Effects of coffee and caffeine anhydrous on strength and sprint performance     

Eric T. Trexler  Erica J. Roelofs  Katie R. Hirsch  Meredith G. Mock 《European Journal of Sport Science》2016,16(6):702-710

Caffeine and coffee are widely used among active individuals to enhance performance. The purpose of the current study was to compare the effects of acute coffee (COF) and caffeine anhydrous (CAF) intake on strength and sprint performance. Fifty-four resistance-trained males completed strength testing, consisting of one-rep max (1RM) and repetitions to fatigue (RTF) at 80% of 1RM for leg press (LP) and bench press (BP). Participants then completed five, 10-second cycle ergometer sprints separated by one minute of rest. Peak power (PP) and total work (TW) were recorded for each sprint. At least 48 hours later, participants returned and ingested a beverage containing CAF (300?mg flat dose; yielding 3–5?mg/kg bodyweight), COF (8.9?g; 303?mg caffeine), or placebo (PLA; 3.8?g non-caloric flavouring) 30 minutes before testing. LP 1RM was improved more by COF than CAF (p?=?.04), but not PLA (p?=?.99). Significant interactions were not observed for BP 1RM, BP RTF, or LP RTF (p?>?.05). There were no sprint?×?treatment interactions for PP or TW (p?>?.05). 95% confidence intervals revealed a significant improvement in sprint 1 TW for CAF, but not COF or PLA. For PLA, significant reductions were observed in sprint 4 PP, sprint 2 TW, sprint 4 TW, and average TW; significant reductions were not observed with CAF or COF. Neither COF nor CAF improved strength outcomes more than PLA, while both groups attenuated sprint power reductions to a similar degree. Coffee and caffeine anhydrous may be considered suitable pre-exercise caffeine sources for high-intensity exercise.  相似文献   

Body composition of female road and track endurance cyclists: Normative values and typical changes     

Eric C. Haakonssen  Martin Barras  Louise M. Burke  David G. Jenkins  David T. Martin 《European Journal of Sport Science》2016,16(6):645-653

The aims of this study were to describe normative values and seasonal variation of body composition in female cyclists comparing female road and track endurance cyclists, and to validate the use of anthropometry to monitor lean mass changes. Anthropometric profiles (seven site skinfolds) were measured over 16 years from 126 female cyclists. Lean mass index (LMI) was calculated as body weight?×?skinfolds^?x. The exponent (x) was calculated as the slope of the natural logarithm of body weight and skinfolds. Percentage changes in LMI were compared to lean mass changes measured using dual-energy X-ray absorptiometry (DXA) in a subset of 25 road cyclists. Compared to sub-elite and elite cyclists, world class cyclists were (mean [95% CI]) 1.18?kg [0.46, 1.90] and 0.60?kg [0.05, 1.15] lighter and had skinfolds that were 7.4?mm [3.8, 11.0] and 4.6?mm [1.8, 7.4] lower, respectively. Body weight (0.41?kg [0.04, 0.77]) and skinfolds (4.0?mm [2.1, 6.0]) were higher in the off-season compared to the early-season. World class female road cyclists had lower body weight (6.04?kg [2.73, 9.35]) and skinfolds (11.5?mm [1.1, 21.9]) than track endurance cyclists. LMI (mean exponent 0.15 [0.13, 0.18]) explained 87% of the variance in DXA lean mass. In conclusion, higher performing female cyclists were lighter and leaner than their less successful peers, road cyclists were lighter and leaner than track endurance cyclists, and weight and skinfolds were lowest early in the season. LMI appears to be a reasonably valid tool for monitoring lean mass changes.  相似文献   

Inaugural Essay     

Daniel W. Noonan 《Journal Of Archival Organization》2016,13(1-2):82-86

New to the Journal of Archival Organization, the “Technology matters in archives” column examines how technology affects archives and archivists. This inaugural column explains the nature of the column and sets the stage for topics and issues that it will address. It examines the meaning of the term technology. Further, the column explores the notion of technological dependence-- not just dependence on digital or electronic systems--as a lens in which to examine the archival enterprise in grappling with twenty-first century issues. Concluding with the suggestion that technology can be considered from three categorical points of view: soft (philosophical approaches and practices), medium (codified processes, guidelines and standards) and hard technology (hardware and software).  相似文献   

