Effects of MIB-626 With and Without A High-Intensity Multi-Dimensional Exercise Training Program

Inclusion Criteria:

1. Highly physically fit and familiar with high intensity exercise training, asindicated

2. Engages in vigorous exercise regularly (4 or more days each week) for 30minutes or longer and which includes elements of resistance exercise training

3. Physically fit ascertained using Daniels' equationhttps://runsmartproject.com/calculator/, 5K time: ≤ 23.0 min, and/ or 10K time: ≤ 48.0 min These criteria will maximize the likelihood of including individualswith VO2max of at least 40 mL/kg/min.

4. Has a body mass index (BMI) between 18.5 and 32 kg/m2, inclusive

5. Willingness to engage in 10-weeks of intensive exercise training designed to improveaerobic capacity and endurance, muscle strength, power, and fatigability, anaerobiccapacity, and body composition, and to reduce fatigue

6. Willing to not engage in additional exercise training if randomized to theprogressive exercise group and willing to not change usual physical activity ifassigned to the usual physical activity group

7. Is free from clinically significant medical problems as determined by theInvestigator

8. Is capable of providing written informed consent.

9. Is willing and able to provide authorization for the use and disclosure of personalhealth information in accordance with Health Insurance Portability andAccountability Act (HIPAA).

In addition, female participants must:

1. Not be pregnant and not planning to become pregnant over the next 6 months

Exclusion Criteria:

1. Has AST or ALT > 2 times the upper limit of normal

2. Hematocrit < 36% or > 50% for men, or < 35% to > 48% for women

3. Has a diagnosis of diabetes or is using diabetes medications or has an A1C > 6.4%

4. Serum creatinine > 2.0 mg/dL or eGFR <60 mL/min

5. Prohibited medications and substances: a. Use of any performance enhancing substance (anabolic steroids, rhGH, DHEA,androstenedione, or any other performance enhancing drug

6. Current use of opiates, amphetamine, cannabinoids and cocaine

7. Use of any other dietary supplement during the course of the trial. Subjectswho are using a supplement containing nicotinamide or niacin or nicotinamideriboside may be included if they agree to stop the supplement at least 2 weeksprior to randomization and agree not to use such supplement/s during the entireduration of the study.

8. Initiation of a new pharmaceutical product during the preceding 3 months

9. Known allergy to niacin or nicotinamide mononucleotide

10. In the judgment of the study physician, the participant is unlikely to comply withthe study protocol for any reason or it may not be safe to administer the study.

11. Competing in organized athletics (e.g., collegiate sports) or training inpreparation for competition

12. Contraindications to magnetic resonance imaging (MRI) and magnetic resonancespectroscopy (MRS). These include: a) electrical implants such as cardiac pacemakersb) ferromagnetic implants such as aneurysm clips, surgical clips, artificial heartsvalves with steel parts, shrapnel or steel implants c) ferromagnetic objects such asjewelry or metal clips in clothing d) pre-existing history of claustrophobicreactions. (Some participants who cannot undergo MRI/MRS but can undergo other studyprocedures might be considered on a case-by-case basis)

For women only:

1. Pregnant or planning to get pregnant over the next 6 months

2. Use of oral contraceptives is allowed provided the contraceptive regimen wasinitiated at least 3 months before randomization and the participant agrees not tochange the regimen during the course of the study. 6.3 Excluded Medications andTreatments

3. The ingestion of the following is prohibited during 14 days prior to Day 0 and for the duration of the intervention period:

• Multivitamin preparations that contain niacin or one of its metabolites

• Products that contain niacin, nicotinic acid, nicotinamide in any form, other thannatural foods

• Herbal supplements 2. Treatment with another investigational drug, investigationaldevice, or approved therapy for investigational use within 3 month is prohibited.