Why your forearms pump out so fast when bouldering, and how climbing with straight arms, hips to the wall, and leg push saves you real energy.
Why do your forearms burn like fire after just three or four routes, while experienced climbers hold on for hours? The honest answer: it's almost never about lacking strength – it's about your arm position. Welcome to the DOMISPORTS Academy! Train Smart. Play Hard.
In climbing lingo, this burning is called the "pump" – your biceps go rock hard, and your hands start opening almost on their own. The good news: for your first months of climbing, you don't necessarily need more strength endurance – you just need smart, efficient technique.
The number one beginner mistake is pulling yourself up the wall with permanently bent arms – we affectionately call this "T-rex climbing." Biomechanics proves a simple law: the force required at the hands drops significantly when your center of mass (CoM) sits as close as possible to the wall and directly below the most active hold. By positioning yourself on a straight arm under the hold, you save an enormous amount of energy.
When you climb with straight arms, the work of holding on shifts from your quickly fatiguing muscles onto your robust skeletal and ligament system – you "hang" from your bones.
For this fundamental basic technique you don't need any special equipment, just:
Instead of frantically pulling yourself into every hold and staying with bent arms, extend your arms almost fully straight. Let your glutes drop down.
Your arms now form a straight line from your shoulders down to your wrists. Your biceps get a complete break – and your forearms can even recover slightly while you climb.
With straight arms, your body initially wants to tip backward away from the wall. This is where your core comes in: by pulling your hips toward the wall through body tension, you increase pressure on your feet, and the hold above becomes noticeably easier to hang onto.
Actively press your hips into the wall – as if your belly button wanted to touch it.
Your legs are many times stronger and more resilient than your arms. When you want to reach the next hold, you do not pull yourself up like a pull-up – you push yourself upward powerfully from your thighs.
The holding arm stays straight for as long as possible, until the push from your legs carries you almost weightlessly to the next hold.
When climbing on straight arms, an extremely important ground rule protects your joints: keep your arms long, but never lock them out fully and passively. Don't hang like a limp sack from your shoulder and elbow joints.
Always keep a minimal, barely visible micro-bend in the elbow and keep your shoulders active (shoulder blades pulled slightly down and back toward the spine). If you don't, you're hanging directly in the joint capsule – long-term, this risks rotator cuff injuries and chronic elbow problems.
Combine climbing on a straight arm with "hip turning" (flagging/rotation)! When you're hanging on a straight arm and need to reach the next hold far up and to the side, rotate your hip sideways into the wall.
When you turn in (one knee pointing toward the wall), you bring your hips even closer to the wall and drastically shorten gravity's lever arm. This lets you reach even extremely far-away holds seemingly effortlessly, using leg power – while your holding arm stays relaxed and fully extended. The ultimate key to mastering even the steepest overhangs while saving energy.
### Is it bad to fully straighten my arms while climbing? Nearly straight is right, fully and passively locked out is not. Always keep a minimal, barely visible micro-bend in the elbow and keep your shoulders active. Hang like a limp sack in your joint capsule and you risk rotator cuff problems long-term – the technique should unload your muscles, not overstretch your joints.
### Why do my forearms stop burning out so fast with straight arms? Because the work of holding on shifts from your quickly fatiguing muscles onto your robust skeletal and ligament system. With straight arms, you essentially "hang" from your bones instead of actively tensing against gravity the whole time. That saves energy in exactly the muscles that would otherwise burn first.
### What is "hip turning" and when do I need it? Hip turning means rotating your hips sideways into the wall while one knee points toward it. This brings your hips even closer to the wall and shortens gravity's lever arm. Use it when the next hold sits far up and to the side – you'll reach it almost effortlessly using leg power instead of pure arm strength.
### How do I stop doing the "duck butt"? The "duck butt" happens when you stick your glutes far out from the wall to see your feet better. That shifts your center of mass outward and dumps your entire body weight onto your fingertips. Instead, actively press your hips into the wall – almost as if your belly button wanted to touch it.
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