Quercetin supplementation promotes recovery after exercise-induced muscle damage: a systematic review and meta-analysis of randomized controlled trials.

Quercetin (Q) is one of the most frequently consumed flavonoids in the human diet. The purpose of this systematic review and meta-analysis was to determine the effects of Q supplementation on muscle damage, muscle soreness and biochemical markers of inflammation, antioxidant capacity and oxidative stress after intense exercise. A literature search of SPORTDiscus, PubMed, Web of Science and Scopus was performed from inception to May 31, 2022. Forest plots were generated with fixed or random-effect models and standardized mean differences (SMD). Data extraction and quality assessment were performed independently by two authors. After application of the inclusion and exclusion criteria, 13 studies with a total of 249 sedentary to well-trained participants were included. For all studies there were some concerns about the risk of bias. All but one study used a supplementation dosage of 1000 mg/day. Q supplementation accelerated recovery of muscle function and significantly decreased muscle soreness 0/24 h after exercise (SMD: -1.33; p = 0.03), creatine kinase levels 24/48 h after exercise (SMD: -1.15; p = 0.02), and post-exercise oxidative stress (SMD: -0.92; p = 0.03). However, Q supplementation had no effect on IL-6 concentration. Q supplementation with a dose of 1000 mg/day for periods of more than seven days and a maximum of 12 weeks appears to be a safe and efficacious strategy to reduce muscle damage and muscle soreness, as well as to enhance recovery after intense exercise in sedentary to well-trained young men. Systematic review registration: PROSPERO CRD42021266801.

Effects of vitamin D supplementation on muscle function and recovery after exercise-induced muscle damage: A systematic review.

BACKGROUND: Vitamin D is essential for the optimal health of the skeletal system. However, this vitamin is also involved in other functions of the human body, such as muscle, immune and inflammatory ones. Some studies suggest that adequate levels of vitamin D support muscular function during exercise and accelerate recovery because they reduce specific pro-inflammatory cytokine levels, but those results have not always been observed. Therefore, this review aims to evaluate the effects of vitamin D supplementation on inflammation, oxidative stress and recovery after exercise. METHODS: This systematic review was conducted using the Preferred Reporting of Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A literature search of SPORTDiscuss, PubMed, Web of Science and Scopus was performed from inception through February 2022. The articles' methodological quality was assessed with the PEDro scale. RESULTS: After the application of the inclusion and exclusion criteria, 11 eligible articles were included. All the studies were considered of moderate methodological quality. Ten studies involved regular vitamin D supplementation for more than 7 days, and one study performed acute vitamin D supplementation 24 h before exercise. CONCLUSIONS: The existing evidence suggests that vitamin D supplementation for periods of more than 1 week with a minimum dose of 2000 IU/day appears to be an efficacious strategy for attenuating muscle damage and inflammation after exercise. The potential positive effects on muscle function, muscle pain and oxidative stress need to be confirmed with new investigations. Further research is also required to determine the adequate vitamin D dosage to obtain positive effects without adverse effects.

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

Studies analyzing tennis players' 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 13-16 years. Twenty-two male (14.45 ± 1.10 years) and 20 female (14.30 ± 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 (13-14 years vs. 15-16 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.

Kinetics and Vertical Stiffness of Female Volleyball Players: Effect of Low-Intensity Plyometric Training.

Purpose: The purpose of this study was threefold: 1) to assess kinematic/kinetic variables and vertical stiffness of recreational young female volleyball players during a vertical jump, 2) to identify the changes in those variables that occurred after low-intensity plyometric training, 3) to determine the relationship between stiffness and performance. Method: Twenty-eight female volleyball players aged 14-18 years were randomly allocated to plyometric group and control group. All participants performed a countermovement jump (CMJ) 3 days prior to and 3 days after the 7-week plyometric training and kinematic and kinetic variables, along with vertical stiffness, were measured. Results: Jump height, average force, average power, peak power and absolute vertical stiffness significantly increased in plyometric group (p < .01). Propulsion impulse and normalized vertical stiffness also increased (p < .05). Maximum displacement of the center of mass significantly decreased in plyometric group (p < .01). Changes in vertical stiffness after the plyometric training showed very strong significant correlations with changes in average force (r = 0.818, p < .01), average power (r = 0.784, p < .01), maximum displacement of the center of mass (r = -0.850, p < .01) and propulsion duration (r = -0.781, p < .01). Conclusion: The 7-week low-intensity plyometric training produced changes in most kinematic and kinetic variables improving CMJ performance. The increase in vertical stiffness after plyometric training may not directly enhance jump performance but it makes the jump quicker increasing the probability of success in volleyball games.

