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The Latest Research-Backed Training Insights for Climbers (Part 1)

Let’s dive into the nitty-gritty of climbing physiology and then discuss training takeaways. This is Part I of a science-based series on how to train smarter to climb better.

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So, you want to get better at climbing? Whether you’re a recent convert or seasoned veteran, welcome to the club. 

Climbing, always a fringe sport in comparison to, say, running, cycling, or swimming, has not historically had scientific backing for even the most basic training protocols. Hangboard routines? Endurance laps? These exercises make intuitive sense but have long lacked research-driven nuance. Luckily, be it due to the growing indoor industry, climbing’s Olympic inclusion, or the collective prayers of our cultish community, this is quickly changing. Over the course of the past decade the pace of publication of climbing-related research has quickened from a trickle to a torrent, and it’s about time that all of us tuned in.

This article series aims to review present knowledge and current training protocols with an aim to help young guns and old chuffers alike get the most out of their climbing. Psyched? Us too! 

Read Part II & Part III

Pitch One: Performance Physiology

All too often, people train to improve without defining what this means. Doing so is like rehearsing dance moves with no choreography, or packing for a trip without picking a destination. If you don’t know what you’re preparing for, chances are you won’t prepare very well.

Correcting for this implies more than, say, climbing all the crimpy routes in the gym because your project’s on crimps. If you want to perform at your peak—and if you don’t, that’s cool, but we assume anyone reading does—you need to take a targeted approach. 

Defining a performance goal involves:

  1. Identifying what’s required.
  2. Gauging where you’re at. 
  3. Determining how to systematically address the difference between the two.

Success here depends on knowing which capacities to evaluate and how to train them. Accordingly, some knowledge about climbing physiology is needed. 

Physiological Determinants of Strength, Power, and Endurance

The climber’s body is a pie cut into slices of power and endurance. Strength, on which both power and endurance depend, is the filling and, to really stretch the comparison, technique is the pan that holds it all together. Pie lovers all agree that the filling is the most important part of any pie, just as researchers all agree that strength is among the most important predictors of climbing performance. You can’t have a good pie without good filling any more than you can have a good climber without a good dose of strength. This isn’t to say that other things don’t matter, but just that strength is paramount.


When we talk about strength we refer to maximum strength, or the highest force that can be generated through voluntary muscular contraction. 

Power and endurance are both a function of maximum strength (more on this later). This means that as you get stronger, you also get more powerful and more resistant. 

Strength is determined by muscle and tendon architecture. The ability to flex your joints comes thanks to the fiber-tendon attachment that anchors your muscles to your bone. The angle of this attachment, alongside other physical properties, determines the amount of force your muscles can generate. Additional structural factors also play a role.

Structural Determinants of Strength

Motor units, which consist of a motor neuron and innervated muscle fibers, are a muscle’s smallest functional part. 

Muscle fibers come in different types. Each type has different contractile properties which determine the fiber’s potential force output. Type II, or “fast-twitch” fibers, are those with the highest output per cross-sectional area, making them the ones that matter most to climbing. 

Your proportion of different muscle-fiber types is half genetics (roughly 45%) and half factors that may be impacted by training. While, yes, this means some people are predisposed to greater maximum strength, it also means proper training plays an enormous role. 

A targeted regimen may not only promote changes in fiber type, but will also increase muscular contractile ability even when no change in fiber type distribution occurs. In other words, strength training may give you more of the Type II fibers you need and, even if it doesn’t, it will certainly strengthen the Type II fibers you already have.

A fiber’s contractile ability depends on its cross-sectional area. Strength training increases cross-sectional area in all types of muscle fibers, but especially those of Type II. As muscle fibers grow stronger, so do the muscles they compose.

Fibers are not the only physiological feature responsible for strength. Bundles of muscle fibers called fascicles (among other things) also contribute, but getting into this goes beyond the scope of this article.

