Running Threshold Test (Anaerobic Threshold): How to Do It and What It's For

If you train runners, you'll know the most common question is: "what pace should I train at?" The running threshold test (also called the anaerobic threshold or lactate threshold test) is the tool that lets you answer that question with real data, instead of generic age-based formulas.

What Does This Test Measure?

The running threshold test identifies the pace (and/or heart rate) at which the body starts accumulating lactate faster than it can clear it. Below that point, the runner can sustain the effort for a long time; above it, fatigue sets in quickly. It's the foundation for defining endurance training zones.

Equipment Needed

• A track or a flat, measured circuit (400 m or 1 km reference)
• Heart rate monitor or GPS watch with heart rate tracking
• Stopwatch
• Optional: portable lactate analyzer (if available, gives the most precise data)

How to Perform the Test

There are several versions; the most practical for coaches without lab access is the 30-minute constant-pace test (modified Conconi / Joe Friel test):

1. Progressive warm-up of 10-15 minutes
2. The runner performs 30 minutes at the fastest pace they can sustain consistently (a "hard 10K" type effort, not a sprint)
3. Record the average heart rate of the last 20 minutes of the test — this average HR is an approximation of threshold heart rate
4. Also record the average pace (min/km) for those 20 minutes — this approximates threshold pace

If you have access to a lactate analyzer, the classic protocol uses incremental steps (4-6 minutes per step, increasing speed or incline, with a capillary lactate sample at the end of each step), identifying the point where lactate starts rising non-linearly (threshold) and the second inflection point (anaerobic threshold).

Common Mistakes

• Starting too fast and being unable to maintain the pace for the full 30 minutes
• Running the test in heat/wind conditions very different from usual, which skews results
• Not warming up enough, which brings on fatigue artificially early
• Using theoretical max HR (220 - age) instead of measuring it directly

How to Interpret the Results

Zone	% of Threshold HR	Use
Zone 1 - Recovery	< 85%	Very easy runs, active recovery
Zone 2 - Aerobic/base	85-89%	Long runs, aerobic base
Zone 3 - Aerobic threshold	90-94%	"Medium" runs, easy tempo
Zone 4 - Anaerobic threshold	95-100% (threshold HR)	Threshold intervals, roughly half-marathon pace
Zone 5 - VO2max/anaerobic	> 100%	Short intervals, 5K-10K pace

Threshold pace is usually close to the pace a trained runner can sustain for about one hour of continuous effort (somewhat faster than half-marathon pace for recreational runners, somewhat slower for elites).

Related Tests

The threshold test pairs well with:

• Running economy test — to find out how much "fuel" a runner burns at a given pace
• 5K time trial test — a quick reference for overall fitness, and lets you estimate zones using Jack Daniels-style formulas

If you combine the threshold test with a 5K, you can triangulate training zones using two independent data sources.

Tracking with Movalytics

Training zones aren't fixed — they shift as fitness changes throughout the season. With Movalytics you can log each threshold test (average HR, average pace for the final 20 minutes) and see how your runner's zones evolve month by month, adjusting training plans without redoing manual calculations every time.

Frequently Asked Questions

Do I need a lactate analyzer to do this test? Not essential. The 30-minute constant-pace test with a heart rate monitor gives a valid estimate for most recreational and intermediate runners. How often should I repeat the threshold test? Every 8-12 weeks, or at the start of each training block/mesocycle, to readjust zones if fitness has improved. Does the threshold change with heat or altitude? Yes, both factors can lower threshold pace and raise HR for the same effort. If you do the test in conditions very different from usual, account for that bias when comparing results.