Energy SYstem

Dehydration synthesis also results in the arrangement of polysaccharides. These are long chains made up of three or more monosaccharides. Poly in polysaccharide means many, and polysaccharides are examples of polymers, a polymer is a chain like molecule made up of smaller molecules. Polysaccharides are different from monosaccharides and disaccharides because they are not normally soluble in water and they are not as sweet. Two of the most important polysaccharides are starch and glycogen. These both come from glucose. Glycogen is the main store of carbohydrate in the human body. It is mainly found in the skeletal muscle but it is also stored in the liver. When you take part in a sporting activity/ exercise or when you need energy, glycogen can be broken down into glucose which helps supply energy. That is also the case for disaccharides; the process is performed by hydrolysis reactions. The name for breaking down glycogen is called glycogenolysis. Starch is a carbohydrate made by plants. When it is eaten, it is digested into glucose molecules.

Disaccharides

Two monosaccharides can be added together to make a ‘double’ carbohydrate or disaccharide. There are three disaccharides that are:

• Sucrose: Common table sugar, this is made from the adding of glucose and fructose.
• Lactose: big carbohydrate in milk, made from the adding of glucose and galactose.
• Maltose: product of starch digestion, made from the adding of glucose to glucose.

Believe it or not the process for that is called a ‘condensation reaction’. When you add the monosaccharides together it results in the loss of a molecule of water.

Polysaccharides:

Starches are made of lots of glucose molecules added together. Animals convert glucose into glycogen. Glycogen is digested back into glucose when energy is needed. The liver and skeletal muscles are major areas for storing glycogen.

Fibre: Dietary fibre is found in cereals, fruits and vegetables. Fibre is made up of the indigestible parts or compounds of plants, which pass relatively unchanged through our stomach and intestines. The main role of fibre is to keep the digestive system healthy.

Other terms for dietary fibre include 'bulk' and 'roughage', which can be misleading since some forms of fibre are water soluble and aren't bulky or rough at all.

Most of the carbohydrates found in nature occur in the form of high molecular weight polymers called polysaccharides. The monomeric building blocks used to generate polysaccharides can be varied; in all cases, however, the predominant monosaccharide found in polysaccharides is D-glucose. When polysaccharides are composed of a single monosaccharide building block, they are termed homopolysaccharides. Polysaccharides composed of more than one type of monosaccharide are termed heteropolysaccharides.

What do we need carbohydrates for?

We need carbohydrates mainly to provide energy for exercise. When you have digested the carbohydrates it will either be used as an energy source or will be turned into glycogen by the liver and stored as glycogen in the liver or the skeletal muscle.

Daily intake of carbohydrates

The daily intake should be at least 50% of total kilocalories but should be from complex carbohydrate sources. Obviously, as I explained in my ‘Nutritional Requirements’ the amount of carbohydrates needed would differ depending on how much exercise you do and what particular sport you do such as a marathon runner would need more than an average person that likes to go to the gym a few times a week.

Glycosidic Bond and Peptide Bond

Glycosidic bonds join monosaccharides to form disaccharides, just like peptide bonds join amino acids to form proteins.

Covalent bonds between the anomeric hydroxyl of a cyclic sugar and the hydroxyl of a second sugar (or another alcohol containing compound) are termed glycosidic bonds, and the resultant molecules are glycosides. The linkage of two monosaccharides to form disaccharides involves a glycosidic bond. Several phyisiogically important disaccharides are sucrose, lactose and maltose.

The resulting C-NO bond is called a peptide bond, and the resulting molecule is called an amide. Polypeptides and proteins are chains of amino acids held together by peptide bonds.

A peptide bond can be broken by amide hydrolysis (the adding of water). The peptide bonds in proteins are metastable, meaning that in the presence of water they will break spontaneously, releasing about 10 kJ/mol of free energy, but this process is extremely slow. In living organisms, the process is facilitated by enzymes. Living organisms also employ enzymes to form peptide bonds; this process requires free energy.

