Muscle Physiology Changes Induced by Every Other Day Feeding and Endurance Exercise in Mice: Effects on Physical Performance

Every other day feeding (EOD) and exercise induce changes in cell metabolism. The aim of the present work was to know if both EOD and exercise produce similar effects on physical capacity, studying their physiological, biochemical and metabolic effects on muscle. Male OF-1 mice were fed either ad libitum (AL) or under EOD. After 18 weeks under EOD, animals were also trained by using a treadmill for another 6 weeks and then analyzed for physical activity. Both, EOD and endurance exercise increased the resistance of animals to extenuating activity and improved motor coordination. Among the groups that showed the highest performance, AL and EOD trained animals, ALT and EODT respectively, only the EODT group was able to increase glucose and triglycerides levels in plasma after extenuating exercise. No high effects on mitochondrial respiratory chain activities or protein levels neither on coenzyme Q levels were found in gastrocnemius muscle. However, exercise and EOD did increase β-oxidation activity in this muscle accompanied by increased CD36 levels in animals fed under EOD and by changes in shape and localization of mitochondria in muscle fibers. Furthermore, EOD and training decreased muscle damage after strenuous exercise. EOD also reduced the levels of lipid peroxidation in muscle. Our results indicate that EOD improves muscle performance and resistance by increasing lipid catabolism in muscle mitochondria at the same time that prevents lipid peroxidation and muscle damage

Bilateral asymmetries and sex differences in the kinematics of running gait cycle of a group of Andalusian recreational runners.

Running gait cycle begins when one foot comes in contact with the ground and ends when the same foot contacts the ground again. In a running gait cycle each lower limb has a stance phase and a swing phase. During the stance phase eversion of the subtalar joint is one of the mechanisms used to absorb impact forces. However, excessive rearfoot eversion may contribute to overuse running injuries of the lower limb. It is necessary to provide additional insight on sex differences or differences between dominant and non-dominant limbs in the different phases of the running gait cycle, as well as in the movements of the subtalar joint in the coronal plane. Therefore, the aim of the current study was to determine bilateral asymmetries, sex differences and peak eversion angle in the running gait cycle of recreational runners. 20 recreational runners aged 20 – 28 years (10 males and 10 females) were recorded on a treadmill at a running speed between 11 km/h and 12 km/ h with high speed camera at 300 Hz. Males and females showed no significant differences between limbs in any of the variables of interest, indicating no bilateral asymmetries in running gait cycle. Female runners demonstrated a greater time to peak eversion than male runners (36.92 ± 5.79% vs 26.37 ± 5.12%, p < .01) and this may be related to some overuse running injuries that are more prevalent in females. The data obtained in this study may serve as a useful reference for future research.Un ciclo de carrera comienza cuando un pie contacta con el suelo y termina cuando el mismo pie contacta con el suelo de forma consecutiva. En un ciclo de carrera cada extremidad inferior tiene una fase de apoyo y una fase de vuelo. Durante la fase de apoyo la pronación de la articulación subastragalina es uno de los mecanismos para absorber las fuerzas de impacto. Sin embargo, una excesiva pronación puede predisponer a lesiones por sobreuso de la extremidad inferior. Son necesarias investigaciones adicionales sobre las diferencias por sexos y las asimetrías en las diferentes fases del ciclo de carrera, así como en los movimientos de la articulación subastragalina. Por tanto, el propósito del presente estudio fue determinar las asimetrías, las diferencias por sexos y la máxima pronación en un ciclo de carrera de corredores recreativos. 20 corredores recreativos de entre 20 y 28 años (10 hombres y 10 mujeres) fueron grabados corriendo en tapiz rodante entre 11 km/h y 12 km/h con una cámara de alta velocidad a 300 Hz. No existieron asimetrías en el ciclo de carrera pues no se encontraron diferencias significativas entre la pierna dominante y la no dominante en ninguna variable. La máxima pronación fue más tardía en mujeres que en hombres (36.92 ± 5.79% vs 26.37 ± 5.12%, p < .01), lo que puede estar relacionado con la mayor prevalencia de ciertas lesiones de la extremidad inferior en mujeres. Los resultados obtenidos en este estudio pueden servir de referencia para futuras investigaciones

