Efekti ketogene dijete na mišićnu silu, telesni sastav, hormonalni i lipidni profil kod sredovečnih treniranih muškaraca

Abstract

Ketogena dijeta je predmet interdisciplinarnog prouĉavanja u više nauĉnih oblasti meĊu kojima je i oblast sportskih nauka. Ono što ovu dijetu izdvaja od ostalih naĉina ishrane je njen specifiĉan uticaj na metabolizam putem izazivanja stanja nutritivne ketoze povećanjem produkcije ketonskih tela u ljudskom organizmu. Ovi molekuli nastaju metabolizmom masti u nedostatku ugljenih hidrata unetih kroz ishranu. Ketonska tela su od posebnog interesovanja u oblasti biomedicinskih nauka jer pored niza metaboliĉkih funkcija imaju specifiĉnu ulogu kao alternativni izvor energije i sposobna su da u odreĊenoj meri zamene glukozu. Dodatno je interesovanje za uticaj ove dijete zbog njene, navodno, veće efikasnosti u smanjenju telesne mase odnosno promeni telesnog sastava. Ova promena podrazumeva smanjenje masne komponente telesnog sastava i oĉuvanje ili povećanje njegove bezmasne komponente koju u najvećoj meri ĉini mišićno tkivo. Treba pomenuti i potencijalni uticaj ketogene dijete na hormonalni profil smanjenjem unosa ugljenih hidrata i povećanjem unosa zasićenih masti i holesterola, ĉime se utiĉe na izluĉivanje insulina i testosterona koji imaju veliki uticaj na telesni sastav i ispoljavanje mišićne sile. Pregledom relevantne literature uoĉeno je da nije dovoljno istraženo pitanje primene ketogene dijete u uslovima fiziĉke aktivnosti kada se ona primenjuje uz trening sa opterećenjem visokog intenziteta u kome su pri uobiĉajenom dijetalnom režimu primarni izvori energije glukoza i glikogenski depoi. U skladu sa navedenim razlozima dizajnirano je istraživanje u kojem je ispitan uticaj ketogene dijete uz trening sa opterećenjem na vrednosti mišićne sile, telesnog sastava i odreĊenih biohemijskih pokazatelja od znaĉaja. Uzorak ispitanika je bio 20 sredoveĉnih muškaraca starosti od 40 do 45 godina sa velikim iskustvom u treningu sa opterećenjem za mišićnu hipertrofiju. Ispitanici su randomizovani i podeljeni u dve grupe, grupu koja je sprovodila ketogeni dijetalni režim sa znaĉajno smanjenim unosom ugljenih hidrata i povećanim unosom masti i kontrolnu grupu koja je sprovodila neketogeni dijetalni režim, takoĊe sa znaĉajno smanjenim unosom ugljenih hidrata i povećanim unosom masti. Ovakav dizajn studije je imao za cilj da se grupe minimalno razlikuju u unosu makronutrijenata a da jedina razlika bude stanje nutritivne ketoze kako bi se izolovao uticaj ketonskih tela u maksimalno izjednaĉenim i kontrolisanim uslovima. Obe grupe su bile ujednaĉene po unosu kalorija i sprovodile su identiĉan trening sa opterećenjem, ciljano dizajniran za mišićnu hipertrofiju. Dijeta je bila nezavisna varijabla dok su mišićna sila, telesni sastav, hormoni testosteron i insulin, lipidni profil i nivo glikemije u krvi ĉinili zavisne varijable u istraživanju. Za statistiĉku obradu podataka, pored deskriptivne statistike, upotrebljen je T test za utvrĊivanje razlika izmeĊu uvodne i eksperimenalne dijete. Mixed (Split plot) ANOVA sa Bonferroni post hoc testom je primenjena kako bi se utvrdio uticaj dijete na merene varijable, odnosno kako bi se utvrdile razlike u zavisnim varijablama izmeĊu grupa za svaku vremensku taĉku kao i za utvrĊivanje razlika u zavisnim varijablama unutar svake grupe tokom vremena. Nivo znaĉajnosti je podešen na p < 0.05...

The ketogenic diet is the subject of interdisciplinary study in several scientific fields, including the field of sports sciences. What sets this diet apart from other diets is its specific effect on metabolism by causing a state of nutritional ketosis through increasing the production of ketone bodies in human organism. These molecules are formed by fat metabolism in the absence of carbohydrates introduced through the diet. Ketone bodies are of special interest in the field of biomedical sciences because, in addition to a number of metabolic functions, they have a specific role as an alternative energy source and are able to replace glucose to a certain extent. There is additional interest in the influence of this diet due to its, allegedly, greater efficiency in reducing body weight and changing body composition. This change means reducing the fat component of the body composition and preserving or increasing its fat-free component, which is mostly made up of muscle tissue. We should also mention the potential influence of ketogenic diet on the hormonal profile by reducing carbohydrate intake and increasing saturated fat and cholesterol intake that affects the secretion of insulin and testosterone, which have a great impact on body composition and muscle strength. A review of the relevant literature showed that the issue of using a ketogenic diet in conditions of physical activity when it is applied with high-intensity training in which the primary energy sources are glucose and glycogen depots in the ordinary diet conditions. In accordance with the stated reasons, a research was designed in which the influence of the ketogenic diet with resistance training was examined on the values of variables of muscle strength, body composition and certain biochemical indicators of importance. The sample of subjects was 20 middle-aged men aged 40 to 45 with extensive experience in resistance training for muscular hypertrophy. Subjects were randomized and divided into two groups, the group that followed a ketogenic diet with significantly reduced carbohydrate intake and increased fat intake and the control group that implemented a non- ketogenic diet also with significantly reduced carbohydrate intake and increased fat intake. This design of the study aimed to minimize the differences between the groups in the macronutrient content and the only difference was aimed to be the state of nutritional ketosis in order to isolate the influence of ketone bodies in maximally equalized and controlled condition. Both groups were uniform in calorie intake and conducted identical resistance training, specifically designed for muscle hypertrophy. Diet was an independent variable while muscle strength, body composition, hormones testosterone and insulin, lipid profile, and blood glucose levels were dependent variables in the study. For statistical data processing, in addition to descriptive statistics, the T test was used to determine differences between the introductory and experimental diet. Mixed (Split plot) ANOVA with Bonferroni post hoc test was used to determine the effect of diet on measured variables, i.e. to determine differences in dependent variables between groups for each time point as well as to determine differences in dependent variables within groups over time. The significance level is set to p <0.05...