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Rowe and Kahn's (1987, 1998) model of successful aging (SA) implies a balance among: (1) low probability of disease and disease-related disability; (2) high cognitive and physical functioning; and (3) active engagement with life. This study assessed the relationship of age to the components of SA across the sixth, seventh and eighth decades of life in Canadian seniors (N = 14,749). Age was a significant predictor of disease-related disability and impaired physical functioning, but age had little impact on engagement. Despite health-related changes, these data suggest that the majority of older Canadians are maintaining connections with their community. Copyright © 2010 SAGE Publications Ltd. [ABSTRACT FROM AUTHOR]

Research has shown that physical activity (PA) is associated with overall successful aging (SA), but it is unknown whether PA promotes each SA component in similar ways. This cross-sectional population-based cohort study investigates SA in adults aged 60 years+ using data from the Canadian Community Health Survey ( N = 12,042). Multivariate comparisons showed that, compared to those who were PA, physical inactivity was a much stronger associate of functional limitations than either chronic disease or being socially unengaged with life. This effect was not found for moderately active participants. Findings reinforce that PA, even at moderate levels, is an efficient way of optimizing biopsychosocial health, particularly functional health, in later life. Copyright © 2010 SAGE Publications Ltd. [ABSTRACT FROM AUTHOR]

The purpose of this study was to quantify decision time and classification errors made during trunk posture assessment tasks using a computerised sampling approach. Ninety (45 male, 45 female) university-aged participants, who had varying expertise with body posture evaluation, were asked to accurately classify a series of static images of the trunk using a computer interface by selecting the posture category or 'bin', within which the presented posture fell. Images were presented randomly in either a flexion/extension or lateral bending view at various distances from the boundary lines of each posture bin. Subjects with the least experience performed the tasks in the shortest amount of time; however, they also made the most errors. Expert participants reduced the number of classification errors by increasing the time of each posture classification decision. The flexion/extension task proved to take more time and resulted in more errors than the lateral bend task. The closer the presented images were to the bin boundaries, the greater was the time taken and errors made during posture classification. These data have implications for the design of posture classification biomechanical software interfaces and the training of operators who utilise the software. [ABSTRACT FROM AUTHOR]

The trunk posture misclassification errors made by novice and experienced operators were quantified as a function of the angular distance from posture bin boundaries, similar to those used in observation-based posture assessment tools such as 3DMatch. The effect that these misclassification errors had on cumulative and peak low back loads was also determined in three simulated lifting scenarios. Ninety subjects in 3 experience groups were randomly presented with images of known trunk angle via a monitor. Subjects were instructed to make quick and accurate bin selections using standardized pictures included below the images on the monitor. Mean % bin misclassification errors were approximately 32% and 22% for the flexion/extension and lateral bend views, respectively. More bin classification errors were made the closer a viewed image was to a posture bin boundary, regardless of expertise level, and the number of errors made decreased as operator experience increased. Approximately 99% of bin selections were made either in the correct bin or in the bins immediately adjacent to the correct bin in both views. Misclassification errors made in the 3 simulated lifting scenarios induced errors in peak and cumulative loads in 66% of the cases assessed, with an average absolute difference of 13.5% across all load variables. Future work is aimed at determining the effect of training and bin size on the error misclassification rate for all body segments and views. [ABSTRACT FROM AUTHOR]

In the face of remarkable aging trends in North American society, organized sport/physical activity is an important vehicle for promoting physical health, and a domain in which long-term participation might mitigate pessimistic trends for age decline. This investigation examined patterns of age-related decline in performance for 45 Masters runners who rigorously trained continuously for at least a decade. Longitudinal data for age and performance were collected for 200 m, 1500 m, and 10 km events retrospectively across participants' careers. Cross-sectional (CS) data representing normal patterns of aging were derived from online archives. Longitudinal data reflected within-participant training effects whereas CS data did not. Second-order regression analyses were performed separately for each data type and quadratic beta coefficients, indicative of accelerated age decline, were compared for CS and longitudinal samples on a within-event basis. Results showed evidence of accelerated decline with advancing age for both samples, although rates for longitudinal samples were moderated for the 200 m and 1500 m events. Findings for the long-distance event were anomalous. Results provide evidence for moderated age-decline in physical performance measures for individuals who sustain engagement in organized sport for lengthy periods. Discussion focuses on methodological considerations for advancing future research that contrasts CS and longitudinal samples, and the importance of encouraging sport involvement opportunities to aging individuals. [ABSTRACT FROM AUTHOR]

