Ciao a tutti, leggete qui a proposito delle diete ricche di carboidrati per le attività di endurance......Tratto da un post di it.sport.palestra...vi consiglio di STAMPARLO e leggervelo con calma..;-)))

 Am J Clin Nutr 1993 Jan;57(1):27-31 Dietary carbohydrate, muscle glycogen, and exerciseperformance during 7 d of training. Sherman WM, Doyle JA, Lamb DR, Strauss RH ExercisePhysiology Laboratory, School of Health, Physical Education, and Recreation, Ohio State University,Columbus 43210. The effects of moderate- or high-carbohydrate dietson muscle glycogen and performance in runners andcyclists over 7 consecutive days of training weredetermined. Muscle biopsies were performed on 4 separate days before exercise for 1 h at 75% peakoxygen consumption (VO2) followed by five, 1-min sprints. After the training session on day 7, subjects ran or cycled to exhaustion at 80% peak VO2.Muscle glycogen for cyclists and runners wasmaintained with the high-carbohydrate diet but wasreduced 30-36% (P < 0.05) with themoderate-carbohydrate diet.All subjects completed all training sessions,and there were no differences in times to exhaustionon day 7. For cyclists and runners, consuming amoderate-carbohydrate diet over 7 d of intensetraining reduces muscle glycogen but has no apparent deleterious effect on training capabilityor high-intensity exercise performance.A high-carbohydrate diet maintains muscle glycogen,but this has no apparent benefit on trainingcapability or high-intensity exercise performance. 

COMMENTO: Una dieta alta in carboidrati mantienele riserve di glicogeno intatte, a differenza diuna moderata in carboidrati, ma questo non influiscesulle prestazioni. 1/3 di glicogeno muscolare in meno e stesse prestazioni, anche sulla prova a sfinimento.

  Med Sci Sports Exerc 1998 Dec;30(12):1677-83   Effects of high fat versus high carbohydrate dietson plasma lipids and lipoproteins in endurance athletes. Brown RC, Cox CMDepartment of Human Nutrition, University of Otago,Dunedin, New Zealand.rachel.brown@stonebow.otago.ac.nz PURPOSE AND METHODS: Recent research suggestingthe performance benefits of high fat diets forendurance athletes have been viewed with cautionbecause of the potential negative health consequences,including increased coronary heart disease risk.This study examined the effects of a high fat(HF: 50% of total energy from fat, 37% carbohydrate)versus a high carbohydrate (HC: 15% of total energyfrom fat, 69% carbohydrate) diet on plasma lipids andlipoproteins in 32 endurance trained cyclists overa 3-month period. Plasma total, low densitylipoprotein (LDL), high density lipoprotein (HDL),HDL2 and HDL3 cholesterol, triglycerides,apolipoprotein A1, and hematocrit (Hct) were measured at baseline and after weeks 4, 8, and 12.RESULTS: Changes in lipids and lipoproteins frombaseline to week 12 did not differ between thetwo groups except for triglycerides, which increased significantly from 1.04 +/- 0.17 mmol.L-1to 1.28 +/- 0.31 mmol.L-1 in HC (P = 0.012).The only significant changes that occurred withineach group from baseline to week 12 was thesignificant increase in total cholesterol and triglycerides in HC.Body composition changes did not differ betweenthe two groups from baseline to week 12 as measuredby dual x-ray absorptiometry.

CONCLUSIONS: Duringperiods of endurance training when energyrequirements are high, increasing the percentage of fat in the diet to approximately 50% of totalenergy didnot result in adverse changes to theplasma lipoprotein profiles of this group of athletes. 

COMMENTO: I timori dei potenziali effetti negatividi una dieta alta in grassi sui parametri di rischio coronarico sono infondati. La cosa divertente è che i ricercatori, quasi vergognandosi, passano sotto silenzio nelle conclusioni un'osservazione interessantissima fatta precedentemente, e cioè che durante le 12 settimane di dieta, nel gruppo ad alti carboidrati c'è un incremento significativo del colesterolo e dei trigliceridi. Volevano dimostrare che la dieta ad alti grassi era pericolosa, ed invece si ritrovano con i risultati opposti, ma visto che lo scopo dell'esperimento non era quello di dimostrare la pericolosità delle diete alte in C, sorvolano!! spassoso ... :-)

