Landing after jumping is a primary source of lower limb injuries, especially in sports like basketball.
Fatigue is known to worsen landing mechanics, but exactly how neuromuscular control changes post-fatigue is unclear.
This study aimed to uncover how fatigue alters muscle synergy during landings.
How does muscle coordination change after fatigue during a landing and does that make athletes more injury-prone?
What did the researchers do?
Participants
- 18 male recreational basketball players (average age ~20 years).
- Played basketball at least 3x per week, no lower limb injuries in past 6 months.
Experimental Design
Landing Task
- Participants performed a drop jump from a 35 cm box onto a force plate.
- Immediately after landing, they jumped as high as possible.
Fatigue Protocol
- 10 sets of 10 maximal effort countermovement jumps (30 seconds rest between sets).
- Designed to replicate stretch-shortening cycle (SSC) fatigue common in basketball.
Measured Variables
- EMG (electromyography) → Surface electrodes placed on 8 muscles (core, hip, thigh, and calf muscles).
- Ground Reaction Force (GRF) → Collected via force plate to mark landing events.
- Timing Focus → Analyzed muscle activation 100ms before and 100ms after ground contact.
What were the results?
Muscle Synergy Changes
Two main synergies identified during landing:
- Synergy 1 → Dominated pre-landing preparation.
- Synergy 2 → Dominated post-landing stabilization.
The structure of synergies remained similar, but activation patterns weakened after fatigue.
Decreased Activation Levels
- Pre-landing Activation (Synergy 1) → Significant reduction between 18–30% of the landing phase after fatigue.Post-landing Activation (Synergy 2) → Significant reduction between 60–100% of the phase after fatigue.
Muscle Weight Shifts
Increased reliance on calf muscles:
- Lateral Gastrocnemius (LG) and Soleus (SM) were more dominant post-fatigue.
- No major changes in thigh or hip muscles’ contribution.
What does this mean?
- Reduced Pre-Activation → Fatigue weakened pre-landing muscle preparation, potentially making initial impact forces harder to absorb.
- Post-Contact Instability → Lower muscle activation after landing compromises joint stability, especially at the knee.
- Over-reliance on Calf Muscles → The body shifts stabilization duties to calf muscles (more fatigue-resistant), which increases ankle stiffness but can transfer harmful forces to the knee.
- Big Picture → Fatigue fundamentally alters how athletes control landing, making them more vulnerable to injuries like ACL tears.
Limitations
Simulated fatigue via jumping only, so it's unknown how in-game factors like decelerations, COD, cognitive load, and more would influence these mechanics. However, this study provides insight into fatigue-related neuromuscular changes in a common sporting task, such as landings.
Coach's Takeaway
- Build thigh muscle endurance → Strong quads and glutes help "absorb" landing forces even when tired.
- Train landing mechanics under fatigue → Don’t just test fresh; challenge technique when tired.
- Add neuromuscular drills after tough sessions → Teach the body to stay sharp under fatigue.
- Train the calf-thigh connection → Focus on how calves and thighs work together, not just isolated strength.
- Prioritize stability, not just power → Stable landings protect knees when fatigue sets in.
I hope this was helpful.
Ramsey
