Yesterday, I led a presentation on training zones. I encourage you to watch the full presentation on our Facebook Page. Today, I want to highlight one aspect of the presentation that is important: The anaerobic threshold (AT).
Practically, the anaerobic threshold is the point of effort where your ability to endure greatly decreases. Below the AT, one can hold pace/effort for 40-60 minutes. Drop pace (increase effort) slightly though and your ability to hold onto that pace/effort is limited to 10-15 minutes. That is a big change and thus a very important metric to know for yourself personally.
Why such a drastic change at this point of effort. This has to do with how we fuel effort. Efforts below AT are largely aerobic (using oxygen) whereas efforts above AT are largely anaerobic (without oxygen). Now, this does not happen like a light switch whereas you are 100% aerobic below and then 100% anaerobic above. Instead, it is more like a dimmer switch whereas there is a mix of anaerobic and aerobic at most intensities though the majority switches at AT. When this happens, we slow down largely due to the production of lactate. Lactate is a by-product of anaerobic effort and is your body’s defense mechanism telling you that your effort is uncomfortable, and you should slow down.
Knowing your AT is vital for so many reasons. It is the point that we use to establish all other training zones, allows you to plan workouts to create exact physiological responses (see chart here), and allows you to pace your races properly. Please note that your AT heart rate will be different for each modality (swim, bike, run, etc) and of course metrics like pace and power will differ as well. You can determine your AT through lab testing such as VO2 testing (which is what we use at EF), field testing, or analyzing workout / race data with a trained eye. Regardless, it is important that you identify your AT and start training to develop it today.