Activitats miscel·lània com a eina metodològica per a l'assoliment de competències

Podeu consultar la Vuitena trobada de professorat de Ciències de la Salut completa a: http://hdl.handle.net/2445/66524L’experiència que es posa de manifest en aquesta comunicació és el resultat d’aplicar a l’assignatura de Nutrició i Dietètica (6 ECTS) del Grau en Ciències de l’Activitat Física i l’Esport impartida a l’INEFC-UB, una sèrie d’activitats complementàries i voluntàries, anomenades Miscel·lània. Aquestes activitats tenen l’objectiu d’ajudar a l’autoformació de l’alumnat en les competències de recerca d’informació i en l’esperit crític en front de noves informacions i coneixements. A través de la lectura d’articles de divulgació, conferències i participació en fòrums, es pretén que l’alumnat vegi l’aplicació dels coneixements adquirits, en la resolució de qüestions més properes als objectius professionals que espera obtenir al finalitzar el grau. Tant el seguiment com l’avaluació d’aquestes activitats..

Integrating external and internal load for monitoring fitness and fatigue status in standard microcycles in elite rink hockey

The aims of this study were 3-fold: firstly, to present an integrative approach to external and internal load dynamics for monitoring fitness and fatigue status of specific in-court rink hockey training sessions in a standard microcycle; secondly, to assess the differences between training sessions and matches; the third and final aim was to assess the association between external and internal load metrics. The external load, using a local positioning system, and internal load, using the declared rate of perceived exertion, were measured during 23 in-season microcycles for nine top-level players. Training load data were analysed with regard to the number of days before or after a match [match day (MD) minus or plus]. In relation to the first aim, internal and external load metrics merged into a single integrated system using pooled data z-scores provided an invisible monitoring tool that places the players in the fitness-fatigue continuum throughout the different microcycle sessions. In this regard, MD-4 and MD-1 sessions tend to place, with a low dispersion, the players in a 'low external and internal load' zone. On the contrary, in MD-3 and MD-2 sessions, as well as in MD, in which higher loads were recorded, most of the players were within a 'high external and internal load' zone with a tendency towards dispersion towards the fitness or fatigue zones. Finally, and with regard to the second and third aims, an inverted 'U-shape' load dynamic related to the specific goals of each training session was the main finding in terms of comparison between MD; a load peak between MD-3 and MD-2 sessions and a significant decrease in all the load variables in MD-1 sessions were found; and high-to-low correlations were found between external and internal load metrics. This study presents an integrative approach to the external and internal load of players for monitoring fitness and fatigue status during a standard microcycle in rink hockey that might provide team sport staff members with a deeper understanding of load distribution in the microcycle in relation to the matc

A novel role of neuregulin in skeletal muscle. Neuregulin stimulates glucose uptake, glucose transporter translocation and transporter expression in muscle cells

Neuregulins regulate the expression of acetylcholine receptor genes and induce development of the neuromuscular junction in muscle. In studying whether neuregulins regulate glucose uptake in muscle, we analyzed the effect of a recombinant neuregulin, (r)heregulin-beta1-(177-244) (HRG), on L6E9 muscle cells, which express the neuregulin receptors ErbB2 and ErbB3. L6E9 responded acutely to HRG by a time- and concentration-dependent stimulation of 2-deoxyglucose uptake. HRG-induced stimulation of glucose transport was additive to the effect of insulin. The acute stimulation of the glucose transport induced by HRG was a consequence of the translocation of GLUT4, GLUT1, and GLUT3 glucose carriers to the cell surface. The effect of HRG on glucose transport was dependent on phosphatidylinositol 3-kinase activity. HRG also stimulated glucose transport in the incubated soleus muscle and was additive to the effect of insulin. Chronic exposure of L6E9 cells to HRG potentiated myogenic differentiation, and under these conditions, glucose transport was also stimulated. The activation of glucose transport after chronic HRG exposure was due to enhanced cell content of GLUT1 and GLUT3 and to increased abundance of these carriers at the plasma membrane. However, under these conditions, GLUT4 expression was markedly down-regulated. Muscle denervation is associated with GLUT1 induction and GLUT4 repression. In this connection, muscle denervation caused a marked increase in the content of ErbB2 and ErbB3 receptors, which occurred in the absence of alterations in neuregulin mRNA levels. This fact suggests that neuregulins regulate glucose transporter expression in denervated muscle. We conclude that neuregulins regulate glucose uptake in L6E9 muscle cells by mechanisms involving the recruitment of glucose transporters to the cell surface and modulation of their expression. Neuregulins may also participate in the adaptations in glucose transport that take place in the muscle fiber after denervation

