To a certain degree, improving your rock climbing is a matter of footwork, core strength and how to best make your body type work for you. The drop knee is a useful technique for short and tall climbers alike, allowing you to turn your hips close into the wall, extending your reach and taking some of the load off your hands. Although this technique is particularly useful on overhangs, you can use it in almost any climbing situation.
The drop knee is an exaggerated back step. It’s easiest to practice, at first, while standing on good-sized footholds. Stand front-on to the wall, hands and feet on solid holds. Then rotate your hips to the left, shifting your right foot so that you’re standing on the outside edge of your right toes, instead of the inside edge or your big toe. Finally, drop your right knee down and in until it points straight down beneath you, snugging your right hip close against the wall. This frees your right hand to reach upward. Because the drop knee forces your hips close to the wall and reduces some of the load on your fixed hand — in this case, the left hand — it’s especially useful when climbing an overhang, but you can also use it for extra stability or reach on vertical walls.
You can perform a drop knee on almost any foothold; anything that offers a nubbin, or even simple friction, to hold your foot in place is fair game. If you place your foot on an adjacent wall or a separate, prominent rock feature from what your other foot and hand rest on, this is known as stemming. Frictioning your foot against the wall as you drop your knee down and in, without an actual hold to rest on, is called smearing.