Improvements in attention and cardiac autonomic modulation after a 2-weeks sprint interval training program: a fidelity approach

This study aimed to: (1) investigate the influence of a 2-weeks sprint interval training (SIT) program on aerobic capacity, cardiac autonomic control, and components of attention in young healthy university students; and (2) to ascertain whether training fidelity would influence these adaptations. One hundred and nine participants were divided into an experimental (EG) and control (CG) groups. The EG performed a SIT program that consisted of 6 sessions of 4 x 30 s "all-out" efforts on a cycle ergometer, interspersed with active rests of 4 min. The criterion for fidelity was achieving >90% of estimated maximum heart rate (HR) during sprint bouts. After analyses, the EG was divided into HIGH (n = 26) and LOW(n = 46) fidelity groups. Components of attention were assessed using the Attention Network Test (ANT). Aerobic capacity (VO(2)max) was estimated while the sum of skinfolds was determined. Autonomic control of HR was assessed by means of HR variability (HRV) and HR complexity at rest and during ANT. Both HIGH and LOW significantly increased aerobic capacity, vagal modulation before and during ANT, and executive control, and decreased body fatness after SIT (p < 0.05). However, only participants from HIGH showed an increase in HR complexity and accuracy in ANT when compared to LOW (p < 0.05). Two weeks of SIT improved executive control, body fatness, aerobic fitness, and autonomic control in university students with better results reported in those individuals who exhibited high fidelity

Relationships between Workload, Heart Rate Variability, and Performance in a Recreational Endurance Runner

[EN] Background: The association between heart rate variability (HRV), training load (TL), and performance is poorly understood. Methods: A middle-aged recreational female runner was monitored during a competitive 20-wk macrocycle divided into first (M1) and second mesocycle (M2) in which best performances over 10 km and 21 km were recorded. Volume (km), session rating of perceived exertion (sRPE), TL, and monotony (mean TL/SD TL) were the workload parameters recorded. The root mean square of the successive differences in R-R intervals (RMSSD), its coefficient of variation (RMSSDcv), and the RMSSD:RR ratio were the HRV parameters monitored. Results: During M2, RMSSD (p = 0.006) and RMSSD:RR (p = 0.002) were significantly increased, while RR was significantly reduced (p = 0.017). Significant correlations were identified between monotony and volume (r = 0.552; p = 0.012), RR (r = 0.447; p = 0.048), and RMSSD:RR (r = −0.458; p = 0.042). A sudden reduction in RMSSD (from 40.31 to 24.34 ms) was observed the day before the first symptoms of an influenza. Conclusions: The current results confirm the practicality of concurrent HRV and sRPE monitoring in recreational runners, with the RMSSD:RR ratio indicative of specific adaptations. Excessive training volume may be associated to both elevated monotony and reduced RMSSD:RR. Identification of mesocycle patterns is recommended for better individualization of the periodization use

Heart rate and cardiovascular responses to commercial flights: relationships with physical fitness

The aim of this study was to examine the influence of physical fitness on cardiac autonomic control in passengers prior to, during and following commercial flights. Twenty-two, physically active men (36.4 +/- 6.4 years) undertook assessments of physical fitness followed by recordings of 24-h heart rate (HR), heart rate variability (HRV), and blood pressure (BP) on a Control (no flight) and Experimental (flight) day. Recordings were analyzed using a two-way analysis of variance for repeated measures with relationships between variables examined via Pearson product moment correlation coefficients. Compared to the Control day, 24-h HR was significantly greater (>7%) and HRV measures (5-39%) significantly lower on the Experimental day. During the 1-h flight, HR (24%), and BP (6%) were increased while measures of HRV (26-45%) were reduced. Absolute values of HRV during the Experimental day and relative changes in HRV measures (Control-Experimental) were significantly correlated with measures of aerobic fitness (r = 0.43 to 0.51;-0.53 to -0.52) and body composition (r = -0.63 to -0.43; 0.48-0.61). The current results demonstrated that short-term commercial flying significantly altered cardiovascular function including the reduction of parasympathetic modulations. Further, greater physical fitness and lower body fat composition were associated with greater cardiac autonomic control for passengers during flights. Enhanced physical fitness and leaner body composition may enable passengers to cope better with the cardiovascular stress and high allostatic load associated with air travel for enhanced passenger well-being

