We get lots of people who book VO2 max testing or lactate threshold testing as they want to establish accurate training zones. Depending upon what and where you read, there are numerous ways of calculating zones. Our advice is keep it simple, keep it practical and use zones that you understand. So here’s our guidelines to help you better understand:

Zone 1 is conversation pace, where you can hold a full conversation (not a broken one). The first threshold (known by numerous names such as LT1, VT1 or aerobic threshold) is the point at which you go from being able to hold a full conversation to holding a broken conversation.

Zone 1 example workout, 90 minutes easy run.

Zone 2 is broken conversation pace, just above the (LT1 / VT1 / aerobic threshold). Most runners who think they are running easy in ‘Zone 1’ will generally always run a little too hard and run in Zone 2.

Zone 2 example workout, 2 x 20 minutes or 20-40 minutes continuous.

Zone 3 is no conversation but it remains ‘aerobic’. For example, 10k race pace would tend to be Zone 3. You’re working hard but it is still an aerobic workout.

Zone 3 example workout, 3 X 10 minutes with 2 minutes recovery after each.

Zone 4 is the point at which you reach the second threshold (LT2 / VT2 / anaerobic threshold or whatever else we’re calling it these days). The 2nd threshold point is the intensity at which you start to use the anaerobic system to a much larger degree. Exercise above the LT2 / VT2 / anaerobic threshold is not sustainable. For most cycling and running events, you need to stay below this threshold point to maintain a consistent pace. If you ran for 15-20 minutes as hard as possible, you wouldn’t be far from your 2nd threshold point.

Zone 4 example workout, 4 X 4-5 minutes with 2 minutes recovery after each.

Zone 5 is often termed VO2 Max as it’s similar to the pace and intensity at which you would reach your VO2 Max during a testing session. It’s not possible to sustain this intensity for long as it’s above LT2 / VT2 / anaerobic threshold.

Zone 5 example workout, 5 X 2-3 minutes with 2 minutes recovery after each.

So here’s the things to know. If you are using a heart rate monitor to guide your training zones, it will be reliable for zones 1,2 & 3 but not reliable at all for zones 4 & 5. For zones 4 & 5, you need to ignore heart rate and let perceived effort and pace be your guide. You may well find that zone 4 is 5k race pace or a little quicker, zone 5 is then a little faster.

If we are identifying thresholds 1 and 2 to help us set training zones then which test is better? VO2 Max or lactate threshold?

We’ve used the terms LT1 / VT1 and LT2 / VT2 above, so let’s just clarify what they actually mean. If we’re measuring blood lactate, there’s a very small rise in blood lactate levels (to 1 mmol) at the broder of zone 1 and zone 2 (full conversation to broken conversation), this is lactate threshold 1 (LT1). As the intensity increases and you gain speed, blood lactate levels continue to rise, but we reach a point where they suddenly rise at an alarming rate which is lactate threshold 2 (LT2).

When lactate levels increase, so does blood acidity. An increase in blood acidity then triggers an increase in breathing rate. So the small rise in lactate we see at LT1, leads to a small increase in breathing rate, which means you can no longer hold a full conversation. We call this small increase in breathing ventilatory threshold 1 (VT1). Likewise, when you reach the 2nd lactate threshold and blood lactate increases at an alarming rate, your breathing will also start to increase at an alarming rate, which is ventilatory threshold 2 (VT2).

So… the difference between LT1/VT1 & LT2/VT2 is simply how we choose to measure it. Are we taking blood samples and measuring lactate to identify thresholds or are we measuring ventilation and breathing rate to identify thresholds.

From our experience, ventilatory thresholds tend to be a little more accurate for the purpose of setting training zones. So in simple terms, if you book a VO2 max test and wear a mask which measures ventilation, the thresholds and training zones calculated, tend to be more accurate than taking blood samples and measuring lactate.

We have gone into some technical details above but as with all training plans, the best advice is to keep it simple, keep it practical and understand the system / zones you are using and why you are using it. Don’t get bogged down in the science too much, after all, it’s just running.

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