How To Improve Lactate Threshold Power As A Cyclist
Traditionally, the VO2max (the maximal volume of oxygen that can be taken in, delivered to the working muscles and utilised at the muscles for energy production) has been deemed to be the largest determinant of performance in most cycling disciplines, including road, MTB and CX.
More recently, the lactate threshold (the maximum power that can be sustained while blood lactate levels remain constant) is now regarded as an equally valid and perhaps even greater predictor of endurance performance, especially when the % of the VO2max at which this lactate threshold occurs (known as “fractional utilisation”, “aerobic power”, or “the performance VO2”) is taken into account.
While lactate itself is not bad, it correlates strongly with the accumulation of fatiguing metabolites, and this is why the concept of a ‘lactate threshold’ - a maximum power at which lactate levels (and importantly, fatiguing metabolites) remain constant - has received such attention, and is widely considered a key performance determinant in a wide range of cycling disciplines.
Given that lactate threshold power and fractional utilisation are such fundamental components of overall endurance capability, they clearly represent extremely important areas to elicit adaptations, through the use of a carefully constructed training program.
In this post, we’ll explain what the physiological mechanisms that comprise the lactate threshold are, how the balance of an athlete’s aerobic and anaerobic capacity influences where this threshold occurs in relation to the VO2max and then we’ll look at some effective workouts to elicit positive changes in the lactate threshold.
Understanding the Lactate Threshold
As explained briefly above, the lactate threshold is the highest intensity at which lactate in the muscles and blood can achieve a steady concentration, which is why it’s commonly referred to as MLSS or “maximum lactate steady state”. You may also see the term lactate threshold used interchangeably with the terms OBLA, anaerobic threshold, LT2 or VT2. However these terms all have subtly different meanings due to different measurement methods. The lactate threshold is generally very close to your functional threshold power (FTP), which is the maximum power you can sustain for around 40-60 minutes.
The lactate threshold is the point at which the production rate of lactate exactly equals the clearance rate, where any reduction in intensity will see lactate levels fall and increases in intensity will cause lactate to accumulate in a non-linear fashion.
Let’s take a look at these two key factors, production and clearance, in a little more depth…
Lactate Production
Lactate is produced by the body at all times, even at rest, since both aerobic and anaerobic energy production (mitochondrial respiration, the glycolytic system and the CP or creatine phosphate system) are in use at any given moment.
As more and more ATP (adenosine triphosphate - the body’s energy currency) is required to meet the demands of an increasing workload, the contribution of the glycolytic anaerobic system also increases. The end product of the glycolytic anaerobic system is pyruvate, which is either oxidised in the mitochondria or turned into lactate. Lowering your lactate production therefore comes from a greater ability of the aerobic system (mitochondrial respiration) to oxidise fat and supply a larger share of this energy need, reducing the contribution of and need for anaerobic energy production at a given power output.
It’s worth mentioning that ‘VLaMax’ (the maximum rate of lactate production) is sometimes used to indicate an athlete’s propensity for lactate production, although there are some fairly sizeable limitations to this measurement approach, which are beyond the scope of this article.
Lactate Clearance
Clearing the lactate produced (and importantly, the associated metabolites linked with the onset of fatigue) involves transporting lactate out of the contracting muscle fibre to other sites, where it’s either oxidised in the mitochondrion or used in a process called gluconeogenesis, which is essentially the conversion of lactate back to glucose/glycogen.
Some adaptations that lead to an improvement in lactate transport appear to be brought on via high volumes of low-intensity riding. However, others appear to be stimulated only via high-intensity interval training, that repeatedly exposes the muscles to high levels of lactate, and challenges the body’s ability to transport and clear lactate.
Another key factor that contributes to the ability to clear lactate is VO2max, because this impacts the rate at which lactate can be oxidised. Lactate oxidation contributes most to lactate clearance during moderate to high intensity exercise (as opposed to gluconeogenesis).
Training The Lactate Threshold
Understanding the mechanisms that comprise the lactate threshold, and the fact that changes in production and/or clearance will affect the point at which the threshold occurs, the logical next question to ask is which training methods best target each specifically in order to stimulate the greatest positive adaptations?
We’ll start by looking at training to reduce lactate production.
Reducing Lactate Production
As explained above, the amount of lactate produced at a given power output depends on the level at which glycolysis contributes to a given amount of energy production, where this system involves the breakdown of carbohydrate to create ATP. The more glycolytic contribution, the greater the lactate production, given that lactate (again, technically pyruvate in the first instance) is the end product of this metabolic activity.
