When it comes to training, there are terms everyone knows – like VO2 max or chafing – and then there are the ones that get tossed around in conversation but that, to be honest, most people don’t fully understand. (No shame!) Case in point: aerobic and anaerobic threshold.
We may throw these words into conversation with our fit-minded friends from time to time – “Hey, does your coach have you doing much aerobic threshold work this season?” – but what do they actually mean, why does it matter, and what should you expect when it shows up on your training plan?
Let’s break it down. Here’s everything athletes should understand about anaerobic threshold. (And click here for a breakdown on all things aerobic threshold.)
What is anaerobic threshold?
“The term anaerobic threshold has actually caused a bit of controversy and discussion over the years,” says Caroline Varriale, DPT, CSCS, FAFS, and a physical therapist at Finish Line Physical Therapy in New York City.
“But in simplest terms, it’s commonly thought of as the point at which lactic acid – a byproduct of energy being made from glucose – starts to build up quickly in the blood.”
This happens because lactic acid can no longer be removed quickly enough and recombined with other molecules to make more energy. “At this point, exercise intensity feels more difficult and some people feel a burning sensation in their muscles,” Varriale says.
Most athletes enter the anaerobic threshold zone when they’re putting in some serious work
Muscles burn glucose two ways: aerobically, which means with oxygen, and anaerobically, or without oxygen.
Most athletes enter the anaerobic threshold zone when they’re putting in some serious work and a lot of power output over a short period of time – like during an interval or sprint. You’re utilizing energy that’s readily available, but that won’t last long.
As you rest and recover, between intervals for example, your aerobic system recharges, readying you for the next push.
What’s the best way to measure anaerobic threshold?
Anaerobic threshold varies from athlete to athlete. For athletes who regularly do interval-style workouts, their anaerobic thresholds will be much higher and more conditioned than those who only do long, steady-state workouts – or don’t train at all.
The more you perform high-intensity workouts, the better you can condition your anaerobic threshold and process lactate in the body – and the faster you’ll be able to swim, bike, or run.
What does anaerobic threshold feel like?
Well, it probably hurts and burns a little, but it shouldn’t be completely uncomfortable. If you’ve ever done a track workout – say 400-meter repeats – you’ve probably gotten into the anaerobic zone on each repeat. You feel it when you’re breathing heavily, can feel a pronounced heartbeat, are slightly gasping for air, and can’t carry on a conversation.
Even as you get fitter, you’ll still find yourself gasping for air during your track workouts – but you’ll probably be shaving a few seconds off each repeat. So as the effort stays consistent, your performance increases. (That means it’s working!)
Why does it matter?
“It’s important for athletes to understand aerobic and anaerobic energy systems,” says Varriale. “The aerobic energy system gives you more long-lasting energy because it burns predominantly fat stores. So for endurance athletes, it’s an important system to train. But the anaerobic energy system can produce energy more quickly, and allows us to exercise at higher intensities, so that’s crucial, too.”
In other words, make sure your training plan includes high-intensity intervals, steady-state workouts, and rest days to recover from both. Because slow, steady, fast, and recovered are what work together to win the race.
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Please note that the information provided in the Polar Blog articles cannot replace individual advice from health professionals. Please consult your physician before starting a new fitness program.