Effects of Beetroot Supplementation on Recovery After Exercise-Induced Muscle Damage: A Systematic Review.

CONTEXT: Beetroots have antioxidant and anti-inflammatory properties, which may help attenuate inflammation and oxidative stress, enhancing recovery from exercise-induced muscle damage (EIMD). OBJECTIVE: To evaluate the effects of beetroot supplementation on oxidative stress, inflammation, and recovery after EIMD. DATA SOURCES: SPORTDiscus, PubMed, Web of Science, and Scopus databases were searched, and hand-searching was performed by looking to relevant studies that were cited in other studies. STUDY SELECTION: For a study to be included in this review, the following inclusion criteria had to be met: (1) research conducted with human participants, (2) original articles in peer-reviewed publications, (3) original studies that had investigated beetroot supplementation intervention on muscle damage and recovery, (4) research conducted with 1 control/placebo group, and (5) articles published from inception to October 2020. STUDY DESIGN: Systematic review using the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement. LEVEL OF EVIDENCE: Level 3. DATA EXTRACTION: Two of the 4 authors independently extracted data and assessed the methodological quality of the articles with the PEDro scale. All discrepancies were resolved through a consensus meeting. RESULTS: A total of 9 studies were included in this review. The methodological quality of the included studies ranged from moderate to high. Most of the studies found a better recovery of functional variables and muscle soreness, but improvements in markers of muscle damage, inflammation, and oxidative stress were not reported. CONCLUSION: The existing evidence suggests that a short-term beetroot supplementation has the potential to accelerate recovery of functional measures and muscle soreness, but further research is needed to clarify if a longer supplementation period (with some days before exercise and some days after) could also promote recovery of markers of muscle damage, inflammation, and oxidative stress.

Heart rate variability is lower in patients with intermittent claudication: a preliminary study / La variabilidad de la frecuencia cardiaca es menor en pacientes con claudicación intermitente: un estudio preliminar

Introduction: Peripheral arterial disease is a chronic disorder affecting blood flow to lower limbs and many patients can develop intermittent claudication (IC). They suffer a blood flow decrease to lower limbs, making impossible to walk short distances without feeling pain or stopping the gait. Heart Rate Variability (HRV) is a non-invasive tool based on the calculation of time variations along consecutive heartbeats. It is reasonable to think that, since HRV assess the autonomic balance through the cardiovascular system, it could be useful in the assessment of patients with IC. Objectives: The aim of this study was to assess if there are differences in resting HRV between patients with IC and age matched controls, both with linear and non-linear analysis, and its possible relation with the gait capacity. Methods: 14 control male subjects (60±5 years) and 14 male IC patients (64±6 years) underwent 10 minutes of HRV analysis. The study calculated Time Domain variables, Poincaré Plot analysis and nonlinear parameters (Entropy and slopes of Detrend Fluctuation Analysis). Results: The main finding of this study is the presence of a clear sympathetic predominance at rest in the IC patients and a significant correlation between the parasympathetic rest tone and the distance covered in the 6MWT when all subjects are included. Conclusions: HRV seems to be an accurate method to detect the sympathetic misbalance present in patients with IC but as a nonspecific finding that could be present in other cardiovascular pathologies. Complex structure of the heartbeat signal is not affected by IC

Introducción: La enfermedad arterial periférica es un trastorno crónico que afecta al flujo sanguíneo de los miembros inferiores y muchos pacientes desarrollan claudicación intermitente (CI), sufriendo una reducción del flujo sanguíneo que les hace imposible caminar cortas distancias sin sufrir dolor o tener que detenerse. La variabilidad de la frecuencia cardiaca (VFC) es una herramienta no invasiva basada en el cálculo de las variaciones de tiempo entre latidos sucesivos. Es razonable pensar que, puesto que la VFC evalúa el balance autonómico a través del sistema cardiovascular, podría ser útil en la valoración de pacientes con CI. Objetivos: Evaluar si hay diferencias en la VFC de reposo entre pacientes con CI y controles de la misma edad (tanto con análisis lineal como no lineal) y su posible relación con la capacidad de marcha. Métodos: Se realiza un análisis de VFC de 10 min a 14 controles (60±5 años) y 14 pacientes con CI (64±6 años). Se calcularon variables del dominio de tiempo, gráfico de Poincaré y parámetros no lineales. Todos los sujetos realizaron a continuación un test de 6 min. Resultados: El principal hallazgo de este estudio es la presencia de un claro predominio simpático en reposo en los pacientes con CI y una correlación significativa entre el tono parasimpático de reposo y la distancia recorrida en el test de 6 min. Conclusiones: La VFC parece ser un método adecuado para detectar la disfunción simpática presente en pacientes con CI pero como un hallazgo inespecífico que puede estar presente en otras patologías vasculares. La estructura compleja de la señal cardiaca no se ve afectada en la CI

