Fluids lost in sweat must be replaced otherwise your body becomes dehydrated and less efficient. Alcoholic drinks are dehydrating. A pint of beer produces more than a pint of urine; spirits have a worse effect. Take plenty of non-alcoholic drinks, especially before the race and in hot weather. Thirst is a poor guide to how much you need. Drink enough to keep your urine copious and a pale straw colour. Drink plenty of liquids after training, especially long runs, and drink during races, especially in the first half of a marathon. Practice drinking during longer training runs. Drink plenty of fluids and reduce alcohol intake in the two days before the race.

Eat what suits you! Large doses of supplementary vitamins and minerals (such as iron) are not essential and produce no benefit if you are on a good mixed diet, but additional vitamin C in small doses is reasonable when fresh fruit and vegetables are in short supply.

Training helps you to sustain a high level of muscle glycogen if you eat a lot of carbohydrate. If you can, eat within two hours of your long runs and the marathon. This helps replace the muscle glycogen quickly and speeds recovery.

Do not change your normal diet drastically in the last week before the marathon, but decrease your intake of protein (meat) and increase your intake of carbohydrate (pasta, bread, potatoes, cereals, rice and sweet things), especially for the last three days when you should also be markedly reducing your training. This loads the muscle with glycogen. Unless you reduce your protein intake you will not eat enough carbohydrate. (Not all runners are helped by first depleting carbohydrate with a long run and low carbo diet and then loading – this can make your muscles very heavy).

When training in the dark, be seen. Wear white clothing and reflective flashes or bandoliers.

Many runners seek medical treatment for blisters at the start. They had either been training too hard in the final two weeks with ill-fitting shoes, or they had worn a new pair of shoes for the last long training run. Use shoes you know from experience will not give you blisters.

Do not run if you feel unwell or have just been unwell. Most medical emergencies occur in people who have been unwell but do not wish to miss the event. If you feel feverish, have been vomiting, have had severe diarrhoea or any chest pains, or otherwise feel unwell, it is unfair to you, your family, your sponsoring charity and the marathon support staff to risk serious illness and become a medical emergency. You are unlikely to do yourself justice. There are many other marathons.

If it is hot, wear loose mesh clothing, start slowly and, if possible, run in the shade. Start the race well hydrated (urine looks pale) and drink whenever you can, especially in the first half of the race when you may not feel thirsty, as you lose a lot of fluid insensibly. This will help you feel better late in the race and may prevent cramp. Cramp is most common in runners who have not trained sufficiently or are dehydrated. Do not gulp large volumes of liquid during or after the race. It is possible to become ill from drinking too much, too quickly.

Do not stand about getting cold. Keep walking, especially if you feel dizzy, and drinking to replace lost liquid, change into warm, dry clothing, and then go to the reunion area.

Keep on drinking and have something to eat. Some runners feel faint more than half-an-hour after finishing the race, often because they have taken insufficient fluid at the finish and/or not eaten anything.

Train sensibly. Follow this simple advice and you will probably not need medical aid. Medical aid posts are located about 20-50 m past the main drink stations and after the finish line. If you drop out, go to an aid station.

Keep this advice and refer to it nearer the day and on marathon eve.