03/11/2014

NUTRIENTI CRITICI NELL’ALIMENTAZIONE DELLO SPORTIVO: prevenzione e intervento nutrizionale

Michelangelo Giampietro  ‐ Erminia Ebner Società Italiana di Alimentazione, Movimento, Ambiente e Benessere [S.I.A.M.A.B.]

03/11/2014

L’alimentazione dello sportivo: principi di nutrizione

Med Sci Sports Exerc. 2009 Mar; 41(3):709-31JADA 2009 Mar; 109 (3): 509-527.

Fabbisogno energetico

Med Sci Sports Exerc. 2009 Mar; 41(3):709-31JADA 2009 Mar; 109 (3): 509-527.

The fundamental differences between an athlete’s diet andthat of the general population are that athletes requireadditional fluid to cover sweat losses and additionalenergy to fuel physical activity. As discussed earlier,it is appropriate for much of the additional energy tobe supplied as carbohydrate. The proportionalincrease in energy requirements seems to exceed theproportional increase in needs for most other nutrients.

03/11/2014

IDRATAZIONE E PRESTAZIONE ATLETICA

100% -

75% -

50% -

25%-

0 2 3 4 5 6

1% - SETE: la regolazione del calore è alterata, la prestazione inizia a calare

4% - la prestazione è ridotta del 20-30%

6% - debolezza, cefalea, fatica, irritabilità, termoregolazione persa

Disidratazione (%)

Brouns et coll. 1998

2% - calo prestazione fisica, psicomotoria e cognitiva

SUMMARYThis Position Stand provides guidance on fluid replacement to sustain appropriate hydration of individualsperforming physical activity. The goal of prehydrating is to start the activity euhydrated and with normalplasma electrolyte levels.Prehydrating with beverages, in addition to normal meals and fluid intake, should be initiated whenneeded at least several hours before the activity to enable fluid absorption and allow urine output to returnto normal levels. The goal of drinking during exercise is to prevent excessive (> 2% body weight loss fromwater deficit) dehydration and excessive changes in electrolyte balance to avert compromised performance.Because there is considerable variability in sweating rates and sweat electrolyte content betweenindividuals, customized fluid replacement programs are recommended. Individual sweat rates can beestimated by measuring body weight before and after exercise. During exercise, consuming beveragescontaining electrolytes and carbohydrates can provide benefits over water alone under certaincircumstances. After exercise, the goal is to replace any fluid electrolyte deficit. The speed with whichrehydration is needed and the magnitude of fluid electrolyte deficits will determine if an aggressivereplacement program is merited.

03/11/2014

Fabbisogno idrico

Med Sci Sports Exerc. 2009 Mar; 41(3):709-31JADA 2009 Mar; 109 (3): 509-527.

Dehydration (water deficit in excess of 2–3% body mass)decreases exercise performance; thus, adequate fluid intakebefore, during, and after exercise is important for healthand optimal performance. The goal of drinking is to preventdehydration from occurring during exercise and individualsshould not drink in excess of sweating rate. After exercise,approximately 16–24 oz (450–675 mL) of fluid for everypound (0.5 kg) of body weight lost during exercise.

Mai disidratati . . .

OK

OK

OK

03/11/2014

Fabbisogno idrico

Med Sci Sports Exerc. 2007 Feb; 39(2): 377-90.

FLUID REPLACEMENT - After ExerciseIf time permits, consumption of normal meals and beverages will restoreeuhydration.Individuals needing rapid and complete recovery from excessivedehydration can drink ~1.5 L of fluid for each kilogram of bodyweight lost. Consuming beverages and snacks with sodium will helpexpedite rapid and complete recovery by stimulating thirst and fluidretention. Intravenous fluid replacement is generally not adventagous,unless medically merited.

03/11/2014

Fabbisogno idrico

Brush border = orletto a spazzola; Junctional complex = giunzioni stretteNa+K+ATPasi = pompa Na+K+ATPasi dipendente; SGLT1 = cotrasportatore sodio-glucosio tipo 1; Glut2 = trasportatore tipo 2 di glucosio; AA = aminoacidi

CDC novembre 2003

SISTEMA ENTEROCITARIO di CO‐TRASPORTO del SODIO e del 

GLUCOSIO

Fabbisogno energetico

Med Sci Sports Exerc. 2009 Mar; 41(3):709-31JADA 2009 Mar; 109 (3): 509-527.

03/11/2014

There is evidence that the body can tolerate a certain level of reduction in energy intake, but energy availability lower than 30 kcal (126 kJ) per kg of lean body mass is associated with impairments of metabolic, hormonal, and reproductive function. This is now identified as being important in the development of menstrual disorders in female athletes.

Calculation of energy availability.

03/11/2014

Fabbisogno glucidico

Med Sci Sports Exerc. 2009 Mar; 41(3):709-31JADA 2009 Mar; 109 (3): 509-527.

Andamento del consumo di glicogenomuscolare con l’aumentare del VO2max. Al 100% il consumo è totale.

Andamento del consumo di glicogeno neltempo. A 75 minuti le scorte sonoterminate.

