The Appliance of Science

By John Swindells 07 May 1996 | Comment
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It's really daft when you consider that most of the folks you see jogging up and down the street 'getting fit' actually have little or no idea about what 'fitness' actually is. It's rather like an extremely short-sighted man saying 'I'm going to drive to Wales' then jumping into a car with no steering wheel and even forgetting to take a road map with him. Without even the most basic understanding of the principles of physical fitness, our enthusiastic jogger will spend the rest of his running career going around in metaphorical circles looking for that elusive turn of speed.

'No pain, no gain' is a commonly held belief. Those awful Rocky and Van Damme films compound this myth, showing blokes absolutely wrecking themselves with excruciating training regimes in order to 'get fit'. I lived in Waveney in my first year and one of my favourite pastimes was to watch the endless stream of nutters absolutely crucifying themselves running up and down Waveney mountain. Up and down, up and down....

I was primarily a touring cyclist before I started at UEA, you know, plodding around at 13mph with all my racks loaded with bags, stopping every few miles for a sandwich etc, etc. Despite this hardly being 'training, when I finally got around to having a go at racing I got quite a shock. I was a helluva lot fitter than I thought I was! So, the moral of the story is 'Take It Easy'. However, I was sufficiently hooked on the mysteries of training and sports science to delve a little further and, not surprisingly, to take a step upwards into higher levels of fitness takes a little more effort.

The basic index of physical fitness is something called 'VO2 Max' which is essentially the maximum rate at which your body can take up oxygen and burn it in the muscles. A 'fit' person has an ability to absorb oxygen much more efficiently than an 'unfit ' person. As oxygen supply is the chief limiting factor in the metabolism of a speeding athlete, the chap with the biggest VO2 Max will go faster. It's rather like tuning a bog standard car to change it into a racing car, the faster you can get the fuel and air into the engine, the more power it will produce. Heart and lungs become carburettors, legs become the 'engine'.

But the car analogy doesn't just stop there. I once tuned a Mini of mine until it was producing nearly three times as much power as it had when when it came out of the factory. Not surprisingly it used to give all the sleek sports cars a good run for their money, it would go from 0-60 faster than an Escort RS turbo and do well over 100mph in third gear! Naturally, all this power had to come from somewhere, namely a petrol pump, so when tearing around like an idiot I would get awful fuel consumption figures for it. However, when driven steadily at 60mph on a motorway, the car was nearly 25% more fuel efficient than its non-tuned counterpart, chiefly because of the increased efficiency of the engine. The same is true for atheletes. A big VO2 Max means that you will run/cycle like the Devil himself when flat out, but you will also be able to cycle longer distances much easier and quicker because your body is so 'tuned' and efficient that it will hardly be working.

So how do I improve my VO2 Max?

Easy answer: Very slowly! To go from a couch potato to an international athlete would probably take 6-8 years of intensive, structured training. But despair not, because the first couple of years or so of this process is very rapid indeed and absolutely staggering increases in fitness can occur in just a few months. After this period, the improvement curve tails off markedly and you go from increasing by huge leaps to only a few per cent per year very quickly. Depends how determined you are really.

At the very highest level it is obviously very important.

VO2 Max is best improved by training at specific intensities. The body is making profound physiological changes to increase it, the lungs and muscles grow new blood vessels and capilliaries to boost fuel supplies and the muscle cells themselves grow ne w mitochondria, the energy producing part, to take advantage of this increased supply. The actual process of 'getting fit' works something like this:

The body is working hard and respiration is becoming stressed. Oxygen supplies are dwindling because the lungs can't quite keep up. As a result, respiration is not quite working properly and the muscles, although continuing to produce power, are having to leave respiration 'incomplete', releasing a cocktail of intermediate compounds into the blood instead of the text book 'Water + Carbon Dioxide'. These compounds are effectively toxins and the body doesn't like having them around. So, the next day w hen everything is back to normal, the body decides to do all it can to stop such a build up of toxins happening again in future. It begins to adapt to training very, very slowly by initiating the physiological effects described above. Repeated frequently, a gradual improvement is inevitable - You are officially 'getting fitter'.

The 'toxin' is in fact Lactic Acid which comes about by the incomplete oxidation of carbohydrate fuel. Lactic acid is removed from the body by eventually oxidising it completely to water and carbon dioxide when there is enough oxygen to spare, i.e. when exercise is stopped or the intensity reduced. It is the result of so-called 'anaerobic' respiration, exactly what those nutters running up and down Waveney mountain are experiencing. Knowing this much, it is tempting to think that more lactic acid equals the most rapid fitness gains. Wrong!! Lactic acid is a toxin, in high concentrations it does profound physical but ultimately repairable damage to the body. Constant high lactate episodes will leave you wrecked and run down, you will feel dreadful, catch every little virus doing the rounds, have no appetite and may even be unable to sleep properly. So, you won't exactly be getting fit! Lower doses aren't so bad though, in fact, the way to get the greatest benefit from training is to just maintain a small amount in the blood (4mM/L to be exact) during exercise. In this way, your body is 'getting the message' to adapt whilst not being damaged in any way.

