Learn About Lactate Threshold from I Love Lucy

October 15 is National Lucille Ball Day. In honor of that day here is a reprint of an old post from my former blog.

The I Love Lucy show provides one of the most humorous and excellent analogies for the lactate threshold (LT). In honor of Lucille Ball, I want to share this hilarious video. I’ve been using this analogy since my early days as a master instructor for Spinning®. It’s kind of fun when I get tagged in social media by another master trainer who is inspired to use this analogy with their audience. If it helps you explain this to your peeps, please feel free to use it! (Then tag me in social media so I know the love is being spread!) 😉 

So, how can I Love Lucy teach us about lactate threshold? Chocolates, of course! 

When we speak about exercise intensity, we refer to the lactate threshold or LT. LT can be a fairly complicated concept to understand, but this famous clip from an episode of I Love Lucy in 1952 should help clarify it for you. Watch this video and then we’ll break it down for you.

What is the lactate threshold?

Lactate is a metabolic byproduct of anaerobic glycolysis. Normally, as lactate is produced, the body clears it from the blood and converts it into useable energy. As long as the body can easily clear the lactate, the effort is still at an aerobic level and can be sustained. As intensity increases, lactate is produced at a faster rate.

When the body cannot clear it as quickly as it’s being produced, lactate—and the accompanying H+ ions that are produced concurrently— begin to accumulate in the blood. This accumulation can interfere with muscle contraction, and the decreasing pH of the blood (meaning more acidic due to increased H+) is assumed to be the source of the “burning” sensation in the muscles at anaerobic intensities. (This is the prevailing theory, though science hasn’t proven it conclusively.)

Lactate threshold is the point at which lactate production exceeds the body’s ability to clear it. One way to identify LT is to relate it to the specific heart rate where this occurs. Below the lactate threshold, metabolism is predominantly aerobic and is sustainable. Above it, metabolism is predominantly anaerobic and is not sustainable. The higher you go above LT, the less sustainable it is, until you can only endure a few seconds of that intensity without backing off or stopping. 

You can raise this threshold when you train wisely around it. When you raise your LT, you effectively “buy yourself” a few more heartbeats before fatigue sets in. In other words, you can go further, faster, and longer before you are forced to back off or quit.

Translation: You are fitter than you were before.

Think of the chocolates on Lucy and Ethel’s conveyor belt as the “lactate” and wrapping them as the body removing the lactate as it’s produced. As long as Lucy and Ethel can wrap the chocolates in a consistent and sustainable way, they are still predominantly “aerobic.” At this point, lactate (i.e., chocolate) is still being produced—but it is at a manageable rate.

Then the conveyor belt starts to speed up. The ladies must work harder to wrap the chocolates, but it is still possible to do it without losing one. With more training, they could go even faster. However, there comes a point when the chocolates arrive at a rate that is too fast, and they begin to accumulate. When this happens, Lucy and Ethel have exceeded their “chocolate-wrapping threshold”! In other words, they’ve exceeded the lactate threshold.

Now, the point when Lucy and Ethel begin stuffing the chocolates into their shirts and mouths—they have totally redlined it and are fully anaerobic. They will surely not be able to maintain that for very long at all!

Imagine different people with various levels of training in wrapping chocolates. Some will be able to go faster and longer before they reach their “wrapping threshold,” but at some point, everyone will be unable to keep up and the chocolates will start to accumulate.

Very experienced wrappers are like highly trained athletes…they have much higher thresholds.

Knowing your LT (or your approximate LT) is one of the more important ways to increase your fitness and performance.

Thank you, Lucille Ball, for so many years of fun and laughter, and most especially for this video!


  1. such a great analogy and fun! Thank you

  2. Great article – thank you!
    PS – It’s Oct. again 🙂

    1. Author

      thanks for the reminder!! I should put this on automatic repost every Oct 15! Dang, it’s a little too late for that. Maybe I’ll do that for next year. =)

      1. Shared the article with my class – thank you!

  3. I hadn’t seen this, and I absolutely LOVE IT! I may even download the video from Youtube and play it for my classes.

    Now…to get them to wear HRMs…sigh. 🙂

  4. Awesome! Lucy is my favourite Lol. I probably won’t forget this analogy.

  5. i so love this, thx!!!

  6. Awesome !! I will have fun sharing this , Thank you ????

  7. Great analogy and explanation. I am using lactate threshold conversations in my classes and this helps better explain how everyone can train to improve theirs with some awareness. Thanks Jennifer.

  8. Author

    I am going to reschedule this post every October 16 to help instructors all over the world…and of course, to honor the greatest comedienne we’ve ever had!

    1. Love it! Thanks, Jennifer

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