Lactate Threshold vs VO2 Max: Ceiling vs Usable Share
Lactate threshold vs VO2 max: what each measures, why riders with identical VO2 max can differ 24% at threshold, and which test answers your question.
Lactate threshold vs VO2 max comes down to ceiling versus usable share. VO2 max is the highest rate at which your body can take up and use oxygen; the lactate threshold is the intensity, often expressed as a percentage of VO2 max, above which blood lactate starts to accumulate. VO2 max sets the upper limit. The lactate threshold decides how much of that limit you can hold for an hour or more, and for long events that second number usually explains more of the result.
Two numbers, two different questions
VO2 max (maximal oxygen uptake) is measured in millilitres of oxygen per kilogram of body mass per minute (ml/kg/min) during an all-out test with a gas analyser. It answers: how big is the engine?
Lactate threshold (LT) is located from blood samples taken during a step test. It answers: at what workload does the engine stop running in balance? It is reported as power, pace, heart rate, or as a fraction of VO2 max.
Bassett and Howley's 2000 review in Medicine and Science in Sports and Exercise describes VO2 max as the variable that "sets the upper limit for endurance performance", with running economy and the fraction of VO2 max an athlete can sustain also shaping the result. The speed at lactate threshold, they conclude, integrates all three and is the best physiological predictor of distance running performance.
Why one can change while the other stays flat
Coyle's 1995 review in Exercise and Sport Sciences Reviews reports that performance improvements after the first two to three years of intense training are associated with improvements in the lactate threshold, whereas VO2 max generally increases very little thereafter. The same review attributes 31 to 72% of the variance in lactate threshold VO2 to VO2 max itself. The two are linked, but far from identical.
The study that separates them most clearly
Coyle's review also describes two groups of competitive cyclists with identical VO2 max but different lactate thresholds: 82% versus 66% of VO2 max. Cycling at 80 to 88% of VO2 max, the low-threshold group showed more than twice the rate of muscle glycogen use and blood lactate concentration, and could exercise only about half as long.
Same ceiling, half the endurance time. That is the core of the comparison.
What those percentages mean in absolute terms
The following is a fictional illustration using the two percentages from Coyle's groups and an assumed VO2 max of 60 ml/kg/min for both riders:
| Rider | VO2 max (ml/kg/min) | LT as % of VO2 max | Oxygen uptake at LT (ml/kg/min) |
|---|---|---|---|
| A | 60 | 82% | 49.2 |
| B | 60 | 66% | 39.6 |
Rider A sustains roughly 24% more oxygen uptake at threshold (49.2 ÷ 39.6 = 1.24) despite an identical VO2 max. A VO2 max test alone would rate them as equal.
A season where only one number moves
A second fictional example: an athlete with a VO2 max of 55 ml/kg/min retests after a winter block. VO2 max is unchanged, but the threshold moves from 72% to 78% of VO2 max.
- Before: 55 × 0.72 = 39.6 ml/kg/min at LT
- After: 55 × 0.78 = 42.9 ml/kg/min at LT
- Change: +8.3% at threshold, 0% at VO2 max
If this athlete only tracked a VO2 max figure, the report would read "no progress". The lactate curve would show a clear shift to the right.
Which test answers your question
Neither test is "better". They measure different things, and the right choice depends on what decision you want to make.
| Your question | Number that answers it | Typical test | Equipment |
|---|---|---|---|
| How large is my aerobic ceiling? | VO2 max | Ramp test to exhaustion with gas exchange | Metabolic cart, lab |
| At what power or pace does lactate start to accumulate? | LT1 / LT2 | Step test with blood samples per stage | Portable lactate meter, ergometer or treadmill |
| Has my sustainable intensity changed since last test? | LT power or pace, same method | Repeat step test, identical protocol | Lactate meter |
| What fraction of my ceiling can I use? | LT as % of VO2 max | Both tests, ideally close together | Lab plus lactate meter |
The last row is the only one that needs both measurements. For the first three, one test is enough, and the lactate step test is the one you can run without a lab. If you are weighing those two routes, Lactate test cost comparison: lab vs. home testing breaks down what each one costs.
LactateThreshold works on the lactate side of this table: you enter the stage data from your step test and get LT1, LT2, the lactate curve and training zones. It does not replace a gas-exchange VO2 max test.
Where the comparison goes wrong
Three mistakes show up repeatedly when people put these numbers side by side.
Mixing a watch estimate with a lab value. Many sports watches display an estimated VO2 max derived from heart rate and pace. That figure is a model, not a gas measurement. Comparing it with a lab-measured lactate threshold percentage produces a ratio of two different kinds of number.
Reading a 4 mmol/L value as "the" threshold. Richardson and colleagues used the percentage of VO2 max at a fixed blood lactate of 4 mM in ten untrained men and found it correlated with time to exhaustion (rho = 0.75), but described the relationship as only modest for that group (Richardson et al., 1989). A fixed-value threshold is one definition among several; the step-by-step differences between methods are in Calculate lactate threshold: methods and formulas explained.
Quoting percentages without a source. Commercial guides often give tidy bands for threshold as a percentage of VO2 max by training level; one widely read example places elite athletes' LT2 at roughly 85 to 90% of VO2 max and attributes that figure to Coyle (1995) (PeakVO2Trainer). Treat such bands as orientation, not as a target for your own report, because they depend on the threshold definition used.
Planning the winter test pair
November and December are, for many road athletes, the start of a base phase with fewer races. If you want both numbers, schedule them so they can be compared:
- Run the VO2 max test and the lactate step test within the same one to two weeks, so fitness has not shifted between them.
- Use the same ergometer type for both, because cycling and running values differ.
- Write down the threshold method used in the lactate analysis (for example fixed 4 mmol/L, Dmax or a baseline-plus method) next to the result.
- For the spring retest, repeat the lactate step test with the identical protocol. Whether a second VO2 max test is worth the lab cost depends on whether the fraction-of-ceiling question actually matters to you.
How hard you then train relative to either number is a coaching decision. If you have a heart condition or other health concern, clear maximal testing with a physician first.
FAQ
Is VO2 max related to lactate threshold?
Yes. Coyle's 1995 review attributes 31 to 72% of the variance in lactate-threshold oxygen uptake to VO2 max, which sets the upper limit. The rest depends on muscle factors, which is why two athletes with the same VO2 max can have very different thresholds.
What is the difference between lactate threshold and aerobic threshold?
The aerobic threshold usually refers to the first rise of blood lactate above baseline, often labelled LT1. "Lactate threshold" is used for either LT1 or the higher LT2, depending on the source, so check which one a report means. LactateThreshold reports both LT1 and LT2 so the label is explicit.
Is lactate threshold or VO2 max more important for endurance?
For prolonged events, Bassett and Howley name the speed at lactate threshold as the best physiological predictor of distance running performance, because it combines VO2 max, economy and the sustainable fraction. VO2 max still matters, because it caps how high the threshold can go.