Thank you in advance for your help, Letsrunners. I am a swimmer, not a runner, but the question I have concerns energy systems so I am certain you can answer most of my questions. I am wondering about lactate threshold.
My goal is to improve my 400 meter freestyle, roughly the same as running a mile. My time right now is 5:45. I am almost 44 years old.
I do lots of slow swimming at approximately 125 HR. I arrived at that HR through Phil Maffetone’s estimated aerobic maximum, 18-my age-adjustments for my asthma and high blood pressure. At first I couldn’t do freestyle at all at that HR. But a few weeks ago I swam 3.5 miles at that heartrate. It took almost 2 hours, but that is progress.
Coming off six weeks of training solely at 125 HR or lower, I performed a 3000 meter freestyle at maximum in an effort to discover my lactate threshold. My time was 47:29. That is the rough equivalent of running 7.5 miles. Right afterwards my HR was 164, so I estimate it was probably around 170 during the actual swim. According to this test, my lactate threshold paces are as follows:
1:35 per 100
3:10 per 200
6:20 per 400
My first 400 was, to my surprise, a 6:02. So you can see I got slower later on.
My questions are as follows:
1. Can I assume that 6:20 is my lactate threshold pace, more or less? If not, what did I do wrong, and what sort of test should I conduct?
2. Once I get my lactate threshold, how should I train? Should I swim repeats at lactate threshold pace, gradually seeking to improve? Or should I start lower than lactate threshold? Hadd suggests training below threshold, and slowly moving up in HR, becoming steady and proficient at every level, I suppose to challenge all muscle fibers, before training at threshold and above. This appealed to me because I have a terrible time finishing my 400s strong.
Thank you very much for any suggestions you can give. God bless.