Gut motility and its control

The gastrointestinal tract is composed of smooth muscle arranged in two layers: longitudinal and circular. Although its activity is influenced by the autonomic nervous system, it is mainly under local reflex control mediated by an enteric nervous system and local hormones. The motility of the gastrointestinal tract has several different well-defined patterns. Its function is to move the gastrointestinal contents through the various phases of homogenization (mixing), digestion, absorption and elimination

Digestion and absorption

Carbohydrates are digested by salivary and pancreatic amylases to di-, tri- and oligosaccharides, and then to monosaccharides by enzymes on the wall of the small intestine to allow them to be absorbed. Proteins are absorbed as amino acids and small peptides that are broken down to amino acids within the cells. Monosaccharides and amino acids pass into the liver via the portal vein. Fats are digested and absorbed as free fatty acids and glycerides that are then mostly reconstituted as triglycerides in the mucosal cells of the small intestine. They combine with phospholipids and a protein to form chylomicrons, which pass via the lymphatics and the thoracic duct into the systemic circulation. Fatty acids are re-esterified and stored as triglycerides in adipose tissue or oxidized for energy. Water is passively absorbed due to the osmotic gradient that results mainly due to the active absorption of sodium ions

The mouth, stomach and intestines

Food is chewed into digestible portions in the mouth and swallowed – a complex reflex process involving several cranial nerves. The stomach homogenizes food, begins digestion and regulates the rate at which food enters the duodenum. Pancreatic juices containing powerful digesting enzymes are added and digestion is completed in the small intestine. The large bowel dehydrates the gastrointestinal contents

Relationship between subjective and external training load variables in youth soccer players.

Purpose: To quantify and describe relationships between subjective and external measures of training load in professional youth soccer players. Methods: Data from differential ratings of perceived exertion and seven measures of external training load were collected from 20 professional youth soccer players over a 46-week season. Relationships were described by repeated measures correlation, principal component analysis and factor analysis with oblimin rotation. Results: Significant positive (0.44 ≤ r ≤ 0.99; p< 0.001) within-individual correlations were obtained across dRPE and all external training load measures Correlation magnitudes were found to decrease when training load variables were expressed per minute. Principal component analysis provided two components that described 83.3% of variance. The first component, which described 72.9% of variance, was heavily loaded by all measures of training load, whilst the second component which described 10.4% of the variance, appeared to have a split between objective and subjective measures of volume and intensity. Exploratory Factor Analysis identified four theoretical factors with correlations between factors ranging from 0.5 to 0.8 These factors could be theoretically described as; objective volume, subjective volume, objective running and objective high intensity measures. Removing dRPE measures from analysis altered the structure of the model, providing a three factor solution. Conclusions: Differential RPE measures are significantly correlated with a range of external training load measures and with each other. More in-depth analysis showed that dRPE measures were highly related to each other, suggesting that, in this population, they would provide practitioners with similar information. Further analysis provided characteristic groupings of variables

The influence of season phase on multivariate load relationships in professional youth soccer.

The purpose of this research was to assess relationships between subjective and external measures of training load in professional youth footballers, whilst accounting for the effect of the stage of the season. Data for ratings of perceived exertion (RPE) and seven global positioning systems (GPS) derived measures were collected from 20 players (age=17.4±1.3yrs, height=178.0±8.1 cm, mass=71.8±7.2 kg) across a 47-week season. The season was categorised by a pre-season phase, and two competitive phases (Comp1, Comp2). The structure of the data were investigated using principal component analysis. An extraction criterion of component with eigenvalues ≥1.0 was used. Two components were retained for the pre-season period explaining a cumulative variance of 77.1%. Single components were retained for both Comp1 and Comp2 explaining 73.3% and 74.3% of variance, respectively. Identification of single components may suggest that measures are related and can be used interchangeably, however these interpretations should be considered with caution. The identification of multiple components in the pre-season phase suggests that univariate measures may not be sufficient when considering load experienced. These results suggest that factoring load based on measures of volume and intensity should be considered

Youth-to-Senior Transition in Elite European Club Soccer

International Journal of Exercise Science 14(6): 1192-1203, 2021. The priority for soccer academies is to develop youth players that graduate and transfer directly to their senior squads. The aim of this study was to assess the effectiveness of this direct youth-to-senior pathway by examining the extent to which club-trained players (CTPs) are currently involved in elite male European soccer. Relevant demographic longitudinal studies between 2009 and 2020 conducted by the International Centre for Sports Studies Football Observatory were analysed. The main findings were that the proportion of CTPs in senior squads has decreased from 23% to 17% over this time period, while the proportion of expatriates (EXPs) has increased from 35% to 42%. Moreover, clubs resorted more frequently to making new signings (NS, i.e. association-trained players (ATPs) and/or EXPs), with squad proportion increasing from 37% to 44%, while only launching one debutant (DBT, i.e. CTP with no previous senior experience) on average per season. Similar trends are observed in the evolution of playing time: while the fielding of CTPs remained constant (15%), EXPs and NS are fielded increasingly more (49% and 36%, respectively), despite a positive relationship between CTP match fielding and league ranking, with a Spearman Rank correlation r = 0.712 (95% confidence interval [0.381-0.881]), p \u3c 0.01. In conclusion, young talents are still provided opportunities; however, these are limited and increasingly less frequent at their parent clubs. This potentially suggests a dysfunctional direct youth-to-senior development pathway

Adiponectin, in contrast to leptin, is not associated with body mass index, waist circumference and HOMA-IR in subjects of a west-African population

