If all you do is shuffle along, then you might get even tighter.

Including sprint sessions in your running can help you biomechanically. Striding out improves your range of motion.

In the long term, including the occasional sprint session will help you keep your form on long runs.

Lactic threshold and VO2 Max

When your muscles contract they create lactic acid as a biproduct. Your lactic threshold is the point when lactic acid concentration rapidly increases – in real terms, it’s when your legs begin to feel heavy.

Typically, lactic acid builds up during high-intensity workouts. Your body cannot get enough oxygen to meet your body’s demand. Therefore, you move from aerobic to anaerobic exercise and produce more acid. The muscle contractions are close enough together that your body does not have time to clear the acid either.

Speed sessions will increase your lactic threshold – you’ll be able to clear or tolerate higher levels of acid.

This will help in an ultra marathon because, although you are generally in the aerobic zone, you will produce some lactic acid that can build up over the many hours you are running. Also, sudden bursts, steep climbs or stairs can push you into your anaerobic zone too.

Your VO2 Max is the maximum amount of oxygen you can use during exercise. Speed sessions will help improve your VO2 Max, to a point. It goes without saying that if you can improve the amount of oxygen you can consume, your ultra running will improve.

Psychological benefits of speed sessions

Speed training can be lung-busting stuff. It’s old-school pain-and-gain training. That’s why you shouldn’t do too much of it.

If you go to the pain cave every now and then during your speed sessions, it will mentally prepare you to run ultra marathons. You can practise ignoring your body’s signals to slow down or give up.

There is great benefit in learning to suffer.

Speed can be useful in an ultra race

Sometimes you’ll need to go fast. Maybe you’re about to miss a cut-off point, maybe the goal you set yourself in terms of finishing time is touch-and-go, maybe you are at the front of the pack and in a race for the podium.

What speed workouts should I do?

There are several ways to incorporate speed into your sessions. The typical three are fartlek, intervals and tempo training.

Fartlek

It is a Swedish word that translates as “playing around with speeds”. It can be structured or unstructured. Run without stopping but vary your speed. For example, one minute jogging, one minute striding, one minute sprinting and back down again. Or even more casually, do something like sprint to the next tree then jog to the next, pick up the speed to the next landmark, and so on.

Intervals

This can be like fartlek but more structured, typically more intense. Sprint and break for periods. Try to go to your maximum effort on the sprints.

For example, sprint for 30 seconds, rest for 30 seconds and repeat it 10 times. Take a longer break, then do it again.

Tempo

Pick a pace that is faster than your race pace and just maintain it for a sustained period of time.

The time is much longer than an interval. It could be for 15 minutes, or 5km. But it’s less intense. Flirt with your lactic threshold by maintaining a serious effort without going into the red zone. Basically, as fast a pace as you think you can maintain for the period set.

Or, you can get more complicated and measure your speed by your heart rate. Run at 80 per cent of your maximum heart rate.

That’s (220-your age) x 0.8. If you are 32, that is (220-32) x 0.8 = 150bpm.

Now get out there and start incorporating speed into your ultra training.