Effect of high-intensity resistance circuit-based training in hypoxia on aerobic performance and repeat sprint ability.

Recent acute studies have shown that high-intensity resistance circuit-based (HRC) training in hypoxia increases metabolic stress. However, no intervention studies have yet proven their effectiveness. This study aimed to analyze the effect of 8 weeks of HRC in hypoxia on aerobic performance, resting energy expenditure (REE), repeat sprint ability (RSA) and hematological variables. Twenty-eight subjects were assigned to hypoxia (FiO2  = 15%; HRChyp : n = 15; age: 24.6 ± 6.8 years; height: 177.4 ± 5.9 cm; weight: 74.9 ± 11.5 kg) and normoxia (FiO2  = 20.9%; HRCnorm : n = 13; age: 23.2 ± 5.2 years; height: 173.4 ± 6.2 cm; weight: 69.4 ± 7.4 kg) groups. Each training session consisted of two blocks of three exercises (Block 1: bench press, leg extension, front pull down; 2: deadlift, elbow flexion, ankle extension). Each exercise was performed at 6 repetitions maximum. Participants exercised twice weekly for 8 weeks and before and after the training program blood test, REE, RSA and treadmill running test were performed. Fatigue index in the RSA test was significantly decreased in the HRChyp (-0.9%; P < .01; ES = 2.75) but not in the HRCnorm . No changes were observed in REE and hematological variables. Absolute (4.5%; P = .014; ES = 0.42) and relative (5.2%; P = .008; ES = 0.43) maximal oxygen uptake (VO2 max), speed at VO2 max (4%; P = .010; ES = 0.25) and time to exhaustion (4.1%; P = .012; ES = 0.26) were significantly increased in HRChyp but not in the HRCnorm . No significant differences between groups were found. Compared with normoxic conditions, 8 weeks of HRC training under hypoxic conditions efficiently improves aerobic performance and RSA without changes in REE and red blood O2 -carrying capacity.

Concurrencia de fatiga y potenciación tras una contracción voluntaria máxima sostenida / Concurrence of fatigue and potentiation after a sustained maximal voluntary contraction

El objetivo del presente estudio fue analizar la concurrencia e interacción existente entre diferentes factores que afectan al rendimiento, tales como son la fatiga central, la fatiga periférica y la potenciación post-activación (PPA) tras la realización de una contracción máxima voluntaria (CMV) sostenida hasta la pérdida del 50% en los valores de fuerza iniciales. Con el objetivo de valorar los efectos de la fatiga central, fatiga periférica y la PPA se utilizó la técnica de interpolación de descargas. Los resultados han revelado pérdidas en los valores de durante aproximadamente 3'30'' y que la fatiga dependió tanto de factores centrales como periféricos. También se produjo una inhibición de la PPA tras la realización de la CMV sostenida, durante un breve periodo de tiempo (entre 30'' y 1'30''). Además, se observó la coexistencia de los distintos fenómenos estudiados, que sin embargo, demostraron tener una curva de recuperación temporal diferente (AU)

The aim of the present study was to analyze the concurrence and interaction between different factors affecting the performance, such as central fatigue, peripheral fatigue and post-activation potentiation (PAP) after the performance of a maximal voluntary contraction (MVC) sustained until the loss of the 50% of the initial torque value. In order to assess the effects of central fatigue, peripheral fatigue and the PAP on the performance of the MVC, the twitch interpolation technique was used. Our findings revealed a loss of the force capability during at least 3'30'' and that the recorded fatigue had central and peripheral contributions. Moreover, it has been observed an inhibition of the PAP after the completion of the sustained MVC during a brief interval (between 30'' and 1'30''). Furthermore, it has been observed the coexistence of the different studied phenomena, however, they showed different time course of the recovery (AU)