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

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 ß, 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.

Caloric restriction reduces IgA levels and modifies cytokine mRNA expression in mouse small intestine.

The aim of this study was to determine the effect of caloric restriction (CR) in mouse small intestine on the production and secretion of immunoglobulin (Ig) A, the population of lymphocytes in the lamina propria, and the expression of cytokines that mediate and regulate innate and adaptive immunity. One group of young Balb/c mice was fed ad libitum, while the CR group was fed ad libitum and fasted on alternate days. When mice were six months old, IgA levels in the proximal small intestine were quantified by enzyme-linked immunosorbent assay, while the number of IgA containing cells, CD4(+) T cells and CD8(+) T cells in the duodenal mucosa was determined by immunohistochemistry. Furthermore, the expression of several intestinal cytokines, the genes for α-chain IgA, and the polymeric Ig receptor (pIgR) were analyzed by real-time polymerase chain reaction. CR decreased the levels of IgA in the intestine, apparently a consequence of a reduced number of IgA(+) cells in the lamina propria that decrease the production and secretion of this Ig, and a reduced secretion of S-IgA into the bile, which in turn discharges into the proximal intestine. Contrarily, CR increased the expression of genes for α-chain IgA, and the pIgR, indicating that transport of IgA was not a key factor in the decrease of this Ig. Additionally, CR modified the expression of genes for tumor necrosis factor-α, interferon-γ, tumor growth factor-ß, interleukin (IL)-2 and IL-10, all of which regulate the synthesis of IgA and pIgR, the inflammatory response, and the immune response in the intestine.

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 ß-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.

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. Key pointsIn the landing phase of a jump there are always sev-eral peak forces. The combination of these peaks forces and the high frequency of jumps during sports produces a large amount of stress in the joints of the lower limbs which can be determinant of injury.In the most common two-footed landings usually appear two peak forces (F1 and F2) in the force-time curve and the second one is usually related to injury's risk. In this article it is shown that increasing the time F2 appears decrease F2.Increasing landing times could be counterproductive with respect to the goals of the sport. In this article it is shown that increasing the time F2 appears makes, however, the whole impact absorption shorter in du-ration.

Impedancia bioeléctrica como método para estimar cambios en los fluídos corporales en remeros / Bioelectric impedance analysis as method to estimate body fluid changes in rowers

La valoración de líquidos corporales en el deportista, agua corporal total (ACT), agua intracelular (AI) y agua extracelular (AE), es un factor de suma importancia para el entrenamiento y la competición. La impedancia bioeléctrica (BIA) es cada vez más utilizada en el ámbito de la salud y del deporte por ser un método simple y no invasivo. El objetivo de este estudio es analizar la capacidad de la BIA de última generación para detectar cambios en los fluidos corporales debidos a la deshidratación inducida por el ejercicio. Se estudiaron 19 remeros. Antes del ejercicio se valoró su composición corporal con método antropométrico como modelo de referencia y se estimaron el ACT, AI y AE con un aparato BIA segmental y multifrecuencia. Seguidamente se sometió a los deportistas a una sesión de entrenamiento sobre remoergómetro de 56 minutos de duración. Al finalizar fueron pesados nuevamente y sometidos a una segunda evaluación con BIA. La pérdida de líquido corporal inducida por el ejercicio y medida con balanza arrojó resultados significativos, siendo de 1,6 ± 0,36 kg. Sin embargo, las diferencias registradas por BIA, antes y después del ejercicio, para el ACT, AI yAE, no fueron significativas (p < 0,05).Tampoco se ha encontrado concordancia entre el método de balanza y el método BIA para estimar cambios en líquidos corporales y se ha hallado una media para las diferencias de 1,24 kg. Por lo tanto, concluimos que BIA no sirve para registrar cambios en los compartimentos acuosos corporales tras una sesión de ejercicio, ya que los niveles hídricos se registraron de forma cuantitativamente incorrecta (AU)

