All Things Endurance Training For Climbers (Part I)
Image source: Hiroko Masuike, The New York Times
When we train endurance in climbing, we are working on local muscular endurance (the muscles in our forearms) rather than systemic aerobic endurance. We almost never fall off of a climb because we are panting or need to catch our breath; We fall because our forearms are pumped and our muscles give in. This is why common forms of cardio like running or cycling have very limited carry-over to climbing endurance.
In this article, we are going to dive deep into what is happening in our body while we are climbing and the various forms of endurance training. This series is going to be useful for both sport climbers and boulderers since, contrary to popular belief, boulderers actually do benefit from having good endurance (as we will get into in this article)!
In part two, we will explore the benefits of training endurance, as well as when and how to train your endurance.
Slow-Twitch Vs. Fast-Twitch Muscle Fibers
Skeletal muscle consists of many muscle fibers, and not all are the same. There are two types of muscle fibers: slow-twitch (or type I) and fast-twitch (or type IIa and type IIx) muscle fibers.
Slow-twitch muscle fibers are more fatigue-resistant and used during prolonged and sustained activity. They contain a higher concentration of mitochondria and myoglobin than fast-twitch fibers. Slow-twitch fibers are slower to reach maximal tension and are not able to produce as much force. These are the fibers we use during sustained easy to moderate climbing.
On the other hand, fast-twitch muscle fibers are much quicker to fatigue as they have a lower concentration of mitochondria, myoglobin, and capillaries compared to our slow-twitch fibers. They are larger than type I muscle fibers which is why they are able to quickly produce a lot more force. Fast-twitch muscle fibers are further divided into Type IIx and Type IIa.
Type IIX fibers produce the most force but are not very efficient due to their high myosin ATPase activity, low oxidative capacity, and heavy reliance on anaerobic metabolism.
Type IIa fibers are a mix of type I and type IIx. They use both aerobic and anaerobic energy systems, have a higher oxidative capacity, and fatigue more slowly than type IIx.
Depending on your genetics, age, and sport, you may have a larger ratio of one type of muscle fiber. If we look at that statement through the lens of climbing, sport climbers may have a higher concentration of type I muscle fibers, whereas boulderers may have a higher concentration of type II muscle fibers.
The Energy Systems
Energy is our ability to do work. We get energy from food to fuel movement and bodily functions. The body breaks down the food we eat into three simple compounds: glucose, amino acids, and fatty acids, which get absorbed into our blood and transported to various cells in the body to be converted to adenosine triphosphate (ATP).
Before we continue, here are a few important definitions:
Anaerobic: Does not use oxygen
Aerobic: Does use oxygen
Alactic: Without the presence of lactate
Lactic: With the presence of lactate
The body uses three energy systems to supply the body with ATP, our primary source of fuel. There is the anaerobic alactic system (Adenosine Triphosphate Phosphocreatine), anaerobic lactate system (glycolysis), and aerobic (oxidative phosphorylation) system.
These energy systems do not work in isolation; Rather, they are all operating at different times depending on the activity and the person’s level of fitness.
Intensity vs. Energy System At Work. Table source.
Different sports have different energy demands. Climbing requires the use of all three in each discipline (of course, at different capacities).
Speed climbing is fueled by the anaerobic alactic system (since speed climbers are on the wall for 10 seconds or less). Bouldering pulls energy from the anaerobic alactic acid but may also pull energy from anaerobic lactate (since boulderers are on the wall for 30 seconds to 5 minutes). Sport climbing uses energy from the anaerobic and aerobic systems since you may be on the wall for 4 to 20 minutes.
Anaerobic Alactic (ATP-PC)
For short and intense bursts of effort, our body uses the anaerobic alactic system. Your body has a small store of ATP in the muscles that it can immediately access for energy; Yet, once this ATP supply is depleted (which occurs in a matter of seconds), additional ATP must be formed from the breakdown of phosphocreatine. This process does not require oxygen, there is little lactic acid buildup (we do not get pumped), and less fatigue.
Anaerobic Lactic (Glycolysis)
This system produces energy from muscle glycogen (storage form of glucose in our muscles) and can occur in the presence or absence of oxygen. Without oxygen, more lactic acid builds up which can cause fatigue and that burning feeling in our muscles.
