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81.
In this study, we assessed the longitudinal effects of social-cognitive mechanisms on the self-reported use of doping substances and supplements among Italian high school students. In total, 1232 students completed questionnaires measuring various psychological factors hypothesized to influence students' intention to use substances. Three months later, 762 of the students completed the same questionnaires a second time and also reported their use of substances during the time between assessments. Overall, the percentages of students using doping substances (2.1%) or supplements (14.4%) were consistent with values reported in the literature. Analysis of the data showed that adolescents' intention to use doping substances increased with stronger attitudes about doping, stronger beliefs that significant others would approve of their use, a stronger conviction that doping use can be justified, and a lowered capacity to resist situational pressure or personal desires. In turn, stronger intentions and moral disengagement contributed to a greater use of doping substances during the previous 3 months. Doping use was also correlated significantly to supplementation. In conclusion, our results provide novel information about some of the psychological processes possibly regulating adolescents' use of doping substances and supplements. The results also highlight possible areas for future study and intervention, focusing on the prevention of adolescents' substance use.  相似文献   
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83.
The psychobiological status of cyclists over a period of 8 months of training was assessed by measuring the sympatho-adrenal level, the central noradrenergic activity, and the cortisol-testosterone ratio status noninvasively. Alteration of these indices after a large increase in training load lasting 4 days (+ 187%) was also examined. Urinary excretion of methoxyamines (metanephrine, normetanephrine) and 3-methoxy-4-hydroxyphenylglycol sulphate (MHPG-S), and salivary concentrations of cortisol and testosterone, were measured in 12 national cyclists after a non-specific training period and 48 h before 4 days of increased training (T1), after these 4 days (T2) and at the end of 4 months of specific training (T3). Urinary and salivary samples were also collected during a rest period (T0). At each of these times, mood states and ratings of perceived muscle soreness were assessed, and a questionnaire of early clinical symptoms of the overtraining syndrome (Profile of Mood States) was administered. A significant increase in normetanephrine (P < 0.05) and a decrease in the testosterone-cortisol ratio (P < 0.05) were observed at T2, while MHPG-S excretion remained unchanged. Over the same periods, increased training loads did not induce mood disturbances. Eight months of training were associated with significant alterations in metanephrine (P < 0.05) and MHPG-S (P < 0.05). These results suggest a dissociation between the neural and endocrine catecholaminergic components systems. Opposite responses between MHPG-S and Profile of Mood States scores show that further investigations are needed to understand the relationship between central noradrenergic function, which is recognized as a regulatory factor of mood, and psychological tests measuring mood.  相似文献   
84.
The aim of this study was to determine whether there is an effect of time of day on the adaptation to strength training at maximal effort. Fourteen participants took part in this experiment. Their peak anaerobic power (Wingate anaerobic test) and peak knee extension torque at six angular velocities (1.05, 2.10, 3.14, 4.19, 5.24 and 6.29 rad x s(-1)) were recorded in the morning (between 07:00 and 08:00 h) and in the evening (between 17:00 and 18:00 h) just before and 2 weeks after a 6 week course of regular training. Seven of them trained only in the morning and seven only in the evening. Multivariate analysis of variance revealed a significant group x pre-/post-training x time of day interaction effect for peak torque and peak anaerobic power. Before training, in both groups, peak torque and peak anaerobic power were significantly higher in the evening than in the morning. After training, there was no significant difference in peak torque and peak anaerobic power between the morning and the evening for the morning training group. In contrast, in the evening training group, peak torque and peak anaerobic power were higher in the evening than in the morning. As a result of training, both peak torque and peak anaerobic power increased from their initial values as expected. The morning training group improved their peak anaerobic power significantly in the morning and in the evening, the absolute increase being larger in the morning than in the evening. The evening training group did not improve their peak anaerobic power in the morning, whereas it improved significantly in the evening. Although peak torque was significantly improved by training in the morning and evening in both groups, the absolute increase was greater in the morning than in the evening in the morning training group, whereas the opposite was the case for the evening training group. These results suggest that training twice a week at a specific hour increases the peak torque and the peak anaerobic power specifically at this hour and demonstrates that there is a temporal specificity to strength training.  相似文献   
85.
