LACTATE THRESHOLD: YOUR MOST TRAINABLE PERFORMANCE METRIC
Of the four REAX metrics, Lactate Threshold responds fastest to training. Understanding it — and targeting it correctly — can transform your performance in 8 weeks.
Your Lactate Threshold is the highest intensity you can sustain before lactic acid begins to accumulate faster than your body can clear it.
Below this threshold, your aerobic system handles the energy demand. You can maintain the pace indefinitely — or close to it.
Above it, the clock starts ticking. Lactate builds. Muscles acidify. Performance drops.
Knowing exactly where that threshold sits changes everything about how you train.
WHY THRESHOLD MATTERS MORE THAN VO₂ MAX IN PRACTICE
VO₂ Max defines your aerobic ceiling. Lactate Threshold defines how much of that ceiling you can actually use.
Two athletes with identical VO₂ Max values — say, 52 ml/kg/min — can perform very differently if one has a threshold at 80% of VO₂ Max and the other at 65%. The first athlete can sustain a higher absolute workload for longer. Their threshold is more valuable than the raw ceiling.
This is why we measure both. They tell different stories.
HOW WE MEASURE IT
At REAX, Threshold Pace is assessed through a structured field test — a standardised protocol that correlates with laboratory lactate measurements without requiring a blood draw. The result is expressed in minutes per kilometre: your fastest sustainable pace before lactate shifts the energy balance.
A REAX athlete targeting Season 01 performance levels should be approaching 4:30–4:45 per km threshold pace by Checkpoint 3.
THE TRAINING PRESCRIPTION
Lactate Threshold is the most trainable of the four REAX metrics. Response times are faster than VO₂ Max adaptations, and the gains are more immediately transferable to performance.
The primary method is Threshold Training — sustained work at or just below the threshold pace for 20–40 minute blocks. This forces the aerobic system to become more efficient at clearing lactate without crossing into heavy accumulation.
Secondary methods include tempo intervals and progressive overload across successive sessions.
At REAX, threshold sessions are periodised within the weekly structure. They are not random. They are timed to allow adequate recovery between high-intensity sessions and scheduled to build across the 8-week checkpoint cycle.
TRACKING THE SHIFT
The threshold moves. In 8 weeks of structured training, a shift of 15–25 seconds per kilometre is achievable for most athletes. Over 52 weeks, the cumulative shift can be substantial.
This is why every REAX checkpoint includes a threshold assessment. Not to judge. To track the trajectory, confirm the training is working, and adjust the dose if it is not.
The data does not guess. It measures.