Evaluating the body fluids in athletes, as well as their total body water (TBW), intra (ICW) and extracelular water (ECW), is an important factor for the training and competition. Bioelectric Impedance Analysis (BIA) is becoming more and more useful in both heath and sport fields becauseit is a simple and non invasive method. The purpose of this study is to analyse the capability of state-of-the-art BIA devices in order to check any changes in body fluids due to de hydration as a consequence of exercise. The 19 rowers participating in this study. Before the exercise we evaluated their body composition with the anthropometric method as a reference model, and we estimated the TBW, ICW and ECW with a segmental and multifrequency BIA. Afterwards, subjects went through a 56-minutetraining session by ergo-rower. When finishing they we reweighed and subjected to a second evaluation. The loss of body fluids due to exercise and measured with the bascule provided us with significant results, 1.6 ± 0.4kg. However, the different values recorded by BIA, before and after the exercise for the TBW, ICW and ECW were not significant (p < 0.05).Concordance Bland-Altman analysis not confirmed good agreement between the bascule and the BIA methods, in order to estimate the change in body fluids. The average one for the estimation difference was 1.24 kg. Therefore we conclude that BIA is not used to record changes in body water compartments after a workout because water levels were recorded on a quantitatively incorrect (AU)

Aplicación de un modelo matemático al taper en jóvenes nadadores / Applying a mathematical model to taper in young swimmers

Ante una competición importante, la dosis de entrenamiento debe reducirse con la intención de mejorar el rendimiento. El presente estudio tiene por objetivo determinar los efectos de la aplicación de un modelo matemático durante la reducción progresiva no lineal de la carga de entrenamientoo taper en jóvenes nadadores. Diez nadadores fueron testados antes y después del taper. Las variables utilizadas para el control fueron el volumen de entrenamiento, la relación entre volumen e intensidad media de entrenamiento en una temporada (MITS) y la frecuencia de entrenamiento. La disminución del volumen de entrenamiento tras aplicar el modelo matemático resultó en la primera semana del 30,9%, y en la segunda semana del 71,2%. La disminución de los MITS tras aplicar el modelo matemático tuvo un resultado en la primera semana del 30,8%, y en la segunda semana del 71,1%. La frecuencia de entrenamiento se disminuyó un 10% en la primera semana, y hasta el 40% en la segunda semana. Las marcas obtenidas entre el primer y el segundo tests fueron significativamente mejores para el segundo (p < 0,05). El lactato máximo también se modificó de manera significativa (p < 0,05), a diferencia del lactato mínimo, en el que no se detectaron diferencias. La correlación entre lactato máximo y la marca obtenida resultó significativa (p < 0,05). El valor de la percepción subjetivo del esfuerzo (RPE), tras aplicar el modelo matemático, disminuyó, aunque no significativamente(p > 0,05). Estos datos indican que el taper propuesto no provoca pérdidas de sensaciones ni de entrenamiento, pues las marcas obtenidas mejoraron de forma significativa, al igual que lo hizo el lactato máximo, lo que demuestra una clara correlación entre lactato máximo y marca (AU)

Before an important competition, the training dose should be reduced with the intention of improving the performance. This study aims to determine the impact of the implementation of a mathematical model during the non-linear, progressive reduction of the training load or taper in young swimmers. Ten swimmers were tested before and after the taper. The control variables measured during the training were the volume, the relationship between the volume and the mean intensity of training season (MITS) and the frequency of training. The decrease in the volume of training after applying the mathematical model was of 30.9% in the first week, and of 71.2% in the second week. The decrease in MITS after applying the mathematical model was of 30.8% in the first week, and of 71.1% in the second week. The training frequency was decreased by 10% in the first week, and up to 40% in the second week. The records obtained between the first and the second tests were significantly better (p < 0.05). The maximum lactate production also increased significantly (p < 0.05), unlike the speed of lactate clarifying that it did not. The correlation between lactate and the maximum mark obtained was significant (p < 0.05). The value SPE (subjective perception of effort)after applying the mathematical model decreased, but not significantly (p > 0.05). These data indicate that the taper proposed does not cause loss of sensation or training, since the records improved significantly, as did the maximum production of lactate, showing a high correlation between maximum lactate and record (AU)