Improvements in Attention and Cardiac Autonomic Modulation After a 2-Weeks Sprint Interval Training Program: A Fidelity Approach

[EN] This study aimed to: (1) investigate the influence of a 2-weeks sprint interval training (SIT) program on aerobic capacity, cardiac autonomic control, and components of attention in young healthy university students; and (2) to ascertain whether training fidelity would influence these adaptations. One hundred and nine participants were divided into an experimental (EG) and control (CG) groups. The EG performed a SIT program that consisted of 6 sessions of 4 × 30 s “all-out” efforts on a cycle ergometer, interspersed with active rests of 4 min. The criterion for fidelity was achieving >90% of estimated maximum heart rate (HR) during sprint bouts. After analyses, the EG was divided into HIGH (n = 26) and LOW (n = 46) fidelity groups. Components of attention were assessed using the Attention Network Test (ANT). Aerobic capacity (VO2max) was estimated while the sum of skinfolds was determined. Autonomic control of HR was assessed by means of HR variability (HRV) and HR complexity at rest and during ANT. Both HIGH and LOW significantly increased aerobic capacity, vagal modulation before and during ANT, and executive control, and decreased body fatness after SIT (p < 0.05). However, only participants from HIGH showed an increase in HR complexity and accuracy in ANT when compared to LOW (p < 0.05). Two weeks of SIT improved executive control, body fatness, aerobic fitness, and autonomic control in university students with better results reported in those individuals who exhibited high fidelity.AdS, AM, and SD enjoy a PROSUP-CAPES grant. DB enjoys a productivity in research grant from CNPq.CNPq (Brazil) (process number 486116/2013-1) supported this project. AdS, SD, and AM were supported by a PROSUP grant from CAPES (Brazil). SB-F is supported by a doctoral fellowship awarded by ANII (Uruguay). DB was supported by a productivity research grant from CNPq (Brazil). We would like to thank all participants for their collaboration and LEEFS’s laboratory staff (Giseli Kelly de Melo Oliveira Gomes, Alessandra Matida) for their assistance during data collection. The authors declare that the results of the study are presented clearly, honestly, and without fabrication, falsification, or inappropriate data manipulation

Heart Rate and Cardiovascular Responses to Commercial Flights: Relationships with Physical Fitness

[EN] The aim of this study was to examine the influence of physical fitness on cardiac autonomic control in passengers prior to, during and following commercial flights. Twenty-two, physically active men (36.4 ± 6.4 years) undertook assessments of physical fitness followed by recordings of 24-h heart rate (HR), heart rate variability (HRV), and blood pressure (BP) on a Control (no flight) and Experimental (flight) day. Recordings were analyzed using a two-way analysis of variance for repeated measures with relationships between variables examined via Pearson product-moment correlation coefficients. Compared to the Control day, 24-h HR was significantly greater (>7%) and HRV measures (5–39%) significantly lower on the Experimental day. During the 1-h flight, HR (24%), and BP (6%) were increased while measures of HRV (26–45%) were reduced. Absolute values of HRV during the Experimental day and relative changes in HRV measures (Control-Experimental) were significantly correlated with measures of aerobic fitness (r = 0.43 to 0.51; −0.53 to −0.52) and body composition (r = −0.63 to −0.43; 0.48–0.61). The current results demonstrated that short-term commercial flying significantly altered cardiovascular function including the reduction of parasympathetic modulations. Further, greater physical fitness and lower body fat composition were associated with greater cardiac autonomic control for passengers during flights. Enhanced physical fitness and leaner body composition may enable passengers to cope better with the cardiovascular stress and high allostatic load associated with air travel for enhanced passenger well-being

