Timeline for Running After ACL Surgery
Return to running should not begin before 12 weeks postoperatively, and only when specific functional criteria are met, including >80% quadriceps strength symmetry, 95% knee flexion range of motion, full extension, no effusion, and pain-free aqua jogging and single-leg hopping. 1
Minimum Time-Based Criteria
The most recent high-quality guideline establishes 12 weeks as the minimum timeframe before initiating running with volume and intensity sufficient for cardiovascular adaptation 1. While some older protocols suggest 8-16 weeks, the 12-week threshold represents the consensus based on graft remodeling biology 1, 2. This is a floor, not a ceiling—many patients will require longer before meeting functional criteria.
Functional Criteria Required Before Running
Beyond the 12-week minimum, you must verify the following objective measures before clearing a patient to run 1:
- Range of motion: 95% knee flexion AND full extension (no deficit)
- Effusion: None or trace only
- Quadriceps strength: Limb symmetry index (LSI) >80%
- Eccentric power: LSI >80% for eccentric impulse during countermovement jump
- Pain-free progression: Successful aqua jogging and Alter-G running without pain
- Repeated hopping: Pain-free single-leg "pogo" hops
Rehabilitation Progression Leading to Running
The path to running follows a structured timeline 1:
- Week 1: Isometric quadriceps exercises when pain-free
- Week 2: Closed kinetic chain exercises initiated
- Week 4: Open kinetic chain exercises in restricted ROM (90-45°)
- Weeks 4-12: Progressive strengthening with neuromuscular training, avoiding effusion or pain increases
- Week 12+: Running initiation if functional criteria met
A critical pitfall is rushing to running based solely on time. 2 Fewer than one in five studies in the literature use performance-based criteria despite strong recommendations to combine both time and functional measures 2.
Subjective Readiness Matters
An International Knee Documentation Committee (IKDC) score >64/100 predicts 3-fold greater likelihood of successful running reintroduction without symptom exacerbation 3. This subjective measure should complement objective testing, as psychological readiness influences rehabilitation success 1.
Common Pitfalls to Avoid
- Time-only clearance: Using 12 weeks as an automatic green light without testing strength, ROM, or effusion status 1, 2
- Ignoring quadriceps deficits: Preoperative quadriceps weakness >20% predicts poor outcomes at 2 years; this must be corrected before running 1
- Neglecting graft type differences: Hamstring grafts require no additional weight in open kinetic chain exercises for the first 12 weeks to prevent graft elongation 1
- Skipping aquatic progression: Pain-free aqua jogging serves as a critical intermediate step before land-based running 1
Full Return to Sport Timeline
Running is a milestone, not the endpoint. Complete rehabilitation requires 9-12 months before return to pivoting/contact sports, with discharge criteria including 100% strength symmetry for high-demand activities, >90% hop test symmetry, and normalized biomechanics 1.