Sweet Spot - Watts & heart rate

When doing Sweet spot sessions (88-94% FTP) I find that my HR is below my Functional Threshold Heart Rate, 75-85% of maximum heart rate… Typically it is around 70% of MHR… Does that mean the my FTP may be a little low and therefore I’m not working quite harder enough to make gains through the sweet Spot training? Just interested to hear if other people have noticed the same…

Do I have my maths wrong?

Your HR at SS (70% of your max HR) is 82% - 93% of your threshold HR as per your estimates. This seems right in line with SS power (88 - 94% of threshold power). Where were you expecting it to be?


Currently mine just about tips the scales at 86% (MHR) but this after a rise in FTP.

Typically it sits at 81-83% MHR. If your’s is at 70%, this falls more within the Tempo range which might suggest your FTP is set low.

How did you set your FTP?

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I think the two are related but not tied together. As my fitness improves my heart rate decreases in SS intervals. Could I increase the watts, maybe. I’ve been trusting the process by doing an ftp test at the start of each block. I am switching from Ramp to the 20 minute test in a few weeks.

So I’d recommend appreciate your fitness is improving at that power output, retest when appropriate, and take the next step no matter how big or small. IMHO

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When I started my TR plan about 2 weeks ago I did the ramp test. In the past I usually do a 20 minute test…

Ideally, what you want to see is your HR being level in your SS intervals. And it should sit somewhere under your threshold HR. If it’s constantly creeping up throughout the interval, then yeah it’s possible you’re working too hard and perhaps an FTP shift is needed.

Depending on the intensity and length of the SS interval, and everyone’s a bit different, my HR can be sometimes only 1-2 bpm lower than my threshold HR (which would be 90% of my MHR). Some days it’s lower for the same intensity and duration. No hard rules but just some guidelines.

TLDR: level HR under threshold HR is what you’re after. :slight_smile: