Why GPS Alone Can’t Measure Tennis Load and Why Muscles Matter
- Myontec
- Dec 22, 2025
- 2 min read
Tennis is often monitored like a running sport. Distance covered, speed, and accelerations are commonly used to estimate workload. But tennis is not about running, it’s about repeated high-force, asymmetrical, and eccentric muscle actions.
A recent applied study done by trainer Silvio Barnaba and Professor Roberto Colli combined full-body muscle monitoring (EMG), motions (IMUs), GPS, and video analysis shows why muscle-based monitoring is essential for understanding real tennis load and fatigue.
Muscles Tell the Real Story
When players move at constant speed, GPS and EMG-based metabolic power match closely. But as soon as tennis-specific actions like forehands, backhands, rapid braking, and rotation begin, GPS dramatically underestimates player's workload.
In static and low-displacement drills:
GPS shows low distance, low speed and low load
But muscle data tells a different story:
EMG reveals high muscle load, sometimes up to three times higher than GPS estimates, because:
Players are rotating explosively
Braking hard
Loading legs eccentrically
Repeating powerful strokes
The body is working hard even when the player is barely moving.
👉 Athlete may look “fresh” on GPS but be accumulating serious fatigue.
Same Rally, Same Distance - Very Diffenret Fatigue
Two rallies can look identical on GPS but produce very different neuromuscular loads.
Muscle data shows that fatigue depends on:
Stroke intensity
Movement efficiency
Technique quality
Muscle coordination
This explains why:
One player recovers well
Another feels heavy or sore
Injuries appear “out of nowhere”
all strongly affect fatigue accumulation, the factors GPS cannot detect.
Asymmetry Is Normal But Too Much Is Risky
Tennis is inherently asymmetric, especially on the forehand side.
Muscle monitoring shows:
Dominant-side overload during forehands
Different trunk and leg strategies in backhands
Accumulated left–right imbalances over time
GPS can’t see this.
Muscle data can.
This means:
Earlier detection of overload patterns
Smarter planning of volume and intensity
Better collaboration with physios and S&C coaches
Eccentric Load: The Hidden Stress
The highest muscle stress in tennis doesn’t happen at ball contact, it happens before the hit, during braking and preparation. By combining EMG and motion data, the study shows that the eccentric phase of strokes produces the highest muscle load especially in the legs and trunk
This eccentric loading:
Drives fatigue
Increases injury risk
Builds up silently over sessions
EMG allows coaches to:
Identify when players are overloading
Adjust drills before problems appear
What This Means for Training, Rehab, and Return to Play
With muscle-based monitoring you can:
Quantify real internal load, not just movement
👉 Understand how hard a session really was
Individualize training beyond “one plan fits all”
Identify asymmetries and overload early
👉 Spot fatigue before performance drops
Optimize rehabilitation exercises
👉 Support safe return-to-play after injury
Validate return-to-sport readiness with objective data
Why Myontec
Myontec technology enables:
Objective feedback beyond distance and speed
Clear muscle-load insights. Even full-body muscle activation.
Real-time insight into neuromuscular fatigue
Data that supports smarter session planning
Evidence-based decisions for performance and injury prevention
Because in tennis, performance and injury risk live in the muscles not in meters covered.
Full body set used in the study:
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