 Int J Sports Med 1998 Aug;19(6):415-8   Carbohydrate ingestion immediately before exercisedoes not improve 20 km time trial performance in welltrained cyclists. Palmer GS, Clancy MC, Hawley JA, Rodger IM, Burke LM,Noakes TD School of Life Science, Kingston University,Kingston Upon Thames, Surrey, England. This study examined the effects of carbohydrateingestion on 20 km cycle time-trial (TT) performancein 14 well-trained cyclists (11 males, 3 females; peakoxygen uptake [VO2peak] 4.52 +/- 0.60 l/min; valuesare mean +/- SD). All subjects performed two experimental trials on their own bicycles mounted on an air-braked ergometry system (Kingcycle). Subjects were instructed to maintain the same training and dietary regimens before trials, whichwere conducted in a random order, 3-7 days apart,and at the same time of day for each subject. On the day of a trial, subjects reported to thelaboratory and ingested an 8 ml/kg body mass bolusof either a 6.8 g/100 ml commercialcarbohydrate-electrolyte (CHO) beverage (39 +/- 4 g of CHO), or a coloured, flavoured placebo.Ten min after finishing the drink, subjects commenceda 5 min warm-up at 150 W, before commencing the 20 km TT.The average power output (312 +/- 40 vs 311 +/- 38 W)and heart-rate (171 +/- 6 vs 171 +/- 5 beats/min forCHO and placebo, respectively) during the two rides did not differ between treatments. Accordingly, the performance times for the two TT's were the same(27:41 +/- 1:39 min:sec, for both CHO and placebo).We conclude that the ingestion of approximately 40 g ofcarbohydrate does not improve maximal cycling performance lasting approximately 30 min, and thatcarbohydrate availability, in the form of circulatingblood glucose, does not limit high-intensity exercise of this duration. 

COMMENTO: Ingerire una bevanda commerciale a base di carboidrati prima dell'allenamento non serve ad un c...o!

Eur J Appl Physiol 1994;69(4):287-93   Enhanced endurance in trained cyclists duringmoderate intensity exercise following 2 weeks adaptation to a high fat diet. Lambert EV, Speechly DP, Dennis SC, Noakes TDLiberty Life Chair of Exercise and Sports Science,University of Cape Town Medical School, Observatory, South Africa. These studies investigated the effects of 2 weeksof either a high-fat (HIGH-FAT: 70% fat, 7% CHO)or a high-carbohydrate (HIGH-CHO: 74% CHO, 12%fat) diet on exercise performance in trainedcyclists (n = 5) during consecutive periods ofcycle exercise including a Wingate test of musclepower, cycle exercise to exhaustion at 85% of peak power output [90% maximal oxygen uptake(VO2max), high-intensity exercise (HIE)] and 50% of peak power output [60% VO2max, moderateintensity exercise (MIE)]. Exercise time toexhaustion during HIE was not significantly different between trials: nor were the rates of muscle glycogen utilization during HIEdifferent between trials, although starting muscle glycogen content was lower [68.1 (SEM 3.9)vs 120.6 (SEM 3.8) mmol.kg-1 wet mass, P < 0.01] after the HIGH-FAT diet.Despite a lower muscle glycogen content at theonset of MIE [32 (SEM 7) vs 73 (SEM 6) mmol.kg-1wet mass, HIGH-FAT vs HIGH-CHO, P < 0.01], exercisetime to exhaustion during subsequent MIE wassignificantly longer after the HIGH-FAT diet[79.7 (SEM 7.6) vs 42.5 (SEM 6.8) min, HIGH-FATvs HIGH-CHO, P < 0.01]. Enhanced endurance duringMIE after the HIGH-FAT diet was associated witha lower respiratory exchange ratio[0.87 (SEM 0.03) vs (SEM 0.02), P < 0.05], anda decreased rate of carbohydrate oxidation[1.41 (SEM 0.70) vs 2.23 (SEM 0.40) g CHO.min-1,P < 0.05]. 

COMMENTO: Nonostante la dieta HI-FAT portasse ad un dimezzamento delle riserve di glicogeno muscolare (68.1 contro 120.6 mmol/kg di massa magra), la prestazione ad alta intensità (90% VO2max) non ne veniva inficiata, e in quella a media (50% VO2max) il tempo nella prova a "sfinimento" passava 42.5 a 79.7 minuti. META' GLICOGENO MA DOPPIA RESISTENZA ALLO FORZO!!! 

