guidelines, was Grade 3 or higher in 21% of patients. Contraction, however, could only be attained by tongue movements, and volitional control was not achieved. CONCLUSIONS: Although recovery of muscle strength was obtained by 12th cranial nerve transfer, the functional gain remained virtually nonexistent because central control was missing.

Adolescent↗
PubMed1982

Environmental interactions: an extension of the model of occupation.

Although occupational therapists historically acknowledged contributions of the environment to the maintenance of productive behavior, their literature has only recently begun to illustrate the interrelationships between persons and settings. Incorporating environmental themes into the model of occupation broadens an examination of the concept of occupational performance and helps establish the clinic as a therapeutic milieu. This paper considers three facets of person-environment interactions: environmental properties that influence the volition subsystem and the person's decision to enter a setting; the influence of the setting's demands for performance on the development of roles, habits, and skills; and factors affecting the individual's engagement in an expanding range of occupational settings.

Adult↗
PubMed1991

Occupational therapy and obsessive-compulsive disorder.

The Model of Human Occupation, used as a frame of reference in the assessment and treatment of obsessive-compulsive disorder, helped identify how major disruptions in habituation and volition can affect a person's ability to perform and adapt in his or her environment. Careful application of this model promoted a more holistic view of John's life-style and guided me, as his occupational therapist, in creating a purposeful and meaningful treatment plan.

Adaptation, Psychological↗
PubMed1993

The association between weight loss and increased longevity. A review of the evidence.

Six published observational epidemiologic studies have reported evidence of reduced mortality rates in persons who have lost weight. In two studies, the reported protective effects of weight loss on mortality could not be justified by the data. In two other studies, weight loss was associated with both increased and decreased longevity in different subgroups. Only one study provided information on whether the weight loss was voluntary, but this study found similar effects of weight loss regardless of volition. These studies provided only limited information on the magnitude of weight loss associated with changes in longevity and no information on the types of methods used to achieve weight loss. Because of difficulties in studying long-term health outcomes related to obesity treatment, randomized, controlled trials are unlikely to provide a practical study design for this issue. Properly designed observational studies will probably provide the most useful information on the effects of voluntary weight loss on longevity.

Epidemiologic Methods↗
PubMed1999

Allocation of attention in dichotic listening: effects on the detection and localization of targets within lists.

In each of two dichotic listening experiments, 48 normal right-handed adults were instructed to attend selectively to the left and right ears and to divide attention equally between ears. Participants listened for specified targets and reported the ear of entry when the target was heard. Stimuli consisted of lists of digit names in Experiment I and lists of words in Experiment 2. Shifts of attention altered ear asymmetry for localizing but not for detecting digit names. For words, attention shifts altered both detection asymmetry and localization asymmetry, but the effect of attention on detection seemed to reflect differential retrieval from short-term memory rather than differential perception. In both experiments, shifting attention toward either ear resulted in a reporting bias such that signals were attributed to the attended ear more often than to the unattended ear. The results confirm our previous findings, for single pairs of stimuli, that volitional shifts of attention alter response selection rather than perception.

Adolescent↗