Dr David Baldwin examines the importance of exercise in his light-hearted but practical guide.
Measuring your physical fitness
The oxygen required for aerobic exercise obviously comes from air that's inhaled into the lungs and then passed to the individual muscle cells via the bloodstream.
The major rate-limiting step in the process of aerobic metabolism is not only the lungs' ability to provide oxygen from inhaled air, but also the heart's ability to pump blood around the body and the number of specialised mitochondria present in the muscle cells. The best way to measure the aerobic power of your body, or your cardio-respiratory fitness, is to work out your VO2max - otherwise known as maximal oxygen uptake.
VO2max can be measured very accurately in the laboratories of bald-headed, brainy bastards by using fancy measuring devices to determine the actual amount of oxygen used by your body (they measure the expired gases - which don't include farts. At least, I don't think so) when you are put on a treadmill and made to perform at graduated levels of intensity.
Most people don't have access to these facilities, however, so the second option is to use your heart-rate response to maximal exercise. This is based on the fact that your heart rate will increase in a direct linear relationship with exercise intensity to a point where the body's maximal heart rate is reached; this will then equate to the body's VO2max.
The accepted method of calculating maximal heart rate during exercise is to use this formula: 220 minus your age equals your maximal heart rate. Example: I am a very young 51 years old, so my expected maximal heart rate will be about 170 beats/minute.
The third option is to calculate your heart-rate response to submaximal exercise using various charts and formulae.
This is the method that's most commonly used by local gyms because it's safer for old farts like me not to be reaching our maximal heart-rates all the time, because of the potential risks of heart strain.
The charts that have been developed can accurately extrapolate your heart rate recordings to your theoretical maximal levels (these are generally plastered all over the gym walls but, unfortunately, they're usually located in between even bigger posters of the gorgeous bodies that I will never have).
It's important to remember when measuring your maximum heart-rate response at either maximal or submaximal exercise levels that it's only a guide, because there is a wide individual variation in heart rates. But still, the advantages of being able to estimate your aerobic fitness reasonably accurately using the VO2max calculation are considerable.
As you train using a given exercise programme, you should be able to see a gradual increase in your VO2max as you progress and become aerobically fitter. The general rule of thumb with regard to quality training to improve your aerobic fitness, and thus to reap the many health benefits of aerobic fitness, is to train at a level that keeps your heart rate at 70 per cent of your maximal heart rate level for a given period of time - in my case, at 51 years young, this would be 120 beats/min.
How to improve your fitness level
Once you have decided to improve your fitness, you can either just do it yourself or head off to the local gym and spend some dough getting expert advice and using good-quality gear.
Using a gym has many added advantages, such as having plenty of mirrors in which you can view yourself from different angles, and the chance to show off your latest one-piece shiny lycra training suit.
On a more sensible note, though, gyms are becoming increasingly popular because many have well-trained staff and good safety procedures to ensure you don't overdo it, don't have any medical conditions that could put your life at risk, and to determine if you have any special needs while exercising.
EXERCISE RULES
Whatever exercise programme you decide to follow, there are a few general rules that should be followed.
Plan out an exercise programme for a prolonged period of time so that you can set goals for what you want to achieve, and make sure they suit your lifestyle and aspirations. This is where a trained advisor is very useful. Many people enjoy a programme that has a mixture of different exercises, like swimming, running, bike riding and yoga, which makes it more fun.
If you have a medical problem, discuss with your GP what type of exercise is appropriate.
Build up your level of exercise slowly to avoid putting an unexpected strain on your possibly unfit cardiovascular system - it can be dangerous! Likewise, don't exercise vigorously when you have a viral infection because it can be very hard to tell if the infection involves the heart - an infected heart is very susceptible to firing off nasty heart rhythms when put under the strain of hard exercise.
Warm up before you start a vigorous exercise programme. When you feel the muscles are warm and relaxed, do some stretching exercises of the main muscle groups (don't stretch cold muscles).
Regular exercise is required to build up fitness (at least 30 minutes of exercise five times a week, in which you get your heart rate up to 70 per cent of your predicted maximum) rather than a burst of activity every now and again.
If you jog or do a bit of fast walking for long distances, then a warm down with a period of slower and more gentle walking followed by some light stretches will help your body recover quickly.
Extracted from Healthy Bastards: A Bloke's Guide to Being Healthy, by Dr Dave Baldwin, Random House, $37.99
