The lactate threshold is one of the most common and effectively used performance markers in sports. Many athletes and coaches use them to discover the highest sustained intensities at which they can compete and train before hitting the proverbial wall.
In simple terms, the lactate threshold (LT) is when the body produces more lactate than it can remove. And with proper training, it can adapt to handle greater and greater workloads while also creating more energy to fuel muscles.
• a better understanding of athletic fitness
• understand proper pace to use in training and racing
• increase performance with tailored race strategies
Why the lactate threshold matters
V02 max, or the maximal oxygen uptake per unit of body weight, is a measure of aerobic fitness. And aerobic exercise can improve V02 max significantly. But if you measured the V02 max of ten world-class competitors before running a race, it would not be easy to predict which of them would win.
Meanwhile, the lactate threshold (sometimes referred to as the anaerobic threshold) is a good predictor of submaximal fitness. Athletes can use their lactate threshold to determine how to periodize training and what sort of race pace they can theoretically maintain during endurance performance.
For instance, in competition, if your pace at the lactate threshold is faster than the sustained speed your competition can maintain at theirs, you will most likely take home the victory.
Similarly, interval training at an ever-improving lactate threshold is the difference in a lighter pace is feeling more comfortable over any distance. Each long term gain is an opportunity to challenge speed at the lactate threshold further. And with races and practices that rely primarily on the aerobic system, valuable energy can be ‘banked’ for stacking future anaerobic efforts later. Like an excellent finishing kick at the end of a long race.
When that critical tipping point is met, the accumulation of blood lactate will coincide with an increase in H+ and a slight drop in pH (from 7.4 to about 7.2). This is widely believed to hinder the muscles’ ability to contract at the rate requested. Forcing athletes to slow down or stop altogether.
So, the lactate threshold essentially defines the upper limit of sustainable efforts in training and competition. And the more work you can do at or before surpassing it, the better the performance outcomes.
Lactate threshold for training
It bears repeating that the lactate threshold is the exercise intensity at which lactate production begins to surpass buffering within the mitochondria to find its way into the bloodstream. But most important for applied training is that it occurs at different speeds for every athlete.
For example, an athlete who can swim 20×50 @:45 and hold :30 per 50 likely has a LT speed of ~:30s/50. While another swimmer may complete the same set of 50’s, but during the last 12 reps, his times slowly drop off with each passing minute. Coach’s do not need an equation to intuitively understand the latter has a lower speed at their LT.
The first way to improve LT/VO2 max is to increase maximal oxygen uptake. This requires aerobic training intensity that progressively increases work time or speeds above the target heart rate (HR) or perceived effort (RPE).
The second is if there are no improvements, increasing the relative intensity or speed (like the scenario above) of the LT inflection point.
Then the LT is equivalent to what is sometimes also called the “ventilatory threshold” – the intensity at which athletes have to start breathing hard and fast.
Proper interval training can buffer blood lactate accumulation
With interval training, the reductions in lactate concentration at any given intensity may be due to decreased lactate production at rest and an increase in lactate clearance before the next repetition.
This study examined the relationship between an individual’s skeletal muscle’s respiratory capacity and the lactate threshold. The results suggest that the muscle’s respiratory capacity is of primary importance in determining the work rate at which blood lactate accumulation begins. They also indicate that the proportion of slow-twitch fibers may play an essential role in determining the relative lactate threshold.J L Ivy, et al
While Donovan and Brooks suggest that aerobic training affects only lactate clearance rather than production. Primarily, improved aerobic capacity likely allows for lactate clearance from the bloodstream, but not production or tolerance. And depending upon the intensity could either be interval or steady-state exercise.
Lactate threshold testing
Because the LT can be significantly increased with training, many athletes and coaches have periodized workloads to take advantage of this benefit. Understanding a personalized lactate profile allows for practice and complementary recovery to improve speed at the lactate threshold.
In the lab, practice facilities, and competition venues, the lactate threshold is measured by drawing blood at specific intervals related to baseline research, improved training, and race performance. It is typically found somewhere between 60% to 85% of VO2 max, depending upon athletic fitness.
- An average person reaches their LT at ~50-60 percent of VO2 max
- Recreational athletes reach their LT at ~65-80 percent of VO2 max
- Elite endurance athletes reach their LT at ~85-95 percent of VO2 max
Gathering information from incremental exercise in the lab adds minimal benefit unless athletes and coaches can incorporate it into personalized training regimens. Efforts to improve pace or power at the lactate threshold typically occurs after aerobic capacity has been established.
By training at 95% to 105% of your LT, you force your body to produce a lot of lactate and learn to tolerate that level of fatigue. Though it’s uncomfortable, athletes can run or cycle faster without increasing blood lactate levels and experience less fatigue in the long run when adaptation occurs. Interval training also creates neuromuscular changes, which improves your ability to tolerate lactate and sustain speed over time.
Racing with lactate
With increasing exercise intensity, the natural expectation is performance gains with these adaptations. Racing strategies should reflect a unique understanding of a sustainable pace at the lactate threshold. While timing a final sprint to the finish, leaving all energy systems depleted.
And naturally, this lactate accumulation was anecdotally correlated with the end of race muscle fatigue. This burning sensation became an easy scapegoat for muscle soreness (lactic acid burn) and bonking. Both can undoubtedly plague athletes for several days after a hard race (actually micro muscle tears presenting as inflammation).
Rather view a race through a chart of the blood lactate curve – OBLA at four mmol and LT at two. Now imagine no linear correlation between the two. They are just a delicate range to be managed during a race until the final timed sprint. When an exponential curve of compounded pain coincides with the blood lactate concentration exceeding 4mmol.