Carbohydrates types and their use
Carbohydrates types and their use |
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There are many different types of carbohydrate, and each type is affects our body in different ways and is therefore treated differently by our bodies. For instance, glucose and oat bran are both carbohydrates, but they are on different ends of the energy spectrum. Glucose enters the bloodstream quickly and initiates a fast and high insulin response, while the energy in bran never makes it into the bloodstream because of its indigestibility and tends to mediate the insulin response by slowing the rate at which other energy sources enter the bloodstream.
These intra-carbohydrate differences mean that athletes should plan their nutritional strategies around the best type of carbohydrate for their training circumstances. Glucose is the main source of fuel for muscular activity, and the higher the exercise intensity, the greater the reliance on glucose as a fuel. When glucose runs out, the athlete stops performing. Therefore, understanding how to keep glucose from becoming depleted should become a major focus of an athlete's nutrition practices.
Sustaining carbohydrate sufficiency is problematic because, unlike either protein or fat, humans have a limited storage capacity for carbohydrate. The average human can store approximately 350 grams (1,400 kilocalories) in the form of muscle glycogen, an additional ‘back-up’ store of 90 grams (360 kilocalories) in the liver, and a small amount of circulating glucose in the blood (~5 grams, or about 20 kilocalories). Carbohydrate adequacy becomes even more critical at higher levels of exercise intensity because there is a greater reliance on carbohydrate as a source of muscular fuel.
Despite years of research confirming the importance of maintaining carbohydrate availability for sustaining muscular endurance and mental function, many athletes still believe protein is the critical substrate for achieving athletic success.
Although all substrates are important, delivering the right amounts of carbohydrate at the right time optimizes the limited carbohydrate stores, ensures better carbohydrate delivery to the brain, and improves endurance performance. There has been in recent years a trend to eat more protein at the expense of carbohydrates. This has been facilitated by perhaps the popularity of the Atkins diet. I do agree that most people to do not eat sufficient protein in terms of both volume and at the wrong time.
Excess protein consumption does little to enhance performance actually in the gym as your energy should be derived from carbohydrates unless you are in a cutting phase when I actually eat more protein than when bulking. I do advocate protein ingestion pre/during and after workouts but that is to provide a more efficient delivery of these nutrients as opposed to them being used as a fuel source to train.
Carbohydrates Types
Not all carbohydrates have the same form, function, and health impact. The basic unit of all carbohydrates is the monosaccharide, or single-molecule carbohydrate. The common mono-saccharides all have six carbons, and while they vary only slightly in hydrogen—oxygen configuration, these subtle variations account for important metabolic differences.
The basic metabolic unit for human cells is the monosaccharide glucose, and the other mono-saccharides have biochemical pathways that enable them to be converted to glucose. The number of mono-saccharides bonded together provides the main basis for classifying carbohydrates.
Each of the three main mono-saccharides (glucose, fructose, and galactose) has different characteristics of solubility, sweetness, and reactivity with the food environment in which it is found. With the exception of fructose, which is present in an increasingly wide variety of processed foods as high-fructose (corn) sweetener, most mono-saccharides are delivered in the food supply as breakdown products of disaccharides, which are two-molecule carbohydrates (i.e., composed of two connected mono-saccharides).
There are three main disaccharides-sucrose, maltose, and lactose-each containing a different combination of mono-saccharides. Together, the mono-saccharides and disaccharides are referred to as simple carbohydrates, or sugars, while the polysaccharides (which have long chains of bonded glucose molecules) are commonly referred to as complex carbohydrates.
The indigestible carbohydrates are also complex carbohydrates, but they are commonly referred to as dietary fibre. The sugars (the mono/disaccharides) have different sweetness characteristics, with fructose tasting the most sweet, followed by sucrose, glucose, and lactose (the least sweet). However, the sugars also differ in mouth feel and solubility (e.g., fructose is less soluble than sucrose), all of which influence food manufacturers in their choice of sugars in food preparation.
Athletes now have a wide array of sports beverages from which to choose, with each containing different proportions of mono/disaccharides. The important factors to consider when selecting your carbohydrate choice are flavour, gut tolerance, gastric emptying, electrolyte replacement, and energy delivery to working muscles.
Courtesy of ProMuscleMag.com