  • Getting Started: Maximum strength gains come primarily from high mechanical tension at the individual muscle fibers level. This is best achieved by slow contractions. Contraction speed is lower when intensity or fatigue is high, which means exercise protocols involving one or the other (or both) are well-suited to training maximum strength. What matters is that an action is performed under intense load or until failure and does not involve rapid contraction (so, not dynamic moves or power-related protocols like campusing).
  • Good, climbing-specific maximum strength exercises include: weighted pull ups, chest flys on gymnast rings, front levers (or related progressions), deadlifts, and so on.


Power is simply the ability to generate as much force as possible in the shortest available time. Put otherwise, power is a measure of how quickly you can generate maximum strength. Gaining power, then, means building stronger, faster muscle fibers. 

Structural factors determine how strong you can get; neurological factors determine how quickly you can put this strength to work. 

Neurological Determinants of Power (i.e. Strength Over Time)

Strength depends on muscle fiber contractions, which in turn depend on motor unit recruitment. To tap maximum power, you want the motor neurons that recruit Type II fibers—those that determine maximum strength—to fire quickly, and yet this isn’t our body’s natural impulse (no pun intended). Instead, something called the size principle means that small motor neurons that innervate slow Type I fibers fire before the larger motor neurons responsible for Type II fibers do the same. This is energy saving—great for evolution, not great for climbing. Luckily, this process can be sped up.

Targeted strength training can both increase motor unit recruitment and lower the threshold at which larger motor neurons are recruited. Likewise, it can increase firing frequency—another crucial determinant of power

Motor unit firing frequency refers to the number of times a motor neuron fires when performing a given action. More firing means more power. Timing matters as much as speed, though. Motor units can fire in different patterns, and, if you want maximum power, you want a pattern that displays a high-firing rate at the start of a given contraction. 

Inter-muscular coordination, or the ability to recruit the right muscles in the right amount at the right time is a final neurological determinant that can be improved through training. This means that, yes, technically demanding moves involving multiple body parts are not just party tricks, but an important part of maximizing strength and power.

  • Getting Started: Power training, in contrast to strength training, requires high contraction velocity. Explosive movement triggers full motor unit activation, leading to the described neurological adaptations and ultimately resulting in a faster rate of force, or a higher power output. Exercise protocols for power training thus involve both relatively high intensity and high contraction speed. Moonboarding, campus boarding, and strength exercises performed at high contraction speeds (i.e. explosive pull ups) are good examples.


Earlier, the climber’s body was described as a pie split into power and endurance and filled with strength. The comparison aimed not only to sweeten your image of training, but to undo the common misconception that endurance is the opposite of power, or that the two are separate capacities. In fact, both depend on maximum strength, and so both benefit from strength training. The details involved in fine-tuning one or the other differ, sure, but this doesn’t mean that as you gain endurance, you lose power, or vice versa.

Muscular endurance (as opposed to the cardiorespiratory endurance addressed below) refers to the muscles’ ability to repeatedly exert force for an extended period. How long is determined by the availability of adenosine triphosphate (ATP), the fuel on which muscles run.

High-intensity exercise can only be sustained for short periods because elevated exertion leads ATP depletion to outpace its production. When battling through a hard crux sequence, for instance, your muscles metabolize ATP—and, importantly, creatine phosphate, but we won’t get into that here—faster than it can be replaced. Metabolic by-products quickly accumulate and inhibit muscular contraction. This is why when bearing down hard, your hands sometimes peel open despite your every effort to hold on. 

Less intense exercise can be sustained for longer because the body has time to transform glycogen into ATP and thereby resupply your muscles with fuel. This process is called glycolysis and it can happen in two ways: either with oxygen (aerobic glycolysis) or without (anaerobic glycolysis). 

Aerobic glycolysis occurs when exercise intensity is low and blood flow can reoxygenate the muscles, recharge them with ATP, and allow you to power on. Think: joy climbing on cruiser terrain. 

