The decrease in training volume leading up to a big event is called the taper. For marathon runners, three weeks is considered the optimum amount of time between the final long run and the race itself. If you haven't been training consistently, or started late, this could be shortened to a two-week taper, purely because you haven't got as many miles to recover from.

Ease off the running

After than final long run, the overall amount of training declines steadily. The length and intensity of all the sessions is reduced – but it’s the long runs that are most significantly slashed. Two weeks out from race day, your ‘long run’ should be just half the time/distance you achieved on your longest session. The week after, it’s cut in half again (so your 'long' run may actually be four to six miles). Do not worry about ‘losing’ your fitness during the taper – bear in mind that it took many weeks, or even months for those physiological adaptations to take place – they aren’t going to disappear overnight.  Research shows that reducing your training volume to a third of your highest level still allows you to maintain your cardiovascular fitness for around eight weeks, so don’t worry about a mere three weeks causing a decline in your potential.

It is not unusual to feel suddenly lethargic and heavy during the taper. This is partly because your glycogen stores are full (since you aren't continually depleting them with training), and each gram of glycogen is stored along with three grams of water. Your body also becomes accustomed to a large volume of activity, and taking this out of the equation can leave you feeling as if you could barely run a mile, let alone a marathon.

However, don’t see this as a signal to go out for a gruelling training run – simply ensure you aren't overeating, that you are well hydrated and try some 'strides' (warm up, then run about 50 metres, gradually accelerating to a nice swift pace as you go) to wake your legs up. The last two weeks of training include shorter runs and a few pacier sessions to keep you ticking over. Sticking to grass and softer surfaces will reduce impact and muscle damage, but be extra careful on uneven ground.

Perfect race planning

So what are you going to do with all this leisure time? Well, it’s a great idea to try a 'race rehearsal' –  ideally prior to one of your two final not-so-long long runs. Have your proposed pre-race dinner the night before and your pre-race breakfast the morning before the run, to ensure it all feels comfortable and nothing repeats on you or causes gastrointestinal distress. Put on the gear you intend to wear to run in, to make sure nothing chafes or flaps about. You don’t want any nasty surprises on the day.

This is also the perfect time to devise your race strategy. (And, no, 'get to the finish line in one piece' does not constitute a race strategy.) Every runner stands on the start line with a target finish time in mind. Beginners are often surprised by me saying this, telling me that most marathon programmes advise that first-timers don’t try to aim for a finish time. But having a finish time in mind isn’t about pushing yourself all the way or putting pressure on yourself – it’s simply an insurance against setting off too fast (or more improbably, holding back too much) so that what you achieve in the race reflects what you were capable to doing in training.

Split times advice

Once you've got an idea of your finish time, you need to work out your 'split times'. Split times are simply the amount of time it takes you to complete any given section of the course – it could be each mile or kilometre, every 10k, or the first and second half of the race, depending on how much information you are willing to cope with.

When projecting your finish time and splits, think about the times and speeds you have accomplished in your training. If you know, for example, that you have run 18 miles at a speed of nine minutes per mile in training – and felt shattered afterwards – let’s face it, it is unlikely that you’ll be able to run a further eight miles at the same speed on race day. But slowing your pace by an extra 30-60 seconds a mile will make the race far more comfortable, and your likelihood of success greater. If this is your first marathon, be conservative in your target – the idea is to complete, not compete.

Once you have established your target time, calculate what that equates to in terms of consistent split times for each mile (bearing in mind that you will undoubtedly be slower on the first two or three miles, as you jostle for space with the thousands of other runners). For more information, see the box below to find out how to convert your target time into splits.

Many experts advocate a ‘negative split’ for marathon running, in which you aim to run the second half of the race slightly faster than the first half. Whether you go for a negative split or even splits, you certainly don’t want to be slowing down as the miles pass – a sure recipe for hitting the dreaded wall.

Put your feet up

Try to get plenty of rest during the final few days. Avoid spending more time than you have to on your feet, or doing tiring activities such as gardening or DIY. Even if you don't sleep well the night before, you will be fine as long as you are well rested in the lead-up to the event. In the last 24 hours, if you aren't travelling to the race start make the most of your advantage and relax. Get out some uplifting videos and relax in front of the TV with a big bottle of water, read an absorbing book or go for a gentle stroll in the fresh air. This is also the ideal time to do your final check of all your kit and race instructions and run through your race plan.

One final thought: no matter how well organised you are, no matter how meticulously you have prepared, you can’t control everything. Whether it’s a sudden change in weather, an ill-timed attack of runner’s trots or simply not feeling good on the day – you must be able and willing to ‘think on your feet’ and re-adjust your strategy where necessary. So by all means, soak up the atmosphere and enjoy the race experience but keep ‘checking in’ with yourself to ensure you continue to stay on track to reach the finish line with a smile on your face.