Speed endurance is the bedrock of a good endurance runner. It is the ability to run at a controlled discomfort tempo / pace for a period of time.
Moses Kiptanui, the former world steeple chase champion, told me that when he could run a solid tempo for 10 miles, then he knew that his speed endurance foundation was in place and that he could start his faster pace training.
Without working on your speed endurance, you will never achieve your race full potential.
The most important thing is to run at an effort level between 8 - 8.5 out of 10 (1 being rest and 10 being flat out effort). This effort level is at your lactic threshold.
As you do more threshold pace running, you will become a more efficient and effective runner. This level of exertion allows you to load the body to a manageable level but also allows the body to recover, adapt and improve. It teaches your body to get used to the lactate, acid and other by products that build up when running at this effort level. Try to think of this as an effort level that is 'controlled discomfort'!
Gradually over time you will find yourself able to sustain this type of running for longer. You will be able to run at a faster tempo (pace) for the same effort level.
For example a beginner’s threshold session could be;
A 10 - 15 minute easy warm up walk / run followed by 4 x 3 minutes of threshold effort running with a 90 seconds easy walk / run recovery between each threshold interval followed by a 10 - 15 minute easy cool down run / walk and stretch
A more advanced threshold session for faster / more experienced runners could be;
A 10 - 15 minute easy warm up run including some strides and high knee drills, followed by 3 x 10 minutes of threshold effort running with a 60 seconds easy run recovery between each threshold interval followed by a 10 - 15 minute easy cool down run and stretch
Depending on the your ability, target race distance and time, you can do 1 or 2 threshold sessions a week. Always allow sufficient recovery / easier days between threshold running to ensure that your legs are not tired going into each session.
You may not get it right first time round but keep trying and after a few weeks or so, you'll notice a huge difference. Not only will your easy runs feel easier and faster, but you'll be finding the threshold sessions themselves more manageable too.
If you make threshold running a mainstay of your training today, you will reap great future rewards.