The Physiological Demands Of Cycling Disciplines
In order to plan effective training, it’s important to have a solid understanding of the cycling physiology that affects performance in your chosen discipline. Armed with this knowledge, you’re then able to use your limited training resources (like time and energy) more efficiently, target the parts of your physiology that will have the biggest positive impact and avoid activities where the results will be minimal or perhaps even detrimental.
In this article, we present the key physiological demands of cycling and aim to give a brief overview of optimal training approaches to improve whatever these key factors may be for your chosen discipline. We also explain some basic principles that will help you to determine the demands of other disciplines or training goals that are not listed.
You should then be well set to identify the areas you need to work on in your own training.
* It’s worth noting that in many disciplines, skills, tactics and other factors like body weight and equipment choice will also be critical and should be given plenty of thought and attention. These factors are however beyond the scope of this article, and we’ll keep focused only on physiological determinants here.
Physiological Demands of Cycling Disciplines
The table above broadly rates the importance of different physiological factors across several cycling disciplines. These ratings are based on a combination of underlying theory, scientific research, and our own experience as coaches.
Let’s take a brief look at what each factor is, and how it can be trained…
VO2max (Maximal Oxygen Uptake)
This is the maximum rate at which oxygen can be taken on and processed by the body to produce energy. It’s best trained through long rides at around a Zone 2 intensity (e.g. 55-75% FTP), intervals that allow relatively large amounts of time to be spent close to max heart rate [4-6] and possibly also via short sprint efforts that seem to help develop mitochondrial efficiency. We write more on how to increase VO2max here.
Fractional Utilisation (AKA ‘Performance VO2’)
This is the location of the lactate threshold relative to aerobic capacity. Fractional utilisation effectively represents the percentage of your aerobic capacity that you can utilise for extended periods of time without rapid fatigue. If you want a full overview of the lactate threshold and fractional utilisation, see here.
Fractional utilisation is increased by training to improve lactate shuttling and fat oxidation, as these factors help reduce the production of lactate and improve its clearance. These factors are discussed in more detail below.
Conversely, fractional utilisation may also be decreased through large amounts of training to develop anaerobic power or VLaMax (see below). That’s because this type of training increases the rate of glycolysis (i.e. anaerobic carbohydrate break-down) and therefore tends to increase lactate production across a spectrum of powers. For this reason, a higher fractional utilisation is not always desirable if anaerobic abilities are particularly important.
Ultimately, the optimal fractional utilisation is a balance between how important aerobic and anaerobic abilities are (or in other words, whether it’s more important you can produce high powers over an extended period or time, or only over a relatively short duration of a few minutes or less).
Lactate Transport
When lactate is produced during exercise, other by-products are also produced. Lactate itself is not bad. However, the by-products are linked with the onset of fatigue in high-intensity exercise. Therefore, the ability to shuttle and/or buffer lactate and the associated byproducts is important in enabling high powers to be tolerated for longer.
Lactate shuttling is the transport of lactate out of an active muscle fibre to other tissues in the body, where it can then be oxidised and the fatiguing byproducts cleared from the body. Training at or just above the lactate threshold seems to be a good way to develop lactate shuttling. We particularly like intervals that oscillate between short periods just above the lactate threshold (e.g. 105-120% FTP) and short periods just below the lactate threshold (e.g. 80-90% FTP). A specific example might be 3x 9-min blocks, oscillating between 1-min over your threshold and 2-mins slightly under your threshold.
Lactate buffering is the ability to neutralise lactate and associated hydrogen ions that are produced alongside lactate, so that exercise can continue without excessive fatigue. Buffering can take place both in muscles and in the blood. The impacts of training on lactate buffering have not been conclusively established, but research suggests that intervals above the lactate threshold, with comparatively short recovery periods that do not allow lactate to be fully cleared may be an effective strategy for developing lactate buffering [7]. An example might be e.g. 2 blocks of 5x 1-min at 130-140% FTP with 2-min recovery.
