How to run a half-marathon

The half-marathon, like its tougher cousin the full marathon, is a ‘below lactate threshold’ race, but there is a key difference between the two. Marathon running is six per cent slower than threshold pace, so there’s little chance that lactate levels will rocket, but your half-marathon speed is only two per cent below the threshold velocity.

Since anything above threshold speed turns on the blood lactate tap, it’s definitely not a good idea to use sudden bursts of speed to pass congested knots of runners in the first few miles of a half-marathon. Stay within yourself and move past other runners slowly but steadily. You have 13 miles to pass your peers, which should be plenty of time.

Attempts to rocket past every herd of hobbling runners blocking your path will produce the pangs of high lactate levels for all 13 miles of the race. Sudden, unnecessary bursts of speed can also eat into the stores of glycogen you’ve tucked away in your leg muscles. While it’s all right to toss around a bit of glycogen during a 10K, you need to be more conservative when running a half-marathon. After all, running for 75-90 minutes can break down enough leg-muscle glycogen to make running feel really difficult.

Since most of us require more time than that to complete a half-marathon, it’s wise to conserve your carbohydrate fuel carefully. That means running at a steady, reasonable pace.

It also means loading up your leg muscles with carbohydrates, but it’s not enough to follow the advice you’ve been given thousands of times before. Yes, it is smart to eat plenty of carbohydrates during the three days leading up to the race, but they should be consumed during the race, too. Carbohydrate drinks can help you to perform at a higher level whenever your exercise lasts longer than about an hour.

To get carbohydrates into your body during the race, you can use sports drinks or prepare your own concoction by mixing 10 tablespoons of sugar and two-thirds of a teaspoon of salt with two litres of water.

Ideally, you should take in 400ml of a sports drink just before the half-marathon begins and then 80-120ml every 10-15 minutes during the race. This will optimise your muscle-fuel situation, but you’ll need to practise this drinking pattern several times before the actual race.

Racing heightens tension, and it’s never wise to pour lots of fluid into a jittery gullet, especially one which has never taken in fluid on the run before.

Amazingly, many half-marathon competitors start the race without a precise idea of how fast they’re going to run. Often, they run according to how they feel, which is generally a really bad idea.

If you run half-marathons often, you probably know what your half-marathon pace should be. If you haven’t, simply take a recent 10K time which reflects your ability as a runner and use that to estimate an appropriate half-marathon tempo.