PrometheusGeneral

Zone 2 training and Cold exposure

Each entry’s own grades, side by side. A grade says how strong the evidence is for one outcome — it does not rank one entry over the other.

Compound or practice

Zone 2 training

The unglamorous aerobic base that moves resting HR, mitochondria, and long-term health risk more than anything else per hour.

Grade A4 graded outcomesrevised Jun 22, 2026

A hand-written entry in Prometheus's bundled library. Its grades are the entry's own reading of the evidence, not a peer-reviewed review.

Compound or practice

Cold exposure

Real alertness and mood effects, honest recovery trade-offs — and much smaller metabolic claims than the internet says.

Grade C4 graded outcomesrevised Jun 10, 2026

A hand-written entry in Prometheus's bundled library. Its grades are the entry's own reading of the evidence, not a peer-reviewed review.

Swap the two

Graded in both

Outcomes are matched by name. Two entries can describe the same outcome in different words, so one listed further down may still be graded in the other.

No outcome has the same name in both entries. They may still overlap under different wording — read the two lists below.

Graded only in Zone 2 training

  • Resting heart rate Moderate effectEvidence grade A
  • VO₂max (untrained→trained) Large effectEvidence grade A
  • Fat oxidation capacity Moderate effectEvidence grade A
  • All-cause mortality (cohort) Large effectEvidence grade B

Graded only in Cold exposure

  • Alertness / mood (acute) Moderate effectEvidence grade B
  • Perceived soreness (endurance) Small effectEvidence grade B
  • Hypertrophy interference (post-lifting) Moderate effectEvidence grade B
  • Fat loss / metabolism Trivial effectEvidence grade D

Conditions

  • DepressionZone 2 training: ImprovesEvidence grade BCold exposure: May improveEvidence grade C

Only in Zone 2 training

Only in Cold exposure

What each entry says about the other

  • Cold exposure’s entry · Goes with: Rest-day or pre-cardio slots avoid the post-lifting hypertrophy conflict

Both columns are read from the entries as they stand in this library. A comparison is not advice to take either one, and it is no substitute for a clinician who knows the person.