The Red Line Method
Know Your Red Line.
Then Move It.
Everything you do as a runner sits on a simple truth: Your body has limits. Training moves those limits. Every athlete has a floor, a red line, and a ceiling.
LT1
The Floor
LT2 / CS
The Red Line
vVO2max
The Ceiling
Part I
The Engine
What actually makes a runner fast
Endurance performance is built on three things:
- How much oxygen you can deliver and use - VO2max, the ceiling
- How efficiently you use it - Running economy, the cost per metre
- How much of that capacity you can sustain - Fractional utilisation (LT2/CS), the red line
Everything else - pacing, fatigue resistance, race execution - is downstream of these three.
Why Aerobic Work Sits at the Centre
When you train aerobically, you increase:
Training doesn't just make you "fitter." It changes the cost of movement. That is the foundation of the Red Line Method.
LT1: Raising the Floor
The real starting point of performance
LT1 is the point where effort stops being trivial. Breathing shifts, lactate rises slightly, and the body begins to move away from pure aerobic stability.
Below LT1, almost everything is "cheap":
- * Low oxygen cost
- * High fat oxidation
- * Minimal drift
- * Type I fibre dominance
- * Easy recovery
A strong LT1:
- * Makes easy running truly easy
- * Reduces fatigue accumulation
- * Increases durability
- * Improves recovery between hard sessions
- * Helps stabilise threshold
The Grey Zone Problem: When LT1 is low, runners live in the grey zone - easy runs too hard, hard runs too easy, nothing builds properly, fatigue accumulates faster than fitness. Most stagnation in amateur runners is a weak LT1 disguised as "bad pacing".
Raise LT1 = raise the athlete.
LT2 / Critical Speed: The Red Line
Where performance actually lives
LT2 (or VT2) marks the point where the body can no longer maintain homeostasis. Critical Speed (CS) is the performance version of that point - the fastest pace the body can stabilise. This is the athlete's red line.
Your red line determines:
- * Race pace
- * Sustainable speed
- * Perceived effort
- * Fatigue resistance
- * Pacing control
- * How close you can race to your ceiling
Key Insight: Two runners with the same VO2max can produce very different results because one has a red line much closer to that ceiling. A strong LT2/CS converts potential into performance.
Build LT2/CS = unlock real performance.
vVO2max: The Ceiling
The upper limit of your aerobic engine
vVO2max is the speed at which the athlete hits maximal oxygen uptake. It tells you how big the engine is, how efficiently fast-twitch fibres contribute, and how oxygen delivery behaves under maximal stress.
A higher ceiling means:
- * More room for LT2 to rise
- * Better economy at high speeds
- * Higher potential for performance
Warning: Most runners chase VO2max too early. They focus on intervals that look impressive but do nothing for long-term development because the floor is weak, the red line is unstable, durability isn't built, and economy is poor.
Raise the ceiling last, not first.
Durability and Economy: The Multipliers
These don't change your thresholds directly - they determine how usable those thresholds are
Durability - How Long the Line Holds
The ability to maintain metabolic stability and form over time.
Signs of poor durability:
- * High HR drift
- * Lactate rising late in long stages
- * Fade in 5K/10K performance
- * Big drop-offs across intervals
Improve durability = extend the red line.
Economy - The Cost Per Metre
Oxygen cost for a given pace. Two runners at the same speed may be working at completely different percentages of max capacity.
How to build economy:
- * Hills and strides
- * Drills and plyometrics
- * Strength training
- * Threshold work
Economy determines how close you can get to your red line without breaking.
LT1 sets the floor - LT2/CS sets the red line - vVO2max sets the ceiling
Durability and economy determine how usable the engine is.
Endurance isn't about random hard sessions. It's about shaping the engine so the red line moves.
Part II
Testing and Interpretation
Seeing the engine so you can train the engine
Testing isn't about data for the sake of data. It's about removing guesswork so every session has direction.
6-Minute Time Trial
Gives you vVO2max - your top-end aerobic power.
3 + 12-Minute Pairing
Gives Critical Speed - the performance expression of threshold.
Lactate Step Test
Shows LT1 and LT2 - where stability ends and instability begins.
VO2 Test
Reveals oxygen cost, substrate usage, drift patterns and ceiling behaviour.
Drift Test
Shows durability under low stress - how well you hold pace over time.
Reading the Numbers
Most runners know their pace. Almost none know their physiology. This is why so many train hard without improving - pace alone hides the internal story.
vVO2max
Tells you whether the athlete can produce high aerobic power
CS as % of vVO2max
Shows how much of the ceiling is usable
LT1 as % of CS
Reveals aerobic foundation strength
Drift patterns
Expose durability and metabolic efficiency
The Limiter Flowchart
RPP uses a systematic approach to identify your primary limiter:
- 1 Is the ceiling (vVO2max) limiting performance?
- 2 Is the red line (LT2/CS) too far from the ceiling?
- 3 Is the floor (LT1) weak, causing grey zone training?
- 4 Is durability the issue - can't hold pace over time?
- 5 Is economy poor - high oxygen cost for given pace?
Note: Diagnostic order is not equal to training order. We identify in this order but train from the floor up.
Part III
Adaptation and Periodisation
Changing the engine systematically
The Adaptive Athlete
Training follows biological laws. Understanding these prevents frustration:
Overload
Stress must exceed current capacity to drive adaptation
Specificity
You get what you train for
Recovery
Adaptation happens during rest, not during work
Non-linear Progress
Improvement comes in waves, not straight lines
Block Durations and Signs You've Peaked Them
6-10
weeks
LT1 Block
Easy runs feel easier, HR lower at same pace, recovery improves
6-8
weeks
LT2/Threshold Block
Threshold pace feels controlled, lactate stable longer, race pace improves
8-12
weeks
Durability Block
Less fade in long runs, HR drift reduces, back-half pace holds
3-6
weeks
VO2max Block
Interval times improve, recovery between reps faster, top-end feels more accessible
Red Line Periodisation
The training pyramid - build from the bottom up:
Build the Floor
Establish LT1 with aerobic volume
Strengthen the Line
Develop LT2/CS with threshold work
Extend the Line
Build durability to hold pace longer
Raise the Ceiling
VO2max work when foundation is solid
Race Specific
Event-specific simulation and pacing
Taper
Reduce volume, maintain intensity, arrive fresh
Part IV
Coaching With the Red Line Model
Putting it to work
The Four Questions That Build Every Plan
Who is the athlete?
Experience, injury history, training age, current fitness
What's the event?
Distance, terrain, demands, pacing requirements
How much time?
Weeks to goal, training availability, life constraints
What's the limiter?
LT1, LT2, ceiling, durability, or economy?
Designing Blocks From a Limiter
If LT1 is weak:
High-volume sub-LT1 running, long steady runs, aerobic progression runs, back-to-back easy days
If LT2/CS is weak:
Threshold intervals, cruise intervals, tempo to threshold progressions, controlled red-line work
If durability is weak:
Long runs, sub-threshold volume, tempo blocks, progression runs, long aerobic intervals
If vVO2max is the limiter:
2-4 min intervals, short severe-domain repeats, controlled speed-endurance, hill reps
If economy is poor:
Hills, strides, drills, plyometrics, strength training, threshold work
How RPP Uses the Red Line System
RPP takes your LT1, LT2, CS, and vVO2max data, runs the limiter flowchart, identifies your primary constraint, and generates targeted training blocks that address your specific weakness.