So the trick then is to train neither too steadily or too intensely.

How do I know if I'm doing it right?

Really hard exercise is 'anaerobic', that is the body continues to produce power, despite not having enough oxygen to burn, by forming lactic acid. It's a 'buy now, pay later' scenario, the lactic acid is oxidised fully only when exercise is stopped an d the body repays its 'oxygen debt'. Clearly then, if the workout is long, lactic acid levels will continue to rise steadily until the body has had enough. That awful tight, stinging feeling in your legs (after running up Waveney mountain for example!!) is lactic acid. Once you have that much crap in your muscles, you physically can't keep going, everyone has experienced this at some point. Anaerobic exercise has a very short endurance therefore.

Aerobic exercise probably speaks for itself, the body is working like an engine on a steady motorway drive, carbohydrates and oxygen burning to give water and carbon dioxide. In theory, providing you were keeping yourself stoked up with chips etc, you could cycle forever! Providing you stay well within your 'aerobic capacity', that is, well below the anaerobic threshold described previously, you will keep big doses of lactic acid at bay.

Another thing that not many people realise is that there are four different energy producing systems in the body. At the most extreme level there is the 'Creatine Phosphate' system which is good for about 20 seconds at the most, it's what the likes of Linford Christie make use of. It's about really fast, explosive power.

Next step down is the 'Lactic Glycolysis', the anaerobic system that I've just explained.

Then we have the 'Alactic (or Aerobic) Glycolysis' system, the aerobic system employed for quite hard aerobic exercise.

Finally, there is the 'Fat Oxidation' system which powers the body most of the time by burning fat as fuel instead of precious muscular glygogen. The hierarchy in these systems is that each successive one needs less oxygen than the other to produce an equivalent amount of power. In times of oxygen shortage, the body will 'turn on' the next one up to maintain the supply of energy. For example, a brisk walk across campus would be maintained fairly well by the Fat Ox system but if you suddenly realised you were late for a lecture and decided to break into a gentle jog, the Fat Ox system would not be able to keep up and so you would begin Alactic Glycolysis. The hourly beep on your watch then tells you just how late you really are and so you pick up the speed of your jog somewhat. Again, demand is increased to such an extent that there is insufficient oxygen to complete respiration fully and so you begin to build your 'oxygen debt' by accumulating lactic acid during Lactic Glycolysis. Horribly late, y ou arrive at the building but the room you want is on the next floor up, so you rocket up the stairs like a loony, an act that even lactic glycolysis can't support. Your body now turns on it's last reserve, the Creatine Phosphate system which just about sees you to the top of the steps. Made it! As you sit in the lecture desperately trying not to puff and pant too much, your body 'reloads' the Creatine Phosphate system and repays your oxygen debt. Within ten minutes, it's as if nothing ever happened a nd you're yawning for all you're worth.

Although you don't know any of this is going on, it's interesting to note that, as you get fitter, you begin to be able to feel quite accurately which system is being turned on and off, i.e. how hard you are working.

So, we now know enough about the energy systems in the body to work out a decent training programme:

Weight loss programmes must by their nature be of a fairly low intensity to promote the fat oxidation system; you are trying to burn fat after all. People attending aerobics sessions, particularly Step sessions and especially Keith Grasby's circuit training sessions, miss this point entirely. Again, like the Waveney mountain loonies, they are all absolutely killing themselves, going at it so hard that their fat oxidation systems gave up the ghost ages ago. Virtually all are well up to their aerobic glycolysis intensity, most are even anaerobic and are defeating the whole object of the exercise. Glycogen, the muscular fuel that they are burning, is simply replaced by the carbohydrates that they eat afterwards, not from their body fat. By coincidence, some might be just at the right intensity to promote a good fitness response but it won't make them thin as quickly as they might like. Those going too hard aren't even getting fitter, they are just wrecking themselves with huge lactate doses. The best way to lose weight is by taking lots of brisk walks or steady bike rides, thus keeping the intensity down. But body fat stores tremendous amounts of energy, that is why we have it. Even a fairly lean person has enough stored body fat to power them through hundreds of hours of steady exercise. Just like fitness training, weight loss programmes have to be taken slowly.

So, fat oxidation intensity is nice for weight loss but not much good for serious fitness training. Similarly anaerobic glycolysis is no good either, it's too much. So the key system is obviously the aerobic or alactic glycolysis one. The good thing about this system is that, even at it's lowest level, it produces tiny amounts of lactic acid that promote the body's fitness response. Unlike the anaerobic system, the ready supply of oxygen means that these small amounts are kept in check, they remain in dynamic equilibrium. At a given, constant intensity, you will have a constant small concentration of lactic acid in you blood, it doesn't run away and go sky high.

