THE CLASSICAL VOLTERRA OPERATOR AND SCHUR’S THEOREM

In this work we provide a counterexample for Schur’s Theorem on triangularmatrices on infinite dimensional spaces. Moreover, the counterexample provided is acompact quasinilpotent operator. Indeed, the result neither depends on the index ofthe chosen basis for the matrix representations nor on the upper-lower choice for thetriangular matrix. As a consequence, we see the optimality of a result by Halmos onmatrix representations of operators. Namely, Halmos proved that each operator canbe represented by a matrix with finite columns. Finally, we ‘answer’ a philosophicalquestion posed by J. B. Conway in [1, p.213]

Editorial: Metabolic pathways and consequences of malnutrition in children and adolescents

Editorial on the Research Topic Metabolic pathways and consequences of malnutrition in children and adolescents

Similar improvements in 5-km performance and maximal oxygen uptake with submaximal and maximal 10-20-30 training in runners, but increase in muscle oxidative phosphorylation occur only with maximal effort training

Objective: The aim of the present study was to examine whether 10-20-30 training (consecutive 1-min intervals consisting of 30 s at low-speed, 20 s at moderate-speed, and 10 s at high-speed), performed with submaximal effort during the 10-s high-speed runs, would lead to improved performance as well as increased maximum oxygen uptake (VO2-max) and muscle oxidative phosphorylation (OXPHOS). In addition, to examine to what extent the effects would compare to 10-20-30 running conducted with maximal effort. Design: Nineteen males were randomly assigned to 10-20-30 running performed with either submaximal (SUBMAX; n = 11) or maximal (MAX; n = 8) effort, which was conducted three times/week for 6 weeks (intervention; INT). Before and after INT, subjects completed a 5-km running test and a VO2-max test, and a biopsy was obtained from m. vastus lateralis. Results: After compared to before INT, SUBMAX and MAX improved (p < 0.05) 5-km performance by 3.0% (20.8 ± 0.4 (means±SE) vs. 21.5 ± 0.4 min) and 2.3% (21.2 ± 0.4 vs. 21.6 ± 0.4 min), respectively, and VO2-max was ~7% higher (p < 0.01) in both SUBMAX (57.0 ± 1.3 vs. 53.5 ± 1.1 mL/min/kg) and MAX (57.8 ± 1.2 vs. 53.7 ± 0.9 mL/min/kg), with no difference in the changes between groups. In SUBMAX, muscle OXPHOS was unchanged, whereas in MAX, muscle OXPHOS subunits (I-IV) and total OXPHOS (5.5 ± 0.3 vs 4.7 ± 0.3 A.U.) were 9%–29% higher (p < 0.05) after compared to before INT. Conclusion: Conducting 10-20-30 training with a non-maximal effort during the 10-s high-speed runs is as efficient in improving 5-km performance and VO2-max as maximal effort exercise, whereas increase in muscle OXPHOS occur only when the 10-s high-speed runs are performed with maximal effort.Danish Ministry of Culture and Team Danmark, the Danish elite sports organization

Nutritional Ergogenic Aids in Combat Sports: A Systematic Review and Meta-Analysis

Nutritional ergogenic aids (NEAs) are substances included within the group of sports supplements. Although they are widely consumed by athletes, evidence-based analysis is required to support training outcomes or competitive performance in specific disciplines. Combat sports have a predominant use of anaerobic metabolism as a source of energy, reaching peak exertion or sustained effort for very short periods of time. In this context, the use of certain NEAs could help athletes to improve their performance in those specific combat skills (i.e., the number of attacks, throws and hits; jump height; and grip strength, among others) as well as in general physical aspects (time to exhaustion [TTE], power, fatigue perception, heart rate, use of anaerobic metabolism, etc.). Medline/PubMed, Scopus and EBSCO were searched from their inception to May 2022 for randomised controlled trials (RCTs). Out of 677 articles found, 55 met the predefined inclusion criteria. Among all the studied NEAs, caffeine (5–10 mg/kg) showed strong evidence for its use in combat sports to enhance the use of glycolytic pathways for energy production during high-intensity actions due to a greater production of and tolerance to blood lactate levels. In this regard, abilities including the number of attacks, reaction time, handgrip strength, power and TTE, among others, were improved. Buffering supplements such as sodium bicarbonate, sodium citrate and beta-alanine may have a promising role in high and intermittent exertion during combat, but more studies are needed in grappling combat sports to confirm their efficacy during sustained isometric exertion. Other NEAs, including creatine, beetroot juice or glycerol, need further investigation to strengthen the evidence for performance enhancement in combat sports. Caffeine is the only NEA that has shown strong evidence for performance enhancement in combat sports

Efecto de la saciedad en la composición corporal y en la ansiedad en atletas universitarios: un estudio de cohortes