The purpose of this study was to assess the ability of subjects to detect a visual difference between trunk postures. Three groups of participants, ranging from novices to experts, were required to make perceptual discriminations between two trunk postures from a series of image pairs on a computer screen. Images were presented for flexion and lateral bending motions from three different reference postures in both ascending and descending directions. Overall, direction played the largest role, interacting with all other variables. Subjects were most sensitive to changes in the ascending direction, where differences were detected at an average of 2°. In the descending direction, subjects detected differences at an average of 7° between postures. These data have implications for the usability and design of posture matching-based biomechanical software interfaces and the accuracy of peak and cumulative load estimates from models that utilize such interfaces to acquire segment posture inputs. [ABSTRACT FROM AUTHOR]

Athlete age-grouping and age-banding has been shown to impact sport participation and athlete development. The current study examined the impact of within-year (WYEs) and between-year effects (BYEs), and their interactions with playing position, on female participation in elite German football. The sample of 1,378 German first-league players revealed expected participation inequities within-year with relatively older players being over-represented and younger players being under-represented. From a between-year perspective there were no participation differences. The interaction of WYEs and BYEs revealed an over-representation of odd-year players in Q1, and Q2 in even years. With respect to the interaction between year effects and playing position, for WYEs the expected effect was present for goalkeepers and defenders, while there was no significant interaction for BYEs. Overall, the results offer insight regarding the impact of system structure on participation, and highlight unique characteristics associated with playing positions., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (© 2024 Smith, Koopmann, Weir and Schorer.)

Relative age effects (RAEs) are commonly associated with advantages for older athletes. However, a variety of benefits attributed to 'advantage reversals' have been observed among relatively younger professional athletes. Considering psychosocial development as a proposed mechanism, the purpose of this study was twofold: (1) To explore an association between developmental assets (i.e., facilitators of positive youth development [PYD]) and RAEs; (2) To assess whether overall developmental asset levels are protective against sport dropout. The Developmental Assets Profile© was distributed to members of a one-year cohort of post-adolescent, female soccer players from Ontario, Canada. The presence of differences between groups of relatively older (H1; n = 64) and younger (H2; n = 57) participants and developmental asset scales were assessed using discriminant analysis. A binary logistic regression was conducted to assess whether overall developmental asset levels are protective against sport dropout, with consideration of relevant factors. Findings suggest that relatively younger, female players score higher in two internal categories: commitment to learning and positive values. The overall developmental asset scores were not found to be protective against dropout. This study provides preliminary, albeit cautious, support that 'advantage reversals' may be in part associated with enhanced PYD resulting from developmental sport experiences.

Despite their prevalence, the longitudinal impacts of relative age effects (RAEs) on sport and other forms of physical activity (PA) are understudied. This study examined longitudinal participation patterns in organized sport (team and individual), unorganized PA, and non-participation with respect to RAEs in a prospective cohort of adolescents. Data from the first 24 cycles of the MATCH study were used for analyses. Elementary students ( n = 929) were recruited from 17 schools in Atlantic Canada. Respondents self-reported PA three times/year. Mixed multilevel logistic models compared the likelihood of participating in each context across birth quarter. Chronological age and gender were considered, along with the interaction between chronological and relative age. Individuals born in Quarter 1/Quarter 2 were more likely to report participation in organized team sport but not individual sports. Relatively older participants born in Quarter 2 were more likely to report participation in unorganized PA. Increasing chronological age was associated with decreased participation in organized sport (particularly team-based) and increased non-participation. Gender was not associated with organized sport participation, but girls were under-represented in unorganized PA and more likely to report non-participation. The interaction parameters suggested that RAEs were consistent throughout adolescence in each context. Longitudinal analyses suggest RAEs are context dependent.

