Improve Muscular Endurance and Fatigue Resistance: The VO2 Slow Component and Cycling
Muscular Endurance and Fatigue Resistance
What contributes to fatigue resistance? How can you train your ability to ride at a hard pace for longer and improve your time-to-exhaustion? The answers might not be what you think.
The answer is a phenomenon called the VO2 slow component. But just what is the VO2 slow component, and how can you reduce it? Before you read this blog, I would highly recommend giving our Science of Cycling blog a read first for some foundational knowledge on exercise physiology.
If you are training for a long gravel race, road race, endurance ride event, gran fondo, hill climb, time trial or triathlon– this one is for you.
See Also: Gran Fondo Training Plan
What Is The Slow Component?
Envision you are tasked with doing a 60 minute time trial on an indoor trainer with constant power, perfect pacing and equal splits. At first, the effort will feel quite easy and your heart rate will remain at, or below your lactate threshold heart rate.
Of course it won’t stay this easy, the effort will get progressively harder. Once you enter the last 20 minutes of the effort, everything changes and you will enter a world of pain. Heart rate and VO2 will approach maximum and you will have to give it every ounce of willpower to complete the effort.
If you were riding at FTP, why did you reach VO2max? You were riding in a steady state, not a VO2max power. So what gives?
This is caused by the VO2 slow component. The VO2 slow component is defined as a gradual rise in VO2 uptake during constant intensity exercise. While riding at FTP, you will notice a progressive rise in perceived exertion and HR even though your power remains constant at what is theoretically a steady state power. Eventually, you will reach VO2max even at FTP. This process is accelerated when riding above FTP.
When riding at, or slightly above FTP, the VO2 slow component is caused by a variety of factors:
Muscle fatigue: When riding around FTP or slightly above, you will recruit only a fraction of your muscle fibers to maintain this intensity. However, these muscles will soon become fatigued and you will need to recruit additional muscle fibers to help out and maintain this intensity.
Eventually, you will rely on your Type II muscle fibers to keep the pace up, which are less efficient and produce more lactate. You will consume more oxygen to recruit these extra muscle fibers and your body will have to work harder to offload the lactate generated by Type II fibers; this will contribute to a rise in VO2 and heart rate.
Loss of efficiency: As you continue to ride at a hard pace, your muscles become less efficient at generating power. Loss of efficiency will require more oxygen and increase VO2 uptake. You may notice that as you near maximum effort, pedaling can tend to get sloppy, this is partly due to loss of efficiency. The cause for this is not fully understood, yet some theorize it can be caused by increasing acidity in the muscle, causing less efficient firing patterns.
Proportion of Type I and Type II muscle fibers: Type I (slow twitch) muscle fibers are far more fatigue resistant and efficient than Type II (fast twitch) muscle fibers. Everyone has a different proportion of Type I and II muscle fibers. Time-trialists and climbers have the highest percentages of Type I fibers, which gives them great fatigue resistance and allows them to sustain hard paces for a long time. Sprinters and puncheurs have a higher number of Type II fibers giving them their explosivity, but sacrifices fatigue resistance.
Have you ever wondered why some “pocket rocket” sprinters (think Caleb Ewan or Bryan Coquard) can’t climb well? It has nothing to do with their weight, but that they have less Type I fibers and can’t sustain hard, aerobic efforts for as long as the diesels.
With a higher number of efficient Type I fibers, the slow component is reduced. As you begin to cycle through muscle fibers during hard exercise, you will have more Type I muscle fibers to rely upon as others become fatigued. Since these are more efficient, you will take longer to reach your max.
Related Post: Try These New Interval Workouts to Improve VO2max
How To Reduce The VO2 Slow Component In Training
With a reduced slow component, you can ride at a sustained pace for longer. In WKO, the “TTE” (time-to-exhaustion) metric is a good real world application of the VO2 slow component. What kind of training can we do to also reduce the slow component and improve fatigue resistance?
Strength Training: I know, I know, it seems like we mention it in every blog post, but yes, strength training can help with this too!! Strength training can reduce the slow component in several ways:
Conversion of Type IIx to Type IIa Fibers: There are actually two kinds of Type II fibers. Type IIx fibers are extremely inefficient and fatigue quite quickly, they’re definitely not useful for cycling. On the other hand, Type IIa fibers are a crossbreed of sorts between Type IIx and Type I. They possess many fast-twitch characteristics, but are also more fatigue resistant. Strength training can convert inefficient Type IIx fibers to IIa fibers.
