Voluntary activation of human knee extensors measured using transcranial magnetic stimulation

The aim of this study was to determine the applicability and reliability of a transcranial magnetic stimulation twitch interpolation technique for measuring voluntary activation of a lower limb muscle group. Cortical voluntary activation of the knee extensors was determined in nine healthy men on two separate visits by measuring superimposed twitch torques evoked by transcranial magnetic stimulation during isometric knee extensions of varying intensity. Superimposed twitch amplitude decreased linearly with increasing voluntary torque between 50 and 100% of mean maximal torque, allowing estimation of resting twitch amplitude and subsequent calculation of voluntary activation. There were no systematic differences for maximal voluntary activation within day (mean ± S.D. 90.9 ± 6.2 versus 90.7 ± 5.9%; P = 0.98) or between days (90.8 ± 6.0 versus 91.2 ± 5.7%; P = 0.92). Systematic bias and random error components of the 95% limits of agreement were 0.23 and 9.3% within day versus −0.38 and 7.5% between days. Voluntary activation was also determined immediately after a 2 min maximal voluntary isometric contraction; in four of these subjects, voluntary activation was determined 30 min after the sustained contraction. Immediately after the sustained isometric contraction, maximal voluntary activation was reduced from 91.2 ± 5.7 to 74.2 ± 12.0% (P < 0.001), indicating supraspinal fatigue. After 30 min, voluntary activation had recovered to 85.4 ± 8.8% (P = 0.39 versus baseline). These results demonstrate that transcranial magnetic stimulation enables reliable measurement of maximal voluntary activation and assessment of supraspinal fatigue of the knee extensors

Voluntary Environmental Governance Arrangements

Voluntary environmental governance arrangements have focal attention in studies on environmental policy, regulation and governance. The four major debates in the contemporary literature on voluntary environmental governance arrangements are studied. The literature falls short of sufficiently specifying whether or not voluntary environmental governance arrangements are successful in addressing environmental risks. This is due to the narrow focus of many contemporary studies and a tendency to study the form and content of voluntary environmental governance arrangements in isolation from their contextual settings. In order to gain a better understanding of voluntary environmental governance arrangements, scholars are challenged to study differently structured voluntary environmental governance arrangements in different contextual settings, to move beyond single country or single voluntary environmental governance arrangements studies, and to combine quantitative and qualitative data in studying these arrangements

Limit setting and player choice in most intense online gamblers: an empirical study of online gambling behaviour

Social responsibility in gambling has become a major issue for the gaming industry. The possibility for online gamblers to set voluntary time and money limits is a social responsibility practice that is now widespread among online gaming operators. The main issue concerns whether the voluntary setting of such limits has any positive impact on subsequent gambling behaviour and whether such measures are of help to problem gamblers. In this paper, this issue is examined through data collected from a representative random sample of 100,000 players who gambled on the win2day gambling website. When opening an account at the win2day site, there is a mandatory requirement for all players to set time and cash-in limits (that cannot exceed 800 Euros per week). During a three-month period, all voluntary time and/or money limit setting behaviour by a subsample of online gamblers (n=5000) within this mandatory framework was tracked and recorded for subsequent data analysis. From the 5,000 gamblers, the 10% most intense players (as measured by theoretical loss) were further investigated. Voluntary spending limits had the highest significant effect on subsequent monetary spending among casino and lottery gamblers.. Monetary spending among poker players significantly decreased after setting a voluntary time limit.. The highest significant decrease in playing duration was among poker players after setting a voluntary playing duration limit. The results of the study demonstrated that voluntary limit setting had a specific and significant effect on the studied gamblers. Therefore, voluntary limits appear to show voluntary limit setting had an appropriate effect in the desired target group (i.e., the most gaming intense players)

