NAD+ in Muscle Development and Regeneration
It is known that strength training exercises result in hypertrophy of the skeletal muscle and atrophy occurs in response to disuse. During oxidation-reduction (redox) metabolic reactions, cellular NAD+ levels can become depleted overtime. With age, the ability of the body to synthesize new NAD+ and self-replenish its reserve reduces significantly. Age related decline in NAD+ has been documented to result in mitochondrial dysfunction and reduced ATP generation, which in turn correlates to fatigue and muscle wastage in conditions such as sarcopenia. Furthermore, reports have found that the ability to recover from neural disorders, ataxia, muscle degeneration, tremors and age is significantly diminished due to low NAD+ levels.
NAD+ and Aging
Post injury, muscle repair is known to be regulated by satellite quiescent cells which reside in the basement membrane in muscle fibers. The production of these self-renewing cells is triggered primarily in response to injury. SIRT1, a crucial nuclear signaling protein is an upstream effector for these quiescent cells. In addition to its many functions, NAD+ is a direct regulator of SIRT1. Therefore, reduced NAD+ levels as we age has an effect on available SIRT1 as well. Ultimately, the ability of the muscle to repair from injury is impaired drastically.
Furthermore, levels of NAD+ have been linked to health and lifespan in organisms. Recent research has shown that NAD+ supplementation indeed does have a beneficial effect on improving lifespan in mouse models of ataxia.
While mental grit, will power, and determination are key factors that contribute towards an effective exercise strategy to achieve your fitness goals, the physiology of skeletal muscle function and its primary molecular components cannot be ignored. From a fitness perspective, NAD+ supplementation can be a great tool to support the capacity of your muscles to improve and function better.