NAD+, MOTS-C, and SS-31: The Mitochondrial Peptides

NAD+ (Nicotinamide Adenine Dinucleotide) is a fundamental coenzyme in cellular energy metabolism. It is essential for mitochondrial function, DNA repair through sirtuin activation, and hundreds of enzymatic reactions. NAD+ levels decline naturally with age, and the theory is that restoring them could slow aspects of aging and improve cellular energy.

When selecting an NAD+ precursor, the practical difference between NR and NMN comes down to dosing and tolerance. NR is typically taken at 300-1000 mg daily, while NMN is often used at 250-500 mg. Both convert to NAD+ in the body, but NMN requires conversion to NR before entering cells, which some researchers argue makes it less efficient. For athletes, the more relevant question is timing. Taking NAD+ precursors with food can reduce GI distress, and splitting the dose morning and evening may maintain steadier levels. Expect no acute effects. Any improvement in energy or recovery appears gradually over four to eight weeks. If you see a dramatic response, question the product's purity or your baseline health.

The most studied precursors are Nicotinamide Riboside (NR) and Nicotinamide Mononucleotide (NMN). Both are well-tolerated in human trials, with the main side effects being mild gastrointestinal discomfort at higher doses. Neither requires significant blood work monitoring for safety.

Blood work on NAD+ precursors: There are no direct blood markers for NAD+ status that a standard lab panel covers. The expected changes are indirect: improved metabolic markers (fasting glucose, insulin, lipids) over months of use. Some users report improved energy and recovery, but these are subjective. If you want to know whether a NAD+ precursor is working for you, the best approach is tracking training performance, recovery, and subjective energy levels rather than looking for blood work changes.

For practical blood work, track fasting glucose, fasting insulin, and HbA1c at baseline and after three months. A common mistake is expecting a drop in glucose within weeks. NAD+ precursors work through sirtuin pathways that influence insulin sensitivity, but the effect is modest in healthy individuals. A more sensitive marker is the homeostatic model assessment of insulin resistance (HOMA-IR), which uses fasting glucose and insulin together. If HOMA-IR stays flat or improves slightly, that is a positive sign. Also monitor liver enzymes (ALT, AST) if you are using higher doses, since some users report transient elevations. These are usually benign, but they warrant attention if you are also using other hepatotoxic compounds.

MOTS-C is a mitochondrial-derived peptide (MDP): a short peptide encoded by mitochondrial DNA that regulates metabolic processes in the cell. Unlike NAD+ precursors, MOTS-C has a specific and measurable effect: it improves insulin sensitivity and glucose disposal.

Early human trials show promising effects on metabolic health, particularly in the context of age-related insulin resistance. For athletes, the theoretical application is improved glucose handling, which could translate to better carb utilization during training and more favorable body composition.

MOTS-C dosing in human trials has ranged from 10-20 mg per day injected subcutaneously, though some research protocols use cyclic regimens. The metabolic effect is not immediate — human data on MOTS-C is still limited, and most of what's published links circulating MOTS-C levels to insulin sensitivity rather than tracking the effect of supplementation over weeks. For athletes, the practical application is to use it during a carb-loading phase or when you are trying to improve glucose disposal during high-volume training. Monitor fasting insulin and HOMA-IR at two and four weeks to see if the peptide is working. If fasting insulin drops by 20-30% while glucose stays stable, that is a strong signal. Do not stack MOTS-C with metformin or other insulin sensitizers without medical supervision, as the additive effect can push glucose too low.

Blood work on MOTS-C: Unlike NAD+ precursors, MOTS-C has measurable metabolic effects. Fasting glucose, fasting insulin, HbA1c, and HOMA-IR are the relevant monitoring markers. A well-functioning MOTS-C protocol should show stable or improving glucose markers over 8-12 weeks. If glucose markers worsen, the compound is either not working or product quality is the issue.

SS-31, also known as Elamipretide, targets cardiolipin: a phospholipid in the inner mitochondrial membrane that is critical for energy production. By stabilizing cardiolipin, SS-31 improves the efficiency of the electron transport chain and reduces mitochondrial oxidative stress.

SS-31's mechanism is unique because it binds directly to cardiolipin, which is essential for the structural integrity of the inner mitochondrial membrane. This stabilizes the electron transport chain and reduces reactive oxygen species production. For healthy athletes, the theoretical benefit is improved mitochondrial efficiency during high-intensity work, but the clinical data are from cardiac and mitochondrial disease populations. Off-label dosing is typically 20-40 mg per day via subcutaneous injection, often in cycles of four to eight weeks. One practical caution: SS-31 is rapidly cleared from the body, so twice-daily dosing may be more effective than a single daily dose. Do not expect a performance boost in the first week. The effect, if any, builds over weeks.

This is the compound with the strongest human evidence: but the evidence is for specific indications. SS-31 has been studied in phase 2 and 3 clinical trials for primary mitochondrial myopathy, Barth syndrome, and age-related heart failure with preserved ejection fraction (HFpEF). The results show real improvements in mitochondrial function and exercise capacity in these patient populations.

The phase 2 and 3 trials for SS-31 in heart failure with preserved ejection fraction showed improvements in exercise capacity and quality of life, but the effect sizes were moderate and the studies were not powered for mortality. For athletes, this means the evidence does not support using SS-31 for general endurance or recovery. It is a targeted compound for mitochondrial dysfunction, not a nootropic or ergogenic aid. If you choose to use it off-label, keep a training log and track subjective markers like perceived exertion and recovery time. A common mistake is expecting a measurable change in VO2 max within weeks. Any meaningful shift would likely require months of use, and even then, the magnitude may be within normal training variation.

Blood work on SS-31: In a cardiac context, relevant markers include CK (creatine kinase) and NT-proBNP (a heart failure marker). For healthy athletes using SS-31 off-label for performance, there are no established blood work monitoring protocols. Standard baseline metabolic panel and CK are reasonable safety checks, but SS-31 has a good safety profile in clinical trials with no significant organ toxicity signals at therapeutic doses.

For SS-31, baseline CK and NT-proBNP are useful to establish a personal reference range. In healthy athletes, CK can be elevated from intense training, so a single elevated value is not alarming. What matters is the trend. If you see a progressive rise in NT-proBNP above the upper reference limit, that is a red flag and warrants stopping the compound. Similarly, CK levels that keep climbing despite rest suggest muscle damage. These markers are not specific to SS-31, but they provide a safety net. In clinical trials, no significant shifts were observed, but those were sicker patients. For a healthy athlete, the risk is low, but the monitoring cost is minimal. Do a baseline panel before starting, then repeat at four and eight weeks.