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Aerobic Efficiency (AE)

What is Aerobic Efficiency?​

Aerobic Efficiency (AE) measures how fast you can run at your aerobic threshold heart rate. As your fitness improves, you'll be able to run faster at the same heart rate - this is the essence of aerobic fitness development.

Why is this important?​

  • Track fitness progress over time without needing regular fitness tests
  • See real improvements in your aerobic capacity from your regular training
  • Objective measurement that shows if your training is working
  • Compare workouts done in similar conditions to see trends

How is it calculated?​

Good Coach App analyzes your workout data to find the relationship between your heart rate and pace. Using statistical methods (linear regression), we determine what pace you would run at your aerobic threshold heart rate. This gives you a single, comparable number across all your workouts.

Which Workouts Work for AE Calculation?​

AE calculation works best with specific types of workouts. The key is to run at relatively constant pace and let your heart rate vary naturally.

Ideal Workouts for AE​

Long steady runs (60+ minutes)

  • Run at a comfortable, conversational pace
  • Keep your pace consistent throughout
  • Your HR will naturally drift upward over time (cardiac drift)
  • Perfect for AE calculation!

Tempo runs on flat terrain

  • Sustained effort at a steady pace
  • Moderate heart rate that may increase gradually
  • Minimal pace variation due to terrain

Easy aerobic runs (30+ minutes)

  • Consistent easy pace
  • Flat or gently rolling terrain
  • Natural HR variation as you warm up and maintain effort

Marathon pace runs

  • Sustained steady pace
  • Long enough for meaningful HR data
  • Consistent effort level

Workouts That Don't Work for AE​

Heart rate controlled runs (Zone training)

  • When you maintain a specific HR zone (e.g., "stay at 145-150 bpm")
  • HR stays constant, pace varies with terrain
  • Cannot establish HR-to-pace relationship
  • Will show: "Heart rate too steady"

Interval workouts

  • Alternating hard/easy efforts
  • Large pace variations
  • Will show: "Intervals detected"

Hilly trail runs

  • High elevation gain (>20m per km)
  • Pace varies significantly with terrain
  • Will show: "High elevation" or "Heart rate too steady"

Short runs (<30 minutes)

  • Not enough data for reliable calculation
  • Will show: "Too short"

Understanding Exclusion Messages​

When a workout doesn't qualify for AE calculation, you'll see one of these reasons:

MessageWhat it meansWhat to do
"Heart rate too steady"You maintained constant HR during the run (HR-controlled training)Run at steady pace instead of constant HR
"Intervals detected"Large pace variations detectedUse steady-state runs instead
"Too short"Workout less than 30 minutesRun for at least 30 minutes
"High elevation"More than 20m elevation gain per kmChoose flatter routes or accept this limitation
"Insufficient data"Less than 10 minutes of qualifying data after filteringRun longer or ensure more time in aerobic zones
"Missing performance data"No aerobic threshold (LT1) or max/resting HR setUpdate your athlete metrics in settings

How to Get Successful AE Calculations​

1. Set Up Your Athlete Profile​

You need either:

  • Your Running Aerobic Threshold (LT1) - preferred method
    • If you've done a lactate threshold test or lab test
    • Typically 70-80% of max HR for trained runners

OR

  • Your Maximum HR and Resting HR
    • We'll calculate your target HR using Heart Rate Reserve (HRR)
    • Target = Resting HR + (HRR × 72.5%)

Tip: Get your LT1 tested for best results. It's more accurate than HRR-based estimates.

2. Run the Right Workouts​

The Golden Formula:

  • Run at consistent pace
  • Let heart rate vary naturally
  • Flat or rolling terrain (not hilly)
  • Duration: 30+ minutes (longer is better)
  • Easy to moderate effort

Practical approach: Once per week, do an easy run focused on pace consistency rather than HR zones. This gives you an AE data point while still fitting your training plan.

3. Example Workouts That Work​

Beginner:

30-40 minute easy run on flat path
- Goal: Keep pace steady at conversational effort
- Watch: Pace, not HR
- Expected: HR gradually increases (cardiac drift)
- Result: AE calculated

Intermediate:

60 minute long run at easy pace
- Goal: Maintain consistent effort/pace
- Terrain: Flat to gently rolling
- Effort: Comfortable, could hold conversation
- Result: AE calculated with high confidence

Advanced:

90 minute progressive long run
- Start: Easy pace for 60 minutes
- Finish: Moderate pace for 30 minutes
- Terrain: Flat
- Result: AE calculated (pace variation is gradual, not intervals)

Common Questions​

Q: Why does my zone 2 run show "Heart rate too steady"?​

A: If you're running with HR control (maintaining a specific zone like 145-150 bpm), your HR stays constant while your pace varies with terrain, wind, and fatigue. This makes it impossible to calculate the HR-to-pace relationship.