Sport dropout rates among children and youth are a concern for researchers and policy makers. The impact of relative age effects (RAEs) on dropout trends has not been adequately examined in female samples. The purpose of this study was to longitudinally examine dropout in a female soccer cohort in Ontario, Canada. Registration entries for a one-year cohort were examined across a seven-year period ( n = 9908; age 10-16 years). A chi-square analysis established the presence of RAEs in the initial year of registration. Survival analyses assessed the impact of relative age, competition level, and community size on athlete dropout. A median survival rate of four years was observed for players born in the first quartile, while all remaining quartiles had a median survival of three years. Community size did not predict dropout in this analysis; however, competition level was a significant predictor, with competitive players being more likely to remain engaged vs. recreational players (55.9% vs. 20.7%). The observed trends are likely to have a significant impact from both a healthy development and systems perspective (e.g., economic/market loss). Intervention is needed to mitigate current dropout trends in female athletes. Practical applications are discussed.

Environmental context can impact youth engagement in sport and athlete development. Previous work has examined the population size of the birthplace of elite athletes; commonly known as the birthplace or community size effect . Community density has also been recognized as an important variable. Exact estimates for the ideal community characteristics and a thorough understanding of the underlying mechanisms has been somewhat elusive. Existing studies are cross-sectional in nature and there is evidence to suggest that significant variation exists within imposed categories. An athlete's birthdate position in a similar-age cohort can also impact development and has been associated with (dis)advantages resulting from subtle age differences (i.e., the relative age effect); it remains unknown if this variable is associated with population density. The objective of this study was to establish longitudinal participation trends among female youth soccer players in Ontario Canada, with consideration of community size, community density, and relative age. Within-category variation and associations between the variables were assessed. Registration entries at age 10 years ( n = 9,826) and 16 years ( n = 2,305) were isolated for analysis. Odds ratio analyses were conducted within each community size and density category for all 10 year old registrants; 95% confidence intervals were obtained. This procedure was repeated for all registrants at 16 years of age using the expected distribution at age 10 years to examine continued engagement. Findings suggest medium-sized communities (i.e., 10,000-249,999 inhabitants) provide the best odds of participation and continued engagement. Less densely populated communities (i.e., 50-<400 population/km 2 ) appeared to be ideal for facilitating participation at age 10 years, but not for engagement at age 16 years. However, within-category variation was evident when each community was inspected individually. Consistent with previous attempts to find an association between community size and the relative age effect, there did not appear to be an association between community density and birth quartile distribution. Observations from this study show that community size and community density are truly unique and separate variables. Future studies should consider the underlying contributions to both low and high participation and continued engagement, while being mindful of within-category variation., (Copyright © 2020 Smith and Weir.)

An Online First version of this article was made available at https://link.springer.com/article/10.1007/s40279-018-0890-8 on 13 March 2018. Some errors were subsequently identified by the authors, particularly in regard to Table 4. Although the details pertained to in the table were correct in the original manuscript, it appears that errors were introduced during production of the article. The published article has now been updated with a corrected version of Table 4. This corrected version of the table is also shown below.

Background: Subtle differences in chronological age within sport (bi-) annual-age groupings can contribute to immediate participation and long-term attainment discrepancies; known as the relative age effect. Voluminous studies have examined relative age effects in male sport; however, their prevalence and context-specific magnitude in female sport remain undetermined., Objective: The objective of this study was to determine the prevalence and magnitude of relative age effects in female sport via examination of published data spanning 1984-2016., Methods: Registered with PROSPERO (No. 42016053497) and using Preferred Reporting Items for Systematic Reviews and Meta-analysis systematic search guidelines, 57 studies were identified, containing 308 independent samples across 25 sports. Distribution data were synthesised using odds ratio meta-analyses, applying an invariance random-effects model. Follow-up subgroup category analyses examined whether relative age effect magnitudes were moderated by age group, competition level, sport type, sport context and study quality., Results: When comparing the relatively oldest (quartile 1) vs. youngest (quartile 4) individuals across all female sport contexts, the overall pooled estimate identified a significant but small relative age effect (odds ratio = 1.25; 95% confidence interval 1.21-1.30; p = 0.01; odds ratio adjusted = 1.21). Subgroup analyses revealed the relative age effect magnitude was higher in pre-adolescent (≤ 11 years) and adolescent (12-14 years) age groups and at higher competition levels. Relative age effect magnitudes were higher in team-based and individual sport contexts associated with high physiological demands., Conclusion: The findings highlight relative age effects are prevalent across the female sport contexts examined. Relative age effect magnitude is moderated by interactions between developmental stages, competition level and sport context demands. Modifications to sport policy, organisational and athlete development system structure, as well as practitioner intervention are recommended to prevent relative age effect-related participation and longer term attainment inequalities.

