Nicotinamide Riboside Supplement Slows Muscle Clocks While Exercise Speeds Them

The Oasis Health Journal - Submitted July 25, 2026 - 6:35 PM EDT

By Marlo Quist · Edited by Priya Raman, C.N.C.

Three research teams gave people a nicotinamide riboside supplement for five months, then measured seven different clocks in their muscle. Three of the clocks ran slower. Then they had different people sprint for four to six weeks and checked the same clocks. Most of them ran faster.

That is the opposite.

The nicotinamide riboside supplement slows muscle clocks while exercise speeds them, at least on paper, in this particular muscle tissue, measured by these particular methylation algorithms. Nobody saw that coming. The paper calls the effects divergent. That is science for we do not know what to do with this.

The clocks are epigenetic. They measure chemical marks on DNA that accumulate as you age. The marks do not measure strength or endurance or how you feel getting out of a chair. They measure marks. The marks moved in opposite directions depending on whether people took the pill or did the training.

What The Nicotinamide Riboside Supplement Slows Muscle Clocks Research Measured

The researchers used seven epigenetic clocks. That is seven different mathematical models that look at methylation patterns and estimate biological age. Some of them have names like PCHannum and MEAT. One is called DunedinPACE, which sounds like a horse.

After five months of NR supplementation, three clocks showed reduced epigenetic age acceleration in muscle tissue. PCHannum, MEAT, and DunedinPACE all indicated slower aging. The other four clocks were less impressed. They did not show much.

Then came the interval training studies. Four to six weeks of high-intensity work. DunedinPACE, which had slowed down with the supplement, went the other direction with exercise. It measured an increased pace of aging. Other clocks showed similar patterns. Exercise made the muscle look older by the numbers.

That does not mean exercise ages you. It means these specific methylation-based algorithms responded to exercise-induced changes in a way that registered as acceleration. The tissue itself might be adapting, remodeling, doing completely healthy things that happen to move the chemical marks around. The clocks just report the marks. They do not know what the marks mean in context.

The Mitochondria Showed Up In The Correlation

The study found that changes in mitochondrial content correlated with changes in one of the clocks, the MEAT clock, after both the NR supplementation and the six-week HIIT intervention. More mitochondria, different clock reading. The direction of the difference depended on the intervention.

Mitochondria are where cellular energy happens. NR is a precursor to NAD+, a molecule mitochondria need to do their job. The idea behind anti-aging supplements like NR is that boosting NAD+ might support mitochondrial function as it declines with age. The clock data suggest the supplement did something to the mitochondria or to the marks that correlate with mitochondrial abundance. What that something means for the actual muscle is still open.

Exercise also changes mitochondria. Interval training is one of the most reliable ways to increase mitochondrial biogenesis. You sprint, your muscles need more energy, they build more mitochondria. The clocks registered that change too, just in the other direction. Same tissue process, opposite epigenetic signature, depending on how you got there.

The paper notes this as a potential link between mitochondrial abundance and epigenetic clocks, which is careful language for we see a pattern but do not understand the mechanism.

What This Does Not Tell You

It does not tell you the supplement makes you younger. Epigenetic age acceleration is a measurement, not a diagnosis. It correlates with aging in population studies, but moving the needle on one clock in one tissue over five months does not mean you reversed anything. It means you changed some marks.

It does not tell you exercise ages you. The clocks that moved faster during training might be measuring adaptation, stress response, tissue remodeling, or methylation noise. The study does not include functional outcomes. Nobody measured how much weight people could lift before and after, or how fast they could run, or whether their knees hurt less. Just the marks.

It does not tell you whether the nicotinamide riboside supplement slows muscle clocks while exercise speeds them in a way that matters outside a lab. The findings come from muscle biopsies analyzed for methylation patterns. That is a long way from how you age in the world.

The research on whether nicotinamide riboside works as an aging intervention is still early. This study showed that both interventions can modulate epigenetic clocks, but in opposing ways, and the biological significance of that opposition is not clear. The authors say further studies are warranted to clarify how NR and exercise regulate epigenetic aging. That is the correct thing to say when your data contain a surprise.

The NAD+ Pathway Keeps Showing Up

NR converts to NAD+ in cells. NAD+ is involved in energy metabolism, DNA repair, and a lot of other processes that decline as people age. Supplementing with NAD+ precursors is one strategy for trying to restore some of that function. Whether it works in humans outside of specific tissue measurements is still being tested.

A separate 2026 review on CD38 inhibition noted that CD38, an enzyme, degrades NAD+ rapidly during aging and inflammation. Blocking CD38 is another approach to keeping NAD+ levels up. The review describes it as restoring NAD+ homeostasis, which is a formal way of saying the molecule stops disappearing so fast. It does not mention epigenetic clocks. It is focused on the enzyme and the small molecules that inhibit it.

The NR studies and the CD38 work are both trying to address the same problem from different angles. NAD+ goes down with age. Fix that, maybe you fix other things. The clock data suggest that fixing it with a supplement produces a different methylation signature than fixing it with exercise, even if both increase mitochondrial health. The muscle does not care how you got there, but the marks do.

The nicotinamide riboside supplement slows muscle clocks while exercise speeds them studies do not recommend one over the other. They just report the measurements. The supplements do not come with an instruction to skip the gym. The exercise studies do not come with a warning about methylation. They are separate findings that happened to contradict each other when the same clocks were applied to both.

If you were hoping for a simple answer, this is not it. The data are interesting. The mechanisms are unclear. The implications are speculative. That is kinda where the field is right now.

This article is education and reporting on published research. It is not medical advice, and nothing here is intended to diagnose, treat, cure or prevent any disease. Talk to your own clinician about your own situation.

Sources

1. The Divergent Effects of Nicotinamide Riboside and High-Intensity Exercise Training on Skeletal Muscle Epigenetic Aging, Aging cell (2026).
2. Emerging chemical strategies for CD38 inhibition: restoring NAD⁺ metabolism and disease control, Bioorganic & medicinal chemistry (2026).
3. Mitochondrial NADK2-dependent NADPH controls tau oligomer uptake in human neurons, Alzheimer's & dementia : the journal of the Alzheimer's Association (2026).
4. Opposing Molecular Programs in Obsessive-Compulsive Disorder and Hoarding: Transcriptome-Wide Association Studies Reveal Distinct Senescence, Complement, and Metabolic Signatures, Cureus (2026).