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    Cardio a digiuno e dimagrimento

    PREMESSA:
    Ok, ci ho pensato un bel pò prima di postarlo perchè sono sicuro che questo è uno dei classici argomenti destinati a creare flames tra i totalmente a favore e i totalmente contro: è la classica discussione da biio si biio no o da squat si squat no, comunque la si veda le cose rimarranno uguali a prima con persone a favore e persone contro. Mi tocca fare la solita premessa onde non venire frainteso: se lo posto è solo per spirito di discussione, per ragionare su qualcosa di diverso, per non appiattirci su nozioni vecchie e su miti magari sbagliati. Non voglio convincere nessuno. Detto questo, trovo che il presente articolo e gli studi a supporto siano una delle cose più interessanti degli ultimi anni. La sezione è quella giusta poichè il tema centrale è il dimagrimento e non la pianificazione dell'allenamento. Gli esiti ultimi dell'articolo non sono però così banali come sembrano quindi occhio a semplificare e a passare da una parte all'altra della barricata. Buona lettura a tutti.


    "A new article on fasted cardio appearing in the Strength and Conditioning Journal by Brad Schoenfeld, MSc, CSCS

    I put the full text below for those who are interested. For those that are lazy to read the whole thing here are the cliffs:

    -research has shown no difference in total fat loss between subjects doing fasted cardio and those doing cardio after eating.

    -fat burning consists of 1) liberating fatty acids from adipose tissue through lipolysis and then transport of those fatty acids to other tissues like muscle, liver, heart where they are then 2) oxidized for energy. When you eat before cardio you reduce lipolysis but it ends up not making a difference because lipolysis is NOT the rate limiting step of fat loss when it comes to cardio, it is oxidation that is rate limiting so you end up oxidizing the same amount

    -you may burn MORE fat over a 24 hour period when you eat beforehand because there is a GREATER thermogenic response to cardio as opposed to eating fasted

    -Lemon et al. demonstrated nitrogen losses were DOUBLED when you train fasted. Fantastic for maintaining muscle in a caloric deficit... NOT

    -not eating before cardio will reduce training intensity and means you will burn less calories during cardio because you won't have as much energy.

    here is the full article

    --------------------------------------------------------------------------------------

    Does Cardio After an Overnight Fast Maximise Fat Loss?

    A common fat burning strategy employed by bodybuilders, athletes, and fitness enthusiasts is to perform cardiovascular exercise early in the morning on an empty stomach. This strategy was popularized by Bill Phillips in his book, ‘‘Body for Life’’ (23). According to Phillips, performing 20 minutes of intense aerobic exercise after an overnight fast has greater effects on fat loss than performing an entire hour of cardio in the postprandial state. The rationale for the theory is that low glycogen levels cause your body to shift energy utilization away from carbohydrates, thereby allowing greater mobilization of stored fat for fuel. However, although the prospect of reducing the body fat by training in a fasted state may sound enticing, science does not support its efficacy.

    First and foremost, it is shortsighted to look solely at how much fat is burned during an exercise session. The human body is very dynamic and continually adjusts its use of fat for fuel. Substrate utilization is governed by a host of factors (i.e., hormonal secretions, enzyme activity, transcription factors, etc), and these factors can change by the moment (27). Thus, fat burning must be considered over the course of days—not on an hour-to-hour basis—to get a meaningful perspective on its impact on body composition (13). As a general rule, if you burn more carbohydrate during a workout, you inevitably burn more fat in the post- exercise period and vice versa.
    It should be noted that high-intensity interval training (HIIT) has proven to be a superior method for maximizing fat loss compared with a moderate- intensity steady-state training (10,26,29). Interestingly, studies show that blood flow to adipose tissue diminishes at higher levels of intensity (24). This is believed to entrap free fatty acids within fat cells, impeding their ability to be oxidized while training. Yet, despite lower fat oxidation rates during exercise, fat loss is nevertheless greater over time in those who engage in HIIT versus training in the ‘‘fat burning zone’’ (29), providing further evidence that 24-hour energy balance is the most important determinant in reducing body fat.

    The concept of performing cardiovascular exercise on an empty stomach to enhance fat loss is flawed even when examining its impact on the amount of fat burned in the exercise session alone. True, multiple studies show that consumption of carbohydrate before low- intensity aerobic exercise (up to approximately 60% V_o2max) in untrained subjects reduces the entry of long-chain fatty acids in the mitochondria, thereby blunting fat oxidation (1,14,18,28). This is attributed to an insulin-mediated attenuation of adipose tissue lipolysis, an increased glycolytic flux, and a decreased expression of genes involved in fatty acid transport and oxidation (3,6,15). However, both training status and aerobic exercise intensity have been shown to mitigate the effects of a pre-exercise meal on fat oxidation (4,5,24). Recent research has shed light on the complexities of the subject.