Objective: To qualitatively examine factors that contribute to successful aging during different decades of older adulthood., Methods: Fundamental qualitative description was adopted as the methodological framework. Through purposeful sampling, 42 community dwelling older adults (mean age = 79.6 years, age range = 65-97 years; 19 males) were recruited. Focus groups (6) segmented by decade of life were conducted with participants 65-74 (n = 17) and 75-84 (n = 17) years of age. Semi-structured interviews (16) were conducted with four participants from each decade, as well as participants 85 years of age and older (n = 8). Data analyses were conducted independently for each decade of life and included inductive analysis of textual data through continuous comparisons of meaning units., Results: Three primary themes related to successful aging were identified across all decades of older adulthood: (1) staying healthy (secondary themes: genetics and lifestyle choices), (2) maintaining an active engagement in life (secondary themes: social engagement and cognitive engagement), and (3) keeping a positive outlook on life. Participants in specific decades of older adulthood identified three additional secondary themes related to maintaining an active engagement in life: finances (65-74 and 85+ years), social support (75+ years), and successful marriage (75+ years). Similarly, only adults 65-84 years of age identified a secondary theme for keeping a positive outlook on life: acceptance and adaptation., Conclusion: Primary themes related to successful aging were agreed upon by participants in all decades of older adulthood, while age-based differences existed among secondary themes. Thus, what it means to age successfully may be age-dependent.

Background: A disconnect in manual patient transfer (MPT) training practices for nurses, between what is taught and used in academic and clinical settings, could have implications for injury., Objective: This study aimed to determine: 1. what MPTs student and staff nurses use in clinical settings, and 2. if the MPTs used most often were also the ones they perceived that they received training for and had the most confidence performing., Methods: Survey responses from student nurses (n=163) (mid-sized university) and staff nurses (n=33) (local hospital) regarding 19 MPTs were analyzed to determine which transfers were perceived to be used most often, and which ones they had received training for and had the greatest confidence performing., Results: The MPTs nurses perceived using most often were the same transfers they had the greatest confidence performing and for which they perceived receiving training. However, these MPTs were not taught at the university at the time of this investigation., Conclusion: Reducing the disconnect between manual patient transfer training obtained in the academic and clinical environments will hopefully reduce the risk of injury for nurses and improve the quality of care for patients.

The concept of aging successfully has become increasingly important as demographics shift towards an aging population. Successful aging has been defined to include (1) a low probability of disease and disease-related disability; (2) a high level of physical and cognitive functioning; and (3) an active engagement in life. The built environment can create opportunities or constraints for seniors to participate in social and productive activities. Universally designed spaces are more easily accessed and used by a spectrum of people without specialized adaptations. Thus, a universally designed environment creates opportunities for older adults to participate in these activities without the stigmatization associated with adapted or accessible designs. Providing older adults with specific universal design options (e.g., lever handle faucets) has the potential to increase the ease of completing activities of daily living, which promotes a continual engagement in life. Literature regarding universal design is promising; however, its theory requires further attention from professionals designing the built environment, evidence of the significance of its application from academics, and the embracement of its core principles from society. Overall, universal design has the potential to provide a stepping stone toward successful aging.

The identification of barriers to physical activity and exercise has been used for many decades to explain exercise behavior in older adults. Typically health concerns are the number one barrier to participation. Data from CCHS-HA dataset (N = 20, 875) were used to generate a sample of Canadians, 60+ years, who did not identify a health condition limitation, illness, or injury as a barrier to participation in physical activity (n = 4,900) making this dataset unique in terms of the study of barriers to participation. While the vast majority of older adults participated in physical activity, 9.4% did not. The relationships between nonparticipation, barriers, self-reported health status, and chronic health conditions were determined using binary logistic regression. The main findings suggest that traditional barriers and self-reported health status are not responsible for nonparticipation. Nonparticipation was best predicted by chronic health conditions suggesting a disconnect between self-reported health status and underlying health conditions. The data are clear in suggesting that barriers are not the limiting factor and physical activity programming must be focused on meeting the health needs of our aging population.

