Power vs Heart Rate for Low and High Intensity Training With Dr. Stephen Seiler

Key wellness / training strategies from the subtitles

1) Don’t treat metrics as interchangeable (use external load + internal load + perception)

• Power is an external load (calibrated to thresholds like FTP/6-minute power), but it doesn’t capture how your body feels after long durations.
• Heart rate is internal physiology and can drift upward over time during “easy” efforts.
• Perception / brain signals matter: athletes should also listen to how hard it feels (e.g., RP scale increasing).

Practical takeaway: Even when power stays constant, internal strain can rise—especially later in long low-intensity sessions.

2) For low-intensity rides, heart rate becomes more important as duration increases

• Early in a ride, staying at a target low power may keep HR stable.
• Later, heart rate can start increasing relative to the same power due to internal factors (e.g., glycogen depletion, reactive oxygen species, dehydration, fitness limits).
• Low intensity should be managed as intensity × duration, not power alone.

Key concept: “200 watts for hour 1” ≠ “200 watts for hour 4” (physiological load differs).

3) Use “quasi-steady” thinking: low intensity can turn stressful if you go long enough

• Low-intensity efforts may start comfortable and gradually become heavy as internal load increases.
• This is compared to marathon pacing where people drift upward and feel progressively worse near the end.

4) Watch out for misleading “stress score” style metrics

• Training Stress Score / load scores may treat each hour the same if calibrated to external load.
• The argument is that this can be physiologically wrong because it ignores duration-related internal strain escalation.

5) Control low intensity with a “trinity”

Use these together to keep sessions truly easy:

• External power (target below LT1 / in your low-intensity zone)
• Internal physiology (heart rate, sometimes lactate)
• Perception (RP) / “brain” feedback (mental and bodily signals)

6) Heart-rate guidance: use heart rate reserve, not just % max HR

A more individualized method:

• Estimate resting HR and maximum HR
• Calculate HR reserve (max − rest)
• Target a percentage of HR reserve (example given: ~60% HR reserve)

This produces different “% of max HR” values across athletes.

General ranges mentioned:

• Many low-intensity sessions tend to land roughly around 55–65% of VO₂max (as described).

7) Switch mental strategy by intensity (distraction vs focus)

• Low intensity: distraction strategy
  • You can notice surroundings; mind can relax/unfocus.
• Higher intensity: focus strategy
  • You become inwardly focused and monitor legs, breathing, bodily signals.

8) Recovery cues: appetite and nervous system effects differ by intensity

• After low-intensity work, people may feel “empty” and want to eat quickly.
• After hard work (sympathetic activation), appetite may be suppressed temporarily due to reduced blood flow to the GI tract—so use appetite as one indirect recovery/stress cue.

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High-intensity interval strategy (power vs heart rate)

9) Early season / building phase: lean more on internal cues

Mentioned approach (from coach Renato Ken):

• Use heart rate + perception rather than strict watt targets during early build-up.
• Allow some variability (e.g., being 20W under can be acceptable early).
• Build toward a target HR (example cited: ~90% max HR).

10) Competitive season / specificity: gradually shift toward external targets

As events approach:

• Increase reliance on specific power + duration.
• Use a “ladder” approach:
  • Increase accumulated minutes at target power
  • Scale set volume/frequency while maintaining target intensity (example: progressing from fewer intervals to more intervals at similar power)

Core method mentioned:

• Use both:
  • Intensity (power targets)
  • Duration (interval minutes / total accumulated time at target)

11) Best athletes don’t just chase peak power—they chase repeatability

• Race advantage often comes from being able to do hard efforts more times, not just the highest 5–6 minute power.
• Training should stretch the “rubber band” repeatedly:
  • Producing quality pushes later (after fatigue) is emphasized.

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Presenters / sources

• Dr. Stephen Seiler (also spelled “Steven Sailer/Steven Seiler” in subtitles)
• Renato Ken (coach mentioned as a source of the high-intensity/internal-vs-external loading approach)
• TrainingPeaks (referenced as the provider of Training Stress Score)