Lactate threshold refers to the intensity at which the blood concentration of lactic acid begins to increase exponentially. When exercising at or below the lactate threshold, any lactate produced by the muscles is removed by the body without it building up. This is why it is important to improve this energy system as well as our lactic threshold, which we will explore how to do in the next article.
Aerobic (Oxidative Phosphorylation)
The aerobic energy system is the most complicated of the three energy systems and relies on our circulatory system to supply oxygen; which is why it is much slower to produce energy than the previous two systems. We get energy from the oxygen consumed through breathing. This system allows us to recover other energy systems while we work at a lower intensity.
Many boulderers (myself included) have an underdeveloped aerobic system. We get fatigued quickly and we may not realize that training this energy system is actually going to help us maintain our strength for longer before tiring (so we can have longer sessions with high-quality climbing all throughout) and improve our body’s ability to utilize oxygen.
Aerobic Endurance vs. Power (Anaerobic) Endurance
In the context of climbing, aerobic endurance can be defined as low to medium-intensity climbing that lasts at least two minutes. This type of endurance is especially important for sport climbers as they are on the wall for prolonged periods, and may be climbing relatively easy sections for prolonged periods.
Aerobic endurance training prevents us from tiring out during easy sections of climbing and enhances our ability to recover on the wall as well as climb more efficiently in a tired state.
Boulderers do not need to train their aerobic endurance as much since there are very few boulder problems that require us to be on the wall for more than a few minutes at a time.
Power endurance refers to medium to high-intensity climbing that lasts from 10 to 90 seconds. Power endurance is important for both sport climbers and boulderers. Training power endurance uses the anaerobic lactic energy system and can reduce the amount of lactic acid that builds up, allowing us to work at a higher intensity for longer.
And where does cardio fit in all of this?
I encourage climbers to integrate some cardiorespiratory work as part of their training (e.g. running, cycling, hiking, etc.) since it is healthy for your heart and decreases blood pressure. If those reasons aren’t compelling enough, just think about how it can improve your fitness and make approaches to your projects way less taxing (i.e. more of your energy goes to projecting).
Conclusion
Endurance does not only apply to sport-climbers. All climbers want to be able to do more difficult climbing in less time, and endurance training gives way to those adaptations. Hopefully, now you have a better understanding of which energy systems are at play while we are climbing and which one is primarily used in each climbing discipline. In the next article, we will learn about why, how, and when to train endurance.
References
Betchel, Steve. “Understanding the Lactic Energy System.” Climb Strong, www.climbstrong.com/education-center/understanding-the-lactic-energy-system/#:~:text=The%20Alactic%20energy%20system%20uses,to%20rest%20or%20slow%20down. Accessed 8 Nov. 2023.
“Government of Canada.” News Article - Royal Canadian Air Force - Canada.Ca, / Gouvernement du Canada, 6 Apr. 2021, www.canada.ca/en/department-national-defence/maple-leaf/rcaf/2020/10/track-and-field-for-masters-athletes-6-understanding-energy-systems.html.
Hughes, David C, et al. “Adaptations to Endurance and Strength Training.” Cold Spring Harbor Perspectives in Medicine, U.S. National Library of Medicine, 1 June 2018, www.ncbi.nlm.nih.gov/pmc/articles/PMC5983157/.
Penney, Stacey. “Fast-Twitch vs. Slow-Twitch Muscle Fiber Types + Training Tips.” NASM, blog.nasm.org/fitness/fast-twitch-vs-slow-twitch. Accessed 8 Nov. 2023.
Polish, Alex. “Everything You Need to Know about Endurance Training for Strength Athletes.” BarBend, 27 July 2023, barbend.com/endurance-training-for-strength-athletes/#:~:text=By%20concurrently%20training%20for%20both,and%20week%2Dto%2Dweek.
“Sport Science Report: Training Energy Systems.” Sport Manitoba, 17 Apr. 2023, www.sportmanitoba.ca/https-www-sportmanitoba-ca-sport-science-report-training-energy-systems/.
