Getting the fuel mix right

Another good question came up in a discussion with a runner last week. He mentioned that when he passes the eight-mile mark in the half marathon, his pace really falls off. He felt he needed more training to combat this.

There are two ways we can look at this. The first is that all runners must expect the pace to drop off at the eight-mile mark in the Malta Half Marathon. This is due to the change in the course from the generally-downhill nature of the first eight miles (which end near Edible Oil, Marsa), to the almost flat (or even uphill) nature of the route for the remaining five miles.

So, all runners must expect that their pace per mile will change at the eight-mile mark.

It makes obvious sense to everyone that it is easier to run downhill, than run on the flat. It is possible to run faster at the same effort when running downhill compared to running on the flat.

So, if you have found that you can run (say) 7:00m/m on the first eight miles, but that your pace changes to 7:15m/m for the last five miles, don't automatically take this as a sign that you are struggling, but that the drop in pace may be due to the change in the elevation of the route.

I would even go so far as to say that you must deliberately slow down by 15-20 seconds per mile once you reach eight miles.

If you insist on continuing with your pace of the first eight miles this will require significantly more effort (because you are now running on the flat) and there is a very real chance that you will crash and be forced to slow drastically in the closing miles. Don't let this happen to you.

The second way we can look at this, is that this runner may indeed need more training to tackle his tendency to slow after (approximately) one hour of racing.

Very simply, to run we all burn a mix of glycogen or fat. These act as fuels for your working muscles in the same way that petrol and diesel do in cars.

How well-trained you are, and how fast you run, will determine what percentage of one fuel and what percentage of the other, you actually burn in your "fuel mix" at race pace.

Limited muscle glycogen

As we run faster and faster, our bodies change to a higher and higher percentage of muscle glycogen (as opposed to fat, which burns too "slow").

Unfortunately, our "fuel tank" of muscle glycogen is very limited and we cannot run a whole half marathon on only glycogen. So, if we get the fuel mix wrong, and use too high a percentage of glycogen, then it is very possible to run out of fuel (well) before the finish line.

Now, you might think that at that point you can change over to burning fat, but the two fuels are not inter-changeable.

When you burn a high-percentage of fat, you must run much slower; it is not as good for fuelling fast running as muscle glycogen.

So, assuming he's having a fuel-mix problem, what can our runner do to improve his ability to maintain race pace past eight miles (and up to the Ferries)?

In short, he needs to learn to burn a higher percentage of fat at race pace, and he cannot do this by training fast.

He must introduce a sizeable percentage of slow(er) running into his training. In that way he will improve the fat-burning enzymes in his leg muscles and thus increase the rate (the running pace) at which he can burn fat.

If he can improve his fuel mix to include a higher percentage of fat, then he can spare his limited store of muscle glycogen and make it last longer, hopefully till the finish line.

Changes in half marathon route

Some runners are unsure of the altered opening miles in the half marathon and wish to try it out over the coming weeks. The new route is explained on the marathon website www.maltamarathon.com.

A brief description is as follows. The race starts as if heading towards St Dominic's church like in previous years but only after a few hundred metres turns right into Triq San Publiju and again right into Triq Il-Kullegg, after which it passes in front of the Rabat Parish Church and down to the end of Triq Santa Rita and from there on to the Mtarfa By-Pass.

After the By-Pass, the course takes the runners straight into Ta' Qali from near the Military Cemetery.

Here there is another change from last year. Instead of turning left past the Aviation Museum, the course goes straight for approximately another 100m and turns right in to the Crafts Village and out on to Triq L-Imdina.

The route then goes up to the Rabat Road roundabout and down the new road towards Zebbug as usual all the way to the Turkish Cemetery and thus to Sliema.