Metabolic adaptations in skeletal muscle after 84 days of bed rest with and without concurrent flywheel resistance exercise

As metabolic changes in human skeletal muscle after long-term (simulated) spaceflight are not well understood, this study examined the effects of long-term microgravity, with and without concurrent resistance exercise, on skeletal muscle oxidative and glycolytic capacity. Twenty-one men were subjected to 84 days head-down tilt bed rest with (BRE; n 9) or without (BR; n 12) concurrent flywheel resistance exercise. Activity and gene expression of glycogen synthase, glycogen phosphorylase (GPh), hexokinase, phosphofructokinase-1 (PFK-1), and citrate synthase (CS), as well as gene expression of succinate dehydrogenase (SDH), vascular endothelial growth factor (VEFG), peroxisome proliferator-activated receptor gamma coactivator- 1 (PGC-1 ), and myostatin, were analyzed in samples from m.vastus lateralis collected before and after bed rest. Activity and gene expression of enzymes controlling oxidative metabolism (CS, SDH) decreased in BR but were partially maintained in BRE. Activity of enzymes regulating anaerobic glycolysis (GPh, PFK-1) was unchanged in BR. Resistance exercise increased the activity of GPh. PGC-1 and VEGF expression decreased in both BR and BRE. Myostatin increased in BR but decreased in BRE after bed rest. The analyses of these unique samples indicate that long-term microgravity induces marked alterations in the oxidative, but not the glycolytic, energy system. The proposed flywheel resistance exercise was effective in counteracting some of the metabolic alterations triggered by 84-day bed rest. Given the disparity between gene expression vs. enzyme activity in several key metabolic markers, posttranscriptional mechanisms should be explored to fully evaluate metabolic adaptations to long-term microgravity with/without exercise countermeasures in human skeletal muscle

Early functional and morphological muscle adaptations during short-term inertial-squat training

Purpose: To assess early changes in muscle function and hypertrophy, measured as increases in muscle cross-sectional areas (CSAs) and total volume, over a 4 weeks inertial resistance training (RT) program. Methods: Ten young RT-naive volunteers (age 23.4 4.1 years) underwent 10 training sessions (2-3 per week) consisting of five sets of 10 flywheel squats (moment of inertia 900 kg cm2). Magnetic resonance imaging (MRI) scans of both thighs were performed before (PRE), and after 2 (IN) and 4 (POST) weeks of training to compute individual muscle volumes and regional CSAs. Scans were performed after 96 h of recovery after training sessions, to avoid any influence of acute muscle swelling. PRE and POST regional muscle activation was assessed using muscle functional MRI (mfMRI) scans. Concentric (CON) and eccentric (ECC) squat force and power, as well as maximal voluntary isometric contraction force (MVIC) of knee extensors and flexors, were measured in every training session. Results: Significant quadriceps hypertrophy was detected during (IN: 5.5% 1.9%) and after (POST: 8.6% 3.6%) the training program. Increases in squat force (CON: 32% 15%, ECC: 31 15%) and power (CON: 51% 30%, ECC: 48% 27%) were observed over the training program. Knee extensor MVIC significantly increased 28% 17% after training, but no changes were seen in knee flexor MVIC. No correlation was found between regional muscular activation in the first session and the % of increase in regional CSAs (r = -0.043, P = 0.164). Conclusion: This study reports the earliest onset of whole-muscle hypertrophy documented to date. The process initiates early and continues in response to RT, contributing to initial increases in force. The results call into question the reliability of mfMRI as a tool for predicting the potential hypertrophic effects of a given strengthening exercise

The effects of high-velocity hamstring muscle training on injury prevention in football players

Background: Explosive and fast body movements, sprints, jumps and quick changes of direction, which are characteristic of the football training, place considerable strain on the hamstring muscles. Due to the high occurrence of hamstring injuries, new preventive strategies are required that focus on high-velocity training. The purpose was to assess the effectiveness of high-velocity elastic-band training in reducing the occurrence of hamstring injuries in football players.Methods: Male football players from 15 teams (n = 319) playing in national competitions participated in this study. The players were involved in a 5-week exercise period in either the intervention group (INT) or the control group (CON), with a follow-up period of ∼4 months where hamstring injuries and exposure time were recorded. The INT group had two to three sessions per week of elastic-band training with low-load, high-velocity leg curls while lying prone; the CON group performed self-paced football-specific drills.Results: The incidence rate of hamstring injuries was 6.5% in the INT group (8 out of 123 players) and 9.2% in the CON group (18 out of 196 players). Although the INT group showed almost 1/3 reduction in hamstring injury incidence compared to the CON group, the difference was not statistically significant (p > 0.05). Moreover, no differences (p > 0.05, odds ratio [OR] = trivial-to-small) in distribution between the groups were found in hamstring injury characteristics (leg dominance and mechanism) except for the distribution of injuries that occurred during matches or training (p = 0.036; OR = 6.14, moderate).Conclusion: The program of high-velocity elastic-band training did not prove to be effective in preventing hamstring muscle injuries in football players despite displaying some positive indications that could be considering when creating injury prevention programs