Lipids

Another major group of organic compounds that is found in the body are lipids. Lipids provide energy for the body. For the same load, lipids contain more energy than carbohydrates. There are various types of lipids. They are made up of carbon, hydrogen and oxygen, similar to carbohydrates. Also, they are big compounds that do not dissolve in water. Phospholipids are one type of lipid, of which lecithin is an example. That is found in blood and is also a component of cell membranes.

Fat is also a type of lipid. Fat offers protection and insulation to the human body and also is a source of energy. Boxers use that to help protect them. If you look at boxers (mainly heavy weight boxers) you will see they are carrying a little bit of extra weight to help protect themselves from the blows they may receive. A fat molecule is made up of glycerol and fatty acids. It consists of one glycerol molecule added with three fatty acid molecules, hence fats are called triglycerides. The formation of triglcerides from fatty acids and glycerol takes place via dehydration synthesis. As said above in my carbohydrates section the opposite is known as hydrolysis.

Fats are divided into different types, which are:

• Saturated: meat, butter, eggs and milk

Picture taken from year one science notes

• Unsaturated
• Monounsaturated
• Polyunsaturated

Picture taken from year one science notes

Saturated fats are so called because each carbon atom is added to as many hydrogen atoms as possible and they are saturated with hydrogen. Not all saturated fasts are found in animal products. Unsaturated fats have fewer hydrogen atoms connected to each carbon atom; they are not completely saturated with hydrogen. Monounsaturated fats have one double bond between carbon atoms. Polyunsaturated fats have several. An example of a monounsaturated fat is olive oil. Corn is a big example of polyunsaturated fat. As shown above, examples of saturated fats are more obvious which are meat, butter, eggs and milk.

Fats provide more energy than carbohydrates. Many marathon runners and certain football players (midfielders mainly) use this to help them last throughout a race or a game. That is why with some football players like Frank Lampard, they do not have such a toned body because they have a little bit of fat on them.

Protein

Proteins are another group of vital organic compounds that humans need to survive. Their structure is more complex than carbohydrates. Like carbohydrates they contain carbon, hydrogen and oxygen but they also contain nitrogen. Also, occasionally some proteins contain sulphur and phosphorous. The body needs proteins to help it perform physical activities and has many other functions. There are structural proteins, which actually form various parts of the body such as skin and hair. Skeletal muscles are largely made up of actin and myosin that are contractile proteins – they allow muscles to contract, which in turn helps the body with movement. Haemoglobin is an example of a transport protein. It is used to transport carbon dioxide and oxygen in the blood. Proteins that function as hormones are known as regulatory proteins. Insulin is an example. If the blood sugar, which is also known as glucose rises too high, the body releases insulin in order to regulate it. Other functions of proteins include acting as enzymes, which control chemical reactions and protecting the body in form of antibodies. Proteins can also be used as a source of energy but during practice not much of this is used. The body prefers to use carbohydrates and fats as the main source of energy.

In a similar way to carbohydrates being made up of monosaccharides, proteins are made up of amino acids. There are 20 familiar amino acids. When amino acids are joined together, such as in a protein, the join or bond is called a peptide bond, and the process is another example of dehydration synthesis. A compound consisting of two amino acids joined together is called a dipeptide. A tripeptide is made up of three amino acids. A peptide of more than ten amino acids is called a polypeptide.

Most of the time proteins are explained by their structure. A primary structure protein is one that consists of a linear chain of amino acids. If these chains are twisted together, this is called a secondary structure. When a secondary structure becomes folded, a more complex molecule is formed, which is known as a tertiary structure.

The main sources of protein are:

• Meat
• Fish
• Eggs
• Milk
• Cheese
• Cereals
• Nuts and Pulses (peas, beans and lentils)

The amount of protein in food varies. A third of the intake comes from animal sources such as meat, fish, eggs and dairy products. Some is also obtained from cereal products, nuts and pulses.