Factors associated with plasma levels of adiponectin and leptin were studied in adult subjects without diabetes from Cotonou in Benin (West‐Africa). Seventy (70) men and 45 women were included in the study. Anthropometric variables were measured and a venous blood sample was drawn from each subject, after an overnight fasting period, for measurement of plasma glucose, insulin, leptin, and adiponectin levels. HOMA‐IR was determined to assess insulin resistance. Adiponectin and leptin levels were higher in women than in men (with adiponectin 18.48 ± 12.77 vs.7.8 ± 10.39 μg/mL, P &lt; 0.0001, and leptin 30.77 ± 19.16 vs. 8.66 ± 8.24 ng/mL, P &lt; 0.0001). Fasting insulin level and HOMA‐IR were also higher in the females. Hyperleptinemia was observed in 66,96% of subjects and hypoadiponectinemia was present in 44.35% of subjects. In both men and women, leptin correlated with age (r = 0.2; P = 0.02), BMI (r = 0.572; P &lt; 0.0001), waist circumference (r = 0.534; P &lt; 0.0001), fasting insulin (r = 0.461; P &lt; 0.001), and HOMA‐IR (r = 0.430; P &lt; 0.0001). No significant correlation was observed for adiponectin levels with these variables. Only in women, adiponectin was inversely correlated with fasting glucose (r = −0.423; P &lt; 0.004). These data confirm previous descriptions of leptin but suggest that variations in factors determining serum adiponectin levels observed between ethnicities could also been seen between populations from the same ethnicity

High cut-off microdialysis catheters to clinically investigate cytokine changes following flap transfer

Background: ‘Choke vessels’ are thought to dilate in the first 72 h when blood flow to an area is disrupted. This study used ‘high cut-off’ microdialysis catheters in clinical research to investigate factors mediating circulatory change within free flaps. Methods: Six patients undergoing DIEP flap breast reconstruction each had three ‘high cut-off’ microdialysis catheters, with a membrane modification allowing molecules as large as 100 kDa to pass, inserted into Hartrampf zones 1, 2 and 4 to assess multiple vascular territories. Microdialysis continued for 72 h post-operatively. Samples were analysed for interleukin-6 (IL-6), tumour necrosis factor alpha (TNFα) and fibroblast growth factor basic (FGFβ). Results: Three hundred and twenty-four samples were analysed for IL-6, FGFβ and TNFα totalling 915 analyses. IL-6 showed an increasing trend until 36 h post-operatively before remaining relatively constant. Overall, there was an increase (p &lt; 0.001) over the time period from 4 to 72 h, fitting a linear trend. TNFα had a peak around 20–24 h before a gradual decrease. There was a significant linear time trend (p = 0.029) between 4 and 76 h, decreasing over the time period. FGFβ concentrations did not appear to have any overall difference in concentration with time. The concentration however appeared to oscillate about a horizontal trend line. There were no differences between the DIEP zones in concentrations of cytokines collected. Conclusion: This study uses high-cut off microdialysis catheters to evaluate changes in cytokines, and requires further research to be undertaken to add to our knowledge of choke vessels and flap physiology

Adiponectin, in contrast to leptin, is not associated with body mass index, waist circumference and HOMA-IR in subjects of a west-African population

Factors associated with plasma levels of adiponectin and leptin were studied in adult subjects without diabetes from Cotonou in Benin (West‐Africa). Seventy (70) men and 45 women were included in the study. Anthropometric variables were measured and a venous blood sample was drawn from each subject, after an overnight fasting period, for measurement of plasma glucose, insulin, leptin, and adiponectin levels. HOMA‐IR was determined to assess insulin resistance. Adiponectin and leptin levels were higher in women than in men (with adiponectin 18.48 ± 12.77 vs.7.8 ± 10.39 μg/mL, P &lt; 0.0001, and leptin 30.77 ± 19.16 vs. 8.66 ± 8.24 ng/mL, P &lt; 0.0001). Fasting insulin level and HOMA‐IR were also higher in the females. Hyperleptinemia was observed in 66,96% of subjects and hypoadiponectinemia was present in 44.35% of subjects. In both men and women, leptin correlated with age (r = 0.2; P = 0.02), BMI (r = 0.572; P &lt; 0.0001), waist circumference (r = 0.534; P &lt; 0.0001), fasting insulin (r = 0.461; P &lt; 0.001), and HOMA‐IR (r = 0.430; P &lt; 0.0001). No significant correlation was observed for adiponectin levels with these variables. Only in women, adiponectin was inversely correlated with fasting glucose (r = −0.423; P &lt; 0.004). These data confirm previous descriptions of leptin but suggest that variations in factors determining serum adiponectin levels observed between ethnicities could also been seen between populations from the same ethnicity

Angiotensin-converting-enzyme gene polymorphisms, smoking and chronic obstructive pulmonary disease

While tobacco smoking is the main risk factor for chronic obstructive pulmonary disease (COPD) only a fraction of smokers go on to develop the disease. We investigated the relationship between the insertion (I) – deletion (D) polymorphisms in the Angiotensin converting enzyme (ACE) gene and the risk of developing COPD in smokers by determining the distribution of the ACE genotypes (DD, ID and II) in 151 life-long male smokers. 74 of the smokers had developed COPD (62 ± 2 years; FEV1 44 ± 6 % reference) whereas the rest retained normal lung function (56 ± 2 yrs; FEV1 95 ± 3 % reference). In addition, we genotyped 159 males recruited randomly from the general population. The prevalence of the DD genotype was highest (p = 0.01) in the smokers that developed COPD and its presence was associated with a 2-fold increase in the risk for COPD (OR 2.2; IC95% 1.1 to 5.5). Surprisingly, the 151 individuals in the smoking population did not demonstrate Hardy-Weinberg equilibrium unlike the 159 recruited from the general population. Our results suggest that ACE polymorphisms are associated with both the smoking history of an individual and their risk of developing COPD