L'esercizio fisico e l'elettro-stimolazione, strategie per contrastare il declino muscolare negli anziani.

Aging is a multifactorial process characterized by a constant and relentless decline of the structure, functions and consequently of muscle performance. One of the most obvious effects of aging in humans is the reduction of muscle mass, known as sarcopenia, which its development changes from individual to individual and which leads to reduced functional capacity (strength and resistance). Factors that contribute to the progress of this state are the decrease in both the number and size of myofibers and the amount of motoneurons that innervate the muscle fibers. Histological examinations carried out on the muscles of the elderly have demonstrated that denervation can contribute to atrophy and in addition the immobility and a life of sedentary accelerates the process, while the physical exercise protects in part from the effects of aging. Several studies have shown that regular exercise can prolong life expectancy and slow the effects of aging. At the molecular level calcium, and consequently the sarcoplasmic reticulum, plays a vital role in metabolic processes and structural adaptation of muscle through the activation of specific signaling pathways, in response to the type of stimulus received. This thesis focuses precisely on the benefits of physical exercise and whether these can be compared to those obtained by using a training protocol induced by electrostimulation. This could be useful in rehabilitation as exercise, especially in the elderly, it is not always applicable due to pathological and psychological problems. To determine the effects of aging and to correlate them with different lifestyles were studied the vastus lateralis muscle of three distinct groups of people (a) healthy sedentary seniors (b) healthy seniors with at least 30 years of regular exercise (c) young athletes. In these subjects muscle was characterized in relation to age and type of exercise to determine the effects of the voluntary exercise on the progress of sarcopenia during aging. From the data obtained through a series of functional tests was showed that the physically active seniors have characteristics most similar to young compared to the sedentary group of the same age. This is evidence of the fact that physically active seniors are a very powerful and performing group and it's possible to compare them to master athletes of the same age. Morphological analysis and histological studies have shown that the sedentary seniors present more denervated fibers than the other two groups, and that the physically active seniors have a significantly higher percentage of slow fibers, which, however, does not depend by the type of exercise done. Also it was detected in all three groups fibers that coexpress both myosin fast and slow and specifically the group of the sedentary seniors presents an higher percentage of coexpressing fibers than the other two groups. However, the serial sections of sedentary seniors showed the presence of coexpressing fibers of small dimensions and angled (denervated); therefore, this fact suggests that these fibers are slow fibers that coexpress fast myosin isoforms through default myogenic programs. On the contrary, the coexpressing muscle fibers in the physically active seniors are similar in size to the innervated "pure" muscle fibers, only fast or only slow. Based on the results obtained high levels of exercise appear to have beneficial effects on reinnervation of muscle fibers, resulting in conservation of muscle function, size and structure, thus delaying the functional decline and loss of independence which are common in older people. However, some pathological conditions and also some psychological situations, typical of the elderly, limit the ability to perform physical activity. It is therefore necessary to find an alternative to physical exercise that can maintain the beneficial properties, and above all that can be safe; these features can all be found in electrostimulation (ES). To determine whether this type of therapy can be effective in the elderly was also developed a study to define the effects of ES on aged human muscle, compared with a group of seniors the performed a voluntary strength training program (Leg Press, LP), for a period of nine weeks. In both groups of seniors, after the two workouts, it was noted an improvement in functional parameters, but only those who received the ES treatment presented an increase in the maximum isometric strength of the muscles vastus lateralis. Electrostimulation, unlike the LP, has kept unchanged the overall average size of the fibers, while there was an increment of the diameter and the number of fast fibers and a decrement of both parameters in slow type fibers. Of note, no sign of fibrosis and/or infiltration of inflammatory cells was detected in the treated muscles for both types of training. In addition, analysis of ultrastructure not viewed any alteration of muscle structure before and after treatment. After both treatments of ES and LP was recorded an activation of both the pathway of calcineurin/NFAT and calcium calmodulin dependent kinase (CaMKII), both key points for muscle remodeling. The quantitative evaluation of all the proteins that constitute the sarcoplasmic reticulum, shows a significant increment in protein levels of SERCA2 and Sarcalumenin and a decrement CASQ1 after ES, while after LP there were no significant changes. Analysis of quantitative PCR (qPCR) were made in order to clarify whether the level of Sarcalumenin SERCA2 and CASQ RNA are regulated by electrostimulation. None of the genes is up-regulated or down-regulated in a statistically significant way by the ES training, suggesting a regulation at the post transcriptional level. The vastus lateralis muscle is a mixture of different types of muscle fibers, consequently, the increase in the average quantity of SERCA2 and Sarcalumenin in total homogenates can be attributed to all the fibers or to a specific subpopulation (ie, slow twitch fibers or intermediate oxidative fibers IIA). To see if the increase in SERCA2 is against fast fibers in muscles treated by electrostimulation, it was developed a protocol immunofluorescence to assess the co-expression of myosin fast and SERCA2. After the ES the number of mixed fiber SERCA2/fast myosin is significantly increased, but was unchanged after LP. From the analysis of the intensity of fluorescence of fast myosin it was found that certain fast-twitch fibers exhibit a lower signal of fast myosin respectively in sections post ES and post LP and about 50% of such fibers were also positive SERCA2. From these observations we conclude that the mixed fibers for fast myosin/SERCA2 are a heterogeneous population and a part of these fibers probably expresses both isoforms of myosin. In conclusion, in this thesis were developed experimental protocols that have allowed to identify some favorable changes induced by physical exercise in the seniors. Moreover, thanks to the stabilization of the nuclear translocation of NFATc1 that remains even after several days last training session, it can be assign to the role of biomarker of inactivity (NFATc1 cytoplasmic) and activation "muscle" (myonuclear translocation), whether induced from ES or LP . Also for the first time it was shown that the ES is able to neuro-modulate with beneficial effects for the quality of the muscle, the mobility and the functional performances of the seniors. Thus the ES may be a viable approach to counter the problems and the atrophy of the muscle caused by the aging process both for healthy seniors and subjects to chronic health conditions, having as ultimate goal to improve lifestyle