Vibrational characterictics of asymmetric metal-ceramic piezocomposites

[ES] Se han estudiado las características mecánico-vibracionales de piezocomposites metal-cerámica asimétricos. Kovar-PZT. Para esta caracterización se utilizó la técnica de vibrometría láser mediante la cual se obtienen perfiles de amplitud a diferentes frecuencias para el piezocomposite. Se muestran los modos diferenciados de vibración en el intervalo de 2 Hz a 20 kHz y se discuten los resultados en la perspectiva de optimizar el diseño de los dispositivos.[EN] The mechanical and vibrational characteristics of asymmetric metal-ceramic piezocomposites, Kovar-PZT, have heen studied. For this characterization a laser vibrometry technique was used to obtain amplitude profiles of vibration at different frequencies for the piezocomposite. The vibration spectra showed modes in the range 2 Hz to 20 kHz. The results were discussed in the framework of design optimization.Los autores agradecen el apoyo financiero para la realización de esta investigación a la Universidad Nacional Autónoma de México, Consejo Nacional de Ciencia y Tecnología de México, Comisión Internacional de Ciencia y Tecnología de España y Programa para la Cooperación y el Desarrollo a través de los proyectos PAPIIT-IN106998, CONACYT-27624U, CICYT MAT97-694-C02-01 y CYTED Red VIII.F.Peer reviewe

Influence of La3+ on the microestructure of bismuth titanate solid solutions

[ES] En este trabajo se reporta la síntesis de la serie de soluciones sólidas de titanato de bismuto, Bi4Ti3O12 con La3+ por coprecipitación de los respectivos hidróxidos. Las soluciones sólidas se caracterizaron por difracción de rayos-X y medidas de densidad. Por técnicas de SEM se determinó la influencia del La3+ en la microestructura del titanato de bismuto puro. En este estudio se prepararon diversas composiciones de la solución sólida a y se sinterizaron a 850ºC. Los resultados se presentan en función de la concentración del dopante.[EN] In this work a solid solution of bismuth titanate Bi4Ti3O12 with La3+ is synthesised by coprecipitation of their hydroxides. The solid solutions were characterised by X-ray powder diffraction and density measurements. By SEM the influence of La3+ in bismuth titanate was analised. In this study several compositions of the solid solution were prepared and sintered at 850ºC. The results are presented as a function of the dopant concentration.Los autores agradecen el apoyo de los proyectos PAPIIT, DGAPA, UNAM No. IN102700 y CONACYT No. 33361-U.Peer reviewe

Squat and countermovement jump performance across a range of loads: A comparison between Smith machine and free weight execution modes in elite sprinters

The aims of this study were to: 1) provide and compare the height achieved during Smith machine (SM) and free weight (FW) loaded jumps executed over a wide spectrum of loads (40–120 % of body mass [BM]); and 2) test the difference between loaded and unloaded squat jump (SJ) and countermovement jump (CMJ) attempts in ten highly trained male sprinters. On the first visit, athletes performed unloaded SJ and CMJ, loaded SJ with loads corresponding to 40, 60, 80, 100, and 120 % BM, and loaded CMJ at 100% BM using an Olympic barbell (FW). On the second visit, they performed loaded SJ and CMJ tests under the same loading conditions on the SM device and, subsequently, a half-squat one-repetition maximum (1RM) assessment. The relative strength (RS = 1RM/BM) of the athletes was 2.54 ± 0.15. Loaded SJ performance was similar between SM and FW, and across all loading conditions. Differences in favour of CMJ (higher jump heights compared with SJ) were superior in the unloaded condition but decreased progressively as a function of loading. In summary, sprinters achieved similar SJ heights across a comprehensive range of loads, regardless of the execution mode (FW or SM). The positive effect of the countermovement on jump performance is progressively reduced with increasing load