Effects of NR Supplementation on Metabolic Flexibility in Zone 2 Training

Recruiting now · Not applicable

Conditions studied: Health Adult Subjects

In brief

Zone 2 training, a low-intensity endurance exercise performed at approximately 66-80% of VO₂max or near the first ventilatory threshold, has gained popularity for improving aerobic capacity, fat metabolism, and mitochondrial efficiency. It preserves glycogen stores and delays fatigue, making it an essential training method for both athletes and recreational exercisers. Nicotinamide adenine dinucleotide (NAD) is a vital metabolite that regulates cellular energy metabolism and redox homeostasis. It participates in oxidative reactions within the tricarboxylic acid cycle and electron transport chain, sustaining ATP synthesis and mitochondrial efficiency. Exercise influences multiple pathways of NAD metabolism, altering the NAD⁺/NADH ratio and thereby affecting energy production and fatigue resistance. Studies have shown that both aerobic exercise and NAD precursor supplementation (e.g., nicotinamide riboside \[NR\]) can elevate body NAD levels and enhance mitochondrial function, though findings remain inconsistent due to variations in dosage and participants' characteristics. This study aims to investigate how acute NR supplementation interacts with Zone 2 cycling training in adults. Specifically, it examines the temporal and dose-dependent effects of NR supplementation on metabolic flexibility and exercise performance. The results may clarify the potential synergistic benefits of combining NAD supplementation with low-intensity endurance training to improve aerobic adaptability.

Key facts

Study ID

NCT07344636

Run by

ZHANG Jiaqi

People needed

16

Starts

2026-01-06

Expected to finish

2027-07-01

Last updated by the study team

2026-03-18

Who can join

Age: 18 and older, up to 80. Sex: any. Healthy volunteers: accepted.

You may qualify if…

• Over 18 years old
• BMI <30 kg/m2

You may not qualify if…

• Present of health conditions that contraindicate participation in exercise training, such as a history of cardiovascular disease, cancer, or musculoskeletal disorders
• Currently taking vitamin B supplements and/or NAD precursors
• Taking medication that may affect the test results

Where it is running

• G02, Kwok Sports Building, The Chinese University of Hong Kong — Hong Kong, Please Select, China (enrolling)

Full record on ClinicalTrials.gov

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