Adaptabilitat del múscul esquelètic a l'exercici de curta durada: metabolisme energètic

[cat] 1) INTRODUCCIÓ: Una característica fonamental del múscul esquelètic és la gran diversitat que presenta. No hi ha cap múscul idèntic a un altre, músculs homòlegs de diferents espècies i fins i tot dins del mateix animal presenten diferències en la composició fibril.lar. Aquesta heterogeneïtat reflecteix l'alt grau d'especialització i a més, és la base de la seva plasticitat funcional.El múscul esquelètic té una gran capacitat d'adaptació. És d'esperar que músculs que estan predominantment involucrats en el manteniment de la posició corporal siguin diferents dels que intervenen en moviments espontanis. Així, músculs que podem dir que estan tot el dia en contracció (músculs posturals), reben molta quantitat d'estímuls i són músculs de contracció lenta que es caracteritzen per l'alta capacitat oxidativa i estan formats principalment per fibres de tipus I. (Per exemple el múscul "Soleus", en el conill).En canvi els músculs que s'utilitzen de forma espontània, només reben impulsos de tant en tant. Són músculs de contracció ràpida i es caracteritzen per la gran capacitat glucolítica, formats majoritàriament per fibres de tipus II (Per exemple el múscul "Tibialis anterior" en el conill).Les fibres musculars estan en un estat dinàmic, la qual cosa explica l'habilitat que tenen de respondre específicament, amb canvis en l'expressió fenotípica, a una demanda funcional diferent.Tant amb l'exercici com amb l'estimulació elèctrica es provoca un augment de l'activitat contràctil. Així, les característiques fenotípiques dels músculs que intervinguin a l'exercici o que siguin sotmesos a l'estimulaci6 elèctrica es modificaran com a resposta adaptativa a la nova demanda funcional.Tots els canvis que es donen en aquesta resposta adaptativa ho fan de forma seqüencial i ordenada, per tant és d'esperar que hi hagi algun tipus de senyal que els iniciï i que es produeixi a les primeres fases del procés adaptatiu. Aquesta hipòtesi ens ha portat a estudiar les modificacions de les concentracions musculars de diferents metabòlits durant períodes curts d'activitat contràctil, amb l'objectiu d'estudiar quins metabòlits podrien actuar com a senyal iniciador dels canvis que es donen en la transformació del múscul esquelètic i el comportament d'aquest durant l'exercici.2) MÈTODESPer poder assolir l'objectiu proposat es varen utilitzar diferents models experimentals. Una part d'aquests es realitzà amb conills ("Oricfolagus cuniculus"). El model consistí a sotmetre el múscul "Tibialis anterior" (TA) a una estimulació crònica a baixa freqüència (l0 Hz) durant un període aproximat de dos mesos.A tots els animals la pota contralateral va ser utilitzada com a control, implantant-hi els elèctrodes però sense estimular-la.Es van obtenir mostres als temps d'estimulaci6: 15 minuts, 1, 3, 12 i 24 hores; 2, 4, 10 i 50 dies. Per cada punt es van utilitzar entre 3 i 4 animals.Després de tenir ben caracteritzats els canvis metabòlics, durant el procés d'estimulació, ens centràrem en una altra situació experimental. Una de les potes posteriors es sotmetia a un període de 24 hores d'estimulació contínua a 10 Hz (pota entrenada), mentre que la contralateral (pota control) es mantenia en repòs. Quan els músculs estaven aïllats aplicàvem un estímul de 10 Hz a les dues potes i extrèiem el TA a diferents temps 0, 1, 3, 10 i 300 segons.Posteriorment ens vàrem plantejar una sèrie d'experiments en humans. Els voluntaris varen ser dividits en dos grups que es diferenciaven en la durada del període d'entrenament i en el tipus d'exercici a realitzar. L'entrenament en els dos grups consistí a efectuar un esforç a un 65% de la VO(2) màx durant dues hores, el període va ser de tres dies en un dels grups i de sis dies a l'altre.L'exercici després de tres dies d'entrenament es caracteritzava principalment pel fet que la intensitat de l'esforç es mantenia constant a un 65% de V02 màx. S'obtenien biòpsies al repòs, als 3 i 15 minuts i a la fatiga abans i després de l'entrenament.En canvi, l'exercici després de sis dies d'entrenament es caracteritzava pel fet que cada vint minuts s'incrementava la intensitat de l'esforç. L'augment va començar en un 60%, després va continuar a un 79% i finalment a un 90% de la VO(2) màx. S'obtenien biòpsies al repòs i cada vint minuts coincidint amb el canvi d'intensitat i a la fatiga.3) RESULTATS I CONCLUSIONSDurant el període de 50 dies