Med Sci Sports Exerc 1994 Jan;26(1):81-8 Effect of dietary fat on metabolic adjustmentsto maximal VO2 and endurance in runners. Muoio DM, Leddy JJ, Horvath PJ, Awad AB, Pendergast DR Department of Physiology, StateUniversity of New York at Buffalo, School of Medicine and Biomedical Sciences 14214. The present study examined the effects of dietarymanipulations on six trained runners. The percentenergy contributions from carbohydrate, fat, and protein were 61/24/14, 50/38/12, and 73/15/12 forthe normal (N), fat (F), and carbohydrate (C)diets, respectively. Expiratory gases and bloodresponses to a maximum (VO2max) and a prolonged treadmill run were determined following 7 d oneach diet. Free fatty acids (FFA), triglycerides,glycerol, glucose, and lactate were measured.Dietary assessment of subjects' N diet indicatedthat they were consuming approximately700 kcal.d-1 less than estimated daily expenditures.Running time to exhaustion was greatest afterthe F diet (91.2 +/- 9.5 min, P < 0.05) ascompared with the C (75.8 +/- 7.6 min, P < 0.05)and N (69.3 +/- 7.2 min, P < 0.05) diets.VO2max was also higher on the F diet (66.4 +/- 2.7ml.kg-1 x min-1, P < 0.05) as compared withthe C (59.6 +/- 2.8 ml.kg-1 x min-1, P < 0.05)and N (63.7 +/- 2.6 ml.kg-1 x min-1, P < 0.05) diets.Plasma FFA levels were higher (P < 0.05) and glycerollevels were lower (P < 0.05) during the F diet thanduring the C and N diets. Other biochemicalmeasures did not differ significantly among diets. These data suggest that increased availability of FFA, consequent to the F diet, may provide forenhanced oxidative potential as evidenced by an increase in VO2max and running time.This implies that restriction of dietary fat may bedetrimental to endurance performance. 

COMMENTO: A costo di ripetermi, la dieta alta in grassi è quella migliore negli sport di endurance.  

Metabolism 1999 Dec;48(12):1509-17  Metabolic adaptations to a high-fat diet inendurance cyclists. Goedecke JH, Christie C, Wilson G, Dennis SC,Noakes TD, Hopkins WG, Lambert EVMedical Research Council/University of Capetown Bioenergetics of Exercise Research Unit,University of Cape Town Medical School, Newlands,South Africa. We examined the time course of metabolic adaptationsto 15 days of a high-fat diet (HFD). Sixteenendurance-trained cyclists were assigned randomly o a control (CON) group, who consumed their habitualdiet (30% +/- 8% mJ fat), or a HFD group, who consumeda high-fat isocaloric diet (69% +/- 1% mJ fat). At 5-day intervals, the subjects underwent an oralglucose tolerance test (OGTT); on the next day,they performed a 2.5-hour constant-load ride at 70% peak oxygen consumption (VO2peak), followed by asimulated 40-km cycling time-trial while ingestinga 10% 14C-glucose + 3.44% medium-chain triglyceride(MCT) emulsion at a rate of 600 mL/h. In the OGTT,plasma glucose concentrations at 30 minutes increased significantly after 5 days of the HFD andremained elevated at days 10 and 15 versus the levelsmeasured prior to the HFD (P < .05). The activity ofcarnitine acyltransferase (CAT) in biopsies of thevastus lateralis muscle also increased from 0.45 to 0.54 micromol/g/min over days 0 to 10 of the HFD(P < .01) without any change in citrate synthase(CS) or 3-hydroxyacyl-coenzyme A dehydrogenase(3-HAD) activities. Changes in glucose toleranceand CAT activity were associated with a shift from carbohydrate (CHO) to fat oxidation during exercise(P < .001), which occurred within 5 to 10 days ofthe HFD. During the constant-load ride, the calculated oxidation of muscle glycogen was reducedfrom 1.5 to 1.0 g/min (P < .001) after 15 days of theHFD. Ingestion of a HFD for as little as 5 to 10 days significantly altered substrate utilizationduring submaximal exercise but did not attenuate the40-km time-trial performance. 

COMMENTO: Il passaggio ad una dieta ad alto contenuto di grassi provoca un adattamento metabolico, alterando l'utilizzazione dei substrati, ovvero aumentando l'ossidazione dei grassi e diminuendo quella del glicogeno. Questo non ha effetti negativi sulla performance.