This is a 3D picture of a protein taken from en.wikipedia.org

Amino Acids

Proteins are made of amino acids. These all have the same basic structure. A central carbon atom is attached to a carboxyl group (COOH) on one side, an amino group (NH2) on the opposite side, a single hydrogen atom, and a side chain ( R ) opposite the hydrogen atom. The side chains are what make each amino acid unique. They range from very simple to very complex in nature. There are twenty-two amino acids. Proteins contain various combinations of these amino acids to form their structure. Amino acids can be acidic, basic or neutral. Those amino acids that are classified as acidic have more carboxyl groups than amino groups. Those that are considered basic have more amino groups than carboxyl groups. Finally, those amino acids that are considered to be neutral have equal numbers of carboxyl and amino groups.

Amino acids are also classified as to whether they are essential or not. Essential amino acids are those that cannot be synthesized by non-ruminant animals. Therefore, essential amino acids are those that can be synthesized by non-ruminants from other compounds. Ruminants do not have essential amino acids because of the microbial activity in the gut of the animal. These microbes synthesize all of the amino acids that the animal requires. Protein quality in feed is based on the amino acid content of that protein. If the protein has a good balance of the essential amino acids, it is considered a low quality protein. Finally, the essential amino acid that is of lowest amount in the feed is considered the limiting amino acid. This limiting amino acid can vary depending on the type of feed and the animal that it is fed to. Proteins are used in the body for growth, maintenance, and reproduction, as well as being a component of all living cells. Protein can also be used as an energy source. This is done when more protein is in the diet of the animal than is needed for all of the other processes that proteins are used for. This is accomplished by concerting the protein to glucose and then using the glucose in the glycolysis and the Kreb’s cycle.

Enzymes:

According to http://web.indstate.edu/thcme/mwking/enzyme-kinetics.html

Enzymes are biological catalysts responsible for supporting almost all of the chemical reactions that maintain animal homeostasis. Because of their role in maintaining life processes, the assay and pharmacological regulation of enzymes have become key elements in clinical diagnosis and therapeutics. The macromolecular components of almost all enzymes are composed of protein, except for a class of RNA modifying catalysts known as ribozymes. Ribozymes are molecules of ribonucleic acid that catalyze reactions on the phosphodiester bond of other RNAs.

Enzymes are found in all tissues and fluids of the body. Intracellular enzymes catalyze the reactions of metabolic pathways. Plasma membrane enzymes regulate catalysis within cells in response to extracellular signals, and enzymes of the circulatory system are responsible for regulating the clotting of blood. Almost every significant life process is dependent on enzyme activity.

Proteins are vital for your sporting performance. Protein is needed for muscle repair. In the morning after exercise you usually feel sore and stiff. This is because when you exercise your muscles are ripping, which protein helps to repair that makes your body enhance. You will find weightlifters and marathon runners have a high intake of protein to help their personal muscle repair heal quickly.

Comparison of fuels and differences between different atheltes

Average person

In the above pie chart you can see the daily intake of an average person. At the side you can see a small reference if you do not totally understand. Half of the daily intake is carbohydrates where as fats are at 30% and proteins are at 20%.

This is because an average person needs an equally balanced diet as they are not getting prepared for a marathon or intending to lift serious weights. The average person will be doing a little bit of everything such as walking up the stairs to get to there office or maybe stacking shelves at Sainsbury’s there for it is vital they have a balanced diet to enable themselves to achieve everything they do in a day.

Weightlifter

Above we can see it is vital that a weightlifter takes on board more carbohydrates than proteins and fats. This is because it is the main source of nutrients you use during exercise. A weightlifter will need to take on board more protein than the average person to help aid muscle growth and muscle repair. Last but not least a weightlifter will try to take on board 15% fats.

Weightlifters would need to take on board more protein as compared to the average person to help repair their muscles after a hard session as weight lifting slightly tears the muscles to enable them to grow back bigger. Weight lifters still need to balance their diet and it may be surprising but would still need more carbohydrates than the average person as they will need to do some cardiovascular work to keep their muscle mass lean instead of it turning into fat.

