The Effects of Caffeine on Arousal, Response Time, Accuracy, and Performance in Division I Collegiate Fencers.

Doyle, TP, Lutz, RS, Pellegrino, JK, Sanders, DJ, and Arent, SM. The effects of caffeine on arousal, response time, accuracy, and performance in Division I collegiate fencers. J Strength Cond Res 30(11): 3228-3235, 2016-Caffeine has displayed ergogenic effects on aerobic performance. However, sports requiring precision and quick reaction may also be impacted by central nervous system arousal because of caffeine consumption. The purpose of this study was to assess the effects of caffeine on arousal, response time (RT), and accuracy during a simulated fencing practice. Using a randomized, within-subjects, placebo-controlled, double-blind design, Division I male and female college fencers (N = 13; 69.1 ± 3.5 kg) were administered caffeine doses of 0, 1.5, 3.0, 4.5, 6.0, or 7.5 mg·kg during separate testing days. Performance was assessed via RT and accuracy to a 4-choice reaction task. A total of 25 trials were performed each day using a random 2- to 8-s delay between trials. Arousal was assessed using the activation-deactivation adjective check list. Results of repeated-measures multivariate analysis of variance revealed a significant dose effect (p = 0.02) on performance. Follow-up analyses indicated this was due to a significant effect for RT (p = 0.03), with the dose-response curve exhibiting a quadratic relationship. Response time was significantly faster (p < 0.01) for the 1.5, 3.0, and 6.0 mg·kg conditions than for the placebo condition. Results also indicated a significant dose effect for composite RT + accuracy performance (p < 0.01). The dose-response curve was again quadratic, with performance beginning to deteriorate at 7.5 mg·kg. Energetic arousal, tiredness, tension, and calmness all significantly changed as a function of caffeine dose (p ≤ 0.05). Based on these results, caffeine improves RT and overall performance in fencers, particularly as doses increase up to 4.5-6.0 mg·kg. Above this level, performance begins to deteriorate, consistent with an "inverted-U" model of arousal and performance.

Taking aim at the Müller-Lyer goalkeeper illusion: an illusion bias in action that originates from the target not being optically specified.

Van der Kamp and Masters (2008) reported that goalkeeper postures that mimic the Müller-Lyer (1889) illusion affect the location of handball penalty throws. In four experiments, we aimed to verify that the effects on throwing are consistent with an illusory bias (Experiments 1 and 2), and to examine how these observations can be understood in the context of Milner and Goodale's (1995, 2008) two-visual systems model (Experiments 3 and 4). Experiments 1 and 2 confirmed that the goalkeeper Müller-Lyer posture may indeed induce an illusory bias in throwing, implying that allocentric information is used in far-aiming action tasks. Experiment 3 demonstrated that the bias was not related to a participant's throwing skill. Experiment 4 suggested that an absence of visual information to instantaneously specify target location may have induced use of context-dependent allocentric information, causing the throwing bias. The results are discussed in the context of recent debates about the roles of the two-visual systems in perception and action. It is suggested that the two systems are first and foremost perceptual systems that serve the pickup of different sources of information.

Cross-lagged relationships among leisure-time exercise and perceived stress in blue-collar workers.

Blue-collar workers (N = 203) from a large food-processing plant in the southwestern U.S. completed measures of perceived stress and leisure-time exercise at an initial test session in addition to a 2-month follow-up session. Mean age of the sample participants equaled 43.61 (SD = 9.79), and 69.5% of the sample were male, 71.4% were Caucasian, and 74.9% were married/cohabitating. Structural equation modeling was employed to examine the cross-lagged relationships between perceived stress and leisure-time exercise at these time points, controlling for gender, marital status, age, and yearly household income. Results indicated that a model with a path from perceptions of Time 1 stress to Time 2 exercise frequency was most parsimonious and provided acceptable model fit, suggesting that perceptions of stress are related to reductions in exercise participation in this population. However, there was little support for a relationship between Time 1 exercise participation and Time 2 perceived stress.

Examination of the hierarchical self-esteem model in adults with physical disability.

The primary purpose of this research was to examine the validity of the hierarchical physical self-perceptions model developed by Fox and Corbin (1989) within a population of physically disabled individuals. The secondary purpose was to compare the physical self-perceptions of those who were physically active and physically inactive. 97 adults with physical disabilities completed a self-esteem scale and the Physical Self-perception Profile, Japanese short version to assess General Physical Self-worth and its subdomains of Perceived Sports Competence, Physical Condition, Attractive Body, and Physical Strength. Path analysis showed adequate fit of the data to the hierarchical physical self-perception model. In general, physical self-perceptions were rated more favorably by physically active participants.

Perceived stress and health complaints: an examination of the moderating roles of personality and physical activity.

275 undergraduate university students were asked to complete a battery concerning their health complaints, perceived stress, strenuous physical activity, and personality ("Big Five" traits). An hierarchical regression showed that Stress and Strenuous Physical Activity Participation, but not Personality, predicted the Number of Health Complaints in this sample. Also, there was a significant interaction for Stress by Strenuous Activity indicating individuals who did not frequently engage in strenuous leisure-time physical activity reported more health complaints than those who did. This finding corroborates the notion that physical activity (or fitness) may serve to attenuate the relation between stress and health complaints.

Social support and social norms: do both contribute to predicting leisure-time exercise?

