The FasCat Maximal Lactate Steady State Protocol

A long time ago in a galaxy far far away we had a physiology lab and used the gold standard maximal lactate steady state (MLSS) protocol to determine athletes’ Functional Threshold Power (FTP) and corresponding Heart Rates.  By measuring steady state blood lactate concentrations and identifying workloads that elicit greater than 1mMol blood lactate concentrations changes we know the maximal sustainable power outputs that cyclists can sustain for a 40k time trial or 1 hour maximally.

The maximal lactate steady state (MLSS) is defined as the highest blood lactate concentration (MLSSc) and work load (MLSSw) that can be maintained overtime without a continual blood lactate accumulation. [1, 2, 4]There have been numerous studies describing and proving the relationship between MLSS and endurance sports performance. [3, 8]  At FasCat we use the concentration of blood lactate at the MLSS to determine the power output at MLSS.  We then use the average power output and heart rates to prescribe training intensities and set benchmarks of athlete’s training progress.


To determine the MLSSw, we use a single day MLSS assessment protocol originally described by Palmer et al in the 1999 Medicine & Science in Sports and Exercise journal.   This protocol was validated five years later by Kuphal et al in the Journal of Sports Medicine and Physical Fitness [9].


After interviewing the athlete and monitoring his or her warm-up via RPE, HR & wattage, we select 3 workloads in 10 watt increments to measure blood lactate, average power output and average heart rate.  The athlete holds each workload for ten minutes and blood lactate is sampled at 4 & 10 minutes during each ten minute stage.

During the ten minute stages we are looking for increases in blood lactate > than 1mMol.   If lactate remains “steady (increase of less than 1mMol) we move onto the next nine minute stage.  When we see > 1 mMol blood lactate increase, the maximal lactate steady state has been exceeded and therefore the previous stage and average power is the athlete’s MLSSw aka Functional Threshold Power.   In other words, the MLSS occurs at the greatest power output that does not elicit a greater than 1mMol rise in blood lactate concentration between the 4 and 10 minute samples for each stage/workload.

This power output is the point in exercise metabolism that defines the maximal lactate steady state and is the greatest wattage athletes can sustain while their lactate levels remain constant, aka a steady state.

MLSS identifies the balance between Lactate accumulation & clearance:

By measuring how an athlete’s blood lactate responds to certain workloads over time, we are able to pinpoint the greatest wattage and average heart rates the athlete can sustain as it relates to their endurance cycling performance.   For example the MLSSw we determine is equivalent to the average power the athlete could sustain in a 40K time trial in the days following the testing.

MLSS protocols are more appropriate for power based training to other methods of Lactate Threshold Testing such, L4 mMol & Dmax:

Other lactate threshold protocols do not measure blood lactateresponse to workloads over time.  Just because one identifies the wattage where an athlete hits L4 (4mMol) doesn’t mean they cansustain that workload as it relates to their endurance cycling performance.  In other words the athlete may be making more blood lactate than they are clearing which is not sustainable for long.  In such a case the athlete’s MLSSc would be < 4mMol.


Conversely, at L4 or the Dmax, the athlete may be clearing more lactate than they are making and capable of sustaining greater workloads.  In this case the athlete’s MLSSc would be > 4mMol.  This is why traditional exercise graded tests report ‘threshold’ power that does not synch up with their power data.

In the scientific literature MLSSc among athletes has been found to range between 2-8mMol/L and that blood lacate concentrations are independent of perforance [4].   In cycling it is the work load at MLSSc that determines endurance cycling performance [7].   Cyclist A with an MLSSc @ 3mMol may have a greater power output than Cyclist B who’s MLSSc is 4mMol or even 6mMol.  Therefore methods of determining power and heart rates at “threshold’ via using 4mMol are not as accurate inaccurate as an MLSS protocol that pinpoints that power output.