To reduce the contribution of anaerobic metabolism, there needs to be an increase in the aerobic capacity of the muscles. Aerobic metabolism is performed at the mitochondria within the muscle cells, which oxidise fat and pyruvate (or indirectly lactate) for energy production. Therefore, training that promotes both greater mitochondrial content (quantity/density within the muscles) as well as mitochondrial function (the speed and efficiency of the enzymes involved in the oxidisation process) will therefore improve this aerobic capacity and correspondingly reduce the contribution of anaerobic metabolism.
Training methods that best stimulate positive changes in mitochondrial ‘content’, which has been shown to be the largest influencer of peripheral aerobic capacity (meaning within the muscle), appear to be largely independent of intensity and instead correlate closely to training volume and session duration. The key stimulants for these adaptations thus appear to be longer duration, lower intensity workouts that feature a large quantity of muscle contractions.
In addition, training that specifically favours adaptations relating to improved fat oxidation rather than carbohydrate oxidation will be particularly beneficial in reducing lactate production, given that fat oxidation results in no lactate whatsoever. Again, long, low-intensity rides at an intensity where fat oxidation rates are maximised (typically around 55-75% FTP) are best for achieving this.
It’s important to reiterate this for those cyclists who have trouble keeping a lid on their power outputs in training (i.e. poor intensity discipline); these adaptations in mitochondrial content are NOT improved by increases in intensity, i.e. pushing harder in workouts does not increase the magnitude of the adaptive stimulus or resulting adaptations. In fact, doing so can reduce the quality of the workout by increasing the risk of curtailing workout duration due to fatigue and by placing less of an emphasis on working the fat oxidation system.
Improving Clearance
As we saw above, the clearance of lactate relates mostly to transporting it to other tissues like active and inactive skeletal muscle, organs like the heart, kidneys and liver etc, so that it can either be oxidised for aerobic energy production or used in gluconeogenesis.
Oxidisation of lactate at other sites around the body (mostly occurring in slow twitch or Type I muscle fibres). is the largest factor in this process. So it’s this factor that we want to target through training.
Unlike training that seeks to reduce lactate production, training methods to improve clearance and transport require a higher intensity to stimulate the necessary changes. Training largely involves creating an abundance of lactate in the muscles and blood, which then challenges the lactate transport systems and stimulates signals for adaptation.
This is why the popularised “lactate threshold” workouts like the ubiquitous 2x20 minutes prescription are typically used. These kinds of intervals are not helping to reduce the amount of lactate produced as many may think, but instead seem to be training the ability to clear and tolerate lactate.
Fractional Utilisation
By now, it should be pretty clear that having a high power output associated with the lactate threshold is a key part of achieving successful cycling performances, but there is another factor which is very important, and we feel should be touched upon here. That is the fractional utilisation, or in other worlds, the percentage of the VO2max that can be utilised before the lactate threshold is crossed.
Achieving a high fractional utilisation is does not solely concern raising your lactate threshold as high as possible, nor does it just involve training your VO2max as high as possible; it is both (and more).
The fractional utilisation is, in essence, the net result of the balance between your aerobic capacity (VO2max) and your anaerobic power (or more specifically your maximal glycolytic power - i.e. the maximum rate at which you can produce energy via anaerobic glycolysis).
A higher aerobic capacity means less lactate production and better lactate clearance at a given power output. In contrast, a higher anaerobic power generally means greater lactate production at a given power output. If anaerobic power is large relative to aerobic capacity, then the fractional utilisation will generally be lower. In contrast, if the anaerobic power is low relative to aerobic capacity, then fractional utilisation will be higher. The ideal ratios for each athlete will depend on the type of fitness needed for the demands of competition and the athlete’s own physiology.
A sprinter or track rider’s success, for example, will heavily depend on their ability to break down glycogen extremely quickly and use a large amount of fast twitch muscle fibres to produce rapid bursts of high power outputs.
On the other hand, a MTB marathon racer or a GC contender in a grand tour does not need to same anaerobic power for success and instead will benefit far more from a high fractional utilisation, meaning they race at an intensity where the concentration of fatiguing byproducts largely remains at a stable level (there will of course be fluctuations in intensity and the production of these metabolites within the race, but on average they will stay at a stable level at least until the final stage of the race).
It is this reason why the aerobic capacity should be maximised in almost all disciplines, whereas the anaerobic system should be moderated to just the right level necessary for the demands of competition. Having a stronger anaerobic system than is necessary will only serve to reduce the lactate threshold and result in an athlete not being able to use as much of their overall aerobic capacity (VO2max) for sustained periods.
