December 2, 2022
As I’ve mentioned before, The Uphill Athlete has become my training bible. There is a lot of useful information in there, and I am regularly testing out ideas therein in my training. After 8 weeks and more than 200 miles of zone training, I thought I am ready to attempt a lactate threshold test. What is that exactly? Here’s some background.
This and other sources divide our heartrate range into 5 zones, with Zone 1 being at the lower end of the heartrate range, while the top of Zone 5 presses up against your maximum heartrate. Zones 1 and 2 are defined as the heartrate range where the athlete burns more fat than carbs. Zone 1 includes brisk walks to maybe slow jogs while Zone 2 includes faster jogs; Zones 1 and 2 are expandable with training and a well-trained athlete can run quite fast in Zone 2. (I am not yet a well-trained athlete ☹.) One begins to burn more carbs than fats in Zone 3, but a Zone 3 pace is sustainable for up to an hour for a well-trained athlete. The top of Zone 3 is the Lactate Threshold. Our muscles produce lactic acid when we run. When we are in Zones 1 and 2 this lactic acid is readily reprocessed to provide more energy. In Zone 3 the amount of lactic acid produced slowly overwhelms the system for transitioning it back into energy. In Zones 4 and 5 the rate of lactic acid production is much higher and quickly overwhelms our ability to reprocess it and we tire quickly.
The Lactate Threshold is valuable information as it’s the border between where we can and cannot reprocess the bulk of the lactic acid we produce. The Uphill Athlete contains a simple test to enable one to find their Lactate Threshold. The test involves a maximum sustained uphill effort for 30 to 60 minutes after a 15–20-minute warmup. Well Geez, is that all. Oh wait, it can also be done on a treadmill. Note, they forgot to write that the treadmill should be set in as steep an uphill position as you can set it, so I figured setting it on flat would suffice.
Once you start your maximum sustainable pace one is supposed to find that their heartrate settles into a narrow range and stays there. If this works, the average heartrate in this range is your lactate threshold. Simple enough, but it didn’t work.
Before going into details about the test failure I will note, as y’all know, I have been running slowly for the past 2 months, and I have been running outside on hilly roads and in the mountains. I finally joined a gym this week as the darkness and cold can sometimes present challenging conditions for a run; the roads are often icy and the short days limit when I can get a run in. But, as a result of not running on a treadmill, and not running fast, I have no idea what my current maximum sustained pace might be. I took a guess and started off at 8:49/mile after a 20 minute warmup.
For the first 8 minutes, my heartrate stayed pretty close to 135, where I currently have my Lacate Threshold set. I thought, this is great, I set it right just by guessing. But then it started trending upward. Fifteen minutes in, it reached 150. I was starting to wonder if I should have brought the book with me. Did I miss some key point? Twenty-three minutes in it started trending upward into the 150s, and I became concerned enough to slow my pace a to 9:05/mile. My lactate threshold couldn’t be this high, my maximum heartrate is only around 159.
I continued at this pace hoping my heartrate would slow. It stabilized for a little while but then it started climbing again. At 33 minutes it was in the mid-150s. I slowed my pace to 9:22/mile. Before I reached 43 minutes in, my heartrate climbed to 165 and I figured my heart attack risk was climbing with it. I decided the test was over. I started cooling down.
Back home I opened the book. The key point I may have missed was that my pace should feel “comfortably hard.” My initial 8:49 pace was maintainable, but definitely not comfortable.
I’ll try again in about 2 weeks starting at a slightly slower pace and let y’all know how it goes.
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