It is known that electromyostimulation (EMS) alone or superimposed over voluntary contraction (EV) can effectively improve muscle strength. However, the effect of this type of training on the ability to control force production at submaximal levels is unknown. The authors examined the effects of EV training on steadiness in force production of knee extensors and flexors in older adults. Forty participants, including 20 men and 20 women, 60-77 years of age, were randomly allocated into a control group (CG) and an electromyostimulation superimposed over voluntary contraction (EVG) group. The EVG performed 30 bilateral isometric knee extension and flexion contractions per session, 3 training sessions per week, for 6 weeks. The variations in force production, expressed in absolute (standard deviation [SD]) and relative (coefficient of variation [CV]) terms, were assessed in isometric contractions at 5%, 15% and 25% maximal voluntary contraction (MVC) levels. Results indicated that MVC increased in knee extension and flexion in EVG (p < .05) after the training; steadiness CV also improved at 15% MVC in knee flexion (p < .05) but no significant changes were found in knee extension and steadiness SD. The training-induced changes in MVC were not correlated to steadiness CV that might indicate different mechanisms underlying these adaptations. 相似文献
The present study had two aims: First, to investigate the joint and specific roles of working memory (WM) and intelligence as predictors of school achievement. And second, to replicate and extend earlier findings (Spinath, Spinath, Harlaar, & Plomin, 2006) on the incremental validity of non-cognitive over cognitive abilities in the prediction of school achievement. The present sample consisted of N = 179 Chinese primary school children in the fourth grade. All measures including working memory (WM), intelligence and motivational items were assessed in class. Teachers provided test scores for the domains of Chinese and Math. We found that WM was a good predictor of school achievement and comparable in predictive power to intelligence. Together, cognitive ability including both WM and intelligence explained 17.8% and 36.4% of the variance in children's Chinese and Math scores, respectively. The relative importance of WM and intelligence varied with school domains with greater predictive power of WM for Math while intelligence explained a greater proportion of the variance in Chinese although the magnitude of this difference was only moderate. Domain-specific motivational constructs contributed only marginally to the prediction of school achievement for both Chinese and Math. 相似文献
Given the prevalence of imagery appeals in today’s marketplace, the current research studies the role of mental imagery in how consumers process and react to advertisements with different numbers of ad claims. Past research has proposed “three” as the magical number of ad claims that maximizes persuasion, with more than three ad claims increasing skepticism and reducing evaluation. In the current research, we replicate this so-called “charm of three” effect, but only when consumers do not engage in mental imagery; when they do, however, we find that the effect is moderated, in that more ad claims beyond three produces more favorable product evaluation. Additionally, we provide evidence that the moderating effect of mental imagery is driven by transportation and skepticism toward the ad claims, with mental imagery increasing transportation and decreasing skepticism when there are more than three ad claims. Our research contributes to a better understanding of the “charm of three” effect, its boundary conditions, and underlying mechanism. 相似文献
Life satisfaction is a key indicator of children’s healthy development. Although the developmental changes of life satisfaction during adolescence have been investigated, the developmental trajectories of life satisfaction and related predictors during childhood remain unclear. Thus, the current study aimed to identify the developmental trajectories of life satisfaction covering the period from middle to late childhood as well as to examine the predictive roles of environmental factors (i.e., family dysfunction and basic psychological needs satisfaction at school), personality factors (i.e., neuroticism and extraversion), and their interactions in these developmental trajectories. An accelerated longitudinal design was used with Chinese elementary school students (N?=?1069, 45.8% girls, Mage?=?9.43, SD?=?0.95) of 3 cohorts (grade 3, grade 4, and grade 5) on 4 occasions at 6-month intervals. Growth mixture modeling analyses revealed three distinct trajectories of life satisfaction: “High-Stable” (88.8%), “High-Decreasing” (6.8%), and “Low-Increasing” (4.4%). Multivariate logistic regression analyses revealed that family dysfunction and neuroticism served as risk factors for adverse developmental trajectories of life satisfaction; whereas basic psychological needs satisfaction at school served as a protective factor. Furthermore, the interaction between family dysfunction and extraversion suggested that higher levels of extraversion buffered children against the negative effect of family dysfunction on the development of life satisfaction. The identification of three heterogeneous trajectory groups of children’s life satisfaction and key personality and environmental predictors associated with the trajectories suggests that specific interventions need to be tailored to the unique characteristics of the relevant trajectory groups.
In the family‐based prevention science literature, family functioning, defined as positive parenting, parental involvement, family cohesion, family communication, parental monitoring of peers, and parent–adolescent communication, has been shown to ameliorate HIV risk behaviors in Hispanic youth. However, the majority of studies have relied solely on parent or adolescent reports and we know very little about parent–adolescent family functioning discrepancies. Therefore, the purpose of this study was to examine whether and to what extent parent–adolescent discrepancies in family functioning increased the risk of HIV risk behaviors, including substance use and sexual risk behaviors, and whether these associations vary as a function of acculturation and youth gender. A total of 746 Hispanic 8th grade youth and their primary caregivers were included in the study. Structural equation modeling findings indicate that parent–adolescent family functioning discrepancies are associated with an increased risk of Hispanic adolescent HIV risk behaviors, including lifetime and past 90‐day alcohol and illicit drug use, and early sex initiation. In addition, study findings indicate that results vary by acculturation and youth gender. Findings are discussed in the context of existing family‐based research and practice in preventing and reducing HIV risk behaviors among Hispanic youth and their families. 相似文献
Abundant research conducted in Western contexts has shown that biological risk factors such as low resting heart rate (HR) might be related to childhood aggression. However, it was unclear (1) how resting HR, as well as other markers of cardiac functions such as resting vagal tone, may be related to subtypes of aggression such as reactive and proactive aggression, and (2) whether the HR-aggression relation can be replicated in non-Western contexts. Therefore, this study examined the concurrent and prospective relations between resting HR, vagal tone, and Chinese children’s reactive and proactive aggression. Participants were 183 children (M age?=?7.64 years, 91 girls) recruited from an elementary school in Zhenjiang, PRC. Children’s resting HR and vagal tone were assessed in the second grade (T1). Teachers rated children’s reactive and proactive aggression in the second (T1) and fourth grade (T2). Results showed that lower resting HR at T1 was associated with higher reactive and proactive aggression at T1 and T2, and higher vagal tone was associated with lower HR, which in turn was related to higher reactive and proactive aggression at T1 and T2. Lower vagal tone was directly related to higher reactive but not proactive aggression at T1 and T2, whereas lower HR was related to higher reactive aggression at T2 for children with low or moderate vagal tone but was not for children with high vagal tone. These psychophysiological findings from a non-Western context add additional support for both similarities and differences between reactive and proactive aggression in childhood. 相似文献