Anaerobic/Glycolytic Power
Anaerobic power is the maximum rate at which energy can be generated anaerobically. This includes energy derived through both the phosphocreatine system, and the glycolytic system (i.e. the anaerobic break-down of carbohydrates). VLaMax is closely related to anaerobic power, and is the maximum rate of lactate production, measured in mmol/L/sec. This is can be used as an indicator for the maximal rate at which energy can be produced through the glycolytic system specifically (although we believe there are some notable limitations inherent in the use of VLaMax as an indicator of the maximal glycolytic rate).
You can read more about anaerobic cycling training here.
Training to improve anaerobic power and the maximal glycolytic rate can be achieved by completing short intervals lasting between ~15-120 seconds at a maximal or near-maximal effort, and using long recovery periods, with at least a 1:5 work-recovery ratio [4].
As alluded to above, there’s an interplay between the aerobic and anaerobic systems, and training to improve fat oxidation (an aerobic process) can contribute to a decline in anaerobic power and the maximal glycolytic rate (although this does not necessarily always occur). There’s therefore typically a trade-off between having a high anaerobic power and a high fractional utilisation.
We discuss more about how to raise and lower your anaerobic power and maximal glycolytic rate here.
Neuromuscular Power
This term relates to the ability to activate high-power (‘Type IIx’) muscle fibres, which are used in short (<20-second) sprints and accelerations. As these fibres are not used very often under normal circumstances, specific training is needed in order to forge better neural connectivity to these fibres. Training to improve neuromuscular power includes completing short 5-20 second maximal sprints, with comparatively long recoveries (at least 2 mins) to allow phosphocreatine stores to replenish.
Fat Oxidation
This is the ability to use fat as an energy source on the bike. As fat oxidation is not linked with the production of any fatiguing by-products, and fat stores within the body are comparatively large compared to carbohydrate stores, then the ability to use fat for fuel is extremely useful in disciplines lasting more than several hours. As mentioned above, increasing fat oxidation also leads to a reduction in lactate production, which in turn helps to improve fractional utilisation and lactate threshold power.
Training to improve fat oxidation can be achieved by riding at low intensities that are close to the maximal rate of fat oxidation (e.g. Zone 2; 55-75% FTP) [4]. Incorporating some carbohydrate restricted training may also help develop fat oxidation ability, particularly if the ‘sleep low’ or ‘twice daily’ strategies are used.
Endurance/Fatigue Resistance
‘Endurance’ is the ability to sustain a predominantly aerobic power output for an extended period. It can also be defined as the ability to produce high-power efforts towards the end of a long ride. Numerous factors contribute to endurance, including fat oxidation ability (as described above) and muscle damage/dysfunction and fatigue of the central nervous system.
Endurance is generally improved through long, low-intensity rides (e.g. Zone 2; 55-75% FTP), increasing weekly training volume, and the inclusion of low-cadence (~60-75RPM) riding at a moderate intensity (e.g. 85-95% FTP).
Fundamentals
To help you get to grips with the physiological demands of other disciplines or training goals, we’ve set out below some fundamental principles that may be helpful to follow/keep in mind:
1. Aerobic capacity is (almost) always important.
Having a high aerobic capacity is useful for pretty much every cycling discipline. In long, endurance disciplines, it sets the ceiling on how high you can raise your lactate threshold power, and thus impacts the maximal power you can sustain for extended periods. In more intermittent and/or shorter disciplines conducted above the lactate threshold (e.g. anything less than ~30-minutes), aerobic capacity is also extremely important because it impacts the rate at which lactate and associated fatiguing metabolites are both produced and cleared from the body. This in turn impacts (i) the length of time you can sustain a hard effort above your lactate threshold power and (ii) the length of time taken to recover from efforts above your lactate threshold [8].
2. Lactate shuttling is nearly always important, except in extremely long events where intensity will stay well below your lactate threshold.