Solution: For AE calculation, flip your approach:

  • Don't: "I'll maintain 145-150 bpm and adjust pace as needed"
  • Do: "I'll run at 5:30/km pace and observe my HR naturally"

Q: Can I still do HR-controlled training?​

A: Absolutely! HR-controlled training is excellent for many purposes. Just understand that those workouts won't generate AE data.

Best of both worlds: Mix your training:

  • 2-3 runs per week: HR-controlled zone training (for specific adaptations)
  • 1 run per week: Pace-controlled easy run (for AE tracking)

Q: How often should I get AE calculations?​

A: For meaningful progress tracking:

  • Minimum: Once every 2 weeks
  • Recommended: Once per week
  • More frequent: Fine, but not necessary - AE changes slowly over weeks/months

Q: My AE is getting slower, not faster. Why?​

Possible reasons:

  1. Fatigue - You're in a heavy training block
  2. Weather - Hot/humid conditions affect HR and pace
  3. Detraining - Taking time off or reducing volume
  4. Illness/recovery - Fighting off a cold or recovering from hard efforts
  5. Route differences - Even small elevation changes matter

Tip: Compare AE from similar workouts (same route, similar conditions, similar time of day) for best insights.

Q: What's a "good" AE pace?​

AE is personal and relative - don't compare with others. Instead:

  • Track your own trend over 4-8 weeks
  • Look for improvement (faster pace at same HR)
  • Typical progress: 2-5 seconds/km improvement per month with consistent training

Example progression:

Week 1:  AE = 5:45/km at 145 bpm
Week 4:  AE = 5:40/km at 145 bpm
Week 8:  AE = 5:35/km at 145 bpm  ← Fitness is improving!

Q: What does "confidence" mean?​

Your AE result includes a confidence level:

  • High: Strong correlation in data, target HR well within workout range

    • Trust this number fully

  • Medium: Good correlation, but target HR near edge of workout data

    • Reliable, but watch for consistency across workouts

  • Low: Weak correlation, or target HR outside workout range

    • Use as rough estimate only

  • Extrapolated: Target HR outside the range of your workout data

    • Calculated by extending the line beyond measured data
    • Less reliable than interpolated values

Quick Reference: Training Week Examples​

Option 1: Mixed HR and Pace Focus​

Monday:    Intervals (no AE - intervals detected)
Wednesday: Easy run - HR zones 1-2 (no AE - HR too steady)
Friday:    Tempo run at steady pace (AE calculated!)
Sunday:    Long run at consistent pace (AE calculated!)

Option 2: All Pace-Focused​

Monday:    Recovery run at easy pace (AE calculated)
Wednesday: Tempo run at steady effort (AE calculated)
Friday:    Easy run at comfortable pace (AE calculated)
Sunday:    Long run progressive pace (AE calculated)

Option 3: Minimal Effort​

Sunday:    Weekly long run at steady easy pace (AE calculated)
           - All other runs: whatever you want
           - Still get weekly AE tracking!

Best Practices​

DO:​

  • Run at steady pace on flat terrain for best results
  • Focus on longer runs (45-90 minutes)
  • Compare AE trends over 4+ weeks
  • Use the same route occasionally for direct comparison
  • Track AE weekly or bi-weekly
  • Update your LT1/max HR/resting HR when you get new data

DON'T:​

  • Obsess over every single AE calculation
  • Compare your AE pace to other athletes
  • Expect every workout to generate AE data
  • Make training changes based on one AE data point
  • Run workouts just for AE - let it happen naturally
  • Compare AE from very different conditions (summer vs winter)

Summary: The Simple Version​

Want to track your aerobic fitness with AE?

  1. Set up: Make sure your athlete profile has LT1 or max/resting HR
  2. Run smart: Once per week, do an easy-to-moderate run at consistent pace on flat terrain for 30+ minutes
  3. Watch the trend: Check your AE over weeks and months - faster pace at same HR = fitter!
  4. Keep training: Most workouts won't calculate AE, and that's fine - keep doing your normal training

Remember: AE is a bonus metric that emerges from good training. Don't change your training to chase AE numbers. Instead, do smart training and let AE confirm your progress!

Technical Notes​

For coaches and data enthusiasts:

  • AE uses linear regression on HR vs. pace data
  • Requires R² ≥ 0.1 (minimum correlation strength)
  • Filters data to 60-85% HRR range
  • Removes first 10 minutes (warmup period)
  • Requires HR std dev > 3 bpm OR range > 15 bpm
  • Calculates pace at LT1 or 72.5% HRR
  • Detects intervals using pace CV > 0.15 threshold

The algorithm is designed to be conservative - better to exclude questionable data than to provide unreliable metrics.