Why Plyometrics Matter
Plyometric training—exercises involving jumping, hopping, and explosive movements—is a critical component of ACL rehabilitation. Landing from jumps creates forces 2-5 times your body weight, so your knee must be prepared to handle these loads before returning to sport.
Benefits of Plyometric Training
- Prepares for sport: Most sports involve jumping and landing
- Improves neuromuscular control: Teaches proper landing mechanics
- Builds power: Strength + speed = power
- Reduces re-injury risk: Proper landing training is protective
- Hop testing: Hop tests are part of return-to-sport criteria
When to Start
Plyometrics are typically introduced around month 4-6 when you have:
- Good quad strength (LSI ≥70%)
- No pain or swelling with current exercises
- Good single-leg squat form
- Clearance from surgeon/PT
Many programs introduce low-level plyometrics before running, as they help prepare tendons for the impact of running.
Proper Landing Mechanics
Before progressing plyometrics, you must demonstrate safe landing technique:
Soft Landings
Land quietly with bent knees. "Toe-to-heel" landing absorbs force gradually.
Knee Over Toes
Knees track over toes—no inward collapse (valgus). This is critical for ACL protection.
Hip & Trunk Control
Hips stay level, trunk upright. No excessive side bending or rotation on landing.
Absorb with Muscles
Use your quads, glutes, and core to absorb force—not just joints and ligaments.
Practice Landing First
Before jumping, practice stepping off a low box and landing softly. Focus on form before adding height or complexity.
Plyometric Progression
Progress through these phases over weeks to months:
Phase 1: Landing Only
Phase 2: Low-Level Plyometrics
Phase 3: Moderate Plyometrics
Phase 4: Advanced Plyometrics
Hop Tests for Return-to-Sport
Hop tests are commonly used to assess readiness for sport. They compare your surgical leg to your non-surgical leg.
Single Hop for Distance
Maximum single-leg hop forward. Compare distance between legs. Goal: LSI ≥90%
Triple Hop for Distance
Three consecutive single-leg hops. Total distance compared between legs.
Crossover Hop for Distance
Three hops crossing back and forth over a line. Tests lateral control.
6-Meter Timed Hop
Hop on one leg for 6 meters as fast as possible. Compare time between legs.
LSI Goal: ≥90%
For return-to-sport, your surgical leg should perform at least 90% as well as your non-surgical leg on hop tests. Some clinicians use 95% as the target.
Programming Guidelines
| Phase | Exercise Level | Volume | Frequency |
|---|---|---|---|
| Introduction | Landing only | 2-3 sets x 5-8 reps | 2-3x/week |
| Low-level | Jump rope, line hops | 2-3 sets x 10-20 sec | 3x/week |
| Moderate | Box jumps, broad jumps | 3 sets x 6-10 reps | 2-3x/week |
| Advanced | Depth jumps, single-leg | 3-4 sets x 5-8 reps | 2x/week |
Key Principles
- Quality over quantity: Stop when form degrades
- Full recovery between sets: 60-90 seconds rest
- Don't plyos when fatigued: Do them early in workout
- Progress slowly: Master each level before advancing
- Monitor soreness: Next-day soreness should be minimal
Common Mistakes
Knee Valgus on Landing
Knees caving inward is the biggest red flag. Stop and regress if this happens.
Stiff Landings
Landing with straight legs and loud impact. Learn to absorb with soft, bent knees.
Progressing Too Fast
Jumping to advanced exercises before mastering basics. Patience prevents re-injury.
Too Much Volume
Plyometrics are demanding. More isn't better—quality and recovery matter.
Ignoring Fatigue
Doing plyometrics when tired leads to poor mechanics and injury risk.