Body Composition, Somatotype and Raw Bioelectrical Impedance Parameters of Adolescent Elite Tennis Players: Age and Sex Differences

Studies analyzing tennis players&rsquo; body composition and morphological and bioelectrical characteristics are scarce, especially among adolescents. This study aimed to explore sex- and age-based differences in body composition, somatotype, and bioelectrical properties among elite young male and female tennis players aged 13&ndash;16 years. Twenty-two male (14.45 &plusmn; 1.10 years) and 20 female (14.30 &plusmn; 1.03 years) elite tennis players participated in this study and were compared according to sex (males vs. females) and, within each sex, according to age (13&ndash;14 years vs. 15&ndash;16 years). Female adolescent elite tennis players had higher body fat (BF) percentage and higher endomorphy than males. They also had lower skeletal muscle mass and total body water (TBW) percentages. Older boys had lower resistance and a higher TBW and phase angle (PhA) than younger boys, likely due to maturation and performance. No significant differences were found between younger and older girls, except for the PhA, potentially associated with better cell function and performance. This study provides valuable reference data for coaches of elite youth tennis players. Due to the few differences found in body composition and somatotype in the different age groups, the PhA may be used by practitioners as a reference for cell function and performance

Effect of moderate exercise on IgA levels and lymphocyte count in mouse intestine

et al.The aim of the present study was to determine the effect of moderate exercise on the production and secretion of IgA in mouse duodenum, on lymphocyte levels in the lamina propria, and on gene expression encoding for cytokines that regulate the synthesis of α-chain of IgA and the expression of pIgR in the lamina propria. Two groups of young Balb/c mice were fed ad libitum, one sedentary and the other with an exercise program (swimming) for 16 weeks. IgA levels in the duodenum were quantified by ELISA; the number of IgA containing cells as well as B cells, CD4+ and CD8+ T cells in the duodenal mucosa was determined by immunohistochemistry; gene expression was analyzed by real-time PCR, and the expression of proteins by Western blotting. Because of physical training, in the duodenum there was a decrease in the number of IgA producing cells, but an increase in the levels of IgA. Additionally, exercise increased the expression of the genes encoding for IL-4, IL-6, IL-10, TNF-α and TGF β, cytokines that regulate the synthesis of IgA and pIgR, the inflammatory response, and the immune response in the intestine. Thus, the increased IgA found in the duodenal lumen is probably due to the increased production of IgA in the LP and the increased transport of the pIgA-pIgR complex across epithelial cells. Possibly the increased S-IgA levels in the bile also contribute to the change in IgA levels.Peer Reviewe

ANALYSIS OF THE VERTICAL GROUND REACTION FORCES AND TEMPORAL FACTORS IN THE LANDING PHASE OF A COUNTERMOVEMENT JUMP

In most common bilateral landings of vertical jumps, there are two peak forces (F1 and F2) in the force-time curve. The combination of these peak forces and the high frequency of jumps during sports produce a large amount of stress in the joints of the lower limbs which can be determinant of injury. The aim of this study was to find possible relationships between the jump height and F1 and F2, between F1 and F2 themselves, and between F1, F2, the time they appear (T1 and T2, respectively) and the length of the impact absorption phase (T). Thirty semi-professional football players made five countermovement jumps and the highest jump of each player was analyzed. They were instructed to perform the jumps with maximum effort and to land first with the balls of their feet and then with their heels. All the data were collected using a Kistler Quattro Jump force plate with a sample rate of 500 Hz. Quattro Jump Software, v.1.0.9.0., was used. There was neither significant correlation between T1 and F1 nor between T1 and F2. There was a significant positive correlation between flight height (FH) and F1 (r = 0.584, p = 0.01) but no significant correlation between FH and F2. A significant positive correlation between F1 and T2 (r = 0.418, p < 0.05) and a significant negative correlation between F2 and T2 (r = -0.406, p < 0.05) were also found. There is a significant negative correlation between T2 and T (r = -0. 443, p < 0.05). T1 has a little effect in the impact absorption process. F1 increases with increasing T2 but F2 decreases with increasing T2. Besides, increasing T2, with the objective of decreasing F2, makes the whole impact absorption shorter and the jump landing faster