Lactate Threshold Test: Protocol, Training Zones, and How to Interpret It

If you want to move from "this is general endurance" to designing training by specific zones, the lactate threshold test is the most widely used reference in endurance sports (running, cycling, triathlon, rowing). It requires a portable lactate analyzer (increasingly affordable) and a controlled incremental protocol.

What Does This Test Measure?

It measures how blood lactate concentration changes as exercise intensity increases, identifying two key points:

• LT1 (first threshold / aerobic threshold): lactate starts rising slightly above baseline (~2 mmol/L)
• LT2 (second threshold / anaerobic threshold): lactate rises more steeply and can no longer stabilize (~4 mmol/L, as a rough reference)

These two points define three broad training zones: below LT1 (easy aerobic zone), between LT1 and LT2 (tempo/threshold zone), and above LT2 (high-intensity zone).

Equipment Needed

• Portable lactate analyzer (e.g., Lactate Plus, Lactate Scout)
• Test strips and lancets
• Treadmill, cycle ergometer, or track, depending on the sport
• Heart rate monitor
• Stopwatch

How to Perform the Test

1. Warm up for 10-15 minutes at low intensity
2. Design an incremental step protocol (e.g., on a treadmill: increase 1 km/h or 2% grade every 3-5 minutes; on a bike: increase 20-30 W every 3-5 minutes)
3. At the end of each step, take a capillary lactate sample (from the earlobe or fingertip) and record HR
4. Continue until lactate is clearly elevated (> 6-8 mmol/L) or until exhaustion
5. Plot lactate values against intensity (speed, power, or HR) and locate LT1 and LT2 using your chosen criteria (fixed thresholds of 2 and 4 mmol/L, or visual/mathematical inflection-point methods)

Common Mistakes

• Steps that are too long or too short (affects lactate stabilization)
• Not cleaning the puncture site properly, which can contaminate the sample
• Applying fixed thresholds (2 and 4 mmol/L) without considering they're population-level reference values, not absolutes for every individual

How to Interpret the Results

Example training zones based on HR relative to LT1 and LT2 (reference values):

Zone	% HR relative to LT2	Description	Use
Z1	< 85%	Recovery / very easy	Recovery runs
Z2	85-90% (below LT1)	Light aerobic	Volume base
Z3	LT1 - LT2	Tempo / aerobic threshold	Medium-quality sessions
Z4	≈ LT2	Anaerobic threshold	Threshold intervals
Z5	> LT2	VO2max / high intensity	Short, intense intervals

In well-trained endurance athletes, LT2 typically falls between 85-92% of max HR, while in less trained individuals it may appear at relatively lower intensities (75-85% of max HR).

Related Tests

The lactate threshold is the "gold standard" field version of concepts that other tests try to estimate indirectly:

• FTP test — practical equivalent in cycling when no lactate analyzer is available
• Ventilatory threshold test — alternative based on expired gases, no need to take blood samples

Track Your Zones with Movalytics

A lactate test generates a lot of data per point (intensity, lactate, HR), and what's really useful is being able to compare how LT1 and LT2 shift between seasons. With Movalytics you can log each step of the test, mark the identified threshold points, and save the resulting training zones in the athlete's profile to reference when planning their intervals.

Frequently Asked Questions

Do I need to go to a lab to do this test? Not necessarily. With a portable lactate analyzer it can be done on a track, road, or training facility, although a lab offers more control over variables (temperature, standardized protocols). Does taking lactate samples hurt? It's a minimal capillary puncture, similar to a glucose check — slightly uncomfortable but not significantly painful. How often should the lactate threshold test be repeated? Every 8-12 weeks, or when switching training blocks, to readjust zones to the athlete's new fitness level.