PROTOCOL OVERVIEW
Critical Force work
System
Anaerobic System
Target
Sustainable force capacity
Primary Goal
Increase Critical Force and improve repeated submaximal force production
Load
60–80% CF
Tempo
7 s ON / 3 s OFF
Hand Switch
Per set
Preparation
AC-FSR–Recruitment
Main Work
1–3 × 24–36 @ 60–80% CF
Rest
~10 min between sets
Retest
Every block
Progression
Increase from 1 → 3 sets across the training cycle
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Calculate your working loads
Critical Force Repeaters Intensity Calculator
Enter your measured 4-minute Critical Force (CF) to calculate working loads.
60%
kg
70%
kg
80%
kg
Execution
Warm-up
- 1–2 min of light rubber ball squeezing to increase blood flow
- A few easy contractions on the hold
Main Work
- 2–3 × 24–36 @ 60–80% CF
- Rest between sets: 5–10 min
Intensity Zones
60–70% CF
More aerobic stimulus / repeatability
70–80% CF
Closer to CF / fatigue resistance
Technical Focus
Focus on smooth, controlled force production:
- Apply steady, controlled force without spikes
- Keep output consistent across all reps
- Avoid compensatory tension in shoulders and body
- Maintain stable grip and engagement
- Prioritize efficiency over maximal effort
Key Rules
Keep intensity submaximal and sustainable:
- Stay below failure — no maximal efforts
- Maintain consistent output across the entire set
- Stop if force drops significantly or form breaks
When to use it
Use when sustainable finger force is the primary limitation:
- Forearms pump before technical failure
- Difficulty maintaining grip during longer sequences
- High Peak Load but low Critical Force (low CF / PL ratio)
Particularly useful during capacity-building phases.
Frequency
- 1× per week during capacity or endurance phases
- Perform as a standalone session or after low-intensity climbing
- Avoid placing before high-intensity or strength sessions
Expected Effects
Over time:
- Increased Critical Force (CF)
- Improved ability to sustain finger force over time
- Delayed onset of forearm pump
- Better performance on longer sequences and routes
Why This Works
AC-CFR targets the highest sustainable level of finger force (Critical Force), improving the ability to maintain grip strength without rapid fatigue. Repeated work near this threshold increases force sustainability and delays the onset of forearm pump.