Effects of heat acclimation on hand cooling efficacy following exercise in the heat     

Elizabeth L. Adams  Lesley W. Vandermark  J. Luke Pryor  Riana R. Pryor  Rachel M. VanScoy  Craig R. Denegar 《Journal of sports sciences》2017,35(9):828-834

This study examined the separate and combined effects of heat acclimation and hand cooling on post-exercise cooling rates following bouts of exercise in the heat. Seventeen non-heat acclimated (NHA) males (mean ± SE; age, 23 ± 1 y; mass, 75.30 ± 2.27 kg; maximal oxygen consumption [VO₂ max], 54.1 ± 1.3 ml·kg^?1·min^?1) completed 2 heat stress tests (HST) when NHA, then 10 days of heat acclimation, then 2 HST once heat acclimated (HA) in an environmental chamber (40°C; 40%RH). HSTs were 2 60-min bouts of treadmill exercise (45% VO₂ max; 2% grade) each followed by 10 min of hand cooling (C) or no cooling (NC). Heat acclimation sessions were 90–240 min of treadmill or stationary bike exercise (60–80% VO₂ max). Repeated measures ANOVA with Fishers LSD post hoc (α < 0.05) identified differences. When NHA, C (0.020 ± 0.003°C·min^?1) had a greater cooling rate than NC (0.013 ± 0.003°C·min^?1) (mean difference [95%CI]; 0.007°C [0.001,0.013], P = 0.035). Once HA, C (0.021 ± 0.002°C·min^?1) was similar to NC (0.025 ± 0.002°C·min^?1) (0.004°C [?0.003,0.011], P = 0.216). Hand cooling when HA (0.021 ± 0.002°C·min^?1) was similar to when NHA (0.020 ± 0.003°C·min^?1) (P = 0.77). In conclusion, when NHA, C provided greater cooling rates than NC. Once HA, C and NC provided similar cooling rates.  相似文献   

A new footwear technology to promote non-heelstrike landing and enhance running performance: Fact or fad?     

Janet H. Zhang  Aislinn J. C. McPhail  Winko W. An  Waqar M. Naqvi  Daniel L. H. Chan  Ivan P. H. Au 《Journal of sports sciences》2017,35(15):1533-1537

This study sought to compare the kinetics and kinematics data in a group of habitual shod runners when running in traditional running shoes and newly designed minimalist shoes with lug platform. This novel footwear design claims to simulate barefoot running and reduce energy loss during impact. We compared footstrike angle (FSA), vertical average (VALR) and instantaneous (VILR) loading rates, energy loss and initial vertical stiffness between two shoe conditions. Runners demonstrated a decreased FSA while running in minimalist shoes with lug platform than traditional shoes (P = 0.003; Cohen’s d = 0.918). However, we did not observe a landing pattern transition. VALR and VILR between two footwear conditions showed no significant difference (P = 0.191–0.258; Cohen’s d = 0.304–0.460). Initial vertical stiffness (P = 0.032; Cohen’s d = 0.671) and energy loss (P = 0.044; Cohen’s d = 0.578) were greater when running in minimalist shoes with lug platform. The results show that minimalist shoes with lug platform reduce the FSA but may not lead to a landing pattern switch or lower vertical loading rates. Interestingly, the new shoe design leads to a greater energy loss than traditional running shoes, which could be explained by a higher initial vertical stiffness.  相似文献   

Changes in kinematics and arm–leg coordination during a 100-m breaststroke swim     

Samuel W. Oxford  Rob S. James  Michael J. Price  Carl J. Payton  Michael J. Duncan 《Journal of sports sciences》2017,35(16):1658-1665

The purpose of this study was to compare arm–leg coordination and kinematics during 100 m breaststroke in 26 (8 female; 18 male) specialist breaststroke swimmers. Laps were recorded using three 50-Hz underwater cameras. Heart rate and blood lactate were measured pre- and post-swim. Arm–leg coordination was defined using coordination phases describing continuity between recovery and propulsive phases of upper and lower limbs: coordination phase 1 (time between end of leg kick and start of the arm pull phases); and coordination phase 2 (time between end of arm pull and start of leg kick phases). Duration of stroke phases, coordination phases, swim velocity, stroke length (SL), stroke rate (SR) and stroke index (SI) were analysed during the last three strokes of each lap that were unaffected by turning or finishing. Significant changes in velocity, SI and SL (P < 0.05) were found between laps. Both sexes showed significant increase (P < 0.05) in heart rate and blood lactate pre- to post-swim. Males had significantly (P < 0.01) faster swim velocities resulting from longer SLs (P = 0.016) with no difference in SR (P = 0.064). Sex differences in kinematic parameters can be explained by anthropometric differences providing males with increased propelling efficiency.  相似文献   