Objective: Patient transfers have been implicated as a contributing factor in the high work-related musculoskeletal disorder (MSD) rate in nursing. However, documenting how much time is spent doing such tasks, compared to other less biomechanically stressful tasks in the workplace, has been limited, and not performed to date using a video-based approach. Therefore, the purpose of this study was to determine the feasibility of documenting all job-related nursing tasks performed during a typical shift in a hospital setting using video., Participants: Ten female nurses from an acute care hospital who worked in different units and during all three shifts., Methods: Nurses working in different units of the hospital were videotaped performing their normal job-related tasks for a 2 hour period. Video records were subsequently analyzed to identify and categorize all tasks performed by each nurse., Results: Overall, nurses spent less than 7% of their time during patient moving and transfer activities. One third of their time was spent walking, standing and sitting, 19.8% charting, 14.7% in patient care, 13.9% preparing medicines, 9.5% in housekeeping, and about 3% in self-care., Conclusions: This study showed that video-based methods are feasible for documenting what nurses do in the workplace. It also highlighted the diversity and non-repetitive nature of the workplace tasks nurses perform and suggests that ergonomic assessments of the cumulative effects of work on nurses in the field should focus on more than just patient handling activities.

Observation-based posture assessment methods (e.g. RULA, 3DMatch) require classification of body postures into categories. This study investigated the effect of improving posture category salience (adding borders, shading and colour to the posture categories) on posture selection error rates and decision times of novice analysts. Ninety university students with normal or corrected normal visual acuity and who were not colourblind, were instructed to select posture categories as quickly and accurately as possible, in five salience conditions (Plain (no border, no shading, no colour); Grey Border; Red Border; Grey Shading (GS) and Red Shading (RS)) for images presented in randomised blocks (240 classifications made by each participant) on a computer interface. Participants responded quickest in the Border conditions, classifying postures about 5% faster than in the Plain condition. Coloured diagrams significantly reduced posture classification errors by approximately 1.5%. Overall, the best performance, based on both error rate and decision time combined, resulted from incorporating a Grey Border to the posture category diagrams; a simple enhancement that could be made to most current observation-based posture assessment tools., Practitioner Summary: The salience of posture diagrams used in observation-based posture assessment tools was evaluated with respect to analyst error rates and decision times. The best performance resulted from incorporating a grey border to the posture diagrams; a simple enhancement that can be made to most current observation-based posture assessment tools.

In 2006, after 44 years of eradication of malaria, Jamaica had an outbreak of Plasmodium falciparum: 406 confirmed cases between September 2006 and December 2009 with a peak of the epidemic in December 2006. In response to the outbreak, the Ministry of Health launched an emergency response through early detection and prompt treatment of cases, vector control, public education and intersectoral collaboration. Ninety percent (361) of cases were residents of Kingston, and 63.6% were identified through house to house surveillance visits. For 56% of the confirmed cases, treatment with chloroquine was initiated within a week of onset of symptoms. Only one (0.3%) of 358 cases who had a post-treatment smear on day 7 had a persistent asexual parasitaemia, while none of the 149 persons who had a follow-up smear on day 28 was positive. The outbreak highlighted the need for increased institutional capacity for surveillance, confirmation and treatment of malaria as well as effective prevention and control of outbreaks which can occur after elimination. Jamaica appears to have successfully eliminated malaria after its reintroduction., (© 2010 Blackwell Publishing Ltd.)

The purpose of this study was to examine the influence of training on the decision times and errors associated with video-based trunk posture classifications. Altogether, 30 amateur and 30 knowledge-based participants completed a three-phase study (pre-training, training, post-training) that required them to classify static trunk postures in images on a computer screen into a posture category that represented the angle of the trunk depicted. Trunk postures were presented in both flexion/extension and lateral bend views and at several distances from the boundaries of the posture categories. Both decision time and errors decreased as distance from the boundaries increased. On average, amateur analysts experienced a larger decrease in decision time per posture classification than knowledge-based analysts (amateur: 0.79 s, knowledge-based: 0.60 s; p <0.05) suggesting that training can have beneficial effects on classification performance. The implications are that the analysis time associated with video-based posture assessment methods can be reduced with appropriate training, making this type of approach feasible for larger-scale field studies. Statement of Relevance:Understanding the role that training can play in reducing errors associated with the use of video-based posture assessment methods may result in more efficient use of these tools by ergonomic practitioners. Reducing decision time and misclassification errors will provide a more efficient, accurate and representative assessment of injury risk.

