Tempo runs: you’ve probably heard of them, and you may even have done them, without necessarily understanding their purpose in your training. There is a lot of confusion surrounding tempo runs, and many runners and triathletes are left scratching their heads wondering how or why they should include them in their training. There is some debate whether they are beneficial for every runner or triathlete training for every distance. A look at the science of tempo runs may help you decide if they’re right for you.
A tempo run is one that includes a portion done at a slightly faster pace than your normal easy run pace – usually a bit slower than race pace, and slower than what you would run if you were doing intervals. The purpose of the tempo run is to train your anaerobic threshold.
Exercise scientists define the anaerobic threshold as the level of intensity at which lactic acid accumulates in the bloodstream faster than your body can clear it. Research suggests that the goal of endurance training shouldn’t be to reduce the amount of lactic acid you produce, but to improve your ability to get rid of it.
You’ll know you’re running fast enough when you feel a burning sensation in your legs, which is caused by the lactic acid building up in your muscles. Improving your ability to get rid of this buildup more efficiently will allow you to run faster before lactic acid takes over.
How fast should you do a tempo run?
Tempo runs specifically train this system, and can help you increase your anaerobic threshold to run farther and faster. Of course, if you want to get the most benefit from tempo runs, it’s important to run them properly, and this is where many runners and triathletes fall short.
The biggest mistake people make is, not surprisingly, with pacing. Running too fast will force you to slow down part way through your run and you’ll lose the training effect. Run them too slow and you’re basically doing an easy run. Tempo runs should be done at a pace that you can hold for about an hour, and should last anywhere from 20 to 30 minutes. If you don’t typically run for an hour, use your best time over a shorter distance (say, a 5 km) to calculate what your tempo pace should be.
Think about some of the races you’ve done in the past — if, for example, you can run a 10 km in one hour, that is your anaerobic threshold pace (6:00/kilometre). If you run 10 km in 45 minutes, your anaerobic threshold pace should be about 4:30/kilometre. If you run 5 km in 35 minutes, your pace should be about 7 minutes/kilometre.
It may seem strange to run for only 20 minutes at a pace you can hold for a longer amount of time, but going faster than this pace during a tempo workout eliminates the training effect. Those faster paces are better left for other workouts, such as a shorter interval session. In fact, running every workout as fast as possible may cause you to burn out and ultimately run slower.
Of course, it is important to remember that as you progress your tempo pace will get faster. The key here is listening to your body: if you’re not feeling that burning sensation in your legs at some point during your workout, you’re likely not running fast enough.
If you’d like some guidance on how to perform a tempo run, check out Canadian Running Magazine’s interview with Under Armour ambassador David Joseph and trainer Rich Hesketh.