Strength is one of the most determining qualities to climb. If you lack strength, you will not be able to perform certain movements. In early climbing, the best way to increase specific strength is by climbing. But inevitably a stalemate will come. Then it will be necessary to resort to specific training. This article will cover the basics of climbing-specific strength training.
Climbing performance depends on several factors. In the beginning, the most decisive will be the technical execution. But over time, other physical and mental limitations will appear. Specific force is one of them.
FORCE PRODUCTION
The amount of force generated by a motor unit during a contraction depends on the number of cross bridges, and the number and size of sarcomeres, which act in parallel. The larger the cross-sectional area of sarcomeres in a motor unit, the greater the potential to generate force.
The maximum force is that which a person can apply voluntarily. As I have already discussed in two articles (on maximal muscle fiber recruitment and on fatigue), not all motor units respond effectively during a contraction. Normally they are enlisted from smaller to a larger sizes, according to need.
Taking into account the above, there will be two main ways to increase strength:
Different studies indicate that hypertrophy requires at least eight weeks to occur. Neural adaptations can manifest in less time.

SPECIFIC FORCE FOR CLIMBING
If your goal is to improve your climbing, you will need to strength train as specifically as possible. It will be of little use to be very strong in certain gestures if they are not transferable to the climbing gesture later. Interested in a useful force.
Grip strength should take an important place in this training. Once you have a good base, it will be interesting to be able to apply it in the least amount of time.
The traction muscles of the upper body and those that make up the core should also be worked. Always looking for the maximum transfer.
GREATER STRENGTH BY INCREASING MUSCLES
Muscle hypertrophy can be divided into:
Therefore, both are important for a climber. However, as climbing is so dependent on the strength/body weight ratio, there is some fear of developing excessive size that will weigh the climber down.
Fortunately, the forearms are relatively small muscles, and their contribution to climbing is key. You will never have overly developed forearms. As the Anderson brothers point out, “they are worth their weight in gold” and their hypertrophy should be pursued.
NEURAL ADAPTATIONS
For years, muscle morphology has been given much prominence to increase strength. But less is known about the specific neural mechanisms.
All muscle contractions start in the brain. A motor neuron controls a motor unit, made up of a group of muscle fibers. The high frequency of these impulses produces greater muscle tension.
The feedback is constant, allowing uninterrupted regulation, adapting the intensity to the needs, and keeping the muscle safe.
These neural processes are inefficient in someone who has never strength trained. The absolute force is the potential of each one, and the voluntary force is that which can be applied. In novice climbers, this difference is very noticeable.
Hence, the initial progression is really fast and without apparent changes in muscle size. Hypertrophy will require a little more time (study).
There are different types of neural adaptations that improve strength (study):
Maximum grip strength training is based on these types of adaptations. The complex method uses them ergogenically, combining a strength exercise with a power exercise.
Verkhoshansky indicates that the duration of such adaptations will be greater if a base of muscular hypertrophy is obtained before. Hence, the importance of good prior physical conditioning.
HOW MANY SETS, REPS, AND REST TO TRAIN STRENGTH?
The answer will depend on the adaptations sought. The stimulus created with training must be based on a balance between metabolic stress and mechanical tension. Therefore, maximal strength training is based on repeated efforts and brief maximal tension methods.

PROGRESSIVE OVERLOAD
Effective training should always adhere to the principle of progressive overload. The body gets used to the stimuli. For this reason, it is essential to increase the demand as progress is made.
Research shows that the stimulus needed to increase muscle strength is not the same for all ages and performance levels. It should be at least one-third of the maximum force. As the force increases, the absolute intensity must be increased to achieve higher stimuli, reaching a limit from which it can be negative.
Verkhoshansky points out that at times it can be interesting to go beyond the level of competition stimulation. In the case of climbing, it would be equivalent to using ballast. González Badillo does not recommend the training to the maximum or 1RM with few exceptions. However, that control precision is lost at the time of climbing.
Controlling the progression and quantity of the load will be important. For it:
Both will be essential to be able to apply a logical and sustainable progression.

TYPES OF FORCE AND CONTRACTIONS
The term force encompasses various types of forces that respond to different qualities, depending on their application. Each of them must be trained in a specific way. You have an article on the types of strength in climbing that goes deeper into the subject.
Regarding muscle contractions, there are basically three:
Isotonic contractions (with movement) generate strength gains throughout the range of motion. However, isometric contractions provide an increase in strength at little more than the angle worked. Hence the need to specify each exercise through logic, objectives, and previous study.
In climbing, all three types of contractions usually occur. While climbing, isometrics are most common on toes and lockouts. The anisometric or isotonic ones are given in dynamic steps, throws, or any change of position.
When training for a particular project you will be able to focus the isometric work on the specific positions of the track.
ISOMETRIC CONTRACTIONS
Some data for effective isometric training:

CHOICE OF EXERCISES
The most specific way to build strength for climbing is bouldering or block climbing. The problem is the difficulty in isolating specific movements and positions. Hence, other exercises are included, such as suspensions on multi-grip boards, the campus board, and exercises with free weights and kettlebells, on the bar, on rings, with TRX or calisthenics.
At an intermediate point would be the MoonBoard. A tool that reduces technique to a minimum, in order to isolate explosive force work with full bodywork.
The choice of exercises should be based on:

STRENGTH TRAINING DURATION
Neural-type adaptations happen quickly (in a matter of days). And they will quickly reach a plateau. That will happen in a few weeks.
The problem is that hypertrophy adaptations take longer (about eight weeks). Hence, the following question arises: How long should the strength mesocycle last?
So, depending on your starting point and the time you have available, the duration should be between one and two mesocycles. You have a complete article on planning climbing training.
FINAL WORDS
The supposed lack of strength may actually be hiding other weaknesses. The great force will be of little use to you if you do not have an appropriate technique to apply it. What’s more, starting to climb with great force can hurt your technical progression as a climber. Good balance management will make you adopt more efficient positions in each movement. Using momentum will be a nice boost to the strength you already have. Many attributes distinguish a good climber.
With age, strength is one of the attributes that are mostly lost. For this reason, his work in the training of older climbers is fundamental. But it can also be part of the training of the youngest, following appropriate parameters.
The best thing about training strength is that it will also improve your resistance as indicated by the Force Drag Theory. By increasing your critical strength, you will be able to scale to a higher intensity below the threshold of fatigue.