In the world of climbing, there’s a critical moment in every move: the contact with the hold. Have you ever wondered why sometimes, even with enough grip strength, the hold just “slips away” during a fast or dynamic move? The answer often lies in a specific and often underestimated physical capacity: contact strength, or RFD (Rate of Force Development).

In this post, we’ll break down what contact strength is, why it’s so crucial in climbing—especially in bouldering and high-difficulty sport climbing—and how we can train it intelligently and safely.

What is contact strength and why is it so important?

Contact strength is the ability that allows us to hold onto holds with the necessary speed. It’s not just about having strength, but about how quickly we can express that strength, mainly through active tension. If we don’t apply force at the required speed when contacting a hold, we won’t be able to stay on it.

This capacity is fundamental because:

It’s the first link in the chain: If we don’t “contact” the hold and stay on, nothing else will happen.
It impacts performance: There’s a moderate correlation between RFD at 200 ms and climbing performance, even stronger among boulderers. It’s especially vital in hard sections that require climbing with unstable balance and no feet.
It’s a key part of the real movement: In deadpoint moves (unstable balance), you not only need to coordinate the movement and maintain body tension, but also exert finger force quickly enough to stay on the hold.

It’s important to note that RFD is an adaptation we must work on independently from maximal strength, though it’s essential to develop it from a high strength base and with an adapted musculo-tendinous system. There’s no point in expressing force quickly if we don’t have enough strength.

The main adaptation: increased recruitment speed

When we train contact strength, our body seeks a key adaptation: increasing the speed at which available motor units are recruited. This doesn’t mean recruiting more units, but doing so more quickly, allowing us to express force at a higher speed without necessarily increasing the amount of force produced.

This process is fascinating: the signal that reaches the muscle is generated before the motor neurons receive feedback from the muscle contraction itself. This means that, to develop it, it’s essential to be able, through conscious control and will, to express maximum force in the shortest possible time. It requires maximum cortical input before contraction, with maximal volitional effort to apply force quickly and efficiently.

Key considerations for developing grip RFD

To optimize RFD training, we must consider several characteristics of the load and the type of fibers involved:

Muscle Fibers and Focus
- We need high-threshold motor units that access most fast fibers for rapid contractions.
- Unfortunately, the finger flexor muscles have a low proportion of fast fibers, and these fatigue quickly.
- RFD requires a constant level of focus and activation.
- Too high a volume in RFD training can lead to loss of coordination in large motor units, increasing injury risk and limiting performance adaptations. When you feel you’ve lost your “spark,” it’s time to stop.
Intensity
- The goal is to express force at a very high speed, not necessarily at maximal intensities.
- We’ll work in the intensity range of climbing: 40–80% of maximal voluntary contraction, or with our body weight (or less, with feet on).
- Maximal intensities require time and don’t allow the highest possible speed of force expression.
Time Under Tension and Effort Character
- Tension times will be very short: one or two contacts, maximum three, each lasting a couple of seconds at most.
- It’s crucial to leave a high margin to avoid failure and initial fatigue.
- The intention is to move quickly, be as coordinated and efficient as possible, and finish the session before losing power.
Rest and Cluster Methods
- Rests will be short (10–30 seconds) between blocks of 1–2 reps (cluster method).
- This allows us to maintain intensity and limit neural fatigue, replenishing phosphocreatine stores.
- Interestingly, the intrinsic hand muscles (lumbricals and interossei) have more fast fibers and may be underestimated in contact strength development. Specific training of these muscles with ball-type grips could be interesting for RFD.
Frequency
- RFD training should be done in the complete absence of prior local fatigue.
- Under these conditions, it can be trained 2–3 times per week, or even 3–4 times if there’s no fatigue.

Progression by level: when and how to train RFD?

RFD training is linked to performance in bouldering and high-difficulty sport climbing (typically >8a).

Children and Youth: Extreme caution! Epiphyseal plate fractures have been observed in young people during growth spurts when using finger RFD training methods. It’s crucial to limit or only work under certain conditions (open hand grips, flat surfaces) during the year of peak growth.
Beginners: This is not a capacity to be trained at this stage.
Intermediate Boulderers (3–10 years climbing, 6C–7B):
- Start on the wall, learning to launch to holds and coordinate movement.
- Begin with diluted loads (feet on), prioritizing open hand and extension grips, as well as flat surfaces.
- Avoid two-finger, mono, or closed crimp exercises on edges due to higher risk.
- Alternate long cycles of strength and tendon compliance with shorter RFD cycles.
- Never train this capacity in a fatigued state.
Advanced Boulderers and Sport Climbers (>10 years climbing, >7B/>8a):
- The athlete already knows deadpoint and dynamic techniques. Specific training beyond bouldering is needed.
- Start with diluted loads, progressing to full body weight and even added weight on campus.
- Prioritize open hand grips (slopers and extensions). Crimping should only be trained with a very high level of passive structure competence.
- Fundamental: avoid training in a fatigued state.
- For sport climbers, integrate RFD in performance phases when fully rested, which is more complex due to the volume of endurance training.

Methods and training examples

To develop RFD, we look for exercises that force us to use useful force (body weight or less) quickly.

Campus Board: Not all exercises are suitable. Choose those that focus on rapid force expression. It’s recommended to work with shorter distances but higher speed, perform simultaneous two-handed work (with or without feet), or short jumps with added weight for high-level athletes. Avoid large flying moves that increase injury risk.
Limit Boulder, No Feet and with Constraints: Create voluntarily unstable balance situations (e.g., feet off, one foot, limited holds) to force rapid force expression upon reaching the hold.
Explosive Unilateral PIMA: Using a portable or fixed hangboard, apply a lot of force very quickly from a slight pre-contact, trying to isolate the finger flexors. Hold for 1–2 seconds, switch hands, rest 10–20 seconds.
Explosive Contacts or Jumps to a Rung: On a hangboard or campus board. Prepare just above the rung and try to grab it quickly while lifting your feet. In advanced phases, jump directly. Prioritize open hand grips.
Campus Jumps (with/without feet) and Simultaneous Ladders/Jumps: From a campus rung, jump to another with one hand (the other below, feet off). Focus on grip difficulty, not distance. Can be trained on the wall. For ladders, use small rungs and few moves to avoid fatigue. Progress to simultaneous two-handed climbs.

Conclusion

Developing RFD is crucial to improving climbing performance, especially in bouldering and high-difficulty sport climbing. It requires a deep understanding of strength and stiffness adaptations and should be trained with appropriate loads, always in the absence of fatigue. A progressive and individualized approach, starting with diluted loads and gradually increasing difficulty, is essential to develop this capacity effectively and safely, protecting our valuable passive structures.

So next time you face a dynamic or contact move, remember that the speed at which you grab that hold is just as important as the strength you have!