Background: Satiety is a determining parameter in nutrient intake control, which in the long run impacts on body weight. Many athletes need strict control on their weight to achieve their aims of the season. Aim: The aim of this study is to analyse the influence of satiety on body weight control and competitive anxiety in a university athletes population when they ingest ad libitum foods (SATIETY), or follow a nutritional dietary programme (DIET). Methods: The present study was a cohort study, in which 40 male university athletes participated. The assessment of body weight was done using the ISAK recommendations in its limited profile. The study of competitive anxiety was evaluated using the CSAI-2 questionnaire. Results: Results showed that the DIET group decreased significantly their body weight compared to the SATIETY group, they also obtained a significant improvement in their body composition, reducing fat mass. The SATIETY group didn’t show significant reductions in fat mass. This group showed higher competitive anxiety values than the DIET group. Conclusions: The university athletes that follow an adapted and individualized diet seem to show improvements in their body composition and anxiety compared to those with ad libitum food.Introducción: la saciedad en un parámetro determinante en el control de la ingesta y que afecta, por tanto, al peso corporal. Muchos atletas necesitan un control estricto del peso para alcanzar sus objetivos deportivos de la temporada. Objetivo: analizar la influencia de la saciedad en el control del peso y en la ansiedad competitiva en atletas universitarios cuando siguen una dieta libre (SATIETY) o un programa de seguimiento nutricional (DIET). Métodos: se trató de una cohorte de 40 atletas universitarios varones. La valoración del peso se realizó de acuerdo a las recomendaciones ISAK, mientras que la ansiedad se evaluó con el cuestionario CSAI-2. Resultados: los resultaron mostraron que el grupo DIET disminuyó significativamente en el peso, comparado con el grupo SATIETY. También se obtuvo una disminución en la masa grasa en el grupo DIET, que no se obtuvo en el SATIETY. Este último grupo obtuvo puntuaciones de ansiedad competitiva superiores. Conclusiones: los atletas universitarios que siguen una dieta adaptada individualizada parecen mejorar su composición corporal y sus niveles de ansiedad cuando se comparan con los que siguen una dieta libre

Validity of a four-factor modelunderlying the physical fitness in adults with intellectual disabilities a confirmatory factor analysis

Purpose: To use confirmatory factor analysis to test whether a four factor might explain the clustering of the components of the physical fitness in adults with intellectual disabilities (FID). Relevance: Individuals with intellectual disabilities (ID) are significantly weaker than individuals without ID at all stages of life. These subjects might be particularly susceptible to loss of basic function because of poor physical fitness. Participants: We studied 267 adults with intellectual disability of the Spanish Special Olympics Games. Methods: The four-factor model included: the flexibility, the strength, the balance and the cardiorespiratory endurance with 9 variables of the fitness assessment. Analysis: The construct validity of the model was assessed through the factor loadings, interpreted as the correlation between the variables in the model and their underlying factor, which is the FID construct. Results: Factor loading were 0,55 for the passive knee extension, o,52 for Functional shoulder rotation, −0.71 for the timed-stand test, 0.58 for the grip test, 0.75 the single leg stance with eyes open, 0.69 single leg stance with eyes closed, 0.72 for the resting heart rate, 0.56 for the two-minute step test (2MST) 0,97 for 2 minutes after finish 2MST. The four-factor model also showed a good fit to the data, as indicated by a high comparative fit index (CFI=0,93) and a low standardized root mean square residual (SRMR=0,072) Conclusions: A four underlying factor has shown acceptable validity to represent FID Implications: The new model of FID can offer understanding better these construct in this special populationUniversidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Effects of lacto-vegetarian diet and stabilization core exercises on body composition and pain in women with fibromyalgia: randomized controlled trial