Marathon Runner

For a marathon runner it is vital they take on board more carbohydrates than anything, as it is the biggest source of nutrients. Secondly, a marathon runner will only take 15% of proteins on board to assist with the little muscle growth they want and more so to help with muscle repair. Finally, a marathon runner will only take 15% of fats on board, as they do not want excessive weight holding them back in a marathon race.

Marathon runners will definitely need more carbohydrates than a weight lifter or the average person as they will need far more energy than either but they will not take on board as much protein as a weight lifter or surprisingly the average person as they need to keep lean but take enough on board to help repair their muscles and enable them to become more powerful at the end of their marathon races.

Energy Pathways

Definitions taken from http://www.brianmac.demon.co.uk/energy.htm

• ATP - Adenosine Triphosphate: a complex chemical compound formed with the energy released from food and stored in all cells, particularly muscles. Only from the energy released by the breakdown of this compound can the cells perform work. The breakdown of ATP produces energy and ADP.
• PC - Phosphate-creatine: a chemical compound stored in muscle, which when broken down aids in the manufacture of ATP. The combination of ADP and PC produces ATP.
• LA - Lactic acid: a fatiguing metabolite of the lactic acid system resulting from the incomplete breakdown of glucose. However Noakes in South Africa has discovered that although excessive lactate production is part of the extreme fatigue process, it is the protons produced at the same time that restrict further performance
• O2 means aerobic running in which ATP is manufactured from food, mainly sugar and fat. This system produces ATP copiously and is the prime energy source during endurance activities

There is also a general consensus as to how long each of these energy pathways last for meaning after a certain period of time of doing physical exercise your body goes onto the next energy pathway and then the next etc.

Below is a great chart that simplifies exactly what I am trying to say above. This was taken from http://www.brianmac.demon.co.uk/energy.htm

Brian Mac, http://www.brianmac.demon.co.uk/energy.htm

The result of muscle contraction produces ADP which when coupled with PC regenerates ATP. PC is stored in the muscles. Actively contracting muscles obtain ATP from glucose stored in the blood stream and the breakdown of glycogen stored in the muscles. Exercise for longer periods of time requires the complete oxidation of carbohydrates or free fatty acids in the mitochondria. The carbohydrate store will last approx. 90 minutes and the free fatty store will last several days.

All three energy systems contribute at the start of exercise but the contribution depends upon the individual, the effort applied or on the rate at which energy is used. The following graph shows how the energy systems give to the formation of ATP over time when exercising at 100% effort. The thresholds (T) indicate the point at which the energy system is exhausted - training will improve the thresholds times.

Brian Mac, http://www.brianmac.demon.co.uk/energy.htm

The anaerobic (ATP-CP) Energy System

Adenosine Triphosphate (ATP) stores in the muscle last for approximately 2 seconds and the resynthesis of ATP from Creatine/Phosphate (CP) will continue until CP stores are depleted, approximately 4 to 5 seconds. This gives us around 5 to 7 seconds of ATP production.

To develop this energy system, sessions of 4 to 7 seconds of high intensity work at near your highest rate are required. Sprinters concentrate on this method of training most.

So therefore your sessions would not last as long as a low intensity workout as you will be pushing your self harder for shorter amount of time. A perfect session to develop this energy system would be:

• 3 × 10 × 30 metres with recovery of 30 seconds/repetition and 5 minutes/set.
• 15 × 60 metres with 60 seconds recovery
• 20 × 20 metres shuttle runs with 45 seconds recovery

The Anaerobic Lactate (Glycolytic) System

Once the CP stores are depleted the body resorts to stored glucose for ATP. The breakdown of glucose or glycogen in anaerobic conditions results in the production of lactate and hydrogen ions. The accumulation of hydrogen ions is the limiting factor causing fatigue in runs of 300 metres to 800 metres.

