NUTRIENTI CRITICI NELL ALIMENTAZIONE DELLO SPORTIVO:

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1 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

2 L alimentazione dello sportivo: principi di nutrizione Med Sci Sports Exerc Mar; 41(3): JADA 2009 Mar; 109 (3): Fabbisogno energetico The fundamental differences between an athlete s diet and that of the general population are that athletes require additional fluid to cover sweat losses and additional energy to fuel physical activity. As discussed earlier, it is appropriate for much of the additional energy to be supplied as carbohydrate. The proportional increase in energy requirements seems to exceed the proportional increase in needs for most other nutrients. Med Sci Sports Exerc Mar; 41(3): JADA 2009 Mar; 109 (3):

3 IDRATAZIONE E PRESTAZIONE ATLETICA 100% - 1% - SETE: la regolazione del calore è alterata, la prestazione inizia a calare 2% - calo prestazione fisica, psicomotoria e cognitiva 75% - 50% - 4% - la prestazione è ridotta del 20-30% 25%- 6% - debolezza, cefalea, fatica, irritabilità, termoregolazione persa Disidratazione (%) Brouns et coll SUMMARY This Position Stand provides guidance on fluid replacement to sustain appropriate hydration of individuals performing physical activity. The goal of prehydrating is to start the activity euhydrated and with normal plasma electrolyte levels. Prehydrating with beverages, in addition to normal meals and fluid intake, should be initiated when needed at least several hours before the activity to enable fluid absorption and allow urine output to return to normal levels. The goal of drinking during exercise is to prevent excessive (> 2% body weight loss from water deficit) dehydration and excessive changes in electrolyte balance to avert compromised performance. Because there is considerable variability in sweating rates and sweat electrolyte content between individuals, customized fluid replacement programs are recommended. Individual sweat rates can be estimated by measuring body weight before and after exercise. During exercise, consuming beverages containing electrolytes and carbohydrates can provide benefits over water alone under certain circumstances. After exercise, the goal is to replace any fluid electrolyte deficit. The speed with which rehydration is needed and the magnitude of fluid electrolyte deficits will determine if an aggressive replacement program is merited.

4 Fabbisogno idrico Dehydration (water deficit in excess of 2 3% body mass) decreases exercise performance; thus, adequate fluid intake before, during, andafter exercise is important for health and optimal performance. The goal of drinking is to prevent dehydration from occurring during exercise and individuals should not drink in excess of sweating rate. After exercise, approximately oz ( ml) of fluid for every pound (0.5 kg) of body weight lost during exercise. Med Sci Sports Exerc Mar; 41(3): JADA 2009 Mar; 109 (3): Mai disidratati... OK OK OK

5 Fabbisogno idrico FLUID REPLACEMENT - After Exercise If time permits, consumption of normal meals and beverages will restore euhydration. Individuals needing rapid and complete recovery from excessive dehydration can drink ~1.5 L of fluid for each kilogram of body weight lost. Consuming beverages and snacks with sodium will help expedite rapid and complete recovery by stimulating thirst and fluid retention. Intravenous fluid replacement is generally not adventagous, unless medically merited. Med Sci Sports Exerc Feb; 39(2):

6 Fabbisogno idrico SISTEMA ENTEROCITARIO di CO TRASPORTO del SODIO e del GLUCOSIO Brush border = orletto a spazzola; Junctional complex = giunzioni strette Na + K + ATPasi = pompa Na + K + ATPasi dipendente; SGLT1 = cotrasportatore sodio-glucosio tipo 1; Glut2 = trasportatore tipo 2 di glucosio; AA = aminoacidi CDC novembre 2003 Fabbisogno energetico Med Sci Sports Exerc Mar; 41(3): JADA 2009 Mar; 109 (3):

7 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

8 Fabbisogno glucidico Med Sci Sports Exerc Mar; 41(3): JADA 2009 Mar; 109 (3): Andamento del consumo di glicogeno muscolare con l aumentare del VO 2 max. Al 100% il consumo è totale. Andamento del consumo di glicogeno nel tempo. A 75 minuti le scorte sono terminate.

9 Fabbisogno glucidico Australian Sports Commission Fabbisogno glucidico 1/2 Australian Sports Commission

10 Fabbisogno glucidico 2/2 Australian Sports Commission Dopo l attività fisica 9/9 Immune System In general, the immune system is suppressed by intensive training, with many parameters being reduced or disturbed during the hours following a work-out. This may place athletes at risk of succumbing to an infectious illness during this time. Many nutrients or dietary factors have been proposed as an aid to the immune system - for example, vitamins C and E, glutamine, zinc and most recently probiotics -but none of these have proved to provide universal protection. The most recent evidence points to carbohydrate as one of the most promising nutritional immune protectors. Ensuring adequate carbohydrate stores before exercise and consuming carbohydrate during and/or after a prolonged or high-intensity work-out has been shown to reduce the disturbance to immune system markers. Thecarbohydrate reduces the stress hormone response to exercise, thus minimizing its effect on the immune system, as well as also supplying glucose to fuel the activity of many of the immune system white cells. Australian Sports Commission

11 TABELLA 1. FASI DELL ALLENAMENTO NEL SOVRAFFATICAMENTO E NELLA SINDROME DA SOVRALLENAMENTO Processo Allenamento (sovraccarico) Allenamento sempre più intenso Conseguenza Affaticamento acuto Sovraffaticamento funzionale (OR breve) Sovraffaticamento NON funzionale (OR estremo) OTS Tempi necessari per il recupero Uno o più giorni Da alcuni giorni a qualche settimana Da poche settimane a mesi Mesi Prestazione sportiva Miglioramento Temporaneo peggioramento Costante decremento Flessione, riduzione, crollo OR: Overreaching = SOVRAFFATICAMENTO OTS: Overtraining Syndrome = SINDROME DA SOVRALLENAMENTO Tradotto e modificato da Meeusen et al 2013

12 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.

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14 Fabbisogno proteico Australian Sports Commission

15 ANEMIA Conclusion 1/2 Iron 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).

16 Conclusion ½ Since 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 hepcidin activity 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 associated variables. 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 consumed during 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.

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