d'estimulació s'observà un increment significatiu i transitori de Glucosa l ,6-P(2) i de Fructosa 2,6-P(2) a les 24h d'iniciar-se l'estimulació. Aquesta pujada podria suggerir una activació de la via glucolítica aeròbica a través de l'enzim fosfofructoquinasa, ja que ambdós metabòlits estan descrits com a uns dels més importants efectors al.lostèrics d'aquest enzim.Degut als resultats anteriors, ens plantejàrem estudiar quin efecte podria tenir l'exercici en unes condicions en què els dos sucres anteriorment esmentats estaven per sobre dels nivells normals. En el múscul estimulat 24 hores a 10 Hz, quan és sotmès a un exercici, es produeix un estalvi de glicogen degut a una major velocitat de resíntesi, l'activitat glicogen sintasa després del període d'estimulaci6 ha augmentat significativament, o a que s'utilitza un altre substrat energètic. L'augment de l'activitat hexoquinasa ens fa pensar que la glucosa podria ser aquest nou substrat. A més, l'acúmul de sucres bisfosforilats activa la PFK, mentre que la no aparició de lactat suggereix que la glucòlisi aeròbica està activada.L'efecte de l'entrenament en humans, ja sigui de tres o de sis dies, millora la resposta a l'esforç ja que tots els atletes han augmentat el temps de durada de l'exercici. Després de l'entrenament s'observa un menor acúmul de lactat intramuscular i sanguini i un estalvi de glicogen durant els dos tipus d'exercici. A més, les variacions dels metabòlits intermediaris durant l'exercici després de l'entrenament no s6n tan accentuades.Amb els resultats que hem obtingut podem concloure que l'exercici muscular de curta durada aplicat tant en forma d'estimulació elèctrica com d'entrenament, produeix una adaptación metabòlica que consisteix en un estalvi de creatinafosfat i de glicogen, i en una disminució de la producció de lactat. Aquesta situació podria ser compatible amb una adaptació a l'augment de la utilització de glucosa sanguínia i de la capacitat de la glucòlisi aeròbica. Les modificacions en les concentracions dels sucres bisfosforilats GJu 1,6-P(2) i Fru 2,6-P(2) durant les fases d'entrenament i/lo exercici jugarien un paper fonamental en el manteniment de la capacitat glucolítica.[eng] This study investigates early adaptative responses of skeletal muscle to increased contractile activity.Two experimental approaches have been used. One of them consists of putting rabbit's tibialis anterior muscle under chronic low-frequency stimulation (10 Hz). The other one was done by untrained male subjects who had carried out an aerobic short term training (3 to 6 days).Changes in metabolite levels and activities of regulatory enzymes of carbohydrate metabolism were investigated.Most of the metabolic enzymes investigated (creatine kinase, glycogen phosphorylase, phosphofructokinase l, pyruvate kinase, lactate dehydrogenase) showed no differences in total cellular activities between control and l-day-prestimulated TA rabbit muscles. However, significant increases were found in the 24h-stimulated muscle for glycogen synthase (1.5-fold), hexoquinase (3-fold) and phosphofructokinase 2 (3.5-fold). These metabolic enzymes have not been studied in human samples, except glycogen phosphorylase and glycogen synthase which modify their active forms in response to exercise.As expected, muscular contraction resulted in a pronounced reduction in PCr and glycogen concentration in non pre-stimulated or non trained muscle, while lactate concentration increased severa1 times. Intermediate metabolites modify their concentration in different ways.Any changes in metabolites concentration after pre-stimulation or training haven 't been observed during exercise.Metabolic concentration of glucose 1,6-P(2) and fructose 2,6-P(2) in control muscle showed a transient elevation, while these metabolites in pre-stimulated muscle were permanently elevated.In humans, only fructose 2,6-P(2) was affected by exercise and training. During exercise, prior to training, fructose 2,6-P(2) was reduced. The effect of training was to eliminate the exercise reduced change in this bisphosphate. Although glucose J,6-P(2) appeared to be persistently reduced with training, the magnitude was not sufficient to result in a significant change.As a consequence of a short term training, by electrical stimulation or exercise, skeletal muscle adapts its metabolism. Adaptative metabolic changes consist of glycogen and PCr sparing effect and the use of glucose as the main fuel through aerobic glycolisis

