Finger Extensor Training for Climbers

Climbers’ finger flexors are on average 6.3 times stronger than their extensors. In a 4-week study, only dedicated high-intensity extensor training raised extensor strength, by 41.4%, in about 15 minutes per session. No study has linked the imbalance to injuries, so treat extensor work as a plausible, low-cost addition, not a proven one.

How big is the imbalance?

A 2023 study tested 78 experienced climbers on an instrumented hangboard, measuring finger flexion (pulling down on a 12 mm hold) and extension (pushing up against an inverted hold with the backs of the fingertips).

Flexors were on average 6.3 times stronger than extensors (men 6.4, women 5.9).
The ratio grew with climbing level: better climbers were more imbalanced.
Flexor strength correlated with grade (r = 0.68); extensor strength did not (r = 0.04).
About 8% of climbers had an “extreme” ratio above 8.75.

What rebalances the ratio?

The same team then trained 52 of the climbers for 4 weeks in four groups:

Group	Training	Extensor strength	Flexor strength	Ratio
Flexors only	Isometric holds at 80% of max	No significant change	+8.4%	Unchanged
Extensors only	Isometric pushes at 80% of max	+41.4%	No change	−27.8% (a trend, not significant)
Paired	Alternating flexor and extensor work	No significant change	+11.9%	−1.9%
Control	Usual climbing	No change	No change	Unchanged

Only the dedicated extensor sessions raised extensor strength. The 27.8% drop in the ratio came from ten climbers over four weeks and was not statistically significant: the authors call it a potential to rebalance, not proof. Pairing extensor work with flexor work in the same session left the ratio where it was.

Does it prevent injuries?

We do not know yet. The authors state that no study has linked the ratio to injury risk, and they call for long-term research.

How do you train finger extensors?

The study’s protocol:

Parameter	Setting
Exercise	Isometric push: fingertips under a fixed hold, pushing up with the backs of the fingers
Load	80% of your maximum push; stop the set once you can no longer reach 70%
Sets	5-second pushes with 6 seconds of rest, up to 10 per set; 4 sets with 2 minutes between them
Session	Its own session of about 15 minutes, not mixed into flexor sets
Frequency	Twice a week for four weeks

Warm up with easier pushes first, since the extensors are small muscles that fatigue quickly. Rubber-band finger openers and reverse wrist curls are popular, but they are probably too light to reach the intensity the study used.

Do this in Entralpi

A force sensor can measure extension too: turn the hold upside down and push up against it, and a ground force plate like Entralpi reads heavier instead of lighter. The app records pulls today, not pushes, so for now the extensor side of the ratio needs another tool. For the flexor side, the app’s tests measure pulling force (Take a test), and the finger strength test measures each finger alone. For the flexor work of your week, pick a workout from the Train tab or build your own.

Sources

Devise M, Pasek L, Goislard De Monsabert B, Vigouroux L (2023). Finger flexion to extension ratio in healthy climbers: a proposal for evaluation and rebalance. Frontiers in Sports and Active Living.