Calsequestrins in skeletal and cardiac muscle from adult Danio rerio

Calsequestrin (Casq) is a high capacity, low affinity Ca2+-binding protein, critical for Ca2+-buffering in cardiac and skeletal muscle sarcoplasmic reticulum. All vertebrates have multiple genes encoding for different Casq isoforms. Increasing interest has been focused on mammalian and human Casq genes since mutations of both cardiac (Casq2) and skeletal muscle (Casq1) isoforms cause different, and sometime severe, human pathologies. Danio rerio (zebrafish) is a powerful model for studying function and mutations of human proteins. In this work, expression, biochemical properties cellular and sub-cellular localization of D. rerio native Casq isoforms are investigated. By quantitative PCR, three mRNAs were detected in skeletal muscle and heart with different abundances. Three zebrafish Casqs: Casq1a, Casq1b and Casq2 were identified by mass spectrometry (Data are available via ProteomeXchange with identifier PXD002455). Skeletal and cardiac zebrafish calsequestrins share properties with mammalian Casq1 and Casq2. Skeletal Casqs were found primarily, but not exclusively, at the sarcomere Z-line level where terminal cisternae of sarcoplasmic reticulum are located

Calsequestrins new calcium store markers of adult Zebrafish cerebellum and optic tectum

Calcium stores in neurons are heterogeneous in compartmentalization and molecular composition. Danio rerio (zebrafish) is an animal model with a simply folded cerebellum similar in cellular organization to that of mammals. The aim of the study was to identify new endoplasmic reticulum (ER) calcium store markers in zebrafish adult brain with emphasis on cerebellum and optic tectum. By quantitative polymerase chain reaction, we found three RNA transcripts coding for the intra-ER calcium binding protein calsequestrin: casq1a, casq1b, and casq2. In brain homogenates, two isoforms were detected by mass spectrometry and western blotting. Fractionation experiments of whole brain revealed that Casq1a and Casq2 were enriched in a heavy fraction containing ER microsomes and synaptic membranes. By in situ hybridization, we found the heterogeneous expression of casq1a and casq2 mRNA to be compatible with the cellular localization of calsequestrins investigated by immunofluorescence. Casq1 was expressed in neurogenic differentiation 1 expressing the granule cells of the cerebellum and the periventricular zone of the optic tectum. Casq2 was concentrated in parvalbumin expressing Purkinje cells. At a subcellular level, Casq1 was restricted to granular cell bodies, and Casq2 was localized in cell bodies, dendrites, and axons. Data are discussed in relation to the differential cellular and subcellular distribution of other cerebellum calcium store markers and are evaluated with respect to the putative relevance of calsequestrins in the neuron-specific functional activity

Electrical stimulation counteracts muscle atrophy associated with aging in humans

Functional and structural muscle decline is a major problem during aging. Our goal was to improve in old subjects quadriceps m. force and mobility functional performances (stair test, chair rise test, timed up and go test) with neuromuscular electrical stimulation (9 weeks, 2-3times/week, 20-30 minutes per session). Furthermore we performed histological and biological molecular analyses of vastus lateralis m. biopsies. Our findings demonstrate that electrical stimulation significantly improved mobility functional performancies and muscle histological characteristics and molecular markers

Long-term high-level exercise promotes muscle reinnervation with age.