    Horowitz et al. (14) studied the fat burning response of 6 moderately trained individuals in a fed versus fasted state to different training intensities. Subjects cycled for 2 hours at varying intensities on 4 separate occasions. During 2 of the trials, they consumed a high-glycemic carbohydrate meal at 30, 60, and 90 minutes of training, once at a low intensity (25% peak oxygen consumption) and once at a moderate intensity (68% peak oxygen consumption). During the other 2 trials, subjects were kept fasted for 12–14 hours before exercise and for the duration of training. Results in the low-intensity trials showed that although lipolysis was suppressed by 22% in the fed state compared with the fasted state, fat oxidation remained similar between groups until 80–90 minutes of cycling. Only after this point was a greater fat oxidation rate observed in fasted subjects. Conversely, during moderate-intensity cycling, fat oxidation was not different between trials at any time—this is despite a 20–25% reduction in lipolysis and plasma Free fatty acid concentration.

    More recently, Febbraio et al. (9) evaluated the effect of pre-exercise and during exercise carbohydrate consumption on fat oxidation. Using a crossover design, 7 endurance- trained subjects cycled for 120 minutes at approximately 63% of peak power output, followed by a ‘‘performance cycle’’ where subjects expended 7 kJ/(kg body weight) by pedaling as fast as possible. Trials were conducted on 4 separate occasions, with subjects given (a) a placebo before and during training, (b) a placebo 30 minutes before training and then a carbohydrate beverage every 15 minutes throughout exercise, (c) a carbohydrate beverage 30 minutes before training and then a placebo during exercise, or (d) a carbohydrate beverage both before and every 15 minutes during exercise. The study was carried out in a double- blind fashion with trials performed in random order. Consistent with previous research, results showed no evidence of impaired fat oxidation associated with consumption of carbohydrate either before or during exercise.

    Taken together, these studies show that during moderate-to-high intensity cardiovascular exercise in a fasted state—and for endurance-trained individuals regardless of training intensity— significantly more fat is broken down than that the body can use for fuel. Free fatty acids that are not oxidized ultimately become re-esterified in adipose tissue, nullifying any lipolytic benefits afforded by pre-exercise fasting.

    It should also be noted that consumption of food before training increases the thermic effect of exercise. Lee et al. (19) compared the lipolytic effects of an exercise bout in either a fasted state or after consumption of a glucose/milk (GM) beverage. In a crossover design, 4 experimental conditions were studied: low-intensity long duration exercise with GM, low-intensity long duration exercise without GM, high- intensity short duration exercise with GM, and high-intensity short duration exercise without GM. Subjects were 10 male college students who performed all 4 exercise bouts in random order on the same day. Results showed that ingestion of the GM beverage resulted in a significantly greater excess postexercise oxygen consumption compared with exercise performed in a fasted state in both high- and low- intensity bouts. Other studies have produced similar findings, indicating a clear thermogenic advantage associated with pre-exercise food intake (7,11).

    The location of adipose tissue mobilized during training must also be taken into account here. During low-to- moderate intensity training performed at a steady state, the contribution of fat as a fuel source equates to approxi- mately 40–60% of total energy expen- diture (30). However, in untrained subjects, only about 50–70% of this fat is derived from plasma Free fatty acids; the balance comes from intra- muscular triglycerides (IMTG) (30).
    IMTG are stored as lipid droplets in the sarcoplasm near the mitochondria (2), with the potential to provide approximately two-thirds the available energy of muscle glycogen (32). Similar to muscle glycogen, IMTG can only be oxidized locally within the muscle. It is estimated that IMTG stores are approximately 3 times greater in type I versus type II muscle fibers (8,21,31), and lipolysis of these stores are max- imally stimulated when exercising at 65%V_o2max(24).

    The body increases IMTG stores with consistent endurance training, which results in a greater IMTG utilization for more experienced trainees (12,16,22,31). It is estimated that nonplasma fatty acid utilization during endurance exercise is approximately twice that for trained versus untrained individuals (24,32). Hurley et al. (17) reported that the contribution of IMTG stores in trained individuals equated to approximately 80% of the total body fat utilization during 120 minutes of moderate- intensity endurance training.
    The important point here is that IMTG stores have no bearing on health and/or appearance; it is the subcutaneous fat stored in adipose tissue that influences body composition. Consequently, the actual fat burning effects of any fitness strategy intended to increase fat oxida- tion must be taken in the context of the specific adipose deposits providing energy during exercise.

