Timing Is Everything: All About Tempo Runs

Improving your lactate threshold is pretty straightforward: You train at or slightly above your lactate threshold. In the training schedule, I call this speed your LT (lactate threshold) pace. Training at your LT pace pushes back the point at which lactate accumulates, allowing you to maintain a faster pace for these mid-range races. How do you know what this pace is for you? If you already race in 15K to half-marathons, your race pace for those races is your LT pace. If you haven’t raced much, you can still approximate what your LT pace is. If you’ve run a 10K, your LT pace will be about 20 seconds slower per mile than your 10K race pace. If you’ve only run a 5K, your LT pace is probably around 30 seconds slower per mile than your 5K race pace is, but you should go run a 10K first anyway before trying to race a 15K to half-marathon.
Regardless of what pace you choose to shoot for, keep this guideline in mind: Your effort during LT workouts should feel “comfortably hard.” You should feel as though you’re working at a high level that you can sustain. If you were to increase your pace by 10 seconds or more per mile, you would have to slow within a few minutes.
It’s important to run as close to the right pace for as much of your LT workouts as possible. Remember what I told you in the last chapter about training to improve your VO2 max:
The biggest gains come from doing the workout in that small window where you’re most stressing the systems that you want to improve.
When you do LT workouts, you’ll probably think in the first mile that you should be going faster. After all, you’re not all that much out of breath. Stick to your pace. The point of the workout is to run it all at your LT pace. That’s different than starting out too fast, and then slowing in the second half of your LT workout. In that case, you might average the right pace for the whole workout, but never run any part of it at the right intensity. That kind of workout won’t improve your LT as much.
The classic workout to improve your lactate threshold is the tempo run, a continuous run of 20 to 40 minutes at LT pace. An example of a tempo run workout is a two-mile warm-up, a four-mile run at your LT pace, and a short cool-down jog. You can also do LT intervals. In these workouts, you do two or three intervals of a fairly long distance at LT pace, jog easily for 25 to 50 percent of the duration of the interval, and then repeat the sequence. For example, after warming up, you would run two miles at your LT pace, jog for five minutes, run two miles at your LT pace, and then do a cool-down jog.
In the training schedule, I start you with LT intervals to get you used to the workouts and to help you learn what your LT pace feels like. Once you’re familiar with your LT pace, I have you do tempo runs. Tempo runs are better because you become more accustomed to concentrating for an extended period while you’re running hard. This kind of training helps you mentally in your races.
At first, you should do LT workouts on the track or other accurately measured courses so that you have a way of checking your pace. After a few LT workouts you should have a feel for the pace. Studies have shown that most runners can accurately produce that “comfortably hard” level of effort on their own once they have learned it. This frees you to do your LT workouts on the roads or trails. Doing a five-mile tempo run on the track can get pretty boring, after all. Doing some of your LT workouts away from the track is an especially good idea if you’ll be running a hilly race because you’ll be more used to running LT pace over a variety of terrain.
Not many runners know about these workouts. They think that to run a faster halfmarathon, they should work on their speed, so they run 800-meter intervals. This type of workout does make them faster, but it doesn’t do much for their ability to sustain a pretty hard pace for more than an hour.
Those who do talk about doing tempo training throw around the words pretty haphazardly. They’ll say they’re doing an “uptempo run,” when all they mean is that they’re going to go a little harder than usual for a few miles in the middle of a run. Or they’ll go out and run a hard 10 miles and say that’s their tempo run for the week. They can call it whatever they want, but these aren’t really tempo runs. Unlike you, they don’t know why they should do these 20- to 40-minute runs at a precise pace.
Because those were workouts that I think all runners should do some version of. LT workouts are only necessary if you’re going to be doing races of 15K or longer.