Professor Sanjay Sharma

Professor Sanjay Sharma, Medical Director of the Virgin Money London Marathon, provides important advice about running The Vitality Big Half. Please read this advice carefully – we want you to enjoy your big day as safely and as comfortably as possible.

Before you take part in The Vitality Big Half, discuss any potential medical problems with your general practitioner (GP). The advice that follows here supplements anything they may say. Make sure you see your GP if you have any problems or concerns.

We are happy for people with serious medical conditions to run the half marathon, but only with their GP or specialist’s agreement. If you have a medical problem that may lead to you having a blackout, such as fits or diabetes, put a cross on the front of your running number and write the details, especially your medication, on the reverse of the number using a permanent marker pen.

If you have a family history of heart disease or sudden death, or you have symptoms of heart disease – such as chest pain or discomfort on exertion, sudden shortness of breath or rapid palpitations – see your GP.


Muscular aches and pains often occur after an increase in training, so aim to increase your training gradually so that you do not suffer prolonged exhaustion. You should also intersperse days of heavy mileage with one or two days of lighter training, so that your body can replace its fuel (muscle glycogen).

Adequate rest

Rest days are also important. If you have flu, a feverish cold or a tummy bug, do not train until you have fully recovered. Once you feel well again, start gently and build up gradually. Do not attempt to catch up on lost mileage after illness or injury.

Variety pack

To reduce injury risk, train on soft surfaces when you can, especially on easy training days. Vary your routes; do not always use the same shoes and run on differing cambers, hills, etc. Always face oncoming traffic.


You should always aim to replace fluids lost in sweat otherwise your body will become dehydrated and less efficient. Remember that alcoholic drinks are dehydrating: a pint of beer produces more than a pint of urine, while spirits have an even worse effect. Take on board plenty of non-alcoholic drinks, especially before the race and in hot weather. Drink enough to keep your urine a pale straw colour.

Drink plenty of liquids after training, especially long runs, and drink during races, especially in the first half of a half marathon. Practise drinking during longer training runs. Drink plenty of fluids and reduce alcohol intake in the two days before the race. But do NOT drink excessively just 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 varied 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 end of the half marathon.

Carbo loading

Do not change your normal diet drastically in the last week before the half 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.

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.)


Wear appropriate clothes for the weather. On a cold, wet day you may become very cold if you reduce your running pace or walk. A hat and gloves will prevent heat loss and are easy to carry. On Race Day, wear running shoes that you know will not give you blisters.

on the day

Do not run The Vitality Big Half if you feel unwell or have just been unwell, even if you are raising money for charity. 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 race support staff to risk serious illness and become a medical emergency. You are also unlikely to do yourself justice. There will be many other races.

drinking safely

Drinking too little can lead to problems, as you need to replace some of the fluid you lose as sweat. Drinking much too much can also be very dangerous and lead to hyponatraemia, fits and even death in The Vitality Big Half and longer distances, but sensible fluid intake is necessary even for a half marathon. Start the race well hydrated and drink when you can, especially in the first half of the race when you may not feel very thirsty.

This will help you to 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 electrolyte-free fluids (like water) before, during or after the race. It is possible to become ill from drinking too much, too quickly. There are frequent water stations but you do NOT need to drink at each one, just swallow a mouthful of water occasionally. If you like Lucozade Sport, drink that as well. Do NOT drink excessively after you finish The Vitality Big Half. You can only rehydrate gradually, so aim to have some salty food as well and you will not get hyponatraemia.

The finish area

Once you cross the Finish Line, do not stand around getting cold. Keep walking, especially if you feel dizzy, and have a drink to replace lost fluids. Go to the baggage area as soon as you can, collect your belongings and change into warm, dry clothes. Keep on drinking slowly 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 and/or not eaten anything. Again, do not drink excessively after the race.


Train sensibly. Follow this simple advice and you are unlikely to need medical aid. If you do, there are first aid points throughout the course and at the Finish Line.There will also be a medical director and full medical team in attendance on Race Day.

Advice on performance enhancing agents

Please read this advice before you run The Vitality Big Half. Adequate preparation for a half marathon requires appropriate nutrition, hydration and rest. Athletes often consume isotonic, protein and carbohydrate drinks as well as energy gels and bars purchased in sports and health food shops in preparation for the event, which is considered safe practice.

However, over the last two decades there have been an increasing number of commercially available compounds that claim to enhance performance. Some have been found to contain substances banned in other countries and other products (such as steroids) that are banned for use among competitive athletes. Such products are usually purchased via the internet and should not be used by anyone training for a sports event.

Runners using performance-enhancing compounds that have not been licensed and regulated properly may experience serious side effects and increase their risk of developing heart disturbances that culminate in sudden death.

There have been well-publicised cases of runners inadvertently using compounds in an attempt to help them fight fatigue during endurance events and this caused detrimental effects on their health, resulting in their death.

In one recent case, toxicology identified traces of DMAA, which is an amphetamine-like substance. Although banned in sport, the product was legally available at the time and advertised as a powerful performance-enhancing agent and the warnings associated with the potential harmful ingredients were not highlighted on the product. Runners should avoid consuming unregulated substances bought via the internet.