Pull-ups to work hands, arms, shoulders. Increase grip strength
Dead Hangs: grab a pull up bar and hang off the ground for as long as you can.
Speed climbing on a moderate route that I can climb easily and without stopping. Teach muscle memory.
Train with variety.
Increase your strength. Climbing depends on both strength and technique
- Arms: Improve your grip by doing exercises that will strengthen the arms and wrist/forearm region. Use a squeeze ball regularly to strengthen the wrist and hand region; lift small weights frontwards and sideways to improve overall arm strength. Try static hangs on a bar to increase your capacity to do static hangs while climbing. Better to discover on the low bar than a high wall that you can't do this!
- Shoulders and upper back: Having this area of your body be strong is an important part of being a great rock climber. These muscle groups will help you lock off on holds as you reach for the next one on steeper terrain. Pull-up exercises, exercise elastics, weights and simple arm rotations are all ideal strengthening exercises for shoulders. As you become stronger, look into more sport-specific training exercises like hang boards, campus boards, and system boards.
- Midsection (or "core"): This is a vital link in the climbing movement chain. Without strong abdominal and lower back muscles, your legs cannot communicate the force they are producing effectively to your arms, and vice versa. The main key here is producing a flexible and stable core. This may be hard to produce, but get creative! Hanging leg raises, dumbbell side bends, and back bridges are all great exercises to strengthen these muscles in a way that is useful for climbing.
- Legs: Legs do more work climbing than some give them credit for, mostly by putting us in a body position to better use the holds available. Don't overdo the leg exercises, just ensure that they are flexible and strong. A focus on single-leg strength is encouraged, like lunges, one-legged squats, etc.
- Watch your growth. With all these exercises, don't go overboard and develop bodybuilder-sized muscles. Climbers don't need the extra weight; climbers need strength and flexibility. Your exercise routine should be regular and short in duration; enough to build strength only. Focus on using enough load that you can do only 8 reps or less of any exercise you choose. Ultimately, for the beginning and intermediate climber, the best physical conditioning for climbing IS CLIMBING
Keep your weight over your feet.
Use the rests when you find them.
more here from Indoor climbing.
Hanging side crunch/twist