The histologic features of aging muscle suggest that denervation contributes to atrophy, that immobility accelerates the process, and that routine exercise may protect against loss of motor units and muscle tissue. Here, we compared muscle biopsies from sedentary and physically active seniors and found that seniors with a long history of high-level recreational activity up to the time of muscle biopsy had 1) lower loss of muscle strength versus young men (32% loss in physically active vs 51% loss in sedentary seniors); 2) fewer small angulated (denervated) myofibers; 3) a higher percentage of fiber-type groups (reinnervated muscle fibers) that were almost exclusive of the slow type; and 4) sparse normal-size muscle fibers coexpressing fast and slow myosin heavy chains, which is not compatible with exercise-driven muscle-type transformation. The biopsies from the old physically active seniors varied from sparse fiber-type groupings to almost fully transformed muscle, suggesting that coexpressing fibers appear to fill gaps. Altogether, the data show that long-term physical activity promotes reinnervation of muscle fibers and suggest that decades of high-level exercise allow the body to adapt to age-related denervation by saving otherwise lost muscle fibers through selective recruitment to slow motor units. These effects on size and structure of myofibers may delay functional decline in late aging

L'esercizio fisico e l'elettro-stimolazione, strategie per contrastare il declino muscolare negli anziani.

Aging is a multifactorial process characterized by a constant and relentless decline of the structure, functions and consequently of muscle performance. One of the most obvious effects of aging in humans is the reduction of muscle mass, known as sarcopenia, which its development changes from individual to individual and which leads to reduced functional capacity (strength and resistance). Factors that contribute to the progress of this state are the decrease in both the number and size of myofibers and the amount of motoneurons that innervate the muscle fibers. Histological examinations carried out on the muscles of the elderly have demonstrated that denervation can contribute to atrophy and in addition the immobility and a life of sedentary accelerates the process, while the physical exercise protects in part from the effects of aging. Several studies have shown that regular exercise can prolong life expectancy and slow the effects of aging. At the molecular level calcium, and consequently the sarcoplasmic reticulum, plays a vital role in metabolic processes and structural adaptation of muscle through the activation of specific signaling pathways, in response to the type of stimulus received. This thesis focuses precisely on the benefits of physical exercise and whether these can be compared to those obtained by using a training protocol induced by electrostimulation. This could be useful in rehabilitation as exercise, especially in the elderly, it is not always applicable due to pathological and psychological problems. To determine the effects of aging and to correlate them with different lifestyles were studied the vastus lateralis muscle of three distinct groups of people (a) healthy sedentary seniors (b) healthy seniors with at least 30 years of regular exercise (c) young athletes. In these subjects muscle was characterized in relation to age and type of exercise to determine the effects of the voluntary exercise on the progress of sarcopenia during aging. From the data obtained through a series of functional tests was showed that the physically active seniors have characteristics most similar to young compared to the sedentary group of the same age. This is evidence of the fact that physically active seniors are a very powerful and performing group and it's possible to compare them to master athletes of the same age. Morphological analysis and histological studies have shown that the sedentary seniors present more denervated fibers than the other two groups, and that the physically active seniors have a significantly higher percentage of slow fibers, which, however, does not depend by the type of exercise done. Also it was detected in all three groups fibers that coexpress both myosin fast and slow and specifically the group of the sedentary seniors presents an higher percentage of coexpressing fibers than the other two groups. However, the serial sections of sedentary seniors showed the presence of coexpressing fibers of small dimensions and angled (denervated); therefore, this fact suggests that these fibers are slow fibers that coexpress fast myosin isoforms through default myogenic programs. On the