So far in the Essential Ingredients series, we have covered how the body adapts to training, the importance of long runs and developing a big aerobic base. In this issue, we discuss the third pillar of distance running success, tempo runs, which are the most effective type of training to improve your lactate threshold pace.
Why should you care about your lactate threshold pace?
Lactate threshold pace (LT pace) is the best physiological predictor of distance running performance. Your LT pace is how fast you can run before the lactate (lactic acid) level in your muscles and blood increases rapidly. Tempo runs are done in an intensity range at which lactate is just starting to accumulate, which provides a strong stimulus to improve your LT pace. By running at your current LT pace, you improve your LT pace (the body is great like that), which leads to improved racing performance. There is also a psychological benefit because the concentration required to sustain LT pace develops mental toughness for racing.
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Your LT pace can be tested in an exercise physiology lab, but for most competitive runners it can be approximated by the pace you could maintain in a one-hour race. You can estimate your LT pace by wearing a heart rate monitor during a 15K race (or a 10K race for slower runners), and find the heart rate zone that coincides with that pace—typically 80 to 90 percent of maximal heart rate.
During a tempo run, your heart rate will increase by several beats per minute even if you hold an even pace, so run the first mile or two towards the low end of your zone, and your heart rate will tend to increase to the high end of the zone during the workout. After a few of these runs, you will likely be able to gauge the correct intensity range fairly accurately without a heart monitor.
Although tempo runs have been around for more than 20 years, the scientific evidence does not indicate precisely how hard or how long your tempo runs should be. My advice for tempo runs has evolved over the past few years as I have become more aware of the benefits of tailoring the run based on the specific purpose of the workout in the runner’s training schedule. I am now convinced that tempo runs should be done at an intensity range from slightly faster to slightly slower than LT pace, depending on the race distance you are preparing for, and how many weeks there are until your goal race.
Tempo runs fit into three categories based on duration and pace:
1. 15- to 25- minute runs at slightly faster (5-10 seconds per mile) than LT pace;
2. classic tempo runs of 25 to 40 minutes at LT pace;
3. efforts of 40 to 50 (and occasionally up to 60) minutes at slightly slower (5-15 seconds per mile) than LT pace.
A typical session consists of a 20-minute warm-up, followed by a tempo run, and a cool-down jog. A similar benefit physiologically (but easier psychologically) can be gained by breaking tempo runs into chunks, called cruise intervals or LT intervals. For example, a 30-minute tempo run can be replaced by three 10-minute efforts, with a brief (2-3 minute) recovery jog between each.
When should you run tempo runs?
Tempo runs have a role in your training schedule most of the year. They provide much-needed variety during base training, which eases the transition to more race-specific workouts, and are an important component of training until two to four weeks before your goal race. Because tempo runs are run at a controlled pace, they cause only minimal muscle soreness and do not require much recovery time. It is reasonable (in fact, a fine tradition), therefore, to do a tempo run on Saturday and a long run on Sunday.
You can do a tempo run during a low-key tune-up race, but be careful not to run harder than planned because these sessions are most effective when run at the correct intensity. Similarly, avoid the common error of starting your tempo runs too fast because that will make your lactate level increase quickly and you will be unlikely to be able to maintain your pace, which will produce a less effective training stimulus.
What type of tempo runs should you do?
Each type of tempo run has a place in training for races of 5K through the marathon, but the optimal mix differs based on the distance of your goal race. During preparation for races of 5K to 10K, you should emphasize 25- to 40- minute tempo runs (typically weekly) up until about 10 weeks before your goal race. To increase the specificity of the workout for the demands of racing, you would then switch to 15- to 25- minute tempo runs at slightly faster than LT pace during the last 10 weeks. For races of 15K through 25K, all three types of tempo runs are useful and should be included in your training program, but the major emphasis should be on 25- to 40- minute efforts at LT pace.
Not surprisingly, marathoners benefit most from tempo runs at the longer end of the spectrum. Both the classic 25- to 40- minute tempo runs at LT pace and longer tempo runs at about half marathon pace are excellent marathon preparation. Many marathoners benefit from a three-week cycle in which they do a tempo run each of the first two weeks and a longer run at marathon race pace during the third week.
