Creatine monohydrate ingestion-related placebo effects on brief anaerobic exercise performance. A laboratory investigation / Efectos placebo de la ingestión de monohidrato de creatina sobre el rendimiento breve del ejercicio anaeróbico. Una investigación de laboratorio / Efeitos de placebo relacionados com a ingestão de monohidrato de creatina no desempenho de exercício anaeróbico breve. Uma investigação laboratorial

People’s thoughts influence their action that led researchers to investigate the placebo effect in exercise performance. In the current study the placebo effects of creatine monohydrate on a one-minute anaerobic step-exercise performance were examined in a double blind laboratory inquiry. University students (n = 79, 64.5% women) were randomly assigned to one of three experimental conditions: 1) intervention (ingestion of 80 mg/kg dissolved creatine monohydrate, n = 26), 2) placebo (ingestion of dissolved corn starch, thought to be creatine, n = 26), and 3) no-intervention control (ingestion of drinking water only, n = 27). After a baseline measurement, participants have consumed their respective drinks and 40 minutes later the 1-minute exercise was repeated. While analysis of variance revealed no group level differences in actual and perceived change in performance, the latter was linked to participants’ expectations regarding performance on the second exercise test in the correlation analysis. Two thirds of the participants in the current study believed that their performance would improve in the actual test-exercise. However, these expectations were not linked to creatine ingestion. These findings suggest that (1) a single dose of creatine monohydrate does not affect anaerobic performance, (2) in low-challenge and low-subjective-importance 'artificial' research conditions sufficient expectations could not be evoked, and probably due to the lack of creatine-related expectations the placebo effects did not emerge (AU)

La influencia de los pensamientos de las personas sobre sus acciones, llevó a los investigadores a investigar el efecto placebo sobre el rendimiento en el ejercicio. En el presente estudio se analiza el efecto placebo de la creatina monohidrato sobre el rendimiento en un ejercicio anaeróbico de un minuto de duración en laboratorio mediante el método de doble ciego. Los participantes fueron estudiantes universitarios (n = 79, 64,5% mujeres) que se asignaron aleatoriamente a una de las tres condiciones experimentales: 1) intervención (ingestión de creatina monohidrato disuelta, n = 26); 2) placebo (ingestión de almidón de maíz disuelto, creyendo que es creatina , n = 26); y 3) grupo control sin intervención (ingestión de agua potable solamente, n = 27). Después de establecer la línea base, los participantes tomaron sus respectivas bebidas y 40 minutos más tarde se repitió el ejercicio de 1 minuto de duración. Si bien el análisis de varianza no reveló diferencias entre los grupos entre el rendimiento real y el percibido, este último se vinculó, mediante análisis de correlación, a las expectativas de los participantes en relación con el rendimiento en la segunda prueba realizada. Dos tercios de los participantes consideraron que su rendimiento mejoraría en la prueba de ejercicio real, sin embargo, estas expectativas no estuvieron relacionadas con la ingesta de creatina. Los resultados sugieren que: (1) una dosis única de creatina monohidrato no afecta al rendimiento anaeróbico; (2) en la condición de bajo desafío y baja importancia subjetiva, no emergió el efecto placebo debido, probablemente, a la falta de expectativas evocadas sobre los efectos de la creatina (AU)

A influência dos pensamentos das pessoas sobre suas ações, levou os pesquisadores a investigar o placebo efeito sobre o desempenho do exercício. No presente estudo, a creatina mono-hidrato de placebo no desempenho no exercício anaeróbio de um minuto no laboratório pelo método de efeito duplo-cego é analisada. Os participantes eram estudantes universitários (n = 79, 64,5% mulheres) que foram atribuídos aleatoriamente a uma de três condições experimentais atribuída: 1) intervenção (ingestão de creatina monohidratada dissolvida, n = 26); 2) placebo (amido de milho dissolvido ingestão, acreditando que a creatina, n = 26); e 3) grupo de controlo sem intervenção (apenas ingestão de água potável, n = 27). Depois de estabelecer a linha de base, os participantes tomaram suas bebidas e 40 minutos depois do exercício de 1 minuto de duração repetido. Enquanto a análise de variância não revelou diferenças entre os grupos de entre o desempenho real e percebidos, a última foi ligada por análise de correlação, as expectativas dos participantes em relação ao desempenho no segundo teste realizado. Dois terços dos participantes sentiram que seu desempenho iria melhorar no teste de esforço real, no entanto, essas expectativas não foram relacionados com a ingestão de creatina. Os resultados sugerem que: (1) uma única dose de mono-hidrato de creatina não afecta o desempenho anaeróbio; (2) a condição sob desafio e menor importância subjetiva, surgiu o efeito placebo, provavelmente devido à falta de expectativas evocado sobre os efeitos da creatina (AU)

Polar OwnIndex is not a reliable indicator of aerobic training status.

Polar watches with heart rate monitoring function have become popular among recreational and professional athletes. In addition to monitoring functions, they calculate a specific index called OwnIndex which is claimed to measure aerobic training status. The current research attempted to shed light on the factors determining the OwnIndex. In Study 1, OwnIndex calculated by the RS-400 Polar watch was estimated using anthropometric (gender, age, height, weight), cardiovascular (resting HR, RMSSD), and exercise-related (maximal oxygen uptake, self-reported physical activity) data of 45 young adults. In Study 2, the OwnIndex was measured in 21 young adults twice, first with self-reported physical activity set to the lowest, then to the highest value. In the regression analysis (Study 1), the only significant predictor of OwnIndex was self-reported physical activity (R² = 0.883; ß = 0.915, p < 0.001). A significant difference with a large effect size (t(20) = -16.657, p <0.001, d = 3.635) and no significant correlation (r = -0.32; p = 0.155) were found between the OwnIndices calculated with different levels of activity in Study 2. As anthropometric and cardiac variables play a practically negligible role in the calculation of the OwnIndex, it cannot be considered an appropriate measure of aerobic fitness.

Subjective and objective effects of coffee consumption - caffeine or expectations?

Impact of 5 mg/kg caffeine, chance of receiving caffeine (stimulus expectancies), and expectations of effects of caffeine (response expectancies) on objective (heart rate (HR), systolic/diastolic blood pressure (SBP/DBP), measures of heart rate variability (HRV), and reaction time (RT)) and subjective variables were investigated in a double-blind, placebo-controlled experiment with a no-treatment group. Participants were 107 undergraduate university students (mean age 22.3 ± 3.96 years). Consumption of 5 mg/kg caffeine had an impact on participants' SBP, standard deviation of normal heartbeat intervals, HR (decrease), and subjective experience 40 minutes later even after controlling for respective baseline values, stimulus and response expectancies, and habitual caffeine consumption. No effects on DBP, high frequency component of HRV, the ratio of low- and high-frequency, and RT were found. Beyond actual caffeine intake, response expectancy score was also a determinant of subjective experience which refers to a placebo component in the total effect. Actual autonomic (SBP, HR) changes and somatosensory amplification tendency, however, had no significant impact on subjective experience. Placebo reaction plays a role in the subjective changes caused by caffeine consumption but it has no impact on objective variables. Conditional vs deceptive administration of caffeine (i.e. stimulus expectancies) had no impact on any assessed variable.

Effect of short-term 50 Hz electromagnetic field exposure on the behavior of rats.

Extremely low-frequency electromagnetic field generated by transformer stations located within buildings has been suspected to initiate non-specific health problems. This possibility was examined in model experiments in rats. Following short-term exposure (50 Hz, 500 mircoT, 20 min), situational and social anxiety as well as locomotor activity pattern were examined by several different tests (elevated plus-maze, novel object exploration, social interaction and territoriality).Based on our results having obtained so far, it seems that these field parameters (that equals the official reference limit for workers) may cause some kind of discomfort, may influence behavior, increase passivity and situational anxiety, but has no verified effect on the social and territorial behavior.