The Baptist Church in Warren: Rehabilitation and Preservation Report

The Baptist Church in Warren is located in the Warren Waterfront Historic National Register District. Warren also has a Voluntary Historic District. Both the National Register Nomination and the Voluntary Historic District have regulations which pertain to changes to the exterior view shed of the building. Exterior work on this project will need to abide by the State of Rhode Island and the Providence Plantations Rehabilitation Code for existing buildings and structures and the Town of Warren Department of Building and Zoning. Exterior work done on a voluntary basis, according to the Warren Voluntary Historic District guidelines, will qualify for a 20% tax credit. The Baptist Church in Warren does not meet the requirements for the local and state tax credit

Differential effects of age on involuntary and voluntary autobiographical memory

"This article may not exactly replicate the final version published in the APA journal. It is not the copy of record." Original article can be found at: http://psycnet.apa.org/journals/pag/24/2/397/ Copyright American Psychological Association. DOI: 10.1037/a0015785Research on aging and autobiographical memory has focused almost exclusively on voluntary autobiographical memory. However, in everyday life, autobiographical memories often come to mind spontaneously without deliberate attempt to retrieve anything. In the present study, diary and word-cue methods were used to compare the involuntary and voluntary memories of 44 young and 38 older adults. The results showed that older adults reported fewer involuntary and voluntary memories than did younger adults. Additionally, the life span distribution of involuntary and voluntary memories did not differ in young adults (a clear recency effect) or in older adults (a recency effect and a reminiscence bump). Despite these similarities between involuntary and voluntary memories, there were also important differences in terms of the effects of age on some memory characteristics. Thus, older adults’ voluntary memories were less specific and were recalled more slowly than those of young adults, but there were no reliable age differences in the specificity of involuntary memories. Moreover, older adults rated their involuntary memories as more positive than did young adults, but this positivity effect was not found for voluntary memories. Theoretical implications of these findings for research on autobiographical memory and cognitive aging are discussedPeer reviewe

Cross-Sectional Survey of Residential and Nursing Homes for Elderly People. Comparisons of residents in residential and nursing homes for elderly people, 1981-1996

This paper compares the characteristics of elderly people living in residential and nursing homes over the period 1981-1996. The paper draws on information collected in four surveys: a 1981 survey of local authority, private and voluntary residential homes; a 1986 survey of private and voluntary residential and nursing homes; a 1988 survey of local authority residential homes; and a 1996 survey of local authority, private and voluntary residential homes, and private and voluntary nursing homes. The distributions of length of stay for permanent residents in local authority and voluntary residential homes and nursing homes in 1996 were similar to those in 1986/88. Mean lengths of stay for voluntary residential homes and nursing homes were slightly shorter in 1996 than in 1986, whereas the reverse appears to be the case for local authority homes. However, the mean length of stay of permanent residents in private residential homes was substantially longer in 1996 than in 1986. In terms of their length of stay, permanent residents in private residential homes resembled those in local authority homes in 1996. In 1996, residents in nursing homes were most likely to have been admitted from hospital and residents in residential homes were most likely to have been living alone prior to admission, particularly in voluntary residential homes. Residents in private residential homes were more likely to have been admitted from hospital than residents in local authority and voluntary residential homes. A larger proportion of residents in voluntary residential homes and nursing homes had been admitted from hospital in 1996 than in 1986, whereas the proportion had decreased for private residential homes and, to a greater extent, for local authority homes. In 1996, residents in nursing homes were substantially more dependent than residents in residential homes, whereas levels of dependency among residents of local authority, private and voluntary residential homes were quite similar. Prior to 1996, residents in voluntary residential homes were less dependent than residents in local authority and private residential homes. Levels of dependency increased in all types of home between 1986/88 and 1996, but the changes were greater for voluntary residential homes and nursing homes, although levels of dependency among residents of nursing homes were also greater than in local authority and private residential homes in 1986/88. In 1981, residents in local authority and private residential homes had similar levels of physical functioning and were much more dependent than residents in voluntary residential homes. Between 1981 and 1986/88 levels of dependency among residents of local authority and voluntary residential homes increased, but levels of dependency among residents of private residential homes were very similar in 1981 and 1986

