Effects of Blood flow Restriction and Load on Mean Propulsive Velocity and Subjective Perceived Exertion During Squat and Bench Press Exercises.

BACKGROUND: The aim of this study was to determine the influence of different percentages of blood flow restriction (BFR) and loads on mean propulsive velocity (MPV) and subjective perceived exertion during squat (SQ) and bench press (BP) exercises. HYPOTHESIS: Higher percentages of BFR will positively affect dependent variables, increasing MPV and reducing perceived exertion. STUDY DESIGN: Cross-sectional study. LEVEL OF EVIDENCE: Level 3. METHODS: Eight healthy young male athletes took part. Two sets of 6 repetitions at 70% 1-repetition maximum (1RM), 2 sets of 4 repetitions at 80% 1RM, and 2 sets of 2 repetitions at 90% 1RM were performed randomly; 5-minute recoveries were applied in all sets. The varying arterial occlusion pressure (AOP) applied randomly was 0% (Control [CON]), 80%, and 100%. RESULTS: No statistically significant differences in MPV were found during the BP exercise at any percentage of BFR at any percentage 1RM. During the SQ exercise, MPV results showed statistically significant increases of 5.46% (P = 0.04; ηp2 = 0.31) between CON and 100% AOP at 90% 1RM. The perceived exertion results for the BP exercise showed statistically significant reductions of -8.66% (P < 0.01; ηp2 = 0.06) between CON and 100% AOP at 90% 1RM. During the SQ exercise, the perceived exertion results showed significant reductions of -10.04% (P = 0.04; ηp2 = 0.40) between CON and 100% AOP at 80% 1RM; -5.47% (P = 0.02; ηp2 = 0.48) between CON and 80% AOP at 90% 1RM; and -11.83% (P < 0.01; ηp2 = 0.66) between CON and 100% AOP at 90% 1RM. CONCLUSION: BFR percentages ~100% AOP at 90% 1RM improved acutely MPV (only in SQ exercises) and reduced acutely perceived exertion (in both exercises). These findings are important to consider when prescribing resistance training for healthy male athletes.

Methodology of dietary surveys, studies on nutrition, physical activity and other lifestyles

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Documento de consenso y conclusiones. La metodología de las encuestas alimentarias, estudios nutricionales, de estimación de la actividad física y otros estilos de vida / No disponible

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Sesgos y ajustes en la valoración nutricional de las encuestas alimentarias / Biases and adjustments in nutritional assessments from dietary questionnaires

En epidemiología nutricional es fundamental una correcta valoración del consumo alimentario de los individuos y grupos de población. Esta estimación debe hacerse con la mayor calidad posible, evitando las fuentes de error y confusión en su estimación. Las cualidades que otorgan calidad a un método de medida son la validez y la precisión, siendo la validez la principal característica. La falta de validez produce sesgos o errores sistemáticos, los cuales pueden aparecer en el proceso de selección de los sujetos o en el proceso de obtención de la información; y la falta de precisión produce los errores aleatorios. Para muchos nutrientes, las variaciones intra-individuales, debidas a muchos factores como el día de la semana o la estación del año valorada, podrían crear problemas en el análisis e interpretación de los resultados. Para minimizar estas fuentes de error se deben utilizar los métodos de ajustes en el proceso de análisis de datos. Los factores de confusión pueden exagerar o subestimar la verdadera magnitud de la asociación o incluso alterar su dirección. El consumo total de energía puede ser una variable de confusión en el estudio de la relación entre la ingesta de un nutriente y el riesgo de enfermedad. Para controlar este efecto se proponen varias aproximaciones: la densidad de nutrientes, el modelo multivariado estándar y el modelo residual de nutrientes (AU)

In nutritional epidemiology, it is essential to use Food Consumption Assessment Methods that have been validated and accepted by the international community for estimating food consumption of individuals and populations. This assessment must be made with the highest quality possible so as to avoid, as far as possible, sources of error and confusion in the processes. The qualities that are required in a measurement method are validity and accuracy; validity being the main factor. Lack of validity produces biases, or systematic errors. These can reside in the process of subject selection, or processes of information gathering where the lack of accuracy produces random errors. For many nutrients, the intra-individual variances are due to many factors such as day-of-the-week or season, and could create problems in the data analyses. Adjustments are needed to minimize these effects. Confounding factors may over- or under-state the real magnitude of the observed association, or even alter the direction of the real association. Total energy intake can be a confounding variable when studying a relationship between nutrient intake and disease risk. To control for this effect several approximations are proposed such as nutrient densities, standard multivariate models and thenutrient residual model (AU)