This morning I had a meeting with a customer so, I was unable to get out on the water. Pity, because it was a beautiful, cool, sunny, windless day. But I was able to make time for an erg session in the early afternoon.

I decided that today would be a good day to run the next installment of my lactate level during endurance session experiment. Last time, I was running at 180W and my HR and lactates blew through the roof! Today, the plan was to back off the power to 170W and measure lactates every 20 minutes during an 80 4×20’/1′ rest session.

Here is the plots for watts, SPM and HR. As it appears, it was incredibly easy. My HR nudged into the UT2 zone, and only by a beat or two and only in the last 25 minutes or so. I tried to do 170W, but it I was in a groove in the first piece at 173W, and then, after that, I just decided to hold 175W. My HR was so ridiculously low, I didn’t see much harm.

Output
Workout Summary – Sep 23, 2015
–_|_Total_|_-Total-_|_–Avg–_|_-Avg-_|_Avg-_|_-Avg-_|_–Avg–_|_-Avg_|_-Avg
–_|_Dist-_|_-Time–_|_-Pace–_|_Watts_|_SPM-_|_-HR–_|_-%HRR–_|_-DPS_|_-SPI
–_|_19047_|_80:00.0_|_02:06.0_|_175.0_|_17.8_|_128.1_|_ 59.7% _|_13.4_|_09.8
Workout Details
#-_|_SDist_|_-Split-_|_-SPace-_|_Watts_|_SPM-_|_AvgHR_|_Avg%HRR_|_DPS-_|_-SPI

01_|_04745_|_20:00.0_|_02:06.5_|_173.1_|_17.8_|_120.3_|_ 54.1% _|_13.3_|_09.7
02_|_04766_|_20:00.0_|_02:05.9_|_175.5_|_17.6_|_125.8_|_ 58.0% _|_13.5_|_10.0
03_|_04766_|_20:00.0_|_02:05.9_|_175.4_|_17.9_|_132.1_|_ 62.5% _|_13.3_|_09.8
04_|_04771_|_20:00.0_|_02:05.8_|_175.9_|_17.8_|_134.2_|_ 64.0% _|_13.4_|_09.9

When you compare these results to the last two tests, it becomes clear just how sharp the between training at an intensity below the aerobic threshold and above it. At 181W, I was producing just a little bit more lactate than I could process and the levels steadily climbed. At 176W, I was able to process all the lactate produced and the levels stayed low and actually declined after 40 minutes.

The other thing that is clear from these results is that when my lactate levels are stable, the amount of HR increase is lower than if I am accumulating lactate, but the effect is not that pronounced. A big difference is the HR after 20 minutes.  And then the rise from 20 minutes to 80 minutes was 13% or 21% for the higher wattages and 10% for the 175W.

But, I think this illustrates that the best way to train at or below 2.0 mmol/l lactate level is to actually measure lactates.  At best, there will be a short term, loose correlation between HR and lactate, and one of the primary effects of endurance training will be to increase the HR at which you are not accumulating lactate.

Here the plot comparing HR and Lactate for the 3 trials.

Pretty remarked the difference 6 watts makes!  Now, I just need to slowly inch up the power and keep testing at 20 minute intervals to make sure I stay at or below 2.0mmol/l.

Now I am on a plane to California.  I plan to do an easy endurance session tomorrow morning (HR cap of 70% HRR, 145).  And then take a rest day on Friday since I have an early flight and don’t arrive home until evening.