The optimum blood lactic acid, or lactate, level is 4mM/L as I mentioned earlier. This is achieved by working at the very threshold of your aerobic capacity, sort of in the no-man's lands between aerobic and anaerobic intensity. Unfortunately, the sup ply of glycogen in the muscles and liver is finite, most people have enough for just over an hour's work at such an intensity before it is gone. Obviously, with no fuel left, you don't go, simple as that! Worse still, it takes a good two to three days t o reload a fully depleted reservoir of glycogen so you'd be limited to a couple of short workouts a week. No good really, the time that your body is subjected to stimulated lactate levels is important, the longer the better obviously. So, a compromise is required. This is obvious too - simply go out and train for two hours at a slightly lower intensity or three hours lower still. Any amount of switching on of the aerobic glycolysis system generates useful amounts of lactic acid. There is considerable overlap of the regimes of the body's energy systems too, there is a similar 'no-man's land' between the fat oxidation and glycolysis sytems as there is between the aerobic and anaerobic glycolysis systems. So, low lactate rides of many hours are possible by say, utilising 50% fat power and 50% glycogen power. In the trade, this is known as a 'Level 2' workout which brings me onto the 'Levels' concept of training.

Intensity and the correlation with heart rate

If you follow cycling or athletics you will probably have heard about heart monitors and their increasing use in training. All they are is an extremely accurate way of knowing exactly what intensity and hence blood lactate level you are training at. The result is extremely high quality training with performance increases to match.

There is an incredibly accurate and reliable relationship between blood lactate levels and heart rate. From day to day, if you're on your bike and know what your pulse rate is, you can predict exactly what your blood lactate level is, simple as that.

Pulse training is built around intensity 'Levels' and you'll frequently see these refered to in cycling mags. 'Level 1' corresponds with solely the fat oxidation system, that is, it is employed at low intensities. 'High Level 1' occurs at the fat burning and glycolysis passing zone so stimulates small amounts of lactic acid. 'Level 2' employs a more equal mix of aerobic fat and glycogen power and is used for slightly harder workouts. Because of the limited supplies of glycogen, these clearly have a limited duration. 'Level 3' employs chiefly the aerobic glycolysis system, it is far too intense for fat burning power to sustain to any degree. A hard level three workout is difficult to do for over an hour as the depletion of muscular glycogen is incredibly rapid. 'Level 4' workouts involve a high degree of anaerobic work because they are so intense. As mentioned earlier, regular anaerobic workouts can damage the body but, if structured properly, can increase the body's tolerance to lactic acid over time. This is particularly important for maintaining very high intensities during short time trials. The intricasies of training to the Level system are beyond the scope of this introductory ramble, but are covered in greater detail in 'Finger on the Pulse'. The great thing about these levels is that they always occur in a zone between specific heart rates and so, once you've 'calibrated' yourself, you can go out and train a particular system very accurately. This is often refered to as 'quality' training (as opposed to 'junk' training). Depending on what exactly you want your body to be good at, you simply chose a training programme to focus on your chosen target. Needless to say, such high quality training yields pretty dramatic increases in performance.

All this high technology is fine, but what if you haven't got a heart monitor? Well, Level 2 represents a good regime for boosting all round fitness and, pretty much like athletes had to in the 'old days', it's easy to do as it has a very wide zone. As a rough guide, if you are riding without pushing too hard on the pedals and just so that you are breathing fairly deeply, then you're about there. Being able to easily hold a conversation is a good guide, as is 'riding without puffing' and try to get out for an hour or so. If you feel knackered after just an hour, you have been probably been at Level 3 - Slow down!

If this is all a bit hit and miss for you, the club has a few heart monitors for members to use. Leave a note on e-mail or in the club pigeon hole if you want one. Failing that, you can ask to borrow one of the Sports Centre heart monitors from reception. Simply produce you registration card, explain you are with the cycling club and one should be handed over. I would advise however that either myself or Dave Cooper accompanies you on your first ride with it. I would especially advise that you at l east read the second instalment of this guide or it will all be completely meaningless anyway.

Any time spent riding your bike is never wasted but the point of this little article is try and show that, just because a little training is good for you, it doesn't follow that more has to be even better. I have experienced what is known as 'Over-Training Syndrome' and it isn't very nice, in fact it is a recognised clinical illness. Your body isn't a machine and is a lot more fragile than you probably like to think. Go easy on yourselves!

Andy Tyler

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About the author

My name is John Swindells and I'm a keen recreational cyclist with a preference for long one-day rides. I've also previously dabbled in time trialling and cyclo-cross. See more of what I get up to on Strava!