contrary, the coexpressing muscle fibers in the physically active seniors are similar in size to the innervated "pure" muscle fibers, only fast or only slow. Based on the results obtained high levels of exercise appear to have beneficial effects on reinnervation of muscle fibers, resulting in conservation of muscle function, size and structure, thus delaying the functional decline and loss of independence which are common in older people. However, some pathological conditions and also some psychological situations, typical of the elderly, limit the ability to perform physical activity. It is therefore necessary to find an alternative to physical exercise that can maintain the beneficial properties, and above all that can be safe; these features can all be found in electrostimulation (ES). To determine whether this type of therapy can be effective in the elderly was also developed a study to define the effects of ES on aged human muscle, compared with a group of seniors the performed a voluntary strength training program (Leg Press, LP), for a period of nine weeks. In both groups of seniors, after the two workouts, it was noted an improvement in functional parameters, but only those who received the ES treatment presented an increase in the maximum isometric strength of the muscles vastus lateralis. Electrostimulation, unlike the LP, has kept unchanged the overall average size of the fibers, while there was an increment of the diameter and the number of fast fibers and a decrement of both parameters in slow type fibers. Of note, no sign of fibrosis and/or infiltration of inflammatory cells was detected in the treated muscles for both types of training. In addition, analysis of ultrastructure not viewed any alteration of muscle structure before and after treatment. After both treatments of ES and LP was recorded an activation of both the pathway of calcineurin/NFAT and calcium calmodulin dependent kinase (CaMKII), both key points for muscle remodeling. The quantitative evaluation of all the proteins that constitute the sarcoplasmic reticulum, shows a significant increment in protein levels of SERCA2 and Sarcalumenin and a decrement CASQ1 after ES, while after LP there were no significant changes. Analysis of quantitative PCR (qPCR) were made in order to clarify whether the level of Sarcalumenin SERCA2 and CASQ RNA are regulated by electrostimulation. None of the genes is up-regulated or down-regulated in a statistically significant way by the ES training, suggesting a regulation at the post transcriptional level. The vastus lateralis muscle is a mixture of different types of muscle fibers, consequently, the increase in the average quantity of SERCA2 and Sarcalumenin in total homogenates can be attributed to all the fibers or to a specific subpopulation (ie, slow twitch fibers or intermediate oxidative fibers IIA). To see if the increase in SERCA2 is against fast fibers in muscles treated by electrostimulation, it was developed a protocol immunofluorescence to assess the co-expression of myosin fast and SERCA2. After the ES the number of mixed fiber SERCA2/fast myosin is significantly increased, but was unchanged after LP. From the analysis of the intensity of fluorescence of fast myosin it was found that certain fast-twitch fibers exhibit a lower signal of fast myosin respectively in sections post ES and post LP and about 50% of such fibers were also positive SERCA2. From these observations we conclude that the mixed fibers for fast myosin/SERCA2 are a heterogeneous population and a part of these fibers probably expresses both isoforms of myosin. In conclusion, in this thesis were developed experimental protocols that have allowed to identify some favorable changes induced by physical exercise in the seniors. Moreover, thanks to the stabilization of the nuclear translocation of NFATc1 that remains even after several days last training session, it can be assign to the role of biomarker of inactivity (NFATc1 cytoplasmic) and activation "muscle" (myonuclear translocation), whether induced from ES or LP . Also for the first time it was shown that the ES is able to neuro-modulate with beneficial effects for the quality of the muscle, the mobility and the functional performances of the seniors. Thus the ES may be a viable approach to counter the problems and the atrophy of the muscle caused by the aging process both for healthy seniors and subjects to chronic health conditions, having as ultimate goal to improve lifestyle.L'invecchiamento e' un processo multifattoriale caratterizzato da un declino costante e inarrestabile della struttura, delle funzioni e di conseguenza delle prestazioni muscolari. Uno degli effetti