Objective: The purpose of this study was to evaluate the perceptions of student and staff nurses regarding training they received and their confidence in performing a variety of common manual patient transfers (MPTs), given that inadequate training may have implications for injury risk., Participants: Student nurses (n=163) from a mid-sized university and staff nurses (n=33) from a small rural hospital in the university's region., Methods: Participants were surveyed to determine which of 19 MPTs they perceived having received training for and had greatest confidence performing., Results: The staff nurses perceived being trained on four MPTs; the same four they indicated they had the greatest confidence performing. However, nursing students were not trained on these MPTs at the local university, indicating an apparent disconnect in training practices between the academic institution and the workplace., Conclusions: It is suggested that a participatory ergonomics training approach may help to provide student nurses more opportunity to practice MPTs and help all nurses reduce work-related musculoskeletal injury risk and increase job satisfaction. Increased training time may also allow student nurses to gain greater mastery and confidence of skills prior to full-time employment.

A relative age effect has been identified in Masters sports (Medic, Starkes, & Young, 2007). Since gender, age, and type of sport have been found to influence the relative age effect in youth sports (Musch & Grondin, 2001), we examined how these three variables influenced possible relative age effects among Masters swimmers and track and field athletes. Using archived data between 1996 and 2006, frequency of participation entries and record-setting performances at the US Masters championships were examined as a function of an individual's constituent year within any 5-year age category. Study 1 investigated the frequency of Master athletes who participated; Study 2 examined the frequency of performance records that were set across constituent years within an age category, while accounting for the distribution of participation frequencies. Results showed that a participation-related relative age effect in Masters sports is stronger for males, that it becomes progressively stronger with each successive decade of life, and that it does not differ across track and field and swimming. In addition, a performance-related relative age effect in Masters sport seems to be stronger for swimming than track and field, but it does not differ across gender and decades of life.

Currently, there are no standards for the development of posture classification systems used in observation-based ergonomic posture assessment methods. This study was conducted to determine if an optimal posture category size for different body segments and posture views could be established by examining the trade-off between magnitude of error and the number of posture category misclassification errors made. Three groups (trunk flexion/extension and lateral bend; shoulder flexion/extension and adduction/abduction; elbow flexion/extension) of 30 participants each selected postures they perceived to correctly represent the video image shown on a computer screen. For each view, 10 images were presented for five different posture category sizes, three times each. The optimal posture category sizes established were 30 degrees for trunk, shoulder and elbow flexion/extension, 30 degrees for shoulder adduction/abduction and 15 degrees for trunk lateral bend, suggesting that posture category size should be based on the body segment and view of the image being assessed. Across all conditions, the posture category sizes were comparable to those used in published ergonomic tools.

Researchers have contended that patterns of age-related decline are not necessarily due to age, but rather to disuse, or declining practice (Bortz, 1982; Ericsson, 2000; Maharam, Bauman, Kalman, Skolnik, & Perle, 1999). A regression approach was used to examine age and training variables as predictors of 10-km running performance between 40 and 59 years of age. A sample of 30 Masters runners (M age=50.1 years, M 10-km time=39:19) reported data for ongoing training, cumulative running in the past 5 years, and cumulative running earlier in a career. In Analysis 1, ongoing training variables explained more variance in performance than age alone, and reduced the unique variance attributable to age in a combined model. In Analysis 2, findings were replicated using past cumulative running variables and age; running in the past 5 years explained more unique variance than age alone. Discussion focuses on how findings relate to the selective maintenance account (Krampe & Ericsson, 1996), how various aspects of training help to preserve performance in aging populations, and recommendations for future research.

In Studies 1 and 2, the authors evaluated deliberate practice theory through analyses of the relationship between practice and performance for 2 populations of athletes: triathletes and swimmers, respectively. In Study 3, the authors obtained evaluations of practice from athletes' diaries. Across athletes, length of time involved in fitness activities was not related to performance. For the triathletes, a significant percentage of variance in performance was captured by practice. This was not so for sprint events for the swimmers, in which gender was a significant predictor. In the diaries, physical activities were perceived as enjoyable. In contrast to the results obtained from questionnaires, enjoyment did not covary with an activity's relevance to improving performance. Although these findings highlight the importance of sport-specific practice, the authors question a domain-independent account of expertise based on deliberate practice., (copyright (c) 2004 APA, all rights reserved.)