Anaerobic glycolysis occurs when an exercise demands more than 50% of your maximum strength. Here, muscle contractions inhibit blood circulation, which means your muscles don’t reoxygenate and aerobic energy production must be supplemented by anaerobic mechanisms. This triggers an increase in lactate and metabolic acidosis (i.e. your muscles start to burn) which cannot be sustained for more than a couple of minutes. Think: every route in Greece until you learn to tufa climb.

Naturally, if anaerobic glycolysis only sets in when you exert more than 50% of your maximum strength, increasing maximum strength will delay the onset of pump and thereby increase your endurance. 

Strength isn’t the whole story, though. Studies show that endurance in elite climbers also benefits from (1) a higher anaerobic threshold, or the ability to use aerobic glycolysis at higher intensities, (2) a capacity to reoxygenate muscles after only a short rest, and (3) a higher lactate tolerance, or an increased ability to climb while pumped. Like maximum strength, all of these capacities can be trained, though the relative benefit of doing so varies.   

  • Getting started: There are many ways to train muscular endurance. The best approach depends on both the energy system targeted and the adaptations sought. Importantly, endurance training for climbing should involve climbing-specific muscles.
  • One approach is to train the phosphagen energy system. Here, exercises up to 30 seconds appear to be more beneficial than short-duration, high intensity exercises lasting only 10 seconds. A good example might be laddering up and down bad holds on a spray wall (you can keep your feet in the same spot) for 30 seconds, resting for two to three minutes, and then repeating for 10 sets.
  • Another approach is to target the anaerobic glycolytic system. This system, which supplies the energy needed for up to 3 minutes of high intensity effort, responds best to high intensity interval training (as opposed to, say, the sort of continuous training performed by running endurance laps). Moonboard boulder circuits repeated at a 1:4 activity to rest ratio, for instance, are a good way to go. So, if a circuit takes you 15 seconds to complete, rest one minute and then do the next circuit.

Cardiorespiratory Endurance

A final physiological determinant of climbing performance is good, old-fashioned cardio. That is, your cardiorespiratory system’s ability to absorb, transport, and utilize oxygen in the working muscles.

Cardio often gets a bad rap in climbing training literature, and yet when measured on a treadwall, VO2 max (the gold-standard measurement) explained 43% of self-reported climbing grades in a study by Fryer et al. (2018).

The physiological effects of training cardiorespiratory endurance include improved cardiac output, increased muscular perfusion capacity (i.e. greater oxygen delivery), and better blood-flow architecture. This said, not all cardio training is equal, and different approaches will benefit climbing in different measures.

  • Getting Started: Cardio-respiratory training can be achieved through traditional endurance sports like running or through climbing exercises focussed on the cardio-respiratory system. What matters is getting enough muscle groups involved to raise your heart rate and quicken your breathing. High Intensity Interval Training (HIIT) aimed at climbing muscles is an example of climbing-specific cardiorespiratory endurance training. 


Physical conditioning is the highest predictor of climbing performance. Better strength, power, and endurance means better climbing (duh) but only to the extent that improvement is sport-specific. This is why training must be grounded in an understanding of climbing physiology. Having achieved that, we can now turn to an in-depth look at how to train smart to climb hard. 

Stay tuned. 


Marvin Winkler earned his BA and MA degrees in sports science at Goethe University, Frankfurt, Germany. He then supervised two climbing-related research projects as a research assistant at the Institute of Sports Science at Augsburg University, where he is currently completing his PhD in performance diagnostics in competitive climbing. When not digging into climbing science, Winkler can be found climbing outdoors, where he has sent routes graded up to 9a/+ (5.14d/5.15a). 

Christopher Schafenacker is a writer and translator who left a career in academia to explore the much more rewarding world of dirtbagging. Previously a visiting assistant professor at the University of Granada, where he worked on editorial issues or poetry and translation, he now travels full-time in search of crags and climbers’ stories. 

Together, Winkler and Schafenacker run spring and summer break camps throughout Europe for competitive youth who seek to both improve as climbers and broaden their knowledge of language and culture.