01/24/2025
Lactate threshold can be defined as the fastest your heart can beat without lactate building up to an unsustainable level. In other words a heart rate that allows your body to flush lactate at the rate that allows you to run approx 75 minutes.
Why is knowing this number so critical?
Staying under your lactate threshold allows you to maintain a pace between 20-75 minutes. This is critical as you run (row, swim or bike) various distances. Have you ever gone out for a run and bonked well before you finished? Most likely you were training above your lactate threshold, resulting in lactate build up and you crashed. Distances under 20 or so minutes of running you can get away with a HR above LT, as there isn’t enough time (in most cases) for lactate to build high enough.
How do you improve your lactate threshold? Ie: running faster at your LT HR?
Enter tempo runs. helped me understand this kind of run much better a few days back.
A tempo run is a run at which you run 10 or so beats slower than your LT but over the course of the run you slightly increase the pace and eventually end at your LT pace. This allows you to cover more mileage than you normally would at LT, creates massive improvement for LT runs and is generally more comfortable, meaning you aren’t in a heaping pile of pain afterwards.
In the attached pic I walked/ran for a warmup to start (part 1) then jumped to zone 2 (part 2) and then started the actual workout (part 3), running 6 miles at sub LT increasing pace 6 sec per mile each mile till the end. HR started at 153 and ended at 170. My LT is 170. Part 4 of the workout was the cooldown walk, which I recommend everyone watch and track how quickly their HR returns to the 100-110 mark. In highly conditioned individuals this will be within 2-4 minutes.
The next time you go for a run, row, bike or swim, ask yourself, what distance am I completing? What is the kind of session Im looking for? (testing, zone 2, lactate threshold, tempo, vo2 etc) Exactly where should my heart rate be? Overtime you will find a consistency that correlates to a certain heart rate and a run pace. IE , my LT mile pace is 7:45, zone 2 is 10:10 etc.
Good luck!