Sessions to develop this energy system:

• 5 to 8 × 300 metres fast - 45 seconds recovery - until pace significantly slows
• 150 metre intervals at 400 metre pace - 20 seconds recovery - until pace significantly slows
• 8 × 300 metres - 3 minutes recovery (lactate recovery training)

There are three different working units within this energy system: Speed Endurance, Special Endurance 1 and Special Endurance 2. Each of these units can be developed as follows according to Brian Mac:

Brian Mac, http://www.brianmac.demon.co.uk/energy.htm

In the chart above you can see you should be working towards your highest intensity throughout each part.

Over the 3 parts of the above session the distance you work over should increase yet the amount of reps and sets you do should decrease.

The Aerobic Energy System

According to Brian Mac, http://www.brianmac.demon.co.uk/energy.htm

The aerobic energy system utilises proteins, fats and carbohydrate (glycogen) for resynthesising ATP. This energy system can be developed with various intensity (Tempo) runs. The types of Tempo runs are:

• Continuous Tempo - long slow runs at 50 to 70% of maximum heart rate. This places demands on muscle and liver glycogen. The normal response by the system is to enhance muscle and liver glycogen storage capacities and glycolytic activity associated with these processes.
• Extensive Tempo - continuous runs at 60 to 80% of maximum heart rate. This places demands on the system to cope with lactate production. Running at this level assists the removal and turnover of lactate and body's ability to tolerate greater levels of lactate.
• Intensive Tempo - continuous runs at 80 to 90% of maximum heart rate. Lactate levels become high as these runs boarder on speed endurance and special endurance. Intensive tempo training lays the base for the development of anaerobic energy systems.

Sessions to develop this energy system:

• 4 to 6 × 2 to 5 minute runs - 2 to 5 minutes recovery
• 20 × 200m - 30 seconds recovery
• 10 × 400m - 60 to 90 seconds recovery
• 5 to 10 kilometre runs

Electron transport chain

Electron transport chains are biochemical reactions that produce , which is the energy currency of life. Only two sources of energy are available to living organisms: oxidation-reduction () reactions and sunlight. Organisms that use redox reactions to produce ATP are called . Organisms that use sunlight are called . Both chemotrophs and phototrophs utilize electron transport chains to convert energy into ATP.

http://en.wikipedia.org/wiki/Electron_transport_chain

http://en.wikipedia.org/wiki/Image:Etc2.png

The kreb cycle

Simplified diagram of metabolic pathways involved in energy release from glycogen and glucose during and immediately after exercise.

COLIN CLEGG, CG. 7/10/06, Exercise Physiology and functional anatomy. Feltham press

The citric acid cycle is a series of chemical reactions of central importance in all living cells that utilize oxygen as part of cellular respiration. In aerobic organisms, the citric acid cycle is part of a metabolic pathway involved in the chemical conversion of carbohydrates, fats and proteins into carbon dioxide and water to generate a form of usable energy. It is the second of three metabolic pathways that are involved in fuel molecule catabolism and ATP production, the other two being glycolysis and oxidative phosphorylation.

The citric acid cycle also provides precursors for many compounds such as certain amino acids, and some of its reactions are therefore important even in cells performing fermentation.

Definition taken from http://en.wikipedia.org/wiki/Kreb_Cycle

Simplified process of the Kreb Cycle - http://en.wikipedia.org/wiki/Kreb_Cycle#A_simplified_view_of_the_process:

• The process begins with the oxidation of pyruvate, producing one CO2, and one acetyl-CoA.
• Acetyl-CoA reacts with the four carbon carboxylic acid, oxaloacetate--to form the six carbon carboxylic acid, citrate.
• Through a series of reactions citrate is converted back to oxaloacetate. This cycle produces 2 CO2 and consumes 3 NAD+, producing 3 NADH and 3 H+.
• It consumes one H2O and consumes one FAD, producing one FADH+.
• 1st turn end= 1 GTP, 3 NADH, 1 FADH2, 2 CO2 
• Since there are two molecules of Pyruvic acid to deal with, the cycle turns once more.
• The complete end result= 2 GTP, 6 NADH, 2 FADH2, 4 CO2