The effect of muscle blood flow restriction on hemodynamics, cerebral oxygenation and activation at rest

This study tested the hypothesis that muscle blood flow restriction reduces muscle and cerebral oxygenation, at rest. In 26 healthy males, aged 332 yrs, physiological variables were continuously recorded during a 10-min period in two experimental conditions: a) with muscle blood flow restriction through thigh cuffs application inflated at 120 mmHg (With Cuffs, WC) and b) without restriction (No Cuffs, NC). Muscle and cerebral oxygenation were reduced by muscle blood flow restriction as suggested by the increase in both muscle and cerebral deoxygenated hemoglobin (Δ[HHb]; pThe accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

The Impact of Obesity on the Fitness Performance of School-Aged Children Living in Rural Areas—The West Attica Project

This study aimed to investigate the relationship of body mass index (BMI) with muscle and cardiorespiratory fitness in children living within rural areas (regional unit of West Attica) in Greece. Participants included 399 students (187 boys, 212 girls), ages 8–12 years old, and were evaluated in physical performance tests. The point prevalence of overweight and obesity was 21.39% and 26.20% in boys, and 19.90% and 23.79% in girls. Significant differences were observed in all physical performance tests (handgrip, long jump, shuttle run, trunk flexors, and extensors endurance) between normal weight and obese participants. BMI was positively correlated with handgrip (r = 0.442−0.462, p < 0.001). There was a negative association with long jump (r = −0.206, p < 0.001), 20 m shuttle run (r = −0.394, p < 0.001), trunk flexors (r = −0.403, p < 0.001) and trunk extensors endurance (r = −0.280, p < 0.001). The regression analysis showed that 20–30% of the overall variation for physical performance assessments could be accounted for by BMI, age, and sex. With the exception of the long jump and the endurance of the trunk extensors, BMI alone may explain more than 10% of the outcome of most tests. This study highlights the determinant of BMI on muscle and cardiorespiratory fitness. The management of obesity should begin early in childhood to prevent adult chronic cardiovascular and metabolic diseases

The importance of aerobic capacity and nutrition in recreational master mountain runners' performance and race-induced changes in body composition and biochemical blood indices

This study aimed to explore the importance of aerobic capacity and nutrition on 28-km mountain running performance and race-induced changes in body composition and biochemical blood indices, in recreational master athletes of different performance levels. Twenty male master runners (age: 44.6 +/- 7.7 years) were divided into two groups, slower and faster runners, according to their race performance. Maximum oxygen uptake ((V)over dotO(2max)), velocity at (V)over dotO(2max) (v(V)over dotO(2max)), oxygen consumption ((V)over dotO(2Thr)), and velocity (v(V)over dotO(2Thr)) during the second ventilatory threshold were evaluated. Nutrition was assessed for one week before and during the race. Body composition was evaluated, and blood samples were collected before and 3 h after the race. Slower runners exhibited a greater reduction in lean body mass and greater changes in all muscle damage/inflammation/metabolism blood indices than the faster runners (eta(2) =0.201-0.927; p< 0.05). When all the participants were assessed as one group (n=20), significant correlations were found between (v(V)over dotO(2max), v(V) over dotO(2Thr), race time, energy intake, expenditure, carbohydrate, protein intakes, and post-race changes in body composition and blood markers (r: -0.825-0.824; p< 0.05). The strongest determinants were (v(V)over dotO(2max) and v(V) over dotO(2Thr), while energy intake, expenditure, carbohydrate, and protein intakes seemed to be the weakest determinants of race performance and race-induced changes in body composition and blood indices. The results suggest that race-induced changes in body composition and blood indices are determined mainly by master runners' race performance and endurance capacity and to a lesser extent by nutrition. However, it seems that carbohydrate and protein intakes have equal importance

