The Science of BodybuildingBy Adam Sinicki
Right class, we've had our fun with these 'Gym Characters' and 'Man Points' articles, but now it's time we got down to some serious learning. I know; learning is boring, but in this case understanding the science can help us make gains in the gym. Science classically is the domain of the scrawny nerd but no longer! Now the bulky bodybuilder can benefit from its dark secrets and fight back! This is learning with real-world benefits, unlike PSE or Maths at school. So pay attention! There might be a test at the end. Really.
We all know if we have a 'fast' or 'slow' metabolism, but do we know what one is? I do. 'Metabolism' refers to the chemical reactions that take place to supply our body with energy (catabolism) and to build and repair tissue with proteins (anabolism) by acting out our DNA code. Here we're going to discuss what that means for bodybuilding.
Skeletal muscle tissue is the most abundant tissue in the human body and makes up over a third of body mass in healthy adults.
Muscle tissue, like every other part of the body, is formed from millions of tiny cells. In muscle they are cleverly named 'muscle fibres'. Unlike other cells these have multiple nuclei (the command centre of a cell) meaning that they cannot multiply through mitosis (cell division). Muscle fibres are composed of smaller 'strands' named myofibrils, which in turn are made of sarcomeres. Inside Sarcomeres are smaller filaments made from the proteins myosin and actin. When the muscle contracts, this is an effect of the myosin 'pedaling' along the actin and so collapsing the sarcomeres inwards like collapsable tubes. As enough of them do it this becomes visible on a macroscopic level and moves your entire arm.
Following so far? I'm not sure I am. Just to complicate matters there are actually 2 different types of muscle fibre; 'fast twitch' and 'slow twitch' (also known as type I and type II). As the names suggest, fast twitch fibres are used in fast explosive movements such as jumping, sprinting and weightlifting, while slow twitch fibres are used for endurance sports such as long-distance running. The difference is due to the amounts of mitochondria, creatine phosphate among other things in the fibres, as well as the myosin isoforms, and we will see how these effect performance later on. Basically it comes down to how quickly/efficiently they get energy from ATP.
Type II can be further divided into Type IIa and Type IIx with the latter being even faster. Certain mamals have another kind of fibre, 'Type IIb' which is used for even more sudden bursts of energy used to change direction suddenly and evade predators (confusingly you will sometimes find Type IIb referred to as Type IIx and vice versa - while most websites and magazines still refer to humans' fastest fibre as Type IIb most scientific journals and papers have now adopted IIx). Generally a bodybuilder will have more Type II fibres, as will sprinters, long distance runners will need more Type I. While our ratio of fast-twitch to slow-twitch fibres is larlgey genetically determined studies have shown that we are able to convert one type of muscle fibre into another through training. There are also muscle fibres that are 'in-betweenies' with aspects of both fast twitch and slow twitch fibres. As we get older up to a third of our muscles become 'in betweenies'.
Muscles get energy from splitting ATP (Adenosine Triphosphate: an adenine nucleotide that's bound to three phosphates), the 'universal energy currency' of life. ATP is produced in the mitochondria of cells from the glucose in our diet and energy is released when the high-energy bonds are broken releasing the phosphate.
Creatine phosphate is used to restore the levels of ATP by converting used ATP, or ADP (Adenosine Diphosphate - an adenine nucleotide with two phosphates (AMP has one)), back into ATP using its own high-energy phosphate bond. This supplies our muscles with energy during fast usage such as during sprinting (the phosphogen system). Our muscles can only store enough ATP for roughly 3 seconds use at full power, but fortunately they can store around 2-3 times more creatine phosphate allowing for 8-10 seconds of exertion at full pelt. This is why bodybuilders use creatine supplements - to supply the muscle with more energy. This is called the Phosphogen System.
ATP can also be obtained from the carbohydrate glycogen, though it is a slightly slower process, in what's called the Glycogen Lactic Acid System. Here glycogen stored in the muscles is split into glucose which is split further releasing four ATP molecules. This provides roughly 1.5 minutes of extra energy on top of the initil 8 seconds, although at lower power and also produces the bi-product lactic acid. This method is used in activities such as swimming or the 400 metre sprint and is 'anaerobic' meaning it does not use oxygen.
Finally the Aerobic System is used to maintain a supply of energy for extended use. It achieved this through the oxydisation of foodstuffs in our mitochondria. The system will 'burn' carbohydrates first, then fats and finally protein to supply the body with a source of energy. This is why bodybuilders should not engage in excessive CV or completely neglect Carbohydrates in their diet - they will risk canabalising their protein. The Aerobic system can sustain an athlete for over two hours, and converts glucose into carbon dioxide and water rather than lactic acid. In order to provide muscles with the necesary oxygen your body will pump blood to them (hence the feeling of being 'pumped'), diverting it from other organs, and increase the depth and rate of your breathing. Oxygen is carried in the blood in hemoglobin and in the muscles is stored in protein molecules called myoglobin.
These three systems kick in in sequence, begining with the Phosphogen System, then moving onto the Glycogen Lactic Acid System and finally the Aerobic System if exertion continues.
As stated earlier - muscle fibres cannot reproduce via mitosis due to their multiple nuclei. This means that in order for the muscle to get bigger, the existing fibres to become thicker. To do this the muscle must add more myofibrils which it does via their longitudinal splitting. This action however requires allot of Myosin, Actin and other proteins. The amount of protein that your muscle fibres can use is limited by the number of nuclei for each one.
When you strain a muscle from overloading you creating 'microtears' in the fibres. Don't worry though, this is how hypertrophy (or 'muscle-getting-bigger-ness') occurs. Once the fibre is recognised as damage you see, 'satellite cells' (AKA stem cells, ones which hang around ready to jump to action) will fly on over in order to repair the damage (in little cell-planes I like to believe). The single nuclei of the satelite cells however will stick around and become incorporated into the repaired fibre meaning that it has more nuclei than it did before and can use more proteins to become thicker.
1. What is ATP short for?
a. Adam Thinks Practically
b. Always Take Pills
c. Andenosine Triphosphate
d. Andronal Triphosphate
2. How many phosphates for AMP?
3. Which is the 'fastest' type of muscle fibre in humans?
a. Type I
b. Type IIa
c. Type IIb
d. Type IIx
4. What is the name of the matabolic system used to supply muscles with energy short-term?
a. Aerobic System
b. Phosphogen System
c. Glycogen Lactic Acid System
d. Glycogenic System
5. What is the name of my dog?
c. Super Bock!
6. Which two proteins make up the tiny filaments in our muscle fibre?
a. Myosin and Actin
b. Hemoglobin and Actin
c. Myosin and myofibrils
d. Sarcomeres and muscle fibres
Answers: c, b, c, b, a, a