NMN for Endurance: What 9 Trials Show (2026 Evidence Grade)

A real but small signal on walking speed and submaximal endurance, nothing on strength or VO2max, and one study suggesting NMN may blunt the training response.

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Partly. In a 2025 meta-analysis of 9 randomized trials with 412 middle-aged and older participants, NMN improved gait speed by a standardized mean difference of 0.34 (95% CI 0.03 to 0.66), while a separate 2025 meta-analysis found no effect on handgrip strength, skeletal muscle index, gait speed or chair-stand time in adults over 60 (PMID 39185644; PMID 40275690). In the one trial of trained people, 48 amateur runners given 300, 600 or 1,200 mg per day for 6 weeks, the two higher doses improved oxygen uptake and power output at the ventilatory thresholds, but VO2max, oxygen pulse and peak power did not change in any group (PMID 34238308). Healthcare Discovery grades the performance claim as preliminary and scores it 56 out of 100 on the HYPE Index, mixed calibration. Labels sell strength and stamina to everyone. Trials show a modest submaximal effect in small groups and no strength effect at all.

What nine trials show

Reading the disagreement

The two meta-analyses are not as contradictory as they look. The 9-trial analysis pooled middle-aged and older adults and found a small gait speed benefit with a confidence interval that nearly touches zero (PMID 39185644). The second analysis restricted itself to adults over 60 and to sarcopenia-relevant outcomes with only 2 to 5 trials per measure, and found nothing (PMID 40275690). The difference is plausibly age and outcome selection. What both agree on is the absence of a strength or muscle mass effect. No NMN trial reports a strength gain versus placebo. The diabetic men over 65 with reduced grip strength or walking speed who took 250 mg per day for 24 weeks, the longest trial in the literature, gained 1.25 kg of grip strength against a loss of 0.44 kg on placebo, a difference whose confidence interval spans from -2.31 to 4.81 kg (PMID 36443648).

The runner trial is the most direct test of the endurance claim, and its abstract is more careful than the claim. Submaximal thresholds improved at 600 and 1,200 mg per day over 6 weeks of training. Maximal aerobic capacity did not. The arms were 12 people each, mostly men, and the magnitudes are not in the abstract (PMID 34238308). The 80-person trial’s six-minute walk improvement is the other endurance result in the record, again with magnitude not reported and in a per-protocol analysis (PMID 36482258).

The mitochondrial finding

The study that should give athletes pause is the smallest. In 11 non-athletic young men, 7 days of NMN at 1,200 mg per day suppressed exercise-induced TNF-alpha and IL-10 gene expression, delayed p21 expression and clearance of infiltrating cells from damaged muscle, and abolished the 171 percent increase in mitochondrial content measured 24 hours after blood-flow-restricted exercise with placebo (PMID 41705654). Mitochondrial biogenesis is a central adaptation to endurance training. A 2023 meta-analysis found that training itself raises muscle NAMPT, the rate-limiting enzyme for NAD synthesis, by about 1.46-fold (PMID 37954044), which raises the possibility that supplementing NMN removes a stimulus the muscle would otherwise respond to. The study is tiny, mechanistic and unreplicated. It is also the only trial to look.

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What we do not know

Whether the threshold gains in runners persist beyond 6 weeks or appear in elite athletes. Whether NMN blunts mitochondrial adaptation over a full training block in trained adults, since the only data are 7 days in non-athletic men. Whether any dose produces a strength gain, since none has. How large the gait speed and walking distance improvements are in absolute terms, since the abstracts report standardized effects or p-values without magnitudes. Who ran the trials matters too. According to PubMed author affiliations and the trial report, the six-minute walk trial was co-sponsored by ABA Chemicals and Abinopharm, the companies that made the NMN tested (PMID 36482258), the 24-week trial in older men had authors from Teijin and NOMON (PMID 36443648), the 12-week walking and sleep trial had authors from Meiji Holdings (PMID 38789831), and the MIB-626 trial had an author from its developer, Metro International Biotech (PMID 36740954). The runner trial and the mitochondrial study list only academic affiliations (PMID 34238308; PMID 41705654). For an ingredient with a deeper exercise record, see Healthcare Discovery’s Creatine for Longevity.

Doses used in studies

These are doses reported by the named sources, not recommendations.

All ten NMN claims, including sleep and blood pressure, are graded in Healthcare Discovery’s NMN evidence review. Method at HYPE Index methodology.

Compiled by Healthcare Discovery from the cited PubMed studies. Every citation, author affiliation and trial sponsor named on this page was checked against PubMed on October 27, 2026. How claims are scored: HYPE Index methodology.

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