Now let’s get back onto the topic of the lactate threshold specifically and take a look at some workouts for stimulating positive adaptations in both production and clearance…
Lactate Threshold Workouts
Below are several workout designs that can be implemented into a balanced training plan in order to improve the lactate threshold from both the production and the clearance standpoints. We’ll start out with production-focused workouts…
Lactate Production Workouts
Here are three workouts that can be used to reduce the production of lactate through increasing mitochondrial development:
3-4H Longer duration, lower intensity:
2H Reduced Carbohydrate Availability (RCA):
*Dr Emma Wilkins has written a number of posts on the topic of RCA training, including why you should train with low glycogen stores and how to use RCA training most effectively.
Sweetspot Interval Training:
Now let’s move on arguably the most important workouts for improving the lactate threshold specifically, which are those that train improved clearance and shuttling…
Lactate Clearance Workouts
You can use the following workout designs to improve the body’s ability to move lactate away from the muscles and blood to help maintain a stable level of lactate and associated metabolites.
Moderate Over/Under:
Significantly Over/Longer Under:
Steady State Intervals - e.g. 2x20:
* It’s important to note that we feel these steady-state workouts with lots of time spent right at the lactate threshold are not as effective as the two designs above, and provide a fairly small adaptive response for the level of fatigue they can create. They can however be used as variations on the two above workouts when a bit of a change is desired, or if you are also looking to develop your ability to sustain power close to your threshold for longer periods.
Final Considerations
The ability to clear lactate quickly should be a large focus of any training where you’re looking to improve threshold power. Generally speaking, the greater the ability to clear and oxidise lactate, the better. This puts further weight behind our repeated point that a greater aerobic capacity is always a good thing for an endurance athlete and should be a maintained focus of a training plan for the entire season.
Lactate production on the other hand needs to be considered and trained in a slightly more nuanced way given that less lactate production isn’t always optimal and the right level should be found. If the ability to breakdown carbohydrates for energy (the athlete’s glycolytic capacity) is driven too low, fast bursts of high power like that used in sprints, short climbs and attacks will be compromised. Thus a lack of speed required to win a race could be absent. Attention needs to be paid to the aerobic-anaerobic balance and the relative importance of fractional utilisation versus anaerobic power. This needs to be tailored to the athlete’s competitive demands.
It is worth mentioning that alongside production of lactate and clearance of lactate is the concept of lactate “tolerance”, which can encompass everything from an individual’s pain threshold and the “buffering” of the accumulating hydrogen ions when above the lactate threshold. Training for long durations at or ideally above the lactate threshold will help accustom an athlete to the discomfort associated with elevated muscle and blood lactate concentrations. Supplementation with beta alanine and sodium bicarbonate can also have an ergogenic (i.e. performance-enhancing) benefit. These improve the ability to ‘buffer’ (i.e. effectively neutralise) the hydrogen ions associated with lactate production. This allows an athlete to ride for longer and with less discomfort at a given lactate concentration.
A final point is that it’s helpful to understand where your fractional utilisation sits before undertaking any training. Let’s take two hypothetical athletes, where Athlete 1 has a high lactate threshold but a relatively low aerobic capacity (56 ml/kg/min), where the threshold occurs at approximately 85% of the VO2max. Athlete B has a well-developed VO2max (e.g. 68 ml/kg/min) but a low threshold and fractional utilisation of this VO2, where they step over their threshold at roughly 65% of their VO2max. Clearly, there is a difference in physiology. Athlete 2 would benefit enormously from plenty of lactate threshold-focused training, whereas Athlete 1 would be much better avoiding threshold training in favour of developing their VO2max. This is because Athlete 1’s VO2max is acting as a ceiling to their lactate threshold rising much further. In contrast, Athlete B is unlikely to see big progression in their high VO2max but has a lot of space to work with to bring their lactate threshold up, in both absolute terms and as a % of their aerobic maximum.
Noteworthy in this example is that Athlete 1, even with their significantly lower VO2max would likely beat Athlete 2 in a typical road or MTB race. That’s because at 46 ml/kg/min, Athlete 1 is below their lactate threshold (and therefore not suffering with an accumulation of fatiguing metabolites) and Athlete 2 is above their threshold, since they step over at 44.2 ml/kg/min (compared to Athlete 2’s 47.6 ml/kg/min performance VO2). This is part of why athlete’s with lower VO2max values can beat those with higher values, and demonstrates why VO2max is not the all-encompassing determinant of success it was once thought to be.
Furthermore, this example highlights the importance of an individualised training program built specifically for each athlete’s particular physiological strengths and limiters. If the same training program, perhaps one focused very heavily on lactate threshold improvement, was provided to the two athletes above, one would likely thrive and the other would in all likelihood find frustratingly little yield from their training.
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References
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