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When Should You Retest Your Lactate Threshold?
A retest always shows where your fitness is. Its real value is after a training block, when it tells you whether the block worked.
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Train smarter, with the science to back it
Plain-English guides to lactate threshold, training zones and what to do with your FitnessCheck results.
All blog posts are written by us as humans based on our real life experiences. AI is used to check grammar and spelling only.
Your Watch's "Lactate Threshold" Feature Isn't Measuring Your Lactate Threshold
Your Garmin gives you a lactate threshold heart rate. It never took a drop of your blood.
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Your FTP Is an Estimate. Your Heart Rate Zones Are an Estimate of an Estimate.
FTP is guessed from a short test. Then your heart rate zones are guessed from that guess. Here's why the errors compound, and how lactate testing measures your zones directly.
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Lactate, VO2 Max, or Combined: Which Test Should You Book?
Three tests, one decision. Here's an honest guide to whether you need a lactate threshold test, a VO2 max test, or the combined profile, based on what you actually train for.
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FitnessCheck Comes to Heathwood Swimming and Triathlon Club in Cardiff
We're bringing lactate threshold and cycling testing to Heathwood Swimming and Triathlon Club in Cardiff. Cycling tests open from 26 August 2026, with swim-specific testing to follow.
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FTP and the Female Cyclist: What the Standard Training Numbers Get Wrong (Both Ways)
FTP and percentage-based zones were built largely on male physiology. Recent data shows they overestimate women's sustainable power at threshold and undersell their durability over distance.
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Why Your VO2 Max Isn't Improving (The Oxygen Cascade Explained)
VO2 max is limited by oxygen delivery, not by your muscles. Follow the oxygen from the air to the mitochondria and you find the one step training actually changes, and why it is not the step most athletes train.
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Lactate vs Ventilatory Thresholds: Our Findings and Why We Measure Blood, Not Breath
Ventilatory thresholds estimate your training zones from your breathing. Blood lactate measures them directly. We regularly see the two disagree by enough to ruin a pace target, which is why we measure blood for thresholds.
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How Quickly Can You Improve Your Lactate Threshold?
One athlete moved her anaerobic threshold from 12.7 to 14.3 km/h in 8 weeks with one session a week. Here's what a lactate curve shift actually looks like, what drove it, and what you can realistically expect from your own retest.
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What an Elite Hyrox Athlete's Lactate Profile Actually Looks Like
We tested Hyrox pro Bodger Rees at KORE gym in Newport. We won't share his exact numbers, but the shape of an elite lactate profile is a lesson for every Hyrox athlete.
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Hyrox Pacing Strategy: Run Below Your Anaerobic Threshold (Here's Why)
Most Hyrox advice says race at threshold. The lactate data from my own race simulations says otherwise, and shows why running below your anaerobic threshold is what stops you blowing up.
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How Your Lactate Zones Match Your Watch’s Zones
Your watch has five heart-rate zones; a lactate test reveals two thresholds and three effort bands. Here is how the two systems fit together.
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Lactate Test Case Study: Garmin Zone 2 Was 17 bpm Too Low
A 45-minute lactate test in South Wales showed Tayla's Zone 2 capped at 157 bpm, not 140. Her Garmin was wrong by 17 bpm. Here's what we found and changed.
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Your Zone 2 Heart Rate Is Probably Wrong. Here's How to Tell.
Most athletes find their zone 2 from the talk test, the 220-age formula, or their watch. All three are wrong for a meaningful share of runners, and you can't tell from the inside which kind of wrong yours is.
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What's Actually in a Lactate Threshold Test Report
A walk through what you actually receive in a lactate threshold test report, section by section, from at-a-glance summary to retest recommendations.
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Why You Blow Up in the Second Half of a Hyrox (And How to Fix It)
Most athletes who blow up in the back half of a Hyrox spent the first half above their lactate threshold without realising it. Here is the fix, station by station.
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Do You Actually Need a Lactate Threshold Test? An Honest Answer
Most athletes who book a lactate threshold test benefit from it, some don't. Here is who walks away with the most useful data, and who should wait.
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