Camp4 Human Performance

Recent discussions in climbing suggested that keeping the DIP joint curled around an edge may be safer than a traditional crimp position.

The idea makes sense at first glance.

A curled DIP may reduce hyperextension, decrease compression on the back of the joint, and feel more comfortable for climbers dealing with DIP irritation.

But comfort and force production aren’t the same thing.

If two climbers grab the same 20 mm edge and pull maximally, the half-crimp will always produce more force.

Why?

Because the curled position requires the FDP to actively maintain DIP flexion throughout the pull. The finger becomes more dependent on muscular stabilization and less dependent on efficient skeletal alignment.

At the same time, the fingertip sits farther in front of the wall. That pushes the hand, shoulder, and center of mass farther away from the hold, increasing leverage against the climber.

As intensity increases, most climbers naturally begin extending the DIP. I don’t think this is simply a habit. I think it’s a mechanical adaptation that improves force transmission and allows the body to stay closer to the wall.

That doesn’t mean the curled position is wrong.

It may be useful for certain rehabilitation scenarios or for reducing stress to specific structures around the DIP joint.

But I remain skeptical that it represents a superior strategy for producing maximal force on small holds.

I hypothesize that when force demands get high enough, the system naturally gravitates toward DIP extension because it is mechanically more efficient.

The interesting question isn’t whether a curled position is safer.

It’s whether elite climbers can actually maintain meaningful DIP flexion once the hold becomes small and the force requirements become maximal.

Tenosynovitis is one of the most common finger injuries I see in climbers, but it’s often misunderstood.

Most climbers feel pain around the A2 or A4 pulley and immediately assume they’ve strained a pulley.

Sometimes that’s true. Often times it isn’t.

The flexor tendons travel through a lubricated sheath. When that sheath becomes irritated, swollen, and sensitive, gripping becomes painful even though the tendon and pulley may be completely healthy.

What I find interesting is that many climbers focus almost entirely on intensity.

“Maybe I crimped too hard.”
“Maybe that move was too powerful.”

Sometimes, but finger tissues don’t only experience force. They experience repetitions.

A max hang might expose the finger to very high forces, but only for a handful of contractions.

A long climbing session might expose the tendon sheath to hundreds or thousands of gripping cycles.

Less force with more total exposure.

That’s why I frequently see symptoms develop during periods of increased climbing volume, longer sessions, more gym days, or lots of easy mileage.

Instead of completely unloading the finger, I usually prefer modifying the stress.

Reduce the things that repeatedly irritate the sheath:
• Full crimping
• Small pockets
• Sharp edges
• Long sessions
• Consecutive climbing days

At the same time, continue exposing the finger to tolerable loading through open-hand gripping, fingerboard loading, recruitment work, and progressive climbing.

Most tissues don’t improve because we stop loading them. They improve because we find a dosage of loading they can successfully recover from.

For many climbers, that’s the difference between symptoms lasting a few weeks versus lingering for months.

Post-activation potentiation (PAP), a concept that sounds great on paper.

Do a heavy lift, wait a few minutes, and perform better.

The reality is more complicated.

Modern researchers have largely shifted toward the term PAPE (post-activation performance enhancement) because improvements in sport performance likely involve much more than the classic PAP mechanisms in textbooks.

The research generally shows small improvements in performance, but those improvements are highly individual.

Some athletes jump higher, sprint faster, and feel more explosive. Others show no improvement at all.

The biggest reason appears to be the balance between potentiation and fatigue.

If the conditioning activity creates too much fatigue, performance drops.

If the athlete is strong, well-trained, and the timing is right, performance may improve.

One of the more interesting findings is that a high-quality warm-up may already provide much of the benefit people attribute to PAP.

In other words, the warm-up itself may be doing most of the work.

For climbers, I generally think of PAP as a low-volume recruitment strategy.

A few high-intent recruitment pulls before limit bouldering or powerful climbing may help some athletes feel more explosive.

The key word is that it may, but the current evidence doesn’t support an “established” protocol.

Instead, think of PAP as something worth testing on yourself.

If performance improves, keep it.

If performance doesn’t improve, move on.

Improved climbing performance is ultimately what determines whether the protocol works.

📸 on GPS Direct

🙏 and for hosting my first Swedish 🇸🇪 UE rehab course.

🙏 to all the participants who made the journey as well.

I’ll be back next year for the S&C course 🤘

Next stop Switzerland 🇨🇭 June 27th .ch

I recently collected self-guided shoulder testing data from 46 climbers examining peak force, RFD, and endurance/capacity metrics in multiple shoulder positions.