piu' evidenti dell'invecchiamento sugli esseri umani e' la riduzione della massa muscolare, nota come sarcopenia, che si verifica in misura diversa da individuo ad individuo e che porta a capacità funzionali ridotte (forza e resistenza). Fattori che contribuiscono al progredire di questo stato sono la diminuzione sia del numero e delle dimensioni delle miofibre che della quantita'  di motoneuroni che innervano le fibre muscolari. Esami istologici effettuati su muscoli di anziani hanno dimostrato che la denervazione puo' contribuire all'atrofia e in aggiunta l'immobilita'  e una vita di tipo sedentario ne accelera il processo, mentre l'esercizio fisico protegge in parte dagli effetti dell'invecchiamento. Diversi studi hanno dimostrato che l'esercizio fisico regolare puo' prolungare l'aspettativa di vita e rallentare gli effetti dell'invecchiamento. A livello molecolare il calcio, e di conseguenza il Reticolo Sarcoplasmatico, svolge un ruolo fondamentale nei processi metabolici e strutturali di adattamento muscolare attraverso l'attivazione di vie di segnalazione specifiche, in risposta al tipo di stimolo ricevuto. Questo lavoro di tesi si focalizza per l'appunto sui benefici dell'esercizio fisico e se questi possono essere comparati a quelli ottenuti se viene utilizzato un protocollo di allenamento indotto dall'elettrostimolazione. Questo potrebbe essere utile in campo riabilitativo in quanto l'esercizio fisico, specialmente negli anziani, non e' sempre applicabile a causa di problemi sia di natura patologica che psicologica. Per determinare gli effetti dell'invecchiamento e correlarli a diversi stili di vita sono stati studiati i muscoli vastus lateralis di tre distinti gruppi di persone (a) anziani sani sedentari (b) anziani sani con un'attivita'  fisica costante da almeno 30 anni (c) giovani sportivi. In questi soggetti e' stato caratterizzato il muscolo in relazione all'eta' e al tipo di esercizio fisico per determinare gli effetti dell'allenamento volontario sull'avanzare della sarcopenia durante l'invecchiamento. Dai dati ottenuti attraverso una serie di test funzionali e' risultato che gli anziani fisicamente attivi presentano caratteristiche piu' simili a quelle dei giovani rispetto a quelli del gruppo sedentario della medesima eta' . Questa e' una prova del fatto che gli anziani fisicamente attivi sono un gruppo molto performante ed e' possibile paragonarli a atleti master della medesima eta' . Analisi morfologiche e istologiche hanno mostrato che gli anziani sedentari presentano pu' fibre denervate rispetto agli altri due gruppi e che gli anziani fisicamente attivi presentano una percentuale di fibre slow significativamente superiore, che pero' non dipende dal tipo di esercizio svolto. Inoltre sono state rilevate in tutti e tre i gruppi fibre che coesprimono sia la miosina rapida che quella lenta e nello specifico il gruppo degli anziani sedentari ne presenta una percentuale piu' alta rispetto agli altri due. Tuttavia, le sezioni seriali di anziani sedentari mostrano la presenza di fibre coesprimenti di piccole dimensioni e angolate (denervate); pertanto, questo fatto suggerisce che si tratta di fibre di tipo lento che coesprimono isoforme fast di miosina attraverso programmi miogenici predefiniti. Al contrario, le fibre muscolari coespriementi negli anziani fisicamente attivi sono di dimensioni simili alle miofibre innervate di tipo puro solo rapido o solo lento. In base ai risultati ottenuti alti livelli di esercizio fisico sembrano avere effetti benefici sulla reinnervazione di fibre muscolari, con conseguente conservazione della funzione muscolare, della dimensione e della struttura, ritardando cosi il declino funzionale e la perdita di indipendenza che sono comuni nelle persone piu' anziane. Tuttavia, alcune condizioni patologiche tipiche degli anziani e anche alcune situazioni psicologiche limitano la capacita'  di svolgere attivita' fisica. Si rende quindi necessario trovare una valida alternativa all'esercizio fisico che pero' ne mantenga le proprietà benefiche e soprattutto che sia sicuro; queste caratteristiche possono essere tutte ritrovate nell'elettrostimolazione (ES). Per determinare se questo tipo di terapia puo' essere efficace anche nell'anziano e' stato messo a punto uno studio degli effetti dell'ES sul muscolo umano di eta'  avanzata, messi a confronto con quelli indotti da un programma di allenamento di forza volontario (Leg Press, LP), per un periodo di nove settimane. In entrambi i gruppi di anziani, dopo i due allenamenti, e' stato rilevato un miglioramento dei parametri funzionali, ma solo i soggetti trattati con l'ES hanno avuto un aumento della forza isometrica massima dei