Introducción: la fibromialgia es una enfermedad de origen desconocido caracterizada por dolor muscular crónico. La falta de conocimientos sobre esta enfermedad es una de las principales causas por las que resulta complejo realizar un diagnóstico y tratamiento adecuados. Objetivo: el objetivo principal de este estudio fue conocer la eficacia de un tratamiento de fisioterapia combinado con una intervención dietético-nutricional lacto-vegetariana, sobre el dolor bajo de espalda y la composición corporal en mujeres con fibromialgia. Métodos: en el estudio participaron 21 mujeres, que fueron divididas aleatoriamente en 3 grupos: A (ejercicios estabilización core + dieta lacto-vegetariana), B (placebo + dieta lacto-vegetariana) y C (control). La intervención tuvo una duración de 4 semanas y se realizaron evaluaciones del dolor (escala EVA), y de la composición corporal (bioimpedancia), al inicio y final de la intervención. Resultados: el grupo A mostró cambios significativos en la reducción del dolor y la composición corporal al final de la intervención, aumentando la masa muscular y disminuyendo la masa grasa. Además, este grupo mejoró significativamente los resultados en comparación con los grupos B y C. Las correlaciones realizadas mostraron una relación entre la masa muscular y la disminución del dolor referido al final del estudio en las pacientes del grupo A. Conclusiones: un programa de intervención de 4 semanas de duración en el que se combina ejercicios de estabilización de core más dieta lacto-vegetariana en pacientes con fibromialgia que presentan dolor bajo de espalda contribuye a la reducción del dolor y la mejora de la composición corporal.Background: fibromyalgia is a disease of unknown origin characterized by chronic muscular pain. The lack of knowledge about this disease is one of the main causes that makes complex to make a diagnosis and an appropriate treatment. Objective: the main objective of this study was to know the efficacy of a physiotherapy treatment combined with a lacto-vegetarian dietary-nutritional intervention, on low back pain and body composition in women with fibromyalgia. Methods: twenty-one women were randomly divided into three groups: A (core stabilization exercises + lacto-vegetarian diet), B (placebo + lacto-vegetarian diet) and C (control). The intervention lasted 4 weeks. Pain assessments (EVA scale) and body composition (bioimpedance) were performed at the beginning and at the end of the intervention. Results: group A showed significant changes in pain reduction and body composition at the end of the intervention, increasing muscle mass and decreasing fat mass. In addition, this group significantly improved outcomes compared to groups B and C. The correlations showed a relationship between muscle mass and pain reduction referred to at the end of the study in patients in group A. Conclusions: four-week intervention program combining core stabilization exercises plus lacto-vegetarian diet in patients with fibromyalgia who have low back pain contributes to pain reduction and improved body composition

Short-term adaptations following Complex Training in team-sports: A meta-analysis

Objective. The purpose of this meta-analysis was to study the short-term adaptations on sprint and vertical jump (VJ) performance following Complex Training (CT) in team-sports. CT is a resistance training method aimed at developing both strength and power, which has a direct effect on sprint and VJ. It consists on alternating heavy resistance training exercises with plyometric/power ones, set for set, on the same workout. Methods. A search of electronic databases up to July 2016 (PubMed-MEDLINE, SPORTDiscus, Web of Knowledge) was conducted. Inclusion criteria: 1) at least one CT intervention group; 2) training protocols ≥4-wks; 3) sample of team-sport players; 4) sprint or VJ as an outcome variable. Effect sizes (ES) of each intervention were calculated and subgroup analyses were performed. Results. A total of 9 studies (13 CT groups) met the inclusion criteria. Medium effect sizes (ES) (ES = 0.73) were obtained for pre-post improvements in sprint, and small (ES = 0.41) in VJ, following CT. Experimental-groups presented better post-intervention sprint (ES = 1.01) and VJ (ES = 0.63) performance than control-groups. Sprint. Large ESs were exhibited in younger athletes (12 total sessions (ES = 0.74). VJ. Large ESs in programs with >12 total sessions (ES = 0.81). Medium ESs obtained for under-Division I individuals (ES = 0.56); protocols with intracomplex rest intervals ≥2 min (ES = 0.55); conditioning activities with intensities ≤85% 1RM (ES = 0.64); basketball/volleyball players (ES = 0.55). Small ESs were found for younger athletes (ES = 0.42); interventions ≥6 weeks (ES = 0.45). Conclusions. CT interventions have positive medium effects on sprint performance and small effects on VJ in team-sport athletes. This training method is a suitable option to include in the season planning

Sarcopenia: Molecular Pathways and Potential Targets for Intervention

Aging is associated with sarcopenia. The loss of strength results in decreased muscle mass and motor function. This process accelerates the progressive muscle deterioration observed in older adults, favoring the presence of debilitating pathologies. In addition, sarcopenia leads to a decrease in quality of life, significantly affecting self-sufficiency. Altogether, these results in an increase in economic resources from the National Health Systems devoted to mitigating this problem in the elderly, particularly in developed countries. Different etiological determinants are involved in the progression of the disease, including: neurological factors, endocrine alterations, as well as nutritional and lifestyle changes related to the adoption of more sedentary habits. Molecular and cellular mechanisms have not been clearly characterized, resulting in the absence of an effective treatment for sarcopenia. Nevertheless, physical activity seems to be the sole strategy to delay sarcopenia and its symptoms. The present review intends to bring together the data explaining how physical activity modulates at a molecular and cellular level all factors that predispose or favor the progression of this deteriorating pathology.This study was supported by ISABIAL (grant number 190290) and the Official Funding Agency for Biomedical Research of the Spanish Government, Institute of Health Carlos III (ISCIII) through CIBEROBN (CB12/03/30038), which is co-funded by the European Regional Development Fund