NMN, Exercise, and Muscle Function Research

What this page covers

This page evaluates human evidence on grip strength, walking/gait speed, the 6-minute walk test, muscle mass, and exercise performance measures including VO2max — separating trained-athlete performance outcomes from muscle-biology/mechanistic outcomes, and separating what improved from what didn't within the same trials.

The Liao 2021 finding, precisely stated

A 6-week trial in 48 recreational runners, combining NMN with structured exercise training, found that certain submaximal, ventilatory-threshold-related oxygen-uptake measures improved more at medium and high NMN doses than at low dose or placebo.[1] VO2max itself — the standard measure of aerobic capacity — did not significantly differ between groups.[1] Describing this trial as "NMN increased aerobic capacity" overstates the result: what improved were specific submaximal threshold measures, in trained athletes already undergoing structured training, not peak aerobic capacity itself.

Grip strength, gait speed, and walking distance across trials

Individual trial results are mixed and mostly null on strength and gait measures specifically. A 24-week trial in older men with diabetes and reduced physical performance found no significant improvement in grip strength or walking speed versus placebo.[2] A 12-week trial's prespecified primary stepping-test outcome was null, though a secondary measure (4-meter walking time) showed a between-group difference.[3] A 60-day, 80-participant dose-ranging trial reported an increase in 6-minute walk distance as a secondary finding.[4] A high-dose (2,000 mg/day) trial found no significant change in muscle strength, fatigability, aerobic capacity, or stair-climbing power.[5]

What pooled analyses conclude

Two independent systematic reviews have now pooled this trial set. One, covering 10 studies and 437 participants, found grip-strength and skeletal-muscle-index changes were non-significant despite the review's own title referencing "improved" performance parameters.[6] A second, focused specifically on skeletal muscle mass and function across NMN and NR trials in adults averaging over 60 years, found no significant effect on skeletal muscle index, handgrip strength (either hand), or gait speed, and concluded that current evidence does not support NMN or NR supplementation for preserving muscle mass and function.[7]

Performance outcomes vs. muscle biology

It's worth separating two different questions this research touches: whether NMN changes measured physical performance (strength, walking speed, VO2max — largely null or mixed, per above), and whether NMN affects muscle-tissue biology at a mechanistic level (NAD+-dependent processes within muscle cells, covered on NAD+, Mitochondria, and Cellular Energy and NAD+ and Sirtuins). A plausible mechanism for muscle-tissue effects existing does not mean measured physical performance has been shown to improve — and the trial evidence above shows performance measures were, in fact, mostly unchanged.

Related reading

For the full trial-by-trial breakdown, see NMN Human Clinical Trials. For the underlying mitochondrial-energy mechanism, see NAD+, Mitochondria, and Cellular Energy.