Lactate Testing
If You Want to Race Your Best Ironman
Get Some Science on Your Side

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Riding even five heartbeats per minute above your true Ironman race pace can turn your marathon into a long walk home. So is there a magic Ironman pace and if so, how do you find it?

The truth is, the fastest-ever Ironman athletes use lactate testing to plan and monitor their progress. Through lactate testing, they find their "lactate threshold," which is the ideal Ironman race pace.

Lactate testing is a highly scientific way of looking inside the body during exercise to see exactly what's going on. It's sound science, exceptionally accurate and reliable. Lactate is the key player in endurance performance. It is far more important than VO2 max, as it is directly related to your ability to perform at race pace.

At its simplest, lactate (or lactic acid) is a byproduct of exercise. At easy paces you metabolize any lactate you create, but the harder you go, the more lactate you produce — and there comes a point when performance is adversely affected.

Lactate testing uses blood samples taken during a test to profile how you respond to different workloads. From this, you find the "thresholds" that limit your performance.

There are two thresholds that are important to the triathlete. Confusingly, they are often spoken of as being one and the same. They are in fact very different, and each one is relevant to a different type of triathlete. Both thresholds are found through the same lactate test and are given to you as specific corresponding heart rates, wattage levels and paces.

Lactate threshold (LT) is a highly aerobic point where lactate levels in the blood are still low but just starting to increase above steady-state levels. LT is the most efficient effort level that you can sustain for long periods of time without digging too deeply into your energy reserves. Go faster than this in the Ironman and you could end up taking an early shower.

Ironman athletes need to be highly aerobic, which means that very little lactate is produced even at peak speeds, which produces a very flat lactate curve. Ironman athletes typically have almost no "anaerobic capacity," which means that practically all their energy comes from aerobic sources.

Optimizing lactate threshold development is the main goal of Ironman training, and racing an Ironman at LT heart rate or wattage is the most efficient route to solid race day performance.

Anaerobic threshold (AT), on the other hand, is much more stressful because it produces much higher lactate levels and is therefore only sustainable for much shorter periods, like an Olympic distance triathlon.

A short-distance triathlete needs a more diverse profile that blends aerobic and anaerobic power, so that they can sprint up a hill to stay with the pack and work at a very high power output for short periods of time. For them, the development of anaerobic threshold is key, and they will produce a much wider range of lactate levels across their test.

Unless you have your lactate levels checked through blood samples taken during exercise, you have no idea where your thresholds are, and you are really shooting in the dark. This kind of testing is the best way to get accurate and valid results. Many companies out there offer so-called lactate testing, but if they do not take blood samples, you are getting a diluted service.

However, once you have found your thresholds, you can start to train very specifically and develop your physiology in the manner most appropriate to your event. Then on race day, you'll know exactly what effort to race at to achieve your optimal performance.

So in reality, if you are looking to qualify for Kona or to achieve your Ironman personal best, the way forward is simple. Get a test to find your thresholds, train smart using this data, re-test during your taper to find your new improved LT — and then race at LT and go faster than you could imagine. What could be simpler?

Gareth Thomas is the high performance coach at Cutting Edge Worldwide, which provide advanced lactate testing service for endurance athletes through their ERGO-LAB system.

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