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Adaptation Engineering
How to Create Effective Workouts
Becoming Your Own Best Coach
In his book Run Faster, coach Brad Hudson encourages athletes to "become your own best coach." It’s a powerful idea, one that goes beyond just following a training plan. It means understanding how training works, why a certain workout matters, and how to make informed decisions when the unexpected happens. Whether you’re an athlete or a coach, the ability to adjust on the fly, interpret your body’s signals, and apply principles instead of rigid rules is what leads to long-term progress. This guide is designed to help you think like a coach, whether you're writing workouts for others or yourself, by breaking down the key decisions that shape effective, adaptable training.

Workout Design — What Are We Trying to Do?
Designing workouts isn’t about copying Elite runners, although that’s sometimes fun, it should not be done at the expense of creating the right stimulus to achieve a specific adaptation.
Too often, we rely on a narrow set of staple workouts. In reality, our only limit is our imagination. Every workout is a chance to evolve. Improvement happens when we challenge the system in a way that forces it to adapt. That means manipulating key elements of training to either:
Qualify the athlete (increase intensity or reduce recovery)
Extend the athlete (increase volume or duration)
Qualify vs. Extend: Two Core Aims of Workout Design
Every time we change a workout, we're doing one of two things: qualifying or extending.
Below I give example progressions using two runner profiles: an advanced athlete that can run 10km in 30:00, and a weekend warrior that can run 10km in 40:00.
If both athlete profiles were to use the same 400m rep distance the slower runner would spend significantly more time at intensity per rep. For example:
The advanced athlete could run 400m in 60 seconds
A 40-minute 10K runner might take 96 seconds for the same distance at the same relative intensity.
That’s 60% more time at intensity, which alters the physiological load and can turn the session into something other than intended.
Solutions:
Use shorter reps (e.g., 300m instead of 400m)
Reduce rep count (e.g., 6–8 instead of 10)
Shift to time-based intervals (e.g., 10x1 minute)
The goal is to match the intended stimulus, not necessarily the format. Be careful when copying the workouts of elite runners or even just trying to copy the sessions of your faster run buddies. It is TIME AT INTENSITY (not distance) that is important!
See Example Progressions below:
Advanced Runner (Level 10K ≈ 30:00, or 3:00/km)
Starting Workout: 10x400m @ 60s per rep (2:30/km pace), 90s rest
Adaptation Type | Workout Adjustment | Goal |
Extend (Volume) | 12x400m @ 60s, 90s rest | Increase total work capacity |
Extend (Distance) | 10x500m @ 75s (same pace), 90s rest | Hold race pace longer |
Qualify (Pace) | 10x400m @ 58s, 90s rest | Increase speed at same volume |
Qualify (Recovery) | 10x400m @ 60s, 60s rest | Increase stress by limiting recovery |
Weekend Warrior (level 10K ≈ 40:00, or 4:00/km)
Equivalent Starting Workout: 10x300m @ 60s per rep (~3:20/km pace), 90s rest
Adaptation Type | Workout Adjustment | Goal |
Extend (Volume) | 12x300m @ 60s, 90s rest | Increase total anaerobic work capacity |
Extend (Distance) | 10x400m @ 80s per rep, 90s rest | Build endurance at higher intensity |
Qualify (Pace) | 10x300m @ 58s, 90s rest | Push speed and lactate tolerance |
Qualify (Recovery) | 10x300m @ 60s, 60s rest | Boost tolerance to incomplete recovery |
In the advanced example, 10x400m @ 60s represents approximately 800m race pace. For an intermediate runner with a 40:00 10K PB, a comparable time at intensity would be 10x300m @ 60s. This maintains both the anaerobic demand and the rep duration, creating a more accurate training equivalent across ability levels.

Workout Manipulators: Your Coaching Toolbox
You can manipulate stress using:
Speed
Recovery (duration, type, or added complexity)
Rep Length
Terrain
Volume
Density
Stuff (e.g., sprints, circuits, aerobic clearing)
Surges
Feedback Constraints (e.g., no-watch, hiding splits or rep count)
Workout Decisions: Putting It All Together
Step 1: Adaptation and Direction
What are we trying to improve?
Endurance → Long runs, steady states, tempos
Speed → Sprints, hills, fast strides with full rest
Fatigue Resistance → Tempo reps with surges, race-pace intervals, short recovery
Step 2: Identify the Athlete’s Norm
Before prescribing a workout, understand:
What pace, volume, and recovery are manageable?
What is challenging physically, mentally, and emotionally?
Example: An elite runner may handle 4x1.6 km @ 3:06/km pace with 3 minutes rest. A 40-minute 10K runner doing the same may take over 6:20 per rep, a very different stimulus.
Match the Stimulus, Not the Structure. Instead of mirroring an elite workout format:
Use time-based intervals (e.g., 4x5 minutes @ threshold)
Or shorten reps (e.g., 4–5x1 km instead of 1.6 km)
The objective is to create the same training effect, not copy the format.
This even applies to your long runs. A high level marathoner will run an easy 30km in under 2 hours - you will not - so match the stimulus not the distance.
Step 3: Build or Maintain?
If building, push intensity or volume to 90–100% of their limit
If maintaining, 60–70% stimulus may be sufficient
Step 4: How Big of a Shift?
Use the “Barbell Strategy” borrowed from Nassim Teleb’s Antifragile. The idea is to do mostly safe, small gains + occasional high-risk/high-reward workouts
Understand Set Point Shifting: Combine hard workouts (perception changers) with follow-ups (cementing adaptations)
Monitor for Productive Fatigue: We want athletes to respond, not collapse, under stress
Aim for the Optimal Challenge Window: Enough to drive adaptation, not enough to destroy
Step 5: How Often Do We Need to Go There?
Once you've decided what quality you want to build or maintain, the next step is figuring out how frequently that type of stimulus needs to show up in the training cycle.
In general, the principle is this:
The faster you gain an adaptation, the faster you lose it.
Neural or speed adaptations (like sprinting or drills) fade quickly and need to be reinforced more often.
Aerobic or endurance adaptations build slowly but are more stable and resilient.
Rather than offer rigid prescriptions, think in adaptive ranges. If you're building a capacity, frequency needs to be a little higher; if you're maintaining it, you can afford more spacing. The key is recognizing that each workout type has a half-life, and managing that over time helps maintain fitness while allowing recovery and focus on other systems.
Final Thoughts
Workout design is part science, part art. Whether you're coaching others or yourself, the job isn’t just to prescribe runs, it’s to engineer adaptation. By focusing on stimulus quality, using your toolbox wisely, and customizing for each athlete’s ability, you’ll create workouts that don't just look good on paper, but actually move the needle.
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