Funding for voluntary sector infrastructure: a case study analysis

This paper outlines the policy context for grant-making to voluntary sector infrastructure organisations, and describes a qualitative research programme undertaken in the UK in which a detailed study of 20 such grants were investigated from multiple perspectives in terms of their perceived impact after the projects had finished. The grants were selected on tightly determined stratification criteria, from a large pool of grants for voluntary sector infrastructure work made by the Community Fund (one of the distributors of funds to “good causes” from the UK National Lottery). Particular emphasis was placed in the study on assessing the impact on other voluntary and community organisations likely to benefit from the support given to infrastructure organisations. The paper concludes that in general terms, grant-making for voluntary sector infrastructure is an effective way of supporting the voluntary and community sector more generally, although there are important lessons both for funders and for grant-recipients to improve the effectiveness of grant-making in this field

Variations in the Relationship Between the Frequency Content of EMG Signals and the Rate of Torque Development in Voluntary and Elicited Contractions

Our purpose was to characterize the relationship between EMG mean power frequency (MPF) or median frequency (MF) and rate of torque development in voluntary ballistic and electrically elicited isometric contractions. Twenty-three healthy adults participated in two sets of experiments performed on elbow flexor muscles. For Experiment 1, subjects were asked to generate voluntary ballistic contractions by reaching four different target torque levels (20, 40, 60 and 100% of the maximal voluntary contraction (MVC)) as fast as they could. For Experiment 2, electrical (M-waves) and mechanical (twitches) responses to electrical stimulation of the nerves supplying the biceps brachii and brachioradialis muscles were recorded with the subjects at rest and with a background isometric contraction of 15% MVC. MPF, MF and rate of torque development (% MVC/s) were calculated for both voluntary and elicited contractions. Significant positive correlations were observed between MPF and rate of torque development for the voluntary contractions, whereas significant negative correlations were observed between the two variables for elicited contractions. This suggests that factors other than muscle fiber composition influence the frequency content of EMG signals and/or the rate of torque development, and that the effect of these factors will vary between voluntary and elicited contractions. 2002 Elsevier Science Ltd. All rights reserved

Voluntary Activation and Variability During Maximal Dynamic Contractions with Aging

Whether reduced supraspinal activation contributes to age-related reductions in maximal torque during dynamic contractions is not known. The purpose was to determine whether there are age differences in voluntary activation and its variability when assessed with stimulation at the motor cortex and the muscle during maximal isometric, concentric, and eccentric contractions. Thirty young (23.6 ± 4.1 years) and 31 old (69.0 ± 5.2 years) adults performed maximal isometric, shortening (concentric) and lengthening (eccentric) contractions with the elbow flexor muscles. Maximal isometric contractions were performed at 90° elbow flexion and dynamic contractions at a velocity of 60°/s. Voluntary activation was assessed by superimposing an evoked contraction with transcranial magnetic stimulation (TMS) or with electrical stimulation over the muscle during maximal voluntary contractions (MVCs). Old adults had lower MVC torque during isometric (− 17.9%), concentric (− 19.7%), and eccentric (− 9.9%) contractions than young adults, with less of an age difference for eccentric contractions. Voluntary activation was similar between the three contraction types when assessed with TMS and electrical stimulation, with no age group differences. Old adults, however, were more variable in voluntary activation than young (standard deviation 0.99 ± 0.47% vs. 0.73 ± 0.43%, respectively) to both the motor cortex and muscle, and had greater coactivation of the antagonist muscles during dynamic contractions. Thus, the average voluntary activation to the motor cortex and muscle did not differ with aging; however, supraspinal activation was more variable during maximal dynamic and isometric contractions in the old adults. Lower predictability of voluntary activation may indicate subclinical changes in the central nervous system with advanced aging