Activitats miscel·lània com a eina metodològica per a l'assoliment de competències

L’experiència que es posa de manifest en aquesta comunicació és el resultat d’aplicar al’assignatura de Nutrició i Dietètica (6 ECTS) del Grau en Ciències de l’Activitat Física il’Esport impartida a l’INEFC-UB, una sèrie d’activitats complementàries i voluntàries,anomenades Miscel·lània. Aquestes activitats tenen l’objectiu d’ajudar a l’autoformacióde l’alumnat en les competències de recerca d’informació i en l’esperit crític en front denoves informacions i coneixements.A través de la lectura d’articles de divulgació, conferències i participació en fòrums, espretén que l’alumnat vegi l’aplicació dels coneixements adquirits, en la resolució deqüestions més properes als objectius professionals que espera obtenir al finalitzar elgrau.Tant el seguiment com l’avaluació d’aquestes activitats...Podeu consultar la Vuitena trobada de professorat de Ciències de la Salut completa a: http://hdl.handle.net/2445/6652

Assessment of muscle fiber adaptation in footballers using a new ELISA assay of myosin isoforms

BACKGROUND: To measure the impact of training models on injury incidence, data of health and performance were integrated to study fiber adaptation during a competitive season. We studied football players over a season, analyzing hours of exposure to sport by serum changes in fast and slow myosin, creatine kinase and lactate dehydrogenase. METHODS: A new assay was developed to measure the myosin isoforms in 49 non-sporting volunteers and in 27 professional football players. RESULTS: Myosin isoforms in volunteers with mean ages of 30±8 were 1553 µg/L fast and 1284 µg/L slow; in the group with of 56±7 were 1426 µg/L fast and 1046 µg/L slow. Slow myosin was significantly lower in older subjects (-18%). Samples from the players in preseason had lower mean scores for fast myosin (1123 µg/L) and higher for slow myosin (2072 µg/L) than reference volunteers. During the season, myosins reached the maximum with the maximum load (1537 µg/L fast, 2195 µg/L slow but decreased and adapted to the high level of demand (425 µg/L fast, 1342 µg/L slow). CK and LDH were maximal at the pre-season (227 U/L, 333 U/L) while myosin levels were maximal at the beginning of season (1537 µg/L, 2195 µg/L). CONCLUSIONS: Measuring serum myosin isoforms we identify the type and amount of damage caused by training and matches, making it a new control tool capable of advising training towards a minimum of blood slow myosin but controlling the fast fiber participating and be able to improve the performance of the players

Fibre-type-specific and Mitochondrial Biomarkers of Muscle Damage after Mountain Races

Consequences of running mountain races on muscle damage were investigated by analysing serum muscle enzymes and fibre-type-specific sarcomere proteins. We studied 10 trained amateur and 6 highly trained runners who ran a 35 km and 55 km mountain trail race (MTR), respectively. Levels of creatine kinase (CK), CK-MB isoform (CK-MB), sarcomeric mitochondrial CK (sMtCK), transaminases (AST and ALT), cardiac troponin I (cTnI) and fast (FM) and slow myosin (SM) isoforms, were assessed before, 1 h, 24 h and 48 h after the beginning of MTR. Significant SM increases were found at 24 h in the 55 km group. Levels of CK, CK-MB, AST and cTnI were significantly elevated in both groups following MTR, but in the 55 km group they tended to stabilize in at 48 h. Using pooled data, time-independent serum peaks of SM and CK-MB were significantly correlated. Moreover, concentration of sMtCK was significantly elevated at 1 and 24 h after the race in the 35 km group. Although training volume could confer protection on the mitochondria, the increase in serum CK-MB and SM in the 55 km group might be related to damage to the contractile apparatus type I fibres. Competing in long-distance MTRs might be related to deeper type I muscle fibre damage, even in highly trained individuals