It’s important to remember that shoulders are not just required to produce maximal force on the wall. They are required to produce force rapidly, repeatedly, and also under fatigue.

Most climbing rehab still centers around pain, mobility, and generic rotator cuff exercises. But climbing demands much more than that, especially on steep terrain, dynamic movement, compression climbing, and high volumes of overhead stress.

Some interesting findings:

Average ER peak force ratios with the arm at the side:
• Males: 0.67
• Females: 0.75

At 90/90:
• Males: 0.79
• Females: 0.78

The ratios moved closer to 1.0 overhead, suggesting external rotation capacity becomes relatively more important in elevated positions common in climbing.

This is likely important for both rehabilitation and performance.

Capacity testing was performed by maintaining ~40–50% of each athlete’s MVC using visual feedback.

Average 90/90 endurance times:
Male climbers:
• ER: ~92 sec
• IR: ~108 sec

Female climbers:
• ER: ~78 sec
• IR: ~101 sec

We also saw substantial RFD demands:
Male ER RFD:
~38–42 kg at 200 ms

Female ER RFD:
~26–31 kg at 200 ms

Remember, the shoulder does not simply need maximal strength.

It needs:
• peak force
• rapid force production
• fatigue resistance
• balanced ER ratios (they’ll never be 1.0, though)
• repeated stabilization under load

This demonstrates why shoulder rehabilitation in climbers needs to move beyond basic theraband work and begin considering measurable force production, endurance, explosive force, and directional coordination.

The side of the PIP joint may be one of the most mechanically stressed regions in climbing.

A lot of climbers develop pain on the sides of the PIP joint during crimping. Usually near the proximal attachment of the middle phalanx.

This often gets labeled broadly as “capsulitis.”

But the biomechanics are more complicated.

The collateral ligaments of the PIP joint change tension as the joint flexes. The proper collateral ligament becomes progressively tighter in flexion, exactly where climbers spend a lot of time during half and full crimp positions.

The PIP joint is also not a simple hinge.

As it flexes, small amounts of rotation and translation occur at the condyles. During climbing, this happens under very high compressive loads, rotational demands, and sustained isometric contractions.

The full crimp likely amplifies this further by adding DIP hyperextension, increased flexor tendon force, dorsal shear, and extensor tension.

So when climbers develop:
• lateral swelling
• pain at the sides of the PIP
• morning stiffness
• synovitis on ultrasound
• dorsal joint irritation

It’s likely not be a single tissue problem.

It’s a combined overload response involving:
• collateral ligaments
• synovium
• capsule
• central slip
• lateral bands
• cartilage

And I think many underappreciate how much load the collateral ligament complex is exposed to during climbing.

Climbers often assume a torn pulley heals back to bone but It doesn’t.

The structure that reforms is fibrous and flexible, aka a pseudo-pulley that restores movement, not true mechanical strength.

Rehab isn’t about waiting for healing. It’s about rebuilding tolerance.

Controlled loading is what organizes new tissue and prevents chronic bowstringing.

A recent climbing paper compared “HIMA” vs “PIMA” finger training using weighted hangs versus unilateral dynamometer pulling.

Both groups improved finger strength, RFD, and hang performance after only 4 weeks.

But the more interesting question is whether the study actually isolated different contraction strategies at all.

The paper frames weighted hangs as a “holding” isometric and dynamometer pulls as an “overcoming” isometric.

I’m not convinced the distinction was that clean.

The methods never clearly described:
• body position
• shoulder contribution
• preload strategy
• finger flexor intent
• whether athletes were truly curling into the edge

If the athlete simply lowered their body into the hold while pulling against the dynamometer, mechanically that still resembles a supported hang.

That is not necessarily a true finger specific overcoming isometric.

The paper also never standardized contraction intent.

Trying to aggressively curl into an immovable edge is probably very different neurologically than simply resisting bodyweight.

Another issue is the testing itself.

Peak force and RFD were both tested using the same instruction:
“pull as fast and hard as possible.”

That may bias both testing and adaptation toward the dynamometer group since they were already training explosive unilateral pulls.

The intervention was also extremely short at only 8 sessions total.

Because overcoming finger contractions require coordination and motor learning, that may not be enough time for athletes to fully adapt to the task.

The study is still valuable because it pushes the conversation forward.

But future climbing research needs to better isolate:
• intent
• position
• muscular contribution
• passive tissue loading
• yielding vs overcoming mechanics

Right now those variables are not clearly distinct.