MLSS Testing is superior to a 20 min Field Test:

While a 20 minute field test is a good estimation of an athlete’s threshold power, it is not an accurate representation of the point at which an athlete’s body balances blood lactate accumulation and clearance.  In our experience, athletes are able to ‘bury’ themselves to exhaustion to set the highest average power output.   After all that is the goal.  However, data from the 20 minute Field test in the graph below shows how blood lactate concentrations increase from 4.4 mMol to 11.6 mMol at the end of the 20 minute test.  This athlete’s 20 minute Field Test power was 7.5% greater than his MLSS power (240w vs 222w) and his MLSSc was 2.75mMol vs. 7.67mMol for the 20 minute Field Test.

mlss to 20 min FT
Bentley et. al studied the relationship between  20 & 90 minute Time Trials to lactate threshold in the 2001 Medicine and Science in Sports & Exercise publication “Peak power output, the lactate threshold, and time trial performance in cyclists”. Not surpisingly they found that maximal power output changes depending on the length of the time trial.

As a result, functional threshold power set from a 20 minute Field Test in our experiences are too high and overshoot the important physiological breakpoint between the balance of lactate production and clearance.  In other words, athletes train too hard using power based training intensities set with a 20 minute field test.


1.     Billat VL, Dilmay F, Anlonini MT, et al. A method for determining the maximal steady state of blood lactate concentration from two levels of submaximal exercise.  Eur J Appl Physiol 1994; 69: 196-202

2.     Billat VL, Sirvent P, Py G, Koralsztein JP, & Mercier J. The Concept of Maximal Lactate Steady State. A bridge between biochemistry, physiology, and sport science.  Med Sci Sports Exerc 2003; 33 (6):407 – 426

3.     Billat VL use of blood lactate measurements for prediction of exercise performance and for control of training. Sports Med 1996; 22: 157-75

4.     Beneke R. Methodological aspects of maximal lactate steady state: implications for performance testing. Eur J Appl Physiol 2003 Marc; 89 (1): 95-9

5.     Beneke R, Hütler M Leihauser R, Maximal lactate steady-state independent of performance. Med Sci Sports Exerc 2000 Sep; 32 1335-9

6.     Bergman BC, Wolfel EE, Butterfield GE, et al. Active Muscle and whole body lactate kinetics after endurance training in men.  J Appl Physiol 1999; 87: 1684-96

7.     Bacon L, Kern M. Evaluating a test protocol for predicting maximum lactate steady state. J Sports Med Phys Fitness 1999; 39: 300-8

8.     Coyle EF, Coggan AR, Hopper MK, et al.  Determinants of endurance in well-trained cyclists, J Appl Physiol 1988; 64(6): 2622-30

9.     Kuphal KE, Potteiger JA, Frey BB, Hise MP. Validation of a single-day maximal lactate steady state assessment protocol. J Sports Med Phys Fitness 2004 June; 44(2):132-40

10.  Myburgh KH, Viljoen A, Tereblanches S.  Plasma lactate concentrations for self-selected maximal effort lasting 1 hour.  Med Sci Sports Exerc 2001; 33:152-6

11.  Lajoie C, Laureneelle L, Trudeau F.  Physiological responses to cycling for 60 minutes at maximal lactate steady state. Can J Appl Physiol 2000 Aug; 25 (4): 250-61

12.  MacIntosh BR, Esau S, Svedahl K.  The lactate minimum test for cycling estimation of the maximal lactate steady state. Can J Appl Physiol 2002 Jun; 27 (3): 232-49

13.  Palmer, AS, Potteiger JA, Nau LK, Tong RJ. A 1-day maximal lactate steady state assessment protocol for trained runners.  Med Sci Sports Exerc 1999 Sep; 31(9) 1336-41

14.  Bentley DJ, McNaughton LR, Thompson D, Vleck VE, Batterham AM. Peak power output, the lactate threshold, and time trial performance in cyclist. Med Sci Sports Exerc 2001 Dec; 33(12) 2077-81

15.  Morris DM, Shafer RS Comparison of power outputs during time trialing and power outputs eliciting metabolic variables in cycle ergometry.  Int J Sports Nutr Exerc Metab 2010; 20(2):115-21

Copyright 2018 , FasCat Coaching

Frank Overton is the owner, founder and head coach at FasCat Coaching, a cycling coaching company  in Boulder, CO.  To talk with Frank or a FasCat Coach about this maximal lactate steady state protocol or any laboratory testing, please call 720.406.7444, or fill out a New Athlete Questionnaire to set up a Coaching Consultation.  Additionally, check out the Training Plans for only $49 that Frank and the FasCat Coaches have designed for DIY athletes.