    Another factor that must be considered when training in a fasted state is its impact on proteolysis. Lemon and Mullin (20) found that nitrogen losses were more than doubled when training while glycogen depleted compared with glycogen loaded. This resulted in a protein loss estimated at 10.4% of the total caloric cost of exercise after 1hourofcyclingat61%V_o2max.This would suggest that performing cardio- vascular exercise while fasting might not be advisable for those seeking to maximize muscle mass.

    Finally, the effect of fasting on energy levels during exercise ultimately has an effect on fat burning. Training early in the morning on an empty stomach makes it very difficult for an individual to train at even a moderate level of intensity. Attempting to engage in a HIIT style routine in a hypoglycemic state almost certainly will impair performance (33). Studies show that a pre-exercise meal allows an individual to train more intensely compared with exercise while fasting (25). The net result is that a greater number of calories are burned both during and after physicalactivity,heightening fat loss.

    In conclusion, the literature does not support the efficacy of training early in the morning on an empty stomach as a tactic to reduce body fat. At best, the net effect on fat loss associated with such an approach will be no better than training after meal consumption, and quite possibly, it would produce inferior results. Moreover, given that training with depleted glycogen levels has been shown to increase proteolysis, the strategy has potential detrimental effects for those concerned with muscle strength and hypertrophy.
    ------------------------------------------------------------------------------------

    As someone who has been arguing against this brotilligent myth for the better part of a decade I would be happy to now see if this myth will finally go away (but probably not... the 'bros' have a way of keeping nonsense alive)

    I also believe I will be discussing this tomorrow with Carl Lanore on Super Human Radio

    -Layne Norton
    "
    "You eat, sleep, and drink hypertrophy. You live for the pump. You're a bodybuilder."
    Joel Marion

    "It's a shame for a man to grow old without seeing the strength and the beauty of which his body is capable"

    Socrate

    "Huge By choice, not by chance."


    #2
    Quindi riassumendo, il top sarebbe sempre allenamenti aerobici ad alta intensità HIIT, ma con 2-3 ore prima un pasto completo alle spalle. Sia dal punto di vista dell'ossidazione muscolare, sia dal punto di vista di un minore catabolismo muscolare...

    Aggiungo che questi studi e considerazioni, anche se sembrano centrare poco con l'argomeno, NON suggeriscono le varie diete IF/Warrior, dal punto di vista del rapporto fra catabolismo e dimagrimento.

    Ottimo thread
    Personal Trainer/Istruttore Fitness & Body Building FIPE/FIPCF

    diario: ???? Road to the Evolution ????

    Commenta


      #3
      Bellissimo Men.
      Underground BodyBuilding Militia


      Originariamente Scritto da Ingegnere88
      lo inserisco tutto e godo,solo che + godo e + ne ho voglia

      Commenta


        #4
        ottimo articolo, specie per il periodo è davvero utile a molte persone, bravo.
        It is criminal to steal a purse, daring to steal a fortune, a mark of greatness to steal a crown. The blame diminishes as the guilt increases.

        Commenta


          #5
          ottimo menph......come sempre non parli per sentito dire ma con dati alla mano
          Last edited by santib; 13-04-2011, 09:46:29.
          DIARIO

          Commenta


            #6
            grazie menph per averlo portato alla luce. interessante e come oramai mi pare di capire, non esiste una scienza esatta, non è mai bianco o nero

            Commenta


              #7
              Ben fatto Menph!!

              E non solo perchè sono d'accordo su quello che scrivi, ma proponi studi (al plurale) scientifici, è vero che alcuni un pò criticabili in quanto operati su pochi soggetti, ma comunque interessanti, sarebbe ancor più interessante avere i rifermenti completi (anche se dall'autore si può risalire....) per valutare meglio gli studi.

              Ovviamente si può discutere su alcuni punti, ad esempio la perdita di massa muscolare potrebbe essere contrastata da una bella dose di BCAA, o del siero idrolizzato.

              Così come la minor resa migliorata da stimolanti quali caffeina ad esempio, che avrebbe maggiore effetto sulla lipolisi.

              Ma quello che mi è piaciuto di più (guarda caso ho fatto lo stesso discorso ieri a lezione.....) è la LIPOLISI, ovvero attivare la lipolisi non significa consumare più grassi, stiamo semplicemente scindendo i trigliceridi in glicerolo ed acidi grassi, se non ci sarà richiesta di "bruciarli" essi ritorneranno ad essere trigliceridi, operando il cosiddetto "circolo futile", che si consuma un pò d'energia, ma niente di calmoroso.