Increasing hip and knee flexion during a drop-jump task reduces tibiofemoral shear and compressive forces: implications for ACL injury prevention training     

Liang-Ching Tsai  Yi-An Ko  Kyle E. Hammond  John W. Xerogeanes  Gordon L. Warren  Christopher M. Powers 《Journal of sports sciences》2017,35(24):2405-2411

Although most ACL injury prevention programmes encourage greater hip and knee flexion during landing, it remains unknown how this technique influences tibiofemoral joint forces. We examined whether a landing strategy utilising greater hip and knee flexion decreases tibiofemoral anterior shear and compression. Twelve healthy women (25.9 ± 3.5 years) performed a drop-jump task before and after a training session (10–15 min) that emphasised greater hip and knee flexion. Peak tibiofemoral anterior shear and compressive forces were calculated using an electromyography (EMG)-driven knee model that incorporated joint kinematics, EMG and participant-specific muscle volumes and patella tendon orientation measured using magnetic resonance imaging (MRI). Participants demonstrated a decrease in peak anterior tibial shear forces (11.1 ± 3.3 vs. 9.6 ± 2.7 N · kg^?1; P = 0.008) and peak tibiofemoral compressive forces (68.4 ± 7.6 vs. 62.0 ± 5.5 N · kg^?1; P = 0.015) post-training. The decreased peak anterior tibial shear was accompanied by a decrease in the quadriceps anterior shear force, while the decreased peak compressive force was accompanied by decreased ground reaction force and hamstring forces. Our data provide justification for injury prevention programmes that encourage greater hip and knee flexion during landing to reduce tibiofemoral joint loading.  相似文献   

Email: An Appraisal Approach     

Daniel W. Noonan 《Journal Of Archival Organization》2016,13(3-4):146-151

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Relationship Understanding Between Emotional Stability,Self-Disclosure and Social Adjustment     

Nagendra Singh Nehra  Santosh Rangnekar 《Journal of Intercultural Communication Research》2017,46(6):558-578

This paper discusses a survey, carried out by the authors, of 211 employees’ employed in public and private manufacturing organizations in North India to determine if emotional stability acts as a mediator between self-disclosure and social adjustment. Capitalization theory has been used as theoretical framework to examine the proposed relationships. Results indicate that high self-disclosure has positive association with social adjustment. Results also suggest that emotional stability partially mediates self-disclosure and social adjustment relationship. Implications for future research include further examination through additional mediators and other dimensions of self-disclosure from capitalization theory in understudied non-U.S. cultures like India.  相似文献   

Educational leadership and pupil achievement in primary education     

W. van de Grift  A.A.M. Houtveen 《School Effectiveness & School Improvement》2013,24(4):373-389

Educational leadership can be defined as the ability of a principal to initiate school improvement, to create a learning-oriented educational climate, and to stimulate and supervise teachers in such a way that the latter may execute their tasks as effectively as possible. In 1989, 1993, and 1998, teacher perceptions of educational leadership of principals in Dutch elementary education were evaluated by means of a Rasch-scale. It turned out that the educational leadership of Dutch principals has grown considerably. In both 1989 and 1993 the effect of educational leadership on pupil achievement was investigated. While in 1989 no significant relationship was found, the results of 1993 show a significant relationship between educational leadership and average pupil achievement over 3 successive years corrected for school environment.  相似文献   

Implications for improving access and outcomes for individuals with disabilities in postsecondary distance education     

Weol Soon Kim‐Rupnow  Peter W. Dowrick  Laure S. Burke 《The American journal of distance education》2013,27(1):25-40

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(6) Commercial libraries     

C. W. Black 《International Information and Library Review》2013,45(4):485-492

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Knowing and teaching science: the constructivist paradox     

W. Louden  J. Wallace 《International Journal of Science Education》2013,35(6):649-657

This paper addresses the parallel between the changes in students' and teachers' learning advocated by constructivist science educators. It begins with a summary of the epistemology of constructivism and uses a vignette drawn from a set of case studies to explore the impact of a constructivist science in‐service programme on an experienced and formal elementary science teacher. Judged by constructivist standards, the teacher described in the vignette makes very little progress. The irony of applying a constructivist critique to his work, however, is that it fails to treat the teachers' imperfect knowledge of teaching with the same respect as constructivists treat students' imperfect learning of science. The remainder of the paper explores this constructivist paradox, and suggests that‐like students' knowledge of science‐teachers' knowledge of constructivist science teaching is likely to grow through slow and gradual re‐formation of their established understanding of classroom theory and practice.  相似文献