Two experiments are reported that focus on manipulating both the context and the spatial precision of a computer-pointing task. Single goal-directed actions are compared to dual-phase tasks, where participants are required to sequentially attain two goal locations. Results support the idea that for movements in series, movement planning, and online feedback, control can occur simultaneously. Additionally, for single-phase tasks and the final phase of dual-phase tasks, the termination requirement influences the temporal components of the movement. The effects of termination and movement context appear to hold regardless of the spatial precision of the task. This suggests that the effects of spatial precision and movement termination are independent, although both have an impact on the deceleration time for goal-directed movements.

To date very little research has addressed the abilities of young participants to respond to a change in visual information provided during movement execution. This study attempted to determine the ability of 45 participants (5, 7, 9 years) to respond to a change in visual information during a discrete rapid aiming movement. A perturbation paradigm where the target size changed after movement onset was used. In the control context, movements were made to each target size (small, medium, large) with no perturbation. In contrast, during the experimental context the target always began as a medium target. Upon movement initiation, the target size could remain constant or might unexpectedly become larger or smaller. Temporal, kinematic, and correction data were collected to determine the control process underlying the aiming movement. No interaction was found between age and condition for movement time (MT), and results indicated that all ages scaled movement time to final target size. The accuracy data revealed the 9-year-old participants were more accurate than the 5- and 7-year-old participants. To determine where the changes in duration were made, the time to and after peak velocity (TTPV, TAPV), and peak velocity values (PV) were examined. The PV values indicated that, during the control context, the participants scaled their movement to the target size. However, during the experimental condition generally no significant differences were found in either measure, suggesting a programmed response based on the original target size. This was supported by the correction data collected prior to peak velocity, lending further support to a programmed response. Following peak velocity, it was found that differences in MT were as a result of time spent in deceleration. This increased TAPV, and increased number of corrections observed, suggest that all participants were using on-line control following peak velocity in response to the change in visual information. The data collected supports a model of control that incorporates both open-loop control during the initial impulse phase, and closed-loop control during the current control phase for participants as young as 5 years.

Tipper (1985; Q J Exp Psychol A 37:571-590) has suggested that competing responses programmed to distracting stimuli are inhibited based on their relationship to the action being performed. The present paper reports two experiments designed to examine the influence of the terminal action of a task on the allocation of visual attention. Taken together the results suggest that when engaging targets in an environment, which includes distracting stimuli, competing responses are likely to be programmed in parallel and that the relationship between competing responses can include both spatial position and action characteristics.

In the present research the authors examined the time course of binocular integration in goal-directed aiming and grasping. With liquid-crystal goggles, the authors manipulated vision independently to the right and left eyes of 10 students during movement preparation and movement execution. Contrary to earlier findings reported in catching experiments (I. Olivier, D. J. Weeks, K. L. Ricker, J. Lyons, & D. Elliott, 1998), neither a temporal nor a spatial binocular advantage was obtained in 1 grasping and 2 aiming studies. That result suggests that, at least in some circumstances, monocular vision is sufficient for the precise control of limb movements. In a final aiming experiment involving 3-dimensional spatial variability and no trial-to-trial visual feedback about performance, binocular vision was associated with greater spatial accuracy. Binocular superiority appeared to be most pronounced when participants were unable to adjust their limb control strategy or procedure on the basis of terminal feedback about performance.

A single study is reported in which the influence of age and task goal on reaching and grasping movements were examined. Ten young and 10 elderly subjects reached and grasped a disk (4.5-cm diameter) and then either (a) placed it in a well, (b) placed It in a box, or (c) threw it in a box, all located 30 cm to the left of the disk. The reach-to-grasp movements were analyzed over two phases: the approach to capture the disk and the transporting of the disk. Differential effects were observed over the two phases as a function of age. Over the approach, the movement times of the elderly subjects were comparable with those of the young subjects, but their relative deceleration and hand enclosing times took longer. During object transport, however, the elderly subjects moved more slowly than the young subjects did, but there were no differences in relative timing. In both phases, the precision required of the task influenced the duration of movement and the relative timing of arm deceleration, suggesting that subjects accurately anticipated the demands of the task. Those results, which are discussed in relation to hardware and software limitations on performance, suggest that the age-related differences reflect changes in the use of software strategies over the two phases of movement.

