Why do exercise or sport?

The aim of exercise is to increase physical fitness and reduce the risk of disease - particularly heart disease. There are additional benefits too: better body shape, weight loss, increase in the 'feel-good' factor caused by release of transmitters in the brain - and it's often a great way to socialise.

Physical fitness means different things to different people. We frequently hear of top class athletes being 'unfit' - usually as a result of a sporting injury. They will still, however, be massively more fit than most of us, whose goals in any exercise programme are necessarily modest.

One way of measuring fitness is to perform a simple test:

The 12-Minute Run-Walk Test

For this you need a watch and a measured running area. The idea is to go round the area as fast as you can during a 12 minute period - running or walking as you wish. Those of us who do not go as far as we might like to - or as far as our friends - might find that you improve over time if it is repeated on a regular basis (it is important that the very unfit don't try to go too far too fast).

Fitness improves over a period of time with regular exercise as a result of a number of different mechanisms. Movement is caused by muscle contraction. Muscles contract using energy that comes from a chemical called ATP. This is high in energy, and the energy released when ATP is broken down, causing the muscle to contract. If the process involves oxygen then this is called Aerobic - and is the main method by which we produce the energy for exercise (some muscles, used for very short bursts of exercise, contract by a method which does not use oxygen - called Anaerobic.

Exercise and Recovery Rates

In order to improve our fitness, we need to exercise at 75% of our maximum level of activity for at least 15 minutes three times a week. Our maximum level is that which produces a heart rate of 220 minus our age in years. So a 30-year old should exercise hard enough to produce a rate of about 140 beats per minute, for at least 15 minutes, at least 3 times a week.

A simple method of assessing any improvement in fitness is to measure how quickly the heart rate returns to normal. An average person should have a heart rate at rest (sitting quietly for 5 minutes) of between 50 and 90 beats per minute. Try stepping up and down two steps at a rate of 25 steps per minute for 3 minutes. Sit down and rest for 10 seconds, and take your pulse again to assess your rate of recovery.

• If the rate is greater than 120 beats per minute (bpm) your recovery is poor.
• If the rate is 95 - 110 bpm it is average.
• If the rate is 80 - 95 bpm then it is good.
• Below 80bpm is excellent.

This gives a guide to how much exercise you should sensibly take: Those with poor recovery should initially exercise only to 50% - 55% of maximum heart rate; the average recovery to 65%, and the good to 75%. As we continue to exercise recovery rates will improve. This comes about because our circulation and the way the muscles use oxygen both become more efficient.

Cardiac Output

The amount of blood the heart pumps each minute - increases, so more blood circulates, and the muscles become more effective in the way they contract and the way they remove the lactic acid that is produced as a by-product of metabolism. So another measure of fitness is how effectively we use the oxygen we breathe. This can be checked in a laboratory and is called the maximum oxygen uptake.

Oxygen Uptake

Different sports demand different amounts of oxygen - billiards less than ballroom dancing, which uses less than basketball. An unfit person might manage about 40ml.kg-1.min-1, while a top class cross-country skier will use 80.
You can assess your own fitness without being wired up in a laboratory by doing another test.

The Step Test

Instructions

You need a bench or chair, 40cm high for males and 33cm high for females.

Step up and down (making sure you stand straight on the chair - so all your weight is lifted) 30 times a minute for 6 minutes. Count your pulse for 10 seconds and multiply by 6.

Use the chart on the right by joining up your weight on the right hand side and your pulse on the left (note male or female). At the point your line crosses in the middle is your maximum oxygen uptake in litres per minute. Change it to mls per kilogram per minute - 40 is, as it says above, unfit. See if you can improve.

Weight loss comes about because we burn off more than we take in. Much of the energy we use comes from glucose - and fat. We don't need to take in a lot extra to put on a lot extra! A little excess of 100kcal (a small chocolate bar) per day will put on 5kg of fat per year. An 80kg 20-year old who is inactive will use roughly 450kcal of energy less per day than one who does light excercise - that equates to 4 chocolate bars. At the end of the day you can either eat less or excercise more - Get fitter, not fatter.

What you need to know

Exercise can mean many things to many people, on one hand it can be something that is fun and enjoyable, whereas on the other it can be seen as a chore and is often avoided. The truth is that most people actually feel better after doing even just moderate amounts of exercise, but unfortunately the problem is that many of us just cannot find the time, energy or inspiration to do it in the first place. Clearly some people are not able to do exercise due to disability, old age or illness, but for everyone else it should be a part of daily routine.

The reasons for doing exercise are numerous and are important for maintaining health, fitness and general well-being. For optimum benefits exercise should always be combined with good basic nutrition and plenty of rest. The following outlines the main benefits of regular exercise.

Reduces heart disease – when we exercise our heart works harder to supply muscles with oxygen and glucose.  The more regularly we exercise the stronger the heart becomes, and as it pumps with more power it improves the flow of blood around the circulatory system so that each cell of every organ gets a good supply nutrients. By the same token, waste products can be carried away more efficiently.

A stronger flow of blood reduces the chance of cholesterol clogging up the arteries, a major cause of Atherosclerosis, stroke and cardiovascular disease (heart disease).
Regular moderate exercise has been shown to be the single most important factor in the survival of elderly cardiac patients and is the factor that is more important than drugs, diet and supplements. It must however be noted that supplementing with Creatine strengthens the heart and enables older athletes to do more exercise.

Lowers blood pressure - aerobic and resistive exercise (weight-training) has been shown to reduce blood pressure. Even gentle movement such as those undertaken when doing T’ai Chi has also shown to be effective. Start with a gentle exercise program and always consult a doctor before lifting very heavy weights or doing very strenuous exercise if you have very High blood pressure.

Lowers Cholesterol – Studies show that regular exercise keeps high cholesterol under control, it not only lowers the bad cholesterol (LDL) and triglycerides, it also raises the level of protective good cholesterol (HDL). This is also an important factor in reducing the risk of heart disease.

Improves insulin sensitivity – Research shows that people who exercise are less likely to develop non-insulin dependent diabetes mellitus (adult onset – type 2) and that those that already have insulin dependant diabetes mellitus (type 1) can get by with lower levels of insulin medication. It is however best to check with a doctor if you already are a diabetic before starting any exercise regime.

Weight control – exercise uses energy, which is measured in calories (Kcal). Many of us consume too many calories from foods due to fact that they are eating high fat, high sugar convenience foods and drinking far too many alcoholic beverages. Unused calories are stored as body-fat, which makes us overweight. Too many calories from food and lack of exercise is the major cause of Obesity in the western world. Exercise helps to burn off these excess calories from both our diet and stored body-fat and can control weight in two main ways.