The lactate threshold – more like lac-GREAT threshold

Puns aside, the lactate threshold is quite important. It represents the body’s transition between exercise feeling great—your ‘all day pace’—to feeling fatigued and potentially experiencing muscle soreness. Understanding and improving your lactate threshold can help you work out stronger and longer before that fatigue starts to set in – so let’s dig in!

Can you tell me more:

Last week, we spent a bit of time discussing energy metabolism: where our body can generate energy from and how. If you recall, two major types of energy metabolism take place: aerobic (with oxygen) and anaerobic (without oxygen). 

Our bodies are incredibly efficient when utilizing oxygen, and an abundance of energy is available when oxygen is plenty. But what happens when we start to increase our intensity? We start to breathe harder, we feel short of breath, and we realize how much we take our oxygen for granted.

In this state, the anaerobic metabolism kicks in while energy is still produced and there is more ‘waste’ produced. This ‘waste’ is the key of this episode: lactate.

Why does lactate matter?

Our bodies are constantly in a state of energy use and recycling. In fact, at any given point in time, we are using multiple methods of energy metabolism, and the ratios simply change as our needs change. Because of this, all of us will have a small amount of lactate in our blood in our normal resting state.

As we begin to increase our exercise intensity, our lactate levels naturally rise. We need more energy; we create more lactate. At first, our body is able to keep up with the changes. The lactate level (if measured via blood sample), will be higher than our resting state but we achieve a new steady state or balance where changes in respiration, muscle activation, and other processes in our brain and liver compensate for the increased production (1). This is called Lactate Threshold 1. We can typically hold this level of exertion for at least 30 minutes, without losing this steady state balance. This typically occurs around 50% of VO2 max (2).

As we increase our exertion even further, our body’s ability to keep up is tested. At this point lactate levels in the blood (and in the muscle) start to accumulate rapidly. This is called Lactate Threshold 2. This tends to occur around 70-90% of VO2 Max (2).

Author’s note: While lactate was traditionally referred to as a ‘waste product.’ That isn’t entirely true. Elevations in lactate have been linked to many of the symptoms of fatiguing, muscle soreness, and decreased muscle contraction. That said, lactate clearance includes mechanisms in the muscle, liver, and even brain that have positive and beneficial downstream effects. Some of the lactate use in the brain is actually thought to play a protective role for memory, cognition, and mood (3)!

Why does this matter for me?

Think of improving your lactate threshold like getting a new (and updated) smartphone. The new phone, with new hardware, is going to have faster processing power, longer battery life, and just runs smoother. Improving your lactate threshold means that you too have more power, you’ll be able to work out longer before fatiguing, and you’ll just run smoother.

One famous example includes the Norwegian family (Ingebrigtsen) brothers who were setting racing records in the 2010s and 2020s. One piece of their impressive training was an innovative (and very important) regimen that used blood lactate levels to monitor their high-intensity training (4). While I can’t promise we will all become Olympians using this singular technique, this helped revolutionize the world of athletic training and brought lactate threshold training further into the spotlight.

What can I do?

While research is still ongoing about the best ways to improve performance in sports, there are a few things we want to be sure to include in our training.

• Strength training is an important component to any training regimen and has been linked to improvements in lactate threshold. Increasing muscle strength likely improves the muscles capacity to utilize and recycle lactate efficiently (5).

• As we talked about in the VO2 Max episode, intervals training is a great way to improve our fitness. High intensity intervals (that stretch beyond our Lactate thresholds) lead to further improvements and adaptations in our performance (6).

While it is not practical to use blood testing to monitor our lactate levels frequently for exercise, we can use other related markers.  Benchmarks such as heart rate, VO2 max, etc. can help us estimate when we hit these thresholds and help formulate better (and more personalized) training plans.

Ultimately, a good mix of strength, endurance, and high-intensity intervals will get you the results you are looking for. So don’t hesitate, get back out there and improve that lactate!

Sources and Further Readings

1. Binder RK, Wonisch M, Corra U, Cohen-Solal A, Vanhees L, Saner H, et al. Methodological approach to the first and second lactate threshold in incremental cardiopulmonary exercise testing. Eur J Cardiovasc Prev Rehabil. 2008 Dec 1;15(6):726–34. 

2. Skinner JS, McLellan TM. The transition from aerobic to anaerobic metabolism. Res Q Exerc Sport. 1980 Mar;51(1):234–48. 

3. Lee S, Choi Y, Jeong E, Park J, Kim J, Tanaka M, et al. Physiological significance of elevated levels of lactate by exercise training in the brain and body. J Biosci Bioeng. 2023 Mar 1;135(3):167–75. 

4. Tjelta LI. Three Norwegian brothers all European 1500 m champions: What is the secret? Int J Sports Sci Coach. 2019 Oct 1;14(5):694–700. 

5. Marcinik EJ, Potts J, Schlabach G, Will S, Dawson P, Hurley BF. Effects of strength training on lactate threshold and endurance performance. Med Sci Sports Exerc. 1991 Jun;23(6):739–43. 

6. Casado A, Foster C, Bakken M, Tjelta LI. Does Lactate-Guided Threshold Interval Training within a High-Volume Low-Intensity Approach Represent the “Next Step” in the Evolution of Distance Running Training? Int J Environ Res Public Health. 2023 Feb 21;20(5):3782.