Similar to aerobic capacity, the ability to shuttle lactate away from working muscles impacts the rate at which lactate and associated fatiguing metabolites can be cleared. This is important in steady-state disciplines carried out close to the lactate threshold, because a better lactate shuttling ability will generally lead to a higher lactate threshold power and thus a higher maximal sustainable power across that discipline [8]. Like the aerobic capacity, strong lactate shuttling is also beneficial in intermittent and/or shorter disciplines above the lactate threshold, because it impacts the length of time a supra-threshold effort can be sustained and the amount of time needed to recover from efforts above the lactate threshold.
3. Lactate buffering is mostly important for any discipline where a majority of time is spent at or above the lactate threshold.
This is because having a better buffering capacity can make high levels of lactate and associated hydrogen ions more tolerable, allowing you to ride harder and/or for longer for a given subjective effort level.
4. High fractional utilisation is most important for relatively steady events that are carried out close to the lactate threshold.
These are generally events that last between around 30-120 minutes. If the intensity is very steady (e.g. a flat time trial), then you might aim for a fractional utilisation of up to 90% VO2max (ml/kg/min).
When events become shorter than ~30-mins, or as the intensity becomes more intermittent, then anaerobic power becomes of increasing importance, and the best performance may be achieved by accepting a slightly lowered fractional utilisation in order to achieve a higher anaerobic power.
Nevertheless, fractional utilisation will still be important in any endurance discipline, and we’d recommend aiming for a fractional utilisation of at least 75-85% VO2max (ml/kg/min) even for very intermittent disciplines such as criterium, cyclocross and XCO.
5. Conversely to point 4, a high anaerobic power is most important for very short (i.e. <5-min) events, and should be at a moderate level for intermittent-intensity endurance disciplines, or events lasting between ~5-30-mins.
Again, this comes down to the balance between having a high fractional utilisation versus a high anaerobic power, where the importance of a very high anaerobic power wins out only over extremely short duration events.
6. As events become increasingly long, factors such as endurance and fat oxidation become the dominant performance determinants.
‘Very long’ refers to events where the average intensity is at a level where fat oxidation provides the majority of energy supply. This is typically around 55-75% FTP, although this ‘fat max’ range can be moved closer to the lactate threshold, which is generally what we want to achieve through training for these types of disciplines. In very long events, the ability to produce energy through glycolysis (i.e. carbohydrate break-down) and to clear lactate quickly are less important than for shorter disciplines. Although having some ability to produce energy through glycolysis is still important e.g. so you can ride up steep climbs.
Free Workout Guide
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References
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2. Peinado, A. B., Benito, P. J., Díaz, V., González, C., Zapico, A. G., Álvarez, M., ... & Calderón, F. J. (2011). Discriminant analysis of the speciality of elite cyclists. Journal of Human Sport and Exercise, 6(3), 480-489.
3. Lucia, A., Pardo, J., Durantez, A., Hoyos, J., & Chicharro, J. L. (1998). Physiological differences between professional and elite road cyclists. International journal of sports medicine, 19(05), 342-348.
4. Bangsbo, J., Mohr, M., Poulsen, A., Perez-Gomez, J., & Krustrup, P. (2006). Training and testing the elite athlete. J Exerc Sci Fit, 4(1), 1-14.
5. Billat, V., Petot, H., Karp, J. R., Sarre, G., Morton, R. H., & Mille-Hamard, L. (2013). The sustainability of VO 2max: effect of decreasing the workload. European journal of applied physiology, 113(2), 385-394.
6. Swain, D. P., Abernathy, K. S., Smith, C. S., Lee, S. J., & Bunn, S. A. (1994). Target heart rates for the development of cardiorespiratory fitness. Medicine and science in sports and exercise, 26(1), 112-116.
7. Sahlin, K. (2014). Muscle energetics during explosive activities and potential effects of nutrition and training. Sports medicine, 44(2), 167-173.
8. Billat, V. L., Sirvent, P., Py, G., Koralsztein, J. P., & Mercier, J. (2003). The concept of maximal lactate steady state. Sports medicine, 33(6), 407-426.
