How to do properly do Threshold Run Training

Mark Cullen
Feb 4
3 min read

Threshold running is one of the most commonly used workouts in endurance training, and also one of the most misunderstood.

When done well, it is one of the highest return on investment sessions you can include in a training plan. When done poorly, it becomes a fast track to excessive fatigue and stalled progress.

This post breaks down what threshold training actually is, why it works, how hard it should feel, and how to use it effectively without overcooking yourself.

What Is Threshold Training?

Threshold training targets the intensity just below the point where lactate begins to accumulate rapidly in the blood. This is often referred to as anaerobic threshold, lactate threshold or LT2.

At this effort, the body is producing lactate, but it is also able to clear and reuse it as fuel.

Improving this intensity allows athletes to:

Sustain faster speeds aerobically
Delay fatigue later in races
Perform longer at higher efforts without blowing up

This is why threshold work shows up so frequently in programs for runners, triathletes, and CrossFit athletes.

How Hard Should Threshold Running Feel?

One of the biggest mistakes athletes make is turning threshold workouts into something harder than they are meant to be. Threshold is well below all out effort.

Pace guidelines

Roughly 5 to 10 seconds per kilometer slower than current 10 km race pace

Effort guidelines

RPE around 7-7.5 out of 10
Comfortably uncomfortable
Breathing is rapid but controlled
You can still speak short phrases
Focus is required, but you are not fighting the pace

*If you are gasping for air or counting seconds until the interval ends, you are likely running too hard.

Why Threshold Work Is So Effective

When threshold training is kept under control, it delivers several key adaptations.

It improves the body’s ability to clear and reuse lactate, allowing you to stay composed at faster speeds. It raises the pace you can hold aerobically, which makes race pace feel more manageable. It also delays fatigue late in races when others start to slow.
This is why threshold running often makes marathon pace, half marathon pace, or long CrossFit conditioning pieces feel easier over time.
From a big picture perspective, threshold work sits in a sweet spot. Hard enough to drive adaptation, but controlled enough to recover from quickly when done correctly.

The Risk of Going Too Hard

The downside of threshold work shows up when athletes treat it like a race and end up doing 5k or 10k pace for it.

Pushing above threshold turns the session into a high fatigue workout that requires significantly more recovery. Over time, this limits how often quality sessions can be stacked in a week. If threshold workouts are leaving you flat for days, impacting your long runs, or forcing you to skip strength or skill work, they are too hard.

When in doubt, err on the easier side.

A Sample Four Week Threshold Progression

Here is an example of how threshold work can be progressed over a short block while keeping intensity controlled.

Week 1: 7 × 3 minutes at threshold w/ 90 seconds easy jog recovery

Week 2: 6 × 4 minutes at threshold w/ 90 to 120 seconds easy jog recovery

Week 3: 5 × 5 minutes at threshold w/ 2 minutes easy jog recovery

Week 4: 4 × 7 minutes at threshold w/ 2 minutes easy jog recovery

For all of these sessions:

Include a 10 to 20 minute easy jog warmup
Add 2 to 3 short 15-20sec/100m strides to activate before the main set
Finish with 5-10 or more minutes of easy jogging to cool down

The goal across the block is controlled progression, not forcing pace improvements week to week but trusting in the RPE based on how you feel

How Threshold Fits Into a Training Plan

For most athletes, one bigger threshold session per week is plenty. In some cases, two lighter threshold sessions can work, but only if overall volume and recovery are well managed. You may see some high level athletes doing double threshold days where they get a hit in the AM of ~5x6mins controlled below LT2 and then again in the PM of something like 10x3mins right at LT2 or a bit quicker