muscoli vastus lateralis. L'elettrostimolazione, a differenza della LP, ha mantenuto la dimensione media complessiva delle fibre invariata, mentre si e' verificato un aumento del diametro e del numero delle fibre rapide e una diminuzione di quelle di tipo lento. Da notare, nessun segno di fibrosi e/o di infiltrazioni di cellule infiammatorie e' stato rilevato nei muscoli trattati per entrambi i tipi di allenamento. Inoltre, analisi di ultrastruttura non hanno visualizzato nessuna alterazione della struttura muscolare prima e dopo il trattamento. In seguito a entrambi i trattamenti di ES e LP e' stata rilevata l'attivazione sia del pathway della calcineurina/NFAT sia delle chinasi calcio calmodulina dipendenti (CaMKII) entrambi punti chiave per il rimodellamento muscolare. La valutazione quantitativa di tutte le proteine che compongono il Reticolo Sarcoplasmatico, mostra un aumento significativo di SERCA2 e Sarcalumenina e una diminuzione di CASQ1 dopo ES, mentre dopo LP non sono stati riscontrati cambiamenti significativi dei livelli proteici. Analisi di PCR quantitativa (qPCR) sono state effettuate al fine di chiarire se il livello di RNA di Sarcalumenina SERCA2 e CASQ sono regolati dall'elettrostimolazione. Nessuno dei geni viene up-regolato o down-regolato in modo statisticamente significativo dal training tramite ES suggerendo una regolazione a livello post trascrizionale. Il muscolo vastus lateralis è una miscela di diversi tipi di fibre muscolari, di conseguenza, l'incremento quantitativo medio di SERCA2 e Sarcalumenina negli omogenati totali puo' essere attribuito a tutte le fibre o ad una specifica sottopopolazione di fibre (cioe' fibre a contrazione lenta o intermedia di tipo ossidativo le fibre IIA). Per verificare se l'aumento di SERCA2 e' a carico delle fibre rapide nei muscoli trattati tramite elettrostimolazione, e' stato messo a punto un protocollo di immunofluorescenza per valutare la co-espressione di miosina del tipo rapido e SERCA2. Dopo l'ES il numero di fibre miste SERCA2/miosina rapida e' significativamente aumentato, mentre e' rimasto invariato dopo LP. Dall'analisi dell'intensita'  della fluorescenza di miosina rapida e' risultato che alcune fibre a contrazione rapida presentano un segnale di miosina rapida piu' bassa rispettivamente nelle sezioni post ES e post LP e circa il 50% di tali fibre erano anche SERCA2 positive. Da queste osservazioni possiamo concludere che le fibre miste per miosina rapida / SERCA2 sono una popolazione eterogenea e che una parte di queste fibre probabilmente esprime le isoforme sia rapida che lenta della miosina. In conclusione con questo lavoro di tesi sono stati messi a punto protocolli sperimentali che hanno permesso di identificare alcuni cambiamenti favorevoli indotti dall'allenamento fisico nell'anziano. Inoltre grazie alla stabilizzazione della traslocazione nucleare di NFATc1 che permane anche dopo diversi giorni dall'ultima sessione di allenamento, si puo' assegnare a quest'ultimo il ruolo di biomarcatore di sedentarieta'  (NFATc1 citoplasmatico) e di attivazione muscolare (sua traslocazione nei mionuclei), sia essa indotta da ES o LP. Infine per la prima volta e' stato dimostrato che l'ES e' in grado di neuromodulare con effetti benefici la qualita'  del muscolo dell'anziano, la mobilita'  e le prestazioni funzionali. Quindi l'ES puo' essere un valido approccio per contrastare l'atrofia e i problemi muscolari dati dal processo di invecchiamento sia per anziani sani che soggetti a condizioni patologiche croniche, avendo come fine ultimo un miglioramento dello stile di vita

Effects of Electrical Stimulation on Skeletal Muscle of Old Sedentary People

Physical activity plays an important role in preventing muscle atrophy and chronic diseases in adults and in the elderly. Calcium (Ca2+) cycling and activation of specific molecular pathways are essential in contraction-induced muscle adaptation. This study attains human muscle sections and total homogenates prepared from biopsies obtained before (control) and after 9 weeks of training by electrical stimulation (ES) on a group of volunteers. The aim of the study was to investigate about the molecular mechanisms that support functional muscle improvement by ES. Evidences of kinase/phosphatase pathways activation after ES were obtained. Moreover, expression of Sarcalumenin, Calsequestrin and sarco/endoplasmic reticulum Ca2+-ATPase (Serca) isoforms was regulated by training. In conclusion, this work shows that neuromuscular ES applied to vastus lateralis muscle of sedentary seniors combines fiber remodeling with activation of Ca2+-Calmodulin molecular pathways and modulation of key Ca2+-handling proteins