              Quindi il discriminante è più come ci si allena VO2max ad esempio, quindi lontananza in media dal crossover point, intensità, eventuali tecniche per aumentarla, che la tempistica, poi il pasto prewo anderebbe ben organizzato....ma questo è un altro discorso ancora.
              Ingegnere biochimico
              Tecnologo alimentare
              Nutrizionista sportivo
              Zone Consultant
              Personal trainer
              Membro ACSM, SiNSEB, ISSN, SINU
              Consulente sviluppo e caratterizzazione integratori
              Docente di nutrizione ed integrazione nello sport presso SaNIS, ACS, 4MOVE ed EdiErmes
              Consulente FIT, FIGC e WKF
              Nutrizionista Benetton Treviso Rugby
              CONSULENZE ONLINE PERSONALIZZATE
              RICEVO IN STUDIO A IVREA, TRENTO, MONZA, MILANO, PADOVA, FIRENZE, ROMA, COSENZA E REGGIO CALABRIA

              Commenta


                #8
                Grazie a tutti ragazzi, sono contento che sia piaciuto.
                La reference completa è questa:

                Strength & Conditioning Journal:
                February 2011 - Volume 33 - Issue 1 - pp 23-25
                doi: 10.1519/SSC.0b013e31820396ec


                Venendo a delle piccolissime considerazioni personali è ovvio che pure io abbia un mio punto di vista sull'argomento e, francamente, l'articolo non ha cambiato di molto la mia visione della cosa. Nella premessa avevo detto che non si deve cadere in considerazioni frettolose. Lo stady cardio (in soglia) infatti, oltre a tutte le proprietà di cui abbiamo ampiamente parlato nell'ultimo anno, aumenta pure la quantità di mitocondri...con maggior possibilità in potenziale di ossidazione dei grassi rilasciati grazie alla lipolisi.
                Non dimentichiamo poi che il cardio a digiuno è cosa differente dal cosìdetto "morning cardio" e che, come ha giustamente sottolineato brosgym ci sono fattori (pro,bcaa,stims) che possono cambiare le carte in tavola. Scusate la risp frettolosa ma sono dal cell.
                "You eat, sleep, and drink hypertrophy. You live for the pump. You're a bodybuilder."
                Joel Marion

                "It's a shame for a man to grow old without seeing the strength and the beauty of which his body is capable"

                Socrate

                "Huge By choice, not by chance."

                Commenta


                  #9
                  grande marco...
                  °° UNDERGROUND BODYBUILDING MILITIA TEAM °°

                  Info Preparazioni
                  :ptmatteo.cresti@gmail.com

                  Commenta


                    #10
                    devo rileggerlo attentamente,perche' in inglese mi ci vuole un po' ...molto interessante
                    La sottile differenza che c'e' tra... fare sport e VIVERE di sport...(auto cit.)
                    Originariamente Scritto da SIRIHA
                    dopo ti mangio gnam gnam

                    Commenta


                      #11
                      Interessante, lo voglio leggere tutto, non capisco bene questa frase che penso sia di importanza centrale nell'articolo:

                      "When you eat before cardio you reduce lipolysis but it ends up not making a difference because lipolysis is NOT the rate limiting step of fat loss when it comes to cardio, it is oxidation that is rate limiting so you end up oxidizing the same amount."

                      Quando mangi prima di fare cardio riduci la lipolisi ma alla fine non fa alcuna differenza perchè la lipolisi non è ...?? E' l'ossidazione che ??? ... così finisci per ossidare la stessa quantità (di grasso).

                      Chi mi aiuta a completare la traduzione?
                      Sotto la panca la capra crepa,
                      sopra la panca la capra spinge.

                      Commenta


                        #12
                        la capacità lipolisi (far staccare il grasso dagli adipociti) non è il collo di bottiglia, nel processo di perdita di grasso, mentre è la capacità di ossidazione (dei grassi già liberi nel sangue) il vero collo di bottiglia so alla fine ne ossidi/bruci la stessa quantità.
                        quindi bisogna aumentare l'ossidazione peerchè è questo il fattore limitante, non la lipolisi.
                        Personal Trainer/Istruttore Fitness & Body Building FIPE/FIPCF

                        diario: ???? Road to the Evolution ????

                        Commenta


                          #13
                          è il concetto che esprimeva bros sopra

                          Commenta


                            #14
                            Originariamente Scritto da lucav79 Visualizza Messaggio
                            è il concetto che esprimeva bros sopra
                            ..in maniera impeccabile.
                            sigpic

                            Commenta


                              #15
                              Originariamente Scritto da xymox67 Visualizza Messaggio
                              ..in maniera impeccabile.
                              come sempre....
                              DIARIO

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