Components of components of components…

By the end of my last post, science had reached the level of GCSE physics/chemistry; the world is made of atoms, atoms consist of electrons orbiting a nucleus, and a nucleus consists of a mixture of positively charged protons and neutrally charged neutrons. Some thought that this was the deepest level things could go; that everything was made simply of these three things and that they were the fundamental particles of the universe. However, others pointed out the enormous size difference between an electron and proton, suggesting that the proton and neutron were not as fundamental as the electron, and that we could look even deeper.

In any case, by this point our model of the inside of a nucleus was incomplete anyway; in 1932 James Chadwick had discovered (and named) the neutron, first theorised about by Ernest Rutherford to act as a ‘glue’ preventing the protons of a nucleus from repelling one another and causing the whole thing to break into pieces. However, nobody actually had any idea exactly how this worked, so in 1934 a concept known as the nuclear force was suggested. This theory, proposed by Hideki Yukawa, held that nucleons (then still considered fundamental particles) emitted particles he called mesons; smaller than nucleons, they acted as carriers of the nuclear force. The physics behind this is almost unintelligible to anyone who isn’t a career academic (as I am not), but this is because there is no equivalent to the nuclear force that we encounter during the day-to-day. We find it very easy to understand electromagnetism because we have all seen magnets attracting and repelling one another and see the effects of electricity everyday, but the nuclear force was something more fundamental; a side effect of the constant exchange of mesons between nucleons*. The meson was finally found (proving Yukawa’s theory) in 1947, and Yukawa won the 1949 Nobel Prize for it. Mesons are now understood to belong to a family of particles called gluons, which all act as the intermediary for the nuclear strong force between various different particles; the name gluon hints at this purpose, coming from the word ‘glue’.

*This, I am told, becomes a lot easier to understand once electromagnetism has been studied from the point of view of two particles exchanging photons, but I’m getting out of my depth here; time to move on.

At this point, the physics world decided to take stock; the list of all the different subatomic particles that had been discovered became known as ‘the particle zoo’, but our understanding of them was still patchy. We knew nothing of what the various nucleons and mesons consisted of, how they were joined together, or what allowed the strong nuclear force to even exist; where did mesons come from? How could these particles, 2/3 the size of a proton, be emitted from one without tearing the thing to pieces?

Nobody really had the answers to these, but when investigating them people began to discover other new particles, of a similar size and mass to the nucleons. Most of these particles were unstable and extremely short-lived, decaying into the undetectable in trillionths of trillionths of a second, but whilst they did exist they could be detected using incredibly sophisticated machinery and their existence, whilst not ostensibly meaning anything, was a tantalising clue for physicists. This family of nucleon-like particles was later called baryons, and in 1961 American physicist Murray Gell-Mann organised the various baryons and mesons that had been discovered into groups of eight, a system that became known as the eightfold way. There were two octets to be considered; one contained the mesons, and all the baryons with a ‘spin’ (a quantum property of subatomic particles that I won’t even try to explain) of 1/2. Other baryons had a spin of 3/2 (or one and a half), and they formed another octet; except that only seven of them had been discovered. Gell-Mann realised that each member of the ‘spin 1/2’ group had a corresponding member in the ‘spin 3/2’ group, and so by extrapolating this principle he was able to theorise about the existence of an eighth ‘spin 3/2’ baryon, which he called the omega baryon. This particle, with properties matching almost exactly those he predicted, was discovered in 1964 by a group experimenting with a particle accelerator (a wonderful device that takes two very small things and throws them at one another in the hope that they will collide and smash to pieces; particle physics is a surprisingly crude business, and few other methods have ever been devised for ‘looking inside’ these weird and wonderful particles), and Gell-Mann took the Nobel prize five years later.