Using Google Forms to track library space usage     

Beth Daniel Lindsay 《Journal Of Access Services》2016,13(3):159-165

This article is a response to the excellent “Using Mobile Technology to Observe Student Study Behaviors and Track Library Space Usage” by Susan Thompson. Thompson reviews the literature regarding user counts on mobile devices and describes the California State University San Marcos (CSUSM) Library's evaluation of SUMA, Counter+, and CloudOn. After trialing these mobile technologies, CSUSM selected CloudOn. At New York University Abu Dhabi, we use Google Forms to conduct user counts on an iPad and Google Sheets to evaluate these data. We find that Google Forms are easy to set up, modify as necessary, and present the data in easy-to-manipulate spreadsheets.  相似文献   

Classroom observation systems in context: A case for the validation of observation systems     

Liu  Shuangshuang  Bell  Courtney A.  Jones  Nathan D.  McCaffrey  Daniel F. 《Educational Assessment, Evaluation and Accountability》2019,31(1):61-95

Educational Assessment, Evaluation and Accountability - Researchers and practitioners sometimes presume that using a previously “validated” instrument will produce “valid”...  相似文献   

Recognition of facial emotions among maltreated children with high rates of post-traumatic stress disorder     

Masten CL  Guyer AE  Hodgdon HB  McClure EB  Charney DS  Ernst M  Kaufman J  Pine DS  Monk CS 《Child abuse & neglect》2008,32(1):139-153

OBJECTIVE: The purpose of this study is to examine processing of facial emotions in a sample of maltreated children showing high rates of post-traumatic stress disorder (PTSD). Maltreatment during childhood has been associated independently with both atypical processing of emotion and the development of PTSD. However, research has provided little evidence indicating how high rates of PTSD might relate to maltreated children's processing of emotions. METHOD: Participants' reaction time and labeling of emotions were measured using a morphed facial emotion identification task. Participants included a diverse sample of maltreated children with and without PTSD and controls ranging in age from 8 to 15 years. Maltreated children had been removed from their homes and placed in state custody following experiences of maltreatment. Diagnoses of PTSD and other disorders were determined through combination of parent, child, and teacher reports. RESULTS: Maltreated children displayed faster reaction times than controls when labeling emotional facial expressions, and this result was most pronounced for fearful faces. Relative to children who were not maltreated, maltreated children both with and without PTSD showed enhanced response times when identifying fearful faces. There was no group difference in labeling of emotions when identifying different facial emotions. CONCLUSIONS: Maltreated children show heightened ability to identify fearful faces, evidenced by faster reaction times relative to controls. This association between maltreatment and atypical processing of emotion is independent of PTSD diagnosis.  相似文献   

The impact of reading at rapid rates on inference generation          下载免费PDF全文

W. Matthew Collins  Frances Daniel 《Journal of Research in Reading》2018,41(3):564-581

Aims

Speed reading is advertised as a way to increase reading speed without any loss in comprehension. However, research on speed reading has indicated that comprehension suffers as reading speed increases. We were specifically interested in how processes of inference generation were affected by speed reading.

Methods

We examined how reading speed influenced inference generation in typical readers, trained speed readers and participants trained to skim read passages. Passages either strongly or weakly promoted a bridging or predictive inference. After reading, participants performed a lexical decision task on either a nonword, neutral or inference‐related word.

Results

Typical readers responded to strong and weak inference words faster than neutral words. There were no statistical differences in reaction time between inference‐related and neutral words for speed and skim readers.

Conclusions

These findings provide no substantive evidence that the appropriate inferences are generated when reading at rapid speeds. Thus, speed reading may be detrimental to normal integrative comprehension processes.  相似文献   

Successive reversals of a discriminated preference for signaled tailshock     

Ralph R. Miller  David Daniel  Alvin M. Berk 《Learning & behavior》1974,2(4):271-274

Three rats received unmodifiable tailshock at random intervals in a shuttlebox. In a continuous-choice situation, Ss could choose between an auditory signal immediately preceding or immediately following the tailshock. Over repeated daily 3-h sessions, each S acquired a spatial discrimination indicating a strong preference for the signal preceding tailshock. This preference continued undiminished through two successive reversals of the position associated with signaled shock. This demonstration precludes explanations of the preference-for-signaled-shock phenomenon based upon primary reinforcement value or acquired value of the signal, position preferences, and overt modification of the aversiveness of the reinforcer through such means as postural adjustments. An explanation of recent failures to obtain the preference-for-signaled-shock effect is offered.  相似文献   

STATISTICAL DIVERSIONS     

Peter Petocz  Eric Sowey 《Teaching Statistics》2003,25(3):96-96

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III. Replication with 5-Year-olds of Types and their Associations with Achievement and Behavior     

Daniel Hart  Robert Atkins  Suzanne G. Fegley 《Monographs of the Society for Research in Child Development》2003,68(1):35-46

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