That kid is ‘fit’; they never look like they are slowing down…
Team sport ‘fitness’ is about producing explosive efforts repeatedly throughout an entire game.
The athlete who wins in the fourth quarter has the best REPEAT SPRINT ABILITY.
It's the one who can still sprint, cut, accelerate, and recover when everyone else has faded.
It seems like a simple fix if you think yours is low - just do more conditioning…more cardio…
Well it’s not that simple. Repeat Sprint Ability is BUILT systematically, over time, with very key protocols - it has a real foundation to it, and that might be where you need to start.
Let me explain:
The Physical Qualities Underpinning Repeat Sprint Ability
1. Maximal Sprint Speed (Highest Importance)
You cannot repeat speed you don't possess.
Athletes with higher maximal velocity generally perform better on RSA tests because each sprint is completed in less time and at a lower relative cost. Faster athletes also tend to maintain higher mean sprint performance across repeated efforts.
If you can't sprint fast, you won't repeatedly sprint fast.
2. Horizontal Power & Acceleration
Most team sports involve repeated accelerations—not flying 100 m sprints.
Athletes need the ability to:
Produce large horizontal forces
Accelerate quickly
Re-accelerate after every deceleration
This depends heavily on:
Relative strength (if you have high mass & low strength and high bodyfat; you will struggle here)
Rate of force development
Horizontal power
3. Elastic / Reactive Strength
Every sprint contact stores and releases elastic energy.
High RSI means:
shorter ground contact
greater stiffness
less energy wasted
lower metabolic cost
This likely allows athletes to preserve performance over repeated efforts.
4. Aerobic Capacity (Often Underappreciated)
This is where many coaches get confused.
The aerobic system is not there to make soccer players marathon runners.
Its job is to:
resynthesize phosphocreatine
restore ATP
remove metabolites
prepare muscles for the next sprint
In other words:
The aerobic system is the recovery system between maximal efforts.
This is one of the major messages of your e-book.
5. Alactic Capacity
Can the athlete repeatedly produce maximal power before significant glycolytic fatigue develops?
This is trainable through:
short maximal sprints
long recoveries
high quality work
6. Change of Direction Efficiency
Most repeated efforts aren't linear.
Athletes who:
brake efficiently
redirect force efficiently
re-accelerate efficiently
waste less energy every effort.
Poor movement mechanics increase the metabolic cost of every sprint.
7. Strength
Strength underpins almost everything.
Greater force production means:
faster acceleration
better deceleration
greater stiffness
improved sprint mechanics
reduced relative effort
A stronger athlete performs the same sprint at a lower percentage of their maximum capacity.
8. Body Composition
This one is often ignored or glossed over.
Extra non-functional FAT mass increases the energetic cost of:
accelerating
stopping
cutting
jumping
Every kilogram matters over 60–100 high-intensity efforts. And athletes with higher body fat, cannot re-produce speed as well.
9. Movement Economy
Athletes with efficient mechanics simply spend less energy.
Think of:
relaxed upper body
efficient arm action
optimal stride frequency
minimal braking
Better mechanics = lower energy cost.
10. Fatigue Resistance
Finally...
All of these qualities interact with an athlete's ability to tolerate accumulated fatigue while maintaining movement quality.
This is the outcome—not the starting point.
My model
Repeat Sprint Ability = Speed × Power × Recovery × Efficiency
Speed
Max velocity
Acceleration
Power
Reactive strength (plyos)
Horizontal force (think broad jump)
Rate of force development
Recovery
Aerobic capacity
PCr resynthesis
Metabolite clearance
Efficiency
Body composition (low body fat; high muscle mass)
Running mechanics
Change of direction technique (low hips, good angles)
= Repeat Sprint Ability
