Smarter Training, Part 2

In Part 1, we talked about cutting through data noise. Now let's get specific. After analyzing thousands of training sessions and working with athletes from beginners to pros, four metrics consistently separate improving athletes from plateauing ones. Master these four, and you'll have a North Star for every training decision.

🎯 What You'll Learn in This Guide

• The 4 metrics that predict training success
• How to measure each metric accurately
• Target ranges for different experience levels
• How to use these metrics to optimize your training

Why These 4 Metrics Matter

Most training metrics are lagging indicators—they tell you what happened. The four metrics we're covering today are leading indicators—they predict what will happen and help you make better decisions before problems arise.

The Big 4:

1. Aerobic Efficiency - How economically you use oxygen
2. Training Load Balance - Your stress-to-recovery ratio
3. Neuromuscular Power - Your ability to recruit muscle fibers
4. Metabolic Flexibility - How well you switch between fuel systems

Metric #1: Aerobic Efficiency

What it is: The relationship between your heart rate and pace/power output
Why it matters: Aerobic efficiency is the foundation of endurance performance
How to measure it: Heart rate vs. pace/power during steady efforts

The Aerobic Efficiency Test

For Running:

• Warm up thoroughly
• Run 20-30 minutes at steady, sustainable effort
• Calculate: Average pace ÷ Average heart rate = Efficiency Factor (EF)

For Cycling:

• Warm up thoroughly
• Ride 20-30 minutes at steady effort
• Calculate: Average power ÷ Average heart rate = Efficiency Factor (EF)

Example:

• Run: 7:00/mile at 150 bpm = 7.0 ÷ 150 = 0.047 EF
• Bike: 200 watts at 145 bpm = 200 ÷ 145 = 1.38 EF

Tracking Aerobic Efficiency

Monthly testing protocol:

• Same warm-up routine
• Same course/conditions when possible
• Same time of day
• Track the trend over 3-6 months

What improvement looks like:

• Running: EF increases (same pace at lower HR)
• Cycling: EF increases (same power at lower HR)
• Swimming: Stroke count decreases at same pace

🏃‍♂️ Pro Tip: Aerobic efficiency improvements are slow but incredibly valuable. A 5% improvement in EF often translates to 10-15% better race performance.

Metric #2: Training Load Balance

What it is: The ratio between training stress and recovery capacity
Why it matters: Prevents overtraining and optimizes adaptation
How to measure it: Acute Training Load (ATL) vs. Chronic Training Load (CTL)

Understanding Training Load

Acute Training Load (ATL):

• Your recent training stress (last 7-14 days)
• Represents fatigue and current fitness debt
• Should fluctuate with training intensity

Chronic Training Load (CTL):

• Your long-term training stress (last 6-12 weeks)
• Represents your fitness foundation
• Should increase gradually over time

Training Stress Balance (TSB):

• Formula: CTL - ATL = TSB
• Positive TSB = Fresh/recovered
• Negative TSB = Fatigued/building fitness

Optimal Training Load Ranges

Practical Application

Weekly monitoring:

• Calculate your TSB every 7 days
• Adjust next week's training based on the number
• TSB too negative? Add recovery
• TSB too positive? You can handle more load

Red flags:

• TSB below -50 for more than 2 weeks
• CTL dropping more than 10% in 2 weeks
• ATL spiking more than 50% week-to-week

Metric #3: Neuromuscular Power

What it is: Your ability to recruit muscle fibers quickly and efficiently
Why it matters: Power determines your top-end speed and race finishing ability
How to measure it: Short, maximal efforts across all three sports

Testing Neuromuscular Power

Swimming: 25-50m Sprint

• Full warm-up
• 25m or 50m all-out effort
• Track time and stroke count
• Test monthly

Cycling: 5-15 Second Power

• Warm up thoroughly
• 5-15 second all-out sprint
• Track peak power output
• Test every 2-3 weeks

Running: 30-100m Sprint

• Dynamic warm-up
• 30-100m all-out effort
• Track time and subjective effort
• Test every 2-3 weeks

Power Development Training

Maintenance phase (base season):

• 1-2 neuromuscular sessions per week
• Short, explosive efforts
• Full recovery between intervals

Development phase (build season):

• 2-3 neuromuscular sessions per week
• Variety of power demands
• Sport-specific movements

Peak phase (race season):

• 1-2 sessions per week
• Race-specific power demands
• Maintain, don't build

⚡ Power Principle: Neuromuscular power fades quickly (7-14 days) but responds rapidly to training.

Metric #4: Metabolic Flexibility

What it is: Your ability to efficiently switch between burning carbs and fats
Why it matters: Determines your fueling strategy and race sustainability
How to measure it: Heart rate drift and fuel utilization during long efforts

The Metabolic Flexibility Test

Protocol:

• Fasted morning session (12+ hours without food)
• Start very easy (Zone 1)
• Gradually increase intensity every 10 minutes
• Stop when you can no longer nose-breathe

What to track:

• Heart rate at different intensities
• Subjective effort ratings
• How long you can maintain each zone
• Where you feel you need external fuel

Metabolic Flexibility Zones

Zone 1 (Fat Burning):

• You can maintain this indefinitely
• No external fuel needed
• Primarily fat oxidation

Zone 2 (Aerobic Threshold):

• You can maintain for 2-6 hours
• Minimal external fuel needed
• Mixed fat/carb oxidation

Zone 3 (Aerobic/Anaerobic Mix):

• You can maintain for 1-3 hours
• External fuel helpful after 90 minutes
• Primarily carb oxidation

Zone 4+ (Anaerobic):

• You can maintain for 30-90 minutes
• Requires external fuel
• Almost entirely carb oxidation

Improving Metabolic Flexibility

Strategies:

• Regular fasted training (1-2x per week)
• Long, steady efforts in Zone 1-2
• Periodized nutrition (match fuel to training)
• Gradual adaptation to fat oxidation

Putting It All Together: The Dashboard Approach

Create a simple dashboard that tracks all four metrics:

Monthly Scorecard:

Decision-Making Framework

If Aerobic Efficiency is declining:

• Add more Zone 1-2 training
• Check for overtraining
• Ensure adequate recovery

If Training Load Balance is too negative:

• Reduce training volume
• Add recovery methods
• Check sleep and nutrition

If Neuromuscular Power is declining:

• Add sprint/power work
• Check training monotony
• Ensure adequate recovery between hard efforts

If Metabolic Flexibility is poor:

• Add fasted training
• Extend Zone 1-2 efforts
• Practice race nutrition strategy

Your 4-Metric Action Plan

✅ Week 1: Establish baseline for all 4 metrics
✅ Week 2: Set up tracking systems and regular testing
✅ Week 3: Complete first monthly assessment
✅ Week 4: Make training adjustments based on findings
✅ Ongoing: Monthly scorecard review and adjustment

🔗 Ready to Master Your Metrics?

These four metrics aren't just numbers—they're your training compass. Master them, and you'll have the insights to train smarter, race faster, and achieve your goals with confidence.

👉 Get training that automatically tracks these key metrics →

Next up:
📖 What Makes You Faster? Exercise Science for Triathletes: The Essentials →

"What gets measured gets improved." - Peter Drucker

Your path to peak performance runs through these four metrics. Start measuring, start improving.