Cerebral blood flow during sprint exercise

Se desconocen los efectos del entrenamiento interválico de alta intesidad (HIIT) sobre el flujo sanguíneo cerebral (FSC) y la oxigenación cerebral. Por ello reclutamos a 20 voluntarios que realizaron una sesión de HIIT (4 test de Wingate con recuperaciones de 4 minutos). Se midió la oxigenación del lóbulo frontal (OLF) y el Vastus lateralis (VL) a través de espectrofotometría cercana a los infrarrojos (NIRS). También se registró la velocidad de la sangre en las arterias cerebrales medias (vACM) mediante Doppler. La vACM disminuyó entre un 5 y 10 % en el primer esprint. En los siguientes esprints se redujo aún más. La vACM descendió en cada esprint coincidiendo con la disminución de la presión tele-espiratoria de dióxido de carbono (PETCO2) y con valores superiores de ventilación pulmonar (VE). Al interrumpirse el pedaleo se redujo bruscamente la vACM. Sin embargo, la OLF se mantuvo estable en el primer esprint sólo reduciéndose ligeramente durante el segundo y tercer Wingate (el cuarto fue similar al tercero). Este estudio muestra que la vACM disminuye durante los ejercicios de esprint, posiblemente debido a la hipocapnia. La reducción de la vACM no ejerce efectos funcionales ni relevantes sobre la oxigenación cerebral, gracias al ajuste de la conductancia vascular a través de los mecanismos de autoregulación, sin que parezca afectar negativamente al rendimiento.The effect of high-intensity interval training (HIIT) on cerebral blood flow (CBF) and cerebral oxygenation remain unknown. Therefore, we recruited 20 voluntaries who performed one HIIT session (4x30s Wingate tests with 4 minutes recovery between them). We measured frontal lobe (FLO) and Vastus lateralis (VL) oxygenation with NIRS. Middle cerebral artery blood flow velocity (MCAv) was measured by Doppler. MCAv decreased between 5 and 10 % during the first sprint. MCAv decreased slightly more during the subsequent sprints. Nevertheless, FLO remained stable during the first sprint and was only reduced slightly during the second and third Wingate (the fourth was similar to the third). MCAv decreased on each sprint with the reduction of End-tidal carbon dioxide pressure (PETCO2), the latter due to hyperventilation. When subjects stopped pedaling MCAv was dropped markedly. The decrease in MCAv did not produce any functional or relevant effect on frontal lobe oxygenation due to the adjustment of cerebral vascular conductance by the auto-regulatory mechanisms and did not seem to negatively affect performance.Sin financiaciónNo data JCR 2016No data SJR 20160.420 IDR (2016) C2, 17/42 Deport

The Effects of High-Intensity Interval Exercise on Skeletal Muscle and Cerebral Oxygenation during Cycling and Isokinetic Concentric and Eccentric Exercise

The aim of the present study was to study the effects of cycling and pure concentric and pure eccentric high-intensity interval exercise (HIIE) on skeletal muscle (i.e., vastus lateralis) and cerebral oxygenation. Twelve healthy males (n = 12, age 26 ± 1 yr, body mass 78 ± 2 kg, height 176 ± 2 cm, body fat 17 ± 1% of body mass) performed, in a random order, cycling exercise and isokinetic concentric and eccentric exercise. The isokinetic exercises were performed on each randomly selected leg. The muscle and the cerebral oxygenation were assessed by measuring oxyhemoglobin, deoxyhemoglobin, total hemoglobin, and tissue saturation index. During the cycling exercise, participants performed seven sets of seven seconds maximal intensity using a load equal to 7.5% of their body mass while, during isokinetic concentric and eccentric exercise, they were performed seven sets of five maximal muscle contractions. In all conditions, a 15 s rest was adopted between sets. The cycling HIIE caused greater fatigue (i.e., greater decline in fatigue index) compared to pure concentric and pure eccentric isokinetic exercise. Muscle oxygenation was significantly reduced during HIIE in the three exercise modes, with no difference between them. Cerebral oxygenation was affected only marginally during cycling exercise, while no difference was observed between conditions. It is concluded that a greater volume of either concentric or eccentric isokinetic maximal intensity exercise is needed to cause exhaustion which, in turn, may cause greater alterations in skeletal muscle and cerebral oxygenation

Impact of data averaging strategies on V̇O2max assessment: Mathematical modeling and reliability

Background: No consensus exists on how to average data to optimize VO2max assessment. Although the VO2max value is reduced with larger averaging blocks, no mathematical procedure is available to account for the effect of the length of the averaging block on VO2max. Aims: To determine the effect that the number of breaths or seconds included in the averaging block has on the VO2max value and its reproducibility and to develop correction equations to standardize VO2max values obtained with different averaging strategies. Methods: Eighty‐four subjects performed duplicate incremental tests to exhaustion (IE) in the cycle ergometer and/or treadmill using two metabolic carts (Vyntus and Vmax N29). Rolling breath averages and fixed time averages were calculated from breath‐by‐breath data from 6 to 60 breaths or seconds. Results: VO2max decayed from 6 to 60 breath averages by 10% in low fit (VO2max 0.97). There was a linear‐log relationship between the number of breaths or seconds in the averaging block and VO2max (R2 > 0.99, P < 0.001), and specific equations were developed to standardize VO2max values to a fixed number of breaths or seconds. Reproducibility was higher in trained than low‐fit subjects and not influenced by the averaging strategy, exercise mode, maximal respiratory rate, or IE protocol. Conclusions: The VO2max decreases following a linear‐log function with the number of breaths or seconds included in the averaging block and can be corrected with specific equations as those developed here