The Power of Core

Forearms are the most important muscle for a climber to develop. They allow a climber to support weight on surfaces that a non-climber could not use. Unfortunately, forearms are also very much over-used; strong forearms sometimes encourage climbers to eschew technique in favor of campusing through routes.

For that reason, the intermediate climber looking to break a performance plateau would benefit greatly from training their core, which refers to the full range of abdominal muscles, and in particular the rectus abdominus (the part that forms a "six-pack"), and external and internal obliques. I must mention in passing that the much-lauded "six-pack" means little except that there is too little body fat to conceal the tendinous inscriptions crossing the two muscles that constitute the rectus abdominus. Don't get too caught up in the desire to get one.

Moving upward on a wall happens one of three ways. The first (and most simple) is contracting a muscle capable of lifting body weight, such as the biceps. The second is to create a center of balance and rotate around it by pushing laterally. The rigidity of the skeleton ensures that lateral movement is also translated into vertical movement. The third is to form a fulcrum (usually with your hips), use a limb below you as a lever, and allow that leverage to lift you.

Basic muscle contractions are the most familiar to a non-climber. A pull-up is a perfect example, required very little technique to perform successfully.

Center-of-balance movements are more complex, requiring the coordination of many muscle groups. The heel hook and weight shift belongs to this group.

Lever movements have variable complexity, ranging from fairly simple (flagging) to extremely difficult (bicycles and toe hooks).

Ultimately, any technique requires an active core that maintains tension on all points of contact. To develop that tension, practice dynamic upward movements on an overhang to difficult holds. Flex your stomach on the way up, and use the body tension it generates to keep your feet on the original holds. For you external and internal obliques, practice climbing routes using extensive flagging that involve twisting your body to move upward.