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Frequency Analysis
Published in Hector J. Rabal, Roberto A. Braga, Dynamic Laser Speckle and Applications, 2018
Lucía Isabel Passoni, Gonzalo Hernán, Gonzalo Hernán Sendra, Constancio Miguel Arizmendi
where |VH|2 and |VL|2 indicate the powers of certain high and low frequency components of speckle signals obtained through different band-pass filters. This parameter was able to reflect quite sensitively the change of blood flow in the physiological test called reactive hyperaemia (response of blood flow change from reduced flow to reopened flow).16
Intramuscular Changes during Long–term Contraction
Published in Nigel Corlett, John Wilson, llija Manenica, The Ergonomics Of Working Postures, 1986
seconds or minutes and then relaxes in order to recover. Such a pattern would in reality allow the muscle as a whole to contract for an unlimited penod without fatiguing. During 5% MVC (range 4-7% MVC) maintained for 1 hour, we could in fact demonstrate alternating recruitment of the various parts of the knee extensors hased on intramuscular pressure and EMG recordings (Sjogaard et al. 1985 b). The mean intramuscular pressure stayed at a low level (10-45 mmHg) throughout the exercise, but, in most recordings, large fluctuations occurred from resting values up to 90 mmHg. EMG recordings confirmed that the changes in intramuscular pressure may in fact be related to this alternating recruitment of muscle fibres. Another indication that 5% MVC may be non-fatiguing was the high muscle blood flow throughout the contraction penod. Within a few minutes of contraction, blood flow increased to a constant level of 158 (l 25-222) l/min or 0 67 (0-51-0 84) l/(min kg). No hyperaemia was observed when the muscle relaxed; on the contrary, blood flow almost immediately decreased. This blood flow supplied the muscle with sufficient substrate for the increased metabolism, since muscic glycogen content and lactatc release were at their resting levels at the end of the contraction. Also, the muscic temperature remained at a constant level after an initial increase. At a depth of 3 cm the temperature increased from 34 2 to 36 within 5 min of contraction and remained at this level throughout the 1 hour contraction period.
Impact of sedentarism due to the COVID-19 home confinement on neuromuscular, cardiovascular and metabolic health: Physiological and pathophysiological implications and recommendations for physical and nutritional countermeasures
Published in European Journal of Sport Science, 2021
Marco Narici, Giuseppe De Vito, Martino Franchi, Antonio Paoli, Tatiana Moro, Giuseppe Marcolin, Bruno Grassi, Giovanni Baldassarre, Lucrezia Zuccarelli, Gianni Biolo, Filippo Giorgio di Girolamo, Nicola Fiotti, Flemming Dela, Paul Greenhaff, Constantinos Maganaris
During exercise, sheer stress and other hemodynamic stimuli induce positive effects on the peripheral circulation, favouring vasodilation, proliferation of blood vessels and an anti-atherogenic phenotype. Inactivity inevitably goes in the opposite direction. According to Boyle et al. (2013) a reduction of physical activity to <5000 steps/day for only a few days impairs flow-mediated vasodilation. Preliminary data from our group suggest that 10 days of bed rest induces, in healthy young subjects, an impaired microvascular function, as shown by a blunted blood flow increase during passive leg movement of one leg (an index of nitric oxide [NO]-mediated vasodilation [Gifford & Richardson, 2017]) (Zuccarelli et al., 2020), and by a less pronounced reactive microvascular hyperaemia following a transient ischaemia, in association with signs of impaired NO metabolism (Porcelli et al., 2020).
Near-infrared spectroscopy-derived total haemoglobin as an indicator of changes in muscle blood flow during exercise-induced hyperaemia
Published in Journal of Sports Sciences, 2020
Thiago Silveira Alvares, Gustavo Vieira de Oliveira, Rogério Soares, Juan Manuel Murias
It is important to note that the association between micro- and macrovascular reactivity has been shown to be controversial when assessing different vascular beds and/or parameters for blood flow measurements (Dhindsa et al., 2008; Gori et al., 2006; Meyer, Lieps, Schatz, & Pfohl, 2008) or even when considering healthy compared to clinical populations (Vieira de Oliveira, Soares, Volino-Souza, Murias, & Alvares, 2019). For example, (Dhindsa et al., 2008) observed no significant correlation between skin reactive hyperaemia and brachial FMD in healthy participants. Similarly, (Meyer et al., 2008) challenged the idea that a reduced FMD response is only the consequence of reduced reactive hyperaemia connected to microvascular dysfunction, as they found no association between reductions in endothelium-dependent vasodilation of the brachial artery impairments in post-occlusion microvascular hyperaemia. Taken together, data from previous and the present study suggest that, although a connection between micro- and macrocirculatory haemodynamic responses can often be established, the type of measure used to determine this connection as well as the population being tested might play an important role in the observed final outcomes. Thus, assessing vascular beds surrounded by different metabolic active tissues and/or exposed to different haemodynamic pressures, consequently differentiating the mechanisms driving the responses, might be the cause of these controversial findings, and more mechanistic studies are needed to better elucidate this association.
The effect of smartphones and playing video games on decision-making in soccer players: A crossover and randomised study
Published in Journal of Sports Sciences, 2020
Leonardo S. Fortes, Dalton De Lima-Junior, Lenamar Fiorese, José R. A. Nascimento-Júnior, Arnaldo L. Mortatti, Maria E. C. Ferreira
The lactate blood concentration was analysed shortly after the overtime. The lactacidemic analysis was performed in samples of 25 μl of blood collected from the athlete’s earlobe, without hyperaemia, in the heparinised capillary. These samples were immediately transferred to 1.5 ml Eppendorf tubes containing 50 μl of 1% NaF solution and stored on ice for further electro-enzymatic reading (YSL 2700 STAT, Yellow Springs Co., USA).