Physical exercise increases blood delivery to most tissues and leads to changes in the systemic environment. Interestingly, numerous studies have documented rejuvenating effects of exercise on the functional and regenerative capacity of peripheral tissues and central nervous system (CNS) in animal models. Outside the CNS, exercise can promote hematopoiesis (regeneration of blood cells) in the aging systemic environment, and increase the proliferative capacity of aged skeletal muscle stem cells. There is research showing that exercise can enhance telomerase activity to protect and even extend telomere length.
For people who cannot exercise, there are other activities that can influence systemic rejuvenation. For example, another study showed that hyperbaric oxygen therapy – exposure to 100% oxygen at elevated environmental pressure to optimize body tissue oxygen absorption – extends telomeres 20-38% in different immune cell types and reduced the senescent cell population 11-37%, depending on the type of cell.
Another systemic manipulation shown to counteract the age-induced effects on tissue regeneration is caloric restriction, a reduction of 20–40% of caloric intake without malnutrition. Caloric restriction has been shown to rejuvenate tissue regeneration in aged organisms, similar to the effects of exercise. A number of studies have shown rejuvenating effects of caloric restriction on the decline of hematopoietic stem cell function. Rejuvenation of regeneration was also observed in skeletal muscle and on intestinal stem cells. The effects of both short-term and long-term caloric restriction on rejuvenation of regeneration are also found in the central nervous system – the brain and spinal cord.
Supplementation through NAD+ precursors in specific settings may also reverse hallmarks of aging, such as improving telomere length. For example, Increasing NAD+ levels has been shown to not only protect but also improve telomere length. One study in mice showed that the NAD+ precursor nicotinamide mononucleotide (NMN) treatment improved the length of telomeres in mice.