03/11/2014

Fabbisogno glucidico

Australian Sports Commissionwww.ausport.gov.au/ais/nutrition

Fabbisogno glucidico

Australian Sports Commissionwww.ausport.gov.au/ais/nutrition

1/2

03/11/2014

Fabbisogno glucidico

Australian Sports Commissionwww.ausport.gov.au/ais/nutrition

2/2

Dopo l’attività fisica 9/9

Australian Sports Commission www.ausport.gov.au/ais/nutrition

Immune SystemIn general, the immune system is suppressed by intensive training, with manyparameters being reduced or disturbed during the hours following a work-out. Thismay place athletes at risk of succumbing to an infectious illness during this time. Manynutrients or dietary factors have been proposed as an aid to the immune system - forexample, vitamins C and E, glutamine, zinc and most recently probiotics - butnone of these have proved to provide universal protection. The most recent evidencepoints to carbohydrate as one of the most promising nutritional immuneprotectors. Ensuring adequate carbohydrate stores before exercise and consumingcarbohydrate during and/or after a prolonged or high-intensity work-out has beenshown to reduce the disturbance to immune system markers. The carbohydratereduces the stress hormone response to exercise, thus minimizing its effect on theimmune system, as well as also supplying glucose to fuel the activity of many of theimmune system white cells.

03/11/2014

TABELLA 1. FASI DELL’ALLENAMENTO 

NEL SOVRAFFATICAMENTO E NELLA SINDROME DA SOVRALLENAMENTO

Processo Allenamento (sovraccarico)

Allenamento sempre più intenso

ConseguenzaAffaticamento

acuto

Sovraffaticamentofunzionale(OR breve)

SovraffaticamentoNON‐funzionale(OR estremo)

OTS

Tempinecessari per il recupero

Uno o più giorniDa alcuni giorni a qualche settimana

Da poche settimane a mesi

Mesi

Prestazione sportiva

MiglioramentoTemporaneo 

peggioramento Costante 

decremento

Flessione, riduzione,

crollo

Tradotto e modificato da Meeusen et al 2013

OR: Overreaching = SOVRAFFATICAMENTOOTS: Overtraining Syndrome = SINDROME DA SOVRALLENAMENTO

03/11/2014

OVER-TRAINING‘An accumulation of training and non training stress

resulting in long term decrement in performance capacity with or without related physiological and psychological signs and symptoms of overtraining in which restoration of performance capacity may take several weeks or months.’

Kreider et al 1998

Uno squilibrio dell'allenamento che si verifica quando l'attività fisica praticata è troppo intensa, tanto che l’organismo non riesce, nei tempi di recupero, a “eliminare" la fatica accumulata.’

03/11/2014

03/11/2014

Fabbisogno proteico

Australian Sports Commission www.ausport.gov.au/ais/nutrition

03/11/2014

ANEMIA

Conclusion 1/2Iron is an essential dietary element, responsible not only for the efficient delivery of oxygen to the working muscle, but also for the production of energy at the level of the mitochondria. These roles of iron are critical to athletic performance, however it is common for athletes to be iron deficient as a result of iron losses occurring during training from hemolysis, hematuria, sweating and gastrointestinal bleeding (Babic et al. 2001; DeRuisseau et al. 2002; McInnis et al. 1998; Zoller and Vogel 2004). In addition to these well known mechanisms of iron loss, it is also possible that the activity of the inflammatory driven, iron regulatory hormone, hepcidin may have an impact on the iron status of an athlete. It is well known that during chronic disease, the circulating levels of IL‐6 are increased, resulting in an up‐regulation of hepcidin activity and subsequent decreases in serum iron levels that may eventually lead to anemia (Nemeth et al. 2004a). 

03/11/2014

Conclusion ½Since the inflammatory symptoms experienced after high intensity exercise are similar to those seen during chronic disease (Fallon 2001; Margeli et al. 2005), it is possible that the hepcidinactivity is also similar, thereby providing new insights into athletic‐induced iron deficiency. However, to date, only one investigation has attempted to show such an association(Roecker et al. 2005), yet in doing so, these authors failed to consider a number of associatedvariables. As a result, a more accurate observation of hepcidin activity is required within the 24 h post‐exercise, in addition to the associated blood profiles of IL‐6, CRP and serum iron.Furthermore, the effect of training intensity, duration and number of sessions completed should be assessed. Finally, the association between hepcidin activity and exercise induced hemolysis should be considered, since the iron lost from senescent RBC’s may be lost to macrophages as a result of the hepcidin activity on ferroportin channels. In light of such conclusions, it is evident that a great deal of research is required to shed light on this currently grey area of iron metabolism in athletes.

Finally, preventative nutritional strategies should be considered, such as the effect of carbohydrate ingestion

during prolonged periods of exercise on post-exercise hepcidin expression, since IL-6 attenuation has been

previously reported when carbohydrates are consumedduring exercise (Nieman et al.2003). Clearly, it is evident that more research is required to further our understanding of the mechanisms that underpin athletics-induced iron deficiency

to help reduce the risk and severity of compromised iron levels in athletes.

03/11/2014

03/11/2014

“ . . . impegnandoci nel vero spiritodella sportività per uno sport senzadoping e senza droghe, per la gloriae l’onore delle nostre squadre”

Giuramento dell’atleta