Threshold Pace: Defined and How to Use It
You might have seen the term “threshold” as you’ve clicked through online running training plans. Maybe you’ve heard your fellow runners throw around the term in casual conversation. What the heck is threshold pace, anyway?
We’ll start with a scientific definition of threshold pace. Then we’ll get into what you really care about: how threshold pace should feel and how fast it is. Then you can use this staple training method to improve your strength and endurance as a distance runner!
Threshold Pace: Defined Scientifically
Threshold is short for lactate threshold. Lactate threshold refers to the intensity of exercise at which there is an abrupt increase in blood lactate levels (1). So what is lactate?
When you exercise, your muscles break down glucose for energy, and one of the byproducts is lactate. Lactate has long been given a bad rap, often being confused with the completely separate compound lactic acid. In fact, lactate production is totally natural, and even occurs in small amounts at rest and during easy running. Lactate is reconverted back into useful energy by the liver in a process called gluconeogenesis during sub-lactate threshold intensities. That means that when you’re running easily, (slower than threshold pace) lactate levels remain relatively constant due to your body’s nifty way of reusing lactate for energy.
You read that correctly: lactate is a good guy!
At a certain point, lactate production surpasses lactate uptake by the liver, and blood lactate levels increase quickly. The running pace at which this occurs is your called your lactate threshold pace.
Lactate vs. Lactic Acid
The “burn” you feel when you run fast for an extended period of time isn’t the result of lactate, but lactic acid accumulation. Lactic acid creation occurs alongside but not because of lactate production. The burn, or acidosis you feel is the accumulation of hydrogen ions (H+) created when muscle protein filaments split ATP (an energy carrying molecule) in order to maintain vigorous muscle contraction (1). As you approach and surpass your lactate threshold pace, lactic acid increasingly accumulates. So does lactate, but this turns out to be a good thing:
Lactate accumulation is not the cause of the burn. It actually works to retard it by neutralizing the acidic muscle environment caused by hard exercise.
This is great news. By targeting the systems that produce lactate in training, we can teach our bodies to more effectively neutralize acidosis and the burn. By running for extended periods at or just slower than our lactate threshold pace, we can gradually improve our lactate threshold pace over time. Doing so, we can run longer and faster before the buildup of lactic acid diminishes muscle power output.
Threshold Pace: Defined Intuitively
You’ve learned something for the day, but you’re probably still wondering how threshold pace should feel.
Although we assign threshold pace a number in minutes/mile, it’s really a tight range of paces that can change slightly from day to day. Your effective lactate threshold pace might be slower or faster depending on a variety of factors. For example, you might be using caffeine, or you’re tired from a hard work week, under the weather, or stressed. All of these are factors that could influence threshold pace. Don’t worry if your watch says one thing and your body is telling you another! Always defer to how you feel on the day. After all, threshold pace is a physiological phenomenon, directly linked to perceived effort during running.
What really matters when you’re attempting to run at threshold pace is maintaining a pace just above (or slower than) the point at which you feel your muscles starting to “burn”. For example, say you set out on a five mile threshold pace run. You should feel as if you’d be able to continue running at the same pace for several more miles. However, a decrease in pace of 15 to 20 seconds per mile would quickly bring you into the burn zone as lactic acid accumulates.
Finding your threshold pace
As a very general rule of thumb, threshold pace corresponds to half marathon race pace(2). A better way to estimate threshold pace is to use a recent race performance and conversion table. Jack Daniels (the coach, not whiskey brand) helped pioneer the science of threshold training. Daniels published tables relating race performances at various distances to appropriate lactate threshold paces. Online running calculators like this one can be used to quickly look up your threshold pace.
For example, if you recently ran a 23 minute 5k, Daniel’s formula says your threshold training pace is approximately 7:21 per mile. You can additionally use 10k, half marathon, and marathon times to find your threshold pace with the calculator. Now that you have a good estimate of where your threshold pace lies, you can plan workouts that use and improve it!
Training at threshold pace
Lactate threshold running is the bread and butter of training for distances 5k to the marathon. Gradually pushing your threshold pace down improves your basic capacity to run faster over a given distance.
Try adding one threshold pace workout day into your training week in the middle of your buildup to your next race. There are a number of ways to run at threshold pace, from individual threshold miles to sustained runs at threshold pace. Here are a few examples.
Threshold miles: Run four to six individual threshold miles with 90 seconds rest in between each. These can be done on a track, the grass in a park, or on the road.
Threshold run: Run three to four miles continuously at your prescribed threshold pace.
Canova kilometers: run seven times one kilometer repeats on a track or road. Alternate between threshold pace on the odd numbered reps and slightly faster than threshold pace on even numbered reps. Take two minutes rest in between each. The faster, even numbered kilometers should be 7 to 10 seconds faster than the threshold reps.
Progression run: This is a longer sustained run of 8 to 12 miles. Start at 20 to 30 seconds slower than threshold pace. Gradually increase the pace of the run until you are running threshold pace for the final 2 to 3 miles.
Threshold pace training is one of the most effective ways to improve your strength over long periods of time. Try some of the workouts above, and you’ll soon find yourself running faster and feeling better!
(1) Kravitz, Len PHD and Dalleck, Lance PHD Lactate Threshold Training
(2)Gaudette, Jeff What is Lactate Threshold