But, before any of this, the principle of the eightfold way had been extrapolated a stage further. Gell-Mann collaborated with George Zweig on a theory concerning entirely theoretical particles known as quarks; they imagined three ‘flavours’ of quark (which they called, completely arbitrarily, the up, down and strange quarks), each with their own properties of spin, electrical charge and such. They theorised that each of the properties of the different hadrons (as mesons and baryons are collectively known) could be explained by the fact that each was made up of a different combination of these quarks, and that the overall properties of  each particle were due, basically, to the properties of their constituent quarks added together. At the time, this was considered somewhat airy-fairy; Zweig and Gell-Mann had absolutely no physical evidence, and their theory was essentially little more than a mathematical construct to explain the properties of the different particles people had discovered. Within a year, supporters of the theory Sheldon Lee Glashow and James Bjorken suggested that a fourth quark, which they called the ‘charm’ quark, should be added to the theory, in order to better explain radioactivity (ask me about the weak nuclear force, go on, I dare you). It was also later realised that the charm quark might explain the existence of the kaon and pion, two particles discovered in cosmic rays 15 years earlier that nobody properly understood. Support for the quark theory grew; and then, in 1968, a team studying deep inelastic scattering (another wonderfully blunt technique that involves firing an electron at a nucleus and studying how it bounces off in minute detail) revealed a proton to consist of three point-like objects, rather than being the solid, fundamental blob of matter it had previously been thought of. Three point-like objects matched exactly Zweig and Gell-Mann’s prediction for the existence of quarks; they had finally moved from the mathematical theory to the physical reality.

(The quarks discovered were of the up and down flavours; the charm quark wouldn’t be discovered until 1974, by which time two more quarks, the top and bottom, had been predicted to account for an incredibly obscure theory concerning the relationship between antimatter and normal matter. No, I’m not going to explain how that works. For the record, the bottom quark was discovered in 1977 and the top quark in 1995)

Nowadays, the six quarks form an integral part of the standard model; physics’ best attempt to explain how everything in the world works, or at least on the level of fundamental interactions. Many consider them, along with the six leptons and four bosons*, to be the fundamental particles that everything is made of; these particles exist, are fundamental, and that’s an end to it. But, the Standard Model is far from complete; it isn’t readily compatible with the theory of relativity and doesn’t explain either gravity or many observed effects in cosmology blamed on ‘dark matter’ or ‘dark energy’- plus it gives rise to a few paradoxical situations that we aren’t sure how to explain. Some say it just isn’t finished yet, and that we just need to think of another theory or two and discover another boson. Others say that we need to look deeper once again and find out what quarks themselves contain…

*A boson is anything, like a gluon, that ‘carries’ a fundamental force; the recently discovered Higgs boson is not really part of the list of fundamental particles since it exists solely to effect the behaviour of the W and Z bosons, giving them mass

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The Science of Iron

I have mentioned before that I am something of a casual gymgoer- it’s only a relatively recent hobby, and only in the last couple of months have I given any serious thought and research to my regime (in which time I have also come to realise that some my advice in previous posts was either lacking in detail or partially wrong- sorry, it’s still basically useful). However, whilst the internet is, as could be reasonably expected, inundated with advice about training programs, tips on technique & exercises to work different muscle groups (often wildly disagreeing with one another), there is very little available information concerning the basic science behind building muscle- it’s just not something the average gymgoer knows. Since I am fond of a little research now and then, I thought I might attempt an explanation of some of the basic biology involved.

DISCLAIMER: I am not a biologist, and am getting this information via the internet and a bit of ad libbing, so don’t take this as anything more than a basic guideline

Everything in your body is made up of tiny, individual cells, each a small sac consisting of a complex (and surprisingly ‘intelligent’) membrane, a nucleus to act as its ‘brain’ (although no-one is entirely sure exactly how they work) and a lot of watery, chemical-y stuff called cytoplasm squelching about and reacting with things. It follows from this that to increase the size of an organ or tissue requires these cells to do one of two things; increase in number (hyperplasia) or in size (hypertrophy). The former case is mainly associated with growths such as neoplasia (tumours), and has only been shown to have an impact on muscles in response to the injection of growth hormones, so when we’re talking about strength, fitness and muscle building we’re really interested in going for hypertrophy.

Hypertrophy itself is still a fairly broad term biologically, and only two aspects of it are interesting from an exercise point of view; muscular and ventricular hypertrophy. As the respective names suggest, the former case relates to the size of cells in skeletal muscle increasing, whilst the latter is concerned with the increase in size & strength of the muscles making up the walls of the heart (the largest chambers of which are called the ventricles). Both are part of the body’s long-term response to exercise, and for both the basic principle is the same- but before I get onto that, a quick overview of exactly how muscles work may be in order.