OBJECTIVE: To clarify the contribution of social support and social norms to exercise behavior. METHODS: A sample of 363 college students completed a questionnaire that assessed social support and social negativity from friends, descriptive and injunctive social norms related to friends, perceived behavioral control, attitude, intention, and leisure-time exercise. RESULTS: Esteem social support was the strongest predictor of total and strenuous leisure-time exercise (P < .001), and descriptive norm was a significant (P < .01 predictor of strenuous leisure-time exercise. CONCLUSION: Social support and social norms contribute independently to our understanding of variation in the frequency of strenuous leisure-time exercise.

Covert muscle excitation is outflow from the central generation of motor imagery.

Two studies were conducted in an attempt to examine inflow and outflow processing by examining covert muscle excitation during motor imagery (MI) and its correlation with motor task performance. Examining 80 novice dart throwers in Experiment 1, MI produced greater levels of covert excitation at the dominant biceps in comparison to control imagery (CI). In addition, covert excitation correlated significantly with imagery ability and imagery vividness. This excitation, however, did not predict motor task acquisition or retention. Experiment 2 attempted to manipulate pre-imagery relaxation states by giving 104 novice dart performers a relaxation task or a distraction task before imagery sessions. MI resulted in improved task retention and resulted in significantly greater covert muscle excitation at the frontalis in comparison to CI. The relaxation condition, however, did not yield greater levels of muscular relaxation in comparison to the distraction condition, and did not yield greater imagery vividness or motor performance. Finally, covert muscle excitation did not predict motor acquisition or retention error. Results suggest that covert excitation is a byproduct of the central generation of the image that does not relate meaningfully to motor skill acquisition or retention gains.

Attitudes about electric and magnetic fields: do scientists and other risk experts perceive risk similarly?

Wherever there is electric power, 60-hertz (60-Hz) electric and magnetic fields (EMFs) are produced. Recently, conflicting reports have been published by government agencies about adverse health effects linked to EMFs. This paper seeks to identify the demographic and job-related factors that may explain differences among experts' perception of risk attributable to EMFs. Eighty-one participants at a bioelectromagnetics conference completed a survey on risk perceptions. Results indicated that education and employment sector were significant predictors of agreement with the statement that EMFs are not a problem. Future studies should look at the role of risk perception on environmental risk communication and determine the extent of message distortion, if any, based upon employment and demographic characteristics.

Clarifying the contribution of subjective norm to predicting leisure-time exercise.

OBJECTIVE: To clarify the contribution of subjective norm to exercise intention and behavior by considering the influence of descriptive as well as injunctive social norms related to family and friends. METHODS: A sample of 530 college students completed a questionnaire that assessed descriptive and injunctive social norms related to family and to friends, perceived behavioral control, attitude, intention, and leisure-time exercise. RESULTS: Friend descriptive social norm was a significant predictor of both intention (p<.05) and leisure-time exercise (p<.001). CONCLUSION: Descriptive norms should be incorporated into tests of the theory of planned behavior in the exercise domain.

Should the threshold limit value for power frequency (60 Hz) magnetic fields be changed? Perceptions among scientists and other risk experts.

Over the past few years several studies have raised questions about childhood cancer and exposure to electric and magnetic fields (EMFs). Reports by the National Academy of Sciences and the National Cancer Institute concluded that there is no clear, convincing evidence that exposure to electric power lines and electric power appliances is a threat to human health, whereas the National Institute of Environmental Health Sciences concluded that there is weak evidence that EMF exposure may be a leukemia hazard. Based on the conflicting agency reports on EMF, what do experts in the field of bioelectromagnetics believe regarding the effectiveness of the American Conference of Governmental Industrial Hygienists (ACGIH) guidelines? Surveys were sent to 163 participants at the 1997 annual Department of Energy Contractors meeting on Electric and Magnetic Fields. Approximately one-half (49%, n = 81) of the participants returned the survey. Utility workers demonstrated greater levels of agreement with the current TLV standard in comparison to government, university, and other private sector workers. Utility workers were less likely to perceive that ACGIH guidelines should be changed to be made more strict. In addition, workers who had worked at their present job for 10 years or more indicated less agreement with the acceptability of ACGIH guidelines to protect workers' health. The scientists and other risk experts in this study illustrate the importance of how type of industry may influence perceptions of TLV effectiveness.

Affect and Cognitive Performance in High School Wrestlers Undergoing Rapid Weight Loss.

Recent research has demonstrated transient affective changes and impairment of short-term memory in college wrestlers as a result of rapid weight loss (RWL) of at least 5% body weight prior to competition. This study examined the effects of RWL on cognition and affect in high school wrestlers. Wrestlers were considered to be engaging in RWL if they were losing over 5% of body weight (n = 14). Those losing less than 1% of body weight (n = 14) were considered maintainers and served as the control group. Both groups were given a battery of tests assessing cognitive performance (Trail Making Tests A & B, Stroop color-word test, Wechsler digit span, and choice reaction/movement time) and affective state (PANAS) at normal weight (5 to 10 days prior to competition) and again 8 to 12 hours prior to weigh-in. Results indicated an average loss of 4.68 kg in the RWL group and 0.29 kg in the control group. A group-by-time MANOVA and univariate follow-up tests indicated a significant group-by-time interaction for positive affect, p < .014, with the RWL wrestlers having less positive affect than the control group just prior to weigh-in. However, none of the cognitive performance tests demonstrated significant differential changes for RWL vs. control groups, p > .10. Given the control for competition effects in the present study, results suggest there are affective disturbances, but not cognitive impairments, associated with RWL of at least 5% body weight in high school wrestlers.