Improved Force Production: The higher your power output on the bike, the more force required, and the more muscles you will need to recruit. Strength training will increase your ability to produce force and if you train your force production, you will actually need to recruit less total muscle fibers to produce a given power output. With strength training, each of your muscle fibers can handle more force, so you won’t need to recruit as many of them. Less muscle recruitment for a given power output means a lower need for oxygen and a reduced slow component.
Improved Economy: If you do heavy squats in the gym, your brain must recruit nearly every muscle in your lower body to lift the object. It must learn to send strong, rapid signals to your muscles and learn to recruit muscle fibers in efficient patterns. Essentially, you are improving your “brain-body” connection. This improved connection also improves your cycling performance because your brain has learned to recruit the muscles needed for cycling more efficiently. This will reduce the slow component by reducing excess oxygen consumption that comes along with inefficient firing patterns.
Related reading: Top Strength Training Mistakes By Cyclists
Low Cadence Cycling: The debate about the usefulness of low cadence cycling training has raged for many years. We know that low cadence cycling intervals are not a replacement for strength training, but many cyclists have found them useful for improving other aspects of performance. There is a reason why many professional cyclists regularly incorporate them into their program.
How does low cadence training for cycling decrease the slow component and improve fatigue resistance? Please keep in mind that most of this is theoretical and anecdotal as we don’t have a ton of research to support these claims, but putting together the pieces of what we know, the evidence is compelling:
Increased Muscle Recruitment: We do know that, similar to strength training, pedaling at a low cadence requires more force and thus recruits more muscle fibers. If you pedal at 300 Watts and 60 rpm, you will recruit more of your Type II muscle fibers than if you pedal at 300 Watts and 90 rpms. By recruiting more Type II fibers, we can train them to become more aerobically efficient.
Improved Core Strength and Pedaling Technique: If you want to get good at something, one of the best ways is to slow it down. Pedaling is no different. When you do low cadence cycling intervals, you can take the time to focus on your pedaling, your breathing, and your core. Are you rocking from side to side or is your core locked in? How is your posture? Are your hips rocking back and forth or is all the power being put into the pedals? With low cadence cycling training, we can take the time to focus on these important aspects and build that silky smooth “pro” pedal-stroke. You will be training your ability to remain in good posture and produce force while maintaining proximal stiffness in your core, you can continue to pedal efficiently even while under duress. This will likely improve your efficiency while riding fatigued and reduce the slow component.
See Also: Cycling Core Exercises
Endurance Cycling Training: As you progress through a long endurance ride your muscles will gradually become more fatigued and you will recruit additional muscle fibers to keep up the pace. Just like low cadence, we can cycle through muscle fibers to train them to become strong and resilient. P.S.-- endurance rides have a billion other benefits, but you can read our comprehensive Endurance Training Pack about that!
See Also: Cycling Endurance Workouts
Long Intervals (duh!): Obviously another way to train fatigue resistance is to do long, sustained efforts like. This will give you the resilience to remain efficient while you are suffering during a hard effort. Extended FTP, tempo training, or sweet spot intervals are good to incorporate into your program as race-specific training if they suit your race demands.
See Also: What is FTP Meaning in Cycling
During the offseason months, focus on the basics of force production and efficiency with strength training and also on the bike with low cadence intervals. This will lay the foundation for improved fatigue resistance. Then, closer to your goal events, incorporate the long intervals to get ready to race.
See Also: How To Increase FTP
Conclusion
Hopefully this post gave you some insight on how you can improve your fatigue resistance by reducing the VO2 slow component. Some of these techniques are a little “outside the box” and could be just the stimulus you need to gain that extra few percent or break out of a fitness plateau!
Questions or comments about this article? Contact the author: Landry@EVOQ.BIKE
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Author- Landry Bobo
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References
Coyle EF, Sidossis LS, Horowitz JF, Beltz JD. Cycling efficiency is related to the percentage of type I muscle fibers. Med Sci Sports Exerc. 1992 Jul;24(7):782-8. PMID: 1501563.
Jones, A. M., & Burnley, M. (2009). Oxygen uptake kinetics: an underappreciated determinant of exercise performance. International journal of sports physiology and performance, 4(4), 524-532
Vikmoen, O., Ellefsen, S., Trøen, Ø., Hollan, I., Hanestadhaugen, M., Raastad, T., & Rønnestad, B. R. (2016). Strength training improves cycling performance, fractional utilization of VO2max and cycling economy in female cyclists. Scandinavian journal of Medicine & Science in sports, 26(4), 384-396.
Vikmoen, O., Rønnestad, B. R., Ellefsen, S., & Raastad, T. (2017). Heavy strength training improves running and cycling performance following prolonged submaximal work in well‐trained female athletes. Physiological reports, 5(5), e13149.