The aim of this study was to analyse the characteristics of the asymmetries in the dominant and non-dominant limbs when kicking stationary and rolling balls. Ten experienced Brazilian amateur futsal players participated in this study. Each participant performed kicks under two conditions (stationary ball vs. rolling ball) with the dominant and non-dominant limbs (five kicks per condition per limb). We analysed the kicking accuracy, ball and foot velocities, angular joint displacement and velocity. The asymmetry between the dominant and non-dominant limbs was analysed by symmetry index and two-way repeated measures ANOVA. The results did not reveal any interaction between the condition and limb for ball velocity, foot velocity and accuracy. However, kicking with the dominant limb in both kicks showed higher ball velocity (stationary ball: dominant – 24.27 ± 2.21 m · s?1 and non-dominant – 21.62 ± 2.26 m · s?1; rolling ball: dominant – 23.88 ± 2.71 m · s?1 and non-dominant – 21.42 ± 2.25 m · s?1), foot velocity (stationary ball: dominant – 17.61 ± 1.87 m · s?1 and non-dominant – 15.58 ± 2.69 m · s?1; rolling ball: dominant – 17.25 ± 2.26 m · s?1 and non-dominant – 14.77 ± 2.35 m · s?1) and accuracy (stationary ball: dominant – 1.17 ± 0.84 m and non-dominant – 1.56 ± 1.30 m; rolling ball: dominant – 1.31 ± 0.91 m and non-dominant – 1.97 ± 1.44 m). In addition, the angular joint adjustments were dependent on the limb in both kicks (the kicks with non-dominant limb showed lower hip external rotation than the kicks with the dominant limb), indicating that the hip joint is important in kick performance. In conclusion, the kicks with the non-dominant limb showed different angular adjustments in comparison to kicks with the dominant limb. In addition, kicking a rolling ball with the non-dominant limb showed higher asymmetry for accuracy, indicating that complex kicks are more asymmetric.  相似文献   
86.
The aim of this study was to compare the training effects based on repeated sprint ability (RSA) (with one change of direction) with an intensive repeated sprint ability (IRSA) (with two changes of direction) on jump performance and aerobic fitness. Eighteen male basketball players were assigned to repeated sprint ability and intensive repeated sprint ability training groups (RSAG and IRSAG). RSA, IRSA, squat jump (SJ), countermovement jump (CMJ) and Yo-Yo intermittent recovery level 1 test were assessed before and after four training weeks. The RSA and IRSA trainings consisted of three sets of six sprints (first two weeks) and eight sprints (second two weeks) with 4-min sets recovery and 20-s of sprints recovery. Four weeks of training led to an overall improvement in most of the measures of RSA, but little evidence of any differences between the two training modes. Jump performance was enhanced: CMJ of 7.5% (< 0.0001) and 3.1% (= 0.016) in IRSAG and RSAG respectively. While SJ improved of 5.3% (= 0.003) for IRSAG and 3.4% (= 0.095) for RSAG. Conversely the Yo-Yo distance increased 21% (= 0.301) and 34% (= 0.017) in IRSAG and RSAG respectively. Therefore, short-term repeated sprint training with one/two changes of direction promotes improvements in both RSA and IRSA respectively but the better increase on jump performance shown a few changes on sprint and endurance performances.  相似文献   
87.
Ethics and Information Technology - In this paper I provide an exposition and critique of the Organic View of Ethical Status, as outlined by Torrance (2008). A key presupposition of this view is...  相似文献   
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89.
The positive impact of intangible assets on several measures of economic performance is well documented in the literature. Less clear is what initially leads firms to invest in intangible assets. The latter is particularly important because, at least for the Italian manufacturing sector, firms exhibit strong heterogeneity in their investments in intangible assets. In line with the capability-based theory of the firm, we argue that the firm's propensity to invest in intangible assets can be explained by factors that are internal and specific to the firm. Making use of a rich dataset, we test and provide support for our hypotheses. In particular, we find that the propensity to invest in intangible assets increases with the firm's size, human capital, and historical intangible asset base. This points towards the existence of a cumulative process of intangible asset accumulation, which may account for most of the heterogeneity observed in the data. The paper adds to the previous literature in two ways: first, it highlights the existence of strong intra-industry heterogeneity in intangible asset investments, and second, it offers an explanation for such heterogeneity.  相似文献   
90.
We draw upon transformational leadership theory to develop an instrument to measure transformational parenting for use with adolescents. First, potential items were generated that were developmentally appropriate and evidence for content validity was provided through the use of focus groups with parents and adolescents. We subsequently provide evidence for several aspects of construct validity of measures derived from the Transformational Parenting Questionnaire (TPQ). Data were collected from 857 adolescents (M(age) = 14.70 years), who rated the behaviors of their mothers and fathers. The results provided support for a second-order measurement model of transformational parenting. In addition, positive relationships between mothers' and fathers' transformational parenting behaviors, adolescents' self-regulatory efficacy for physical activity and healthy eating, and life satisfaction were found. The results of this research support the application of transformational leadership theory to parenting behaviors, as well as the construct validity of measures derived from the TPQ.  相似文献   
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