Tree transpiration was determined by xylem sap flow and eddy correlation measurements in a temperate broad-leaved forest of Nothofagus in New Zealand (tree height: up to 36 m, one-sided leaf area index: 7). Measurements were carried out on a plot which had similar stem circumference and basal area per ground area as the stand. Plot sap flux density agreed with tree canopy transpiration rate determined by the difference between above-canopy eddy correlation and forest floor lysimeter evaporation measurements. Daily sap flux varied by an order of magnitude among trees (2 to 87 kg day -1 tree -1 ). Over 50% of plot sap flux density originated from 3 of 14 trees which emerged 2 to 5 m above the canopy. Maximum tree transpiration rate was significantly correlated with tree height, stem sapwood area, and stem circumference. Use of water stored in the trees was minimal. It is estimated that during growth and crown development, Nothofagus allocates about 0.06 m of circumference of main tree trunk or 0.01 m 2 of sapwood per kg of water transpired over one hour.Maximum total conductance for water vapour transfer (including canopy and aerodynamic conductance) of emergent trees, calculated from sap flux density and humidity measurements, was 9.5 mm s -1 that is equivalent to 112 mmol m -2 s -1 at the scale of the leaf. Artificially illuminated shoots measured in the stand with gas exchange chambers had maximum stomatal conductances of 280 mmol m -2 s -1 at the top and 150 mmol m -2 s -1 at the bottom of the canopy. The difference between canopy and leaf-level measurements is discussed with respect to effects of transpiration on humidity within the canopy. Maximum total conductance was significantly correlated with leaf nitrogen content. Mean carbon isotope ratio was -27.76±0.27‰ (average ±s.e.) indicating a moist environment. The effects of interactions between the canopy and the atmosphere on forest water use dynamics are shown by a fourfold variation in coupling of the tree canopy air saturation deficit to that of the overhead atmosphere on a typical fine day due to changes in stomatal conductance.

The present experiment determined whether object texture influenced the transport and grasp components of human prehension. Infrared markers placed on the index finger, thumb, and wrist were recorded using a WATSMART system. The test objects were cylindrical dowels (103 mm high, 25 mm diameter, and 150 g in weight) of various surface materials (plain metal, coated with Vaseline, and covered with coarse sandpaper). Only temporal kinematic measures were affected by texture: Movement time (ms), time after peak deceleration (ms), percentages of movement time following maximum aperture, velocity, and deceleration were all significantly greater for the slippery dowel than the normal and rough dowels. Results indicated that the increased time associated with the slippery dowel could be explained entirely by increased time between contact with the dowel and dowel lift. Thus, these results are like those of Weir, MacKenzie, Marteniuk, Cargoe, and Frazer (1991), in which object weight was shown not to affect the free-motion phase, which includes the transport and grasp components of prehension. It appears that intrinsic object properties like weight and texture affect only the finger-object interaction phase of prehension; subsequent research is needed to dissociate inertial and surface friction effects while in contact with objects

The purpose of these experiments was to determine the effects of object weight and condition of weight presentation on the kinematics of human prehension. Subjects performed reaching and grasping movements to metal dowels whose visible characteristics were similar but whose weight varied (20, 55, 150, 410 g). Movements were performed under two conditions of weight presentation, random (weight unknown) and blocked (weight known). Three-dimensional movements of the thumb, index finger, and wrist were recorded, using a WATSMART system to obtain information regarding the grasp and transport components. The results of the first experiment indicated that object weight and condition of presentation affected the temporal and kinematic measures for both the grasp and transport components. In conjunction with the results of a second experiment, in which time in contact with the dowel was measured, it was shown that the free-motion phase of prehension (i.e., up to object contact) was invariant over the different conditions, however. The changes were observed in the finger-object interaction phase (when subjects applied forces after contact with the dowel), prior to lift-off. These results were interpreted as indicating (a) object weight does not influence the planning and execution of the free-motion phase of prehension and (b) there are at least two motor control phases involved in prehension, one for making contact with the object and the other for finger-object interaction. The changing contributions of visual, kinesthetic, and haptic information during these two phases is discussed.