Once you’ve put in the miles and built a solid aerobic base, you might wonder: what’s the next logical step to get faster and run stronger? Enter Threshold Training—the ultimate way to develop what we call "Cardio Strength." Whether you’re aiming for a new personal record in your next 5K or looking to hold a strong pace late into a marathon, understanding lactate threshold training will unlock a whole new tool in your training.
What is Lactate Threshold, Anyway?
To understand why threshold training works, it helps to look at what’s happening inside your muscles when you push the pace:
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Glycogen as Fuel: During higher-intensity running, your body primarily burns glycogen (stored carbohydrates) for energy.
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The Lactate Breakpoint: As you run faster, your body produces blood lactate. Lactate Threshold (LT) is the exact tipping point where blood lactate production exceeds your body's ability to clear it.
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The Goal: LT workouts train your engine to oxidize glycogen more efficiently while teaching your body to clear lactic acid faster, allowing you to sustain faster speeds for longer periods before fatiguing.
How to Structure Lactate Threshold Intervals
While there are several ways to target your threshold system, Lactate Threshold Intervals are one of the most effective methods to build this specific fitness. Here are the key parameters to keep in mind when planning your LT interval session:
| Parameter | Target Zone | What It Means |
| Effort / Intensity | 85–90% of VO2Max | Comfortably hard effort—controlled, not an all-out sprint. |
| Heart Rate Zone | 150–180 bpm (~88% max HR) | Keep HR below 180 bpm to stay strictly within the threshold zone. |
| Interval Duration | 2 to 6 minutes | Short enough to maintain proper form and stay within target HR. |
| Rest Periods | 30 to 120 seconds | Incomplete recovery keeps your heart rate elevated between reps. |
The Secret Ingredient: Incomplete Rest
The key to making these workouts work is not allowing full recovery. Keeping your recovery intervals short (30–120 seconds) keeps your heart rate and VO2Max effort within the target window throughout the workout, forcing your metabolic system to adapt and become far more economical.
What If You Don't Run with a Heart Rate Monitor?
Not everyone tracks heart rate on their watch while running intervals—and that’s completely fine! Time and pace are the next best indicators.
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Check your personalized Pace Chart to find your calculated Threshold Pace.
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Run your 2-to-6-minute intervals strictly at that recommended target pace.
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Resist the urge to go faster early in the workout. Precision matters more than raw speed here; running too fast pushes you out of the threshold zone and defeats the physiological purpose of the workout.
Ready to Test Your Cardio Strength?
Stop by Dave's Running Shop to get fitted for the right gear, check your pace zones, or grab expert advice on how to build Threshold Training into your current training block. Happy running!