A muscle cell (or muscle fibre) is on of the largest in the body, vaguely tubular in shape and consisting in part of many smaller structures known as myofibrils (or muscle fibrils). Muscle cells are also unusual in that they contain multiple cell nuclei, as a response to their size & complex function, and instead of cytoplasm contain another liquid called sarcoplasm (more densely packed with glycogen fuel and proteins to bind oxygen, and thus enabling the muscles to respire more quickly & efficiently in response to sudden & severe demand). These myofibrils consist of multiple sections called myofilaments, (themselves made of a family of proteins called myosins) joined end-to-end as repeating units known as sarcomeres. This structure is only present in skeletal, rather than smooth muscle cells (giving the latter a more regular, smoothly connected structure when viewed under the microscope, hence the name) and are responsible for the increased strength available to skeletal muscles. When a muscle fibril receives an electrical impulse from the brain or spinal cord, certain areas or ‘bands’ making up the sarcomeres shrink in size, causing the muscle as a whole to contract. When the impulse is removed, the muscle relaxes; but it cannot extend itself, so another muscle working with it in what is known as an antagonistic pair will have to pull back on it to return it to its original position.

Now, when that process is repeated a lot in a small time frame, or when a large load is placed on the muscle fibre, the fibrils can become damaged. If they are actually torn then a pulled muscle results, but if the damage is (relatively) minor then the body can repair it by shipping in more amino acids (the building blocks of the proteins that make up our bodies) and fuel (glycogen and, most importantly, oxygen). However, to try and safeguard against any future such event causing damage the body does its bit to overcompensate on its repairs, rebuilding the protein structures a little more strongly and overcompensating for the lost fuel in the sarcoplasm. This is the basic principle of muscular hypertrophy; the body’s repair systems overcompensating for minor damage.

There are yet more subdivisions to consider, for there are two main types of muscular hypertrophy. The first is myofibrillated hypertrophy, concerning the rebuilding of the myofibrils with more proteins so they are stronger and able to pull against larger loads. This enables the muscle to lift larger weights & makes one stronger, and is the prominent result of doing few repetitions of a high load, since this causes the most damage to the myofibrils themselves. The other type is sarcoplasmic hypertrophy, concerning the packing of more sarcoplasm into the muscle cell to better supply the muscle with fuel & oxygen. This helps the muscle deal better with exercise and builds a greater degree of muscular endurance, and also increases the size of the muscle, as the increased liquid in it causes it to swell in volume. It is best achieved by doing more repetitions on a lower load, since this longer-term exercise puts more strain on the ability of the sarcoplasm to supply oxygen. It is also advisable to do fewer sets (but do them properly) of this type of training since it is more tiring; muscles get tired and hurt due to the buildup of lactic acid in them caused by an insufficient supply of oxygen requiring them to respire anaerobically. This is why more training on a lower weight feels like harder work, but is actually going to be less beneficial if you are aiming to build muscular strength.

Ventricular (or cardiac) hypertrophy combines both of these effects in a response to the increased load placed on the muscles in the heart from regular exercise. It causes the walls of the ventricles to thicken as a result of sarcoplasmic hypertrophy, and also makes them stronger so that the heart has to beat less often (but more powerfully) to supply blood to the body. In elite athletes, this has another effect; in response to exercise the heart’s response is not so much to beat more frequently, but to do so more strongly, swelling more in size as it pumps to send more blood around the body with each beat. Athletic heart syndrome, where the slowing of the pulse and swelling of heart size are especially magnified, can even be mistaken for severe heart disease by an ill-informed doctor.

So… yeah, that’s how muscle builds (I apologise, by the way, for my heinous overuse of the word ‘since’ in the above explanation). I should point out quickly that this is not a fast process; each successive rebuilding of the muscle only increases the strength of that muscle by a small amount, even for serious weight training, and the body’s natural tendency to let a muscle degrade over time if it is not well-used means that hard work must constantly be put in to maintain the effect of increased muscular size, strength and endurance. But then again, I suppose that’s partly what we like about the gym; the knowledge that we have earned our strength, and that our willingness to put in the hard work is what is setting us apart from those sitting on the sofa watching TV. If that doesn’t sound too massively arrogant.