·       In middle-aged runners, supplementing 600 to 1200 mg/day of NMN for six weeks improves muscle oxygen absorption and efficient usage for energy production.
·       The muscle oxygen utilization improvements increased with higher NMN doses during endurance exercise.
·       No adverse health effects while taking up to 1200 mg/day of NMN for six weeks were reported.

From supplements to anabolic steroids, athletes across the globe are constantly seeking ways to improve their endurance and athletic performance. In recent years, we’ve accrued substantial research showing that supplementing with nicotinamide mononucleotide (NMN) increases exercise endurance, at least in rodents. So, do these NMN-related athletic endurance benefits apply to humans?

In a human trial, Hu and colleagues from Guangzhou Sport University published in the Journal of the International Society of Sports Nutrition showing that NMN powder taken orally can increase the aerobic capacity — the consumption of oxygen by our muscles — of adult runners. What’s more, this NMN treatment also improves the ability of our skeletal muscles to utilize oxygen for more efficient energy production during endurance exercise. Hu and colleagues’ results support that NMN may increase athletic endurance by enhancing this skeletal muscle oxygen utilization capacity.

“NMN as adjunct treatment may help to improve performance during exercise training,” proposed Hu and colleagues. “Exercise training combining with NMN supplementation may be a novel and practical strategy to increase endurance performance of athletes.”

Do NMN’s Physiological Benefits Apply to People?

Over the past decade, research has shown the positive effects of NMN in rodents on healthy aging, improved longevity, and exercise performance. For example, NMN supplementation enhances energy production, increases physical endurance by over 50%, and helps with various physiological characteristics like neuron function and insulin sensitivity.

Moreover, some recent studies provide evidence that this research does indeed carry on into humans, with NMN improving insulin sensitivity in prediabetic menopausal women and muscle function in men over the age of 60. But whether the positive influence of NMN on health, aging, and exercise apply to younger adults has remained an open question.

Combining NMN with Training Improves Endurance Exercise

To determine whether healthy, middle-aged people can reap similar benefits from NMN, Hu and colleagues supplemented runners with 300, 600, or 1200 mg/day of orally administered NMN powder for six weeks. During this time, these three dosage groups trained five to six times per week for 40-60 minutes and then underwent heart and lung (cardiopulmonary) exercise testing.

The endurance exercise testing revealed that the body’s ability to absorb oxygen and deliver it to tissues significantly improved with the 600 and 1200 mg/day dosages. Hu and colleagues also examined the effect of NMN on aerobic power, the muscles’ ability to use oxygen from the heart and lungs for energy production, which they found improved at these doses compared to runners who didn’t take NMN. What’s more, the ventilatory threshold — the point where the breathing rate increases faster than oxygen absorption — significantly improved at 600 and 1200 mg/day doses with training. These findings show that taking NMN in addition to exercising can improve the body’s oxygen utilization capabilities, especially at higher doses.

(Liao et al., 2021 | Journal of the International Society of Sports Nutrition) Oxygen uptake and aerobic power — the muscle utilization of oxygen to produce energy – significantly improved after six weeks of NMN supplementation and training. The increased oxygen absorption (VO2) and aerobic power significantly improved after six weeks of NMN supplementation and training in a dose-dependent manner.

(Liao et al., 2021 | Journal of the International Society of Sports Nutrition) Oxygen uptake and utilization to produce energy improved most significantly when comparing high NMN supplementation doses to runners trained without taking NMN. The middle (600 mg/day) and the high (1200 mg/day) NMN doses yielded more significant gains in oxygen utilization capacity compared to the lower dose (300 mg/day). These findings indicate that NMN supplementation at higher doses combined with training can stimulate substantial improvements in oxygen utilization capacity.

NMN is Well Tolerated at High Doses

Hu and colleagues examined whether NMN had any adverse effects on the runners. Importantly, none of the runners noted any detrimental physical events at the doses given. They did not find any abnormalities in heart examinations (electrocardiograms) or exercise testing, suggesting that middle-aged people can safely take doses up to 1200 mg/day.

Hu and colleagues’ results show that NMN improves skeletal muscle oxygen utilization more than exercise alone.

“Our data suggest that skeletal muscle is one of the most sensitive tissues to NMN in humans,” said Hu and colleagues.

Supplementing Training Regimens with NMN to Improve Performance

The study’s findings that NMN and training improve middle-aged runners’ oxygen utilization capabilities suggest that people can add NMN supplementation to their exercise regimens. Doing so may improve performance during training and could also increase endurance following weeks or months of training.