# NAD+ and biological age

1 paper in the library, strongest Preliminary.

**Graded Preliminary**: Exploratory analysis across three human muscle studies of 5-month NR and 4 to 6 weeks of HIIT, though results varied by epigenetic clock and sample sizes were not reported.

## Papers (1)

- [NR May Slow Muscle Aging Clocks While Hard Interval Training Speeds Some Up](https://usa-longevity.com/en/research/nr-may-slow-muscle-aging-clocks-while-hard-interval-training-speeds-some-up) · Preliminary · 2026 · Aging cell

## How this map is computed

A mark's size is the number of papers we hold on that pairing. It is a count, not a weighting by study design or sample size.

The fill shows the strongest grade in the cell. One Strong paper among four Preliminary ones still fills it dark, so open the cell to see the rest.

Grades and verdicts are assigned by a named person, never by counting.

An empty cell is a finding: nobody in our library has run that trial yet.

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_Canonical: https://usa-longevity.com/en/evidence/nad-precursors/biological-age · Part of Longevity Cities_