Nitric oxide (NO) is a messenger molecule. What controls human NO production?

In simplicist thinking there are two forms of exercise - endurance and strength. Endurance exercise has many positive health effects - including improved heart function and lower cholesterol levels and so on. Strength training might therefore not be seen as important. However, there are two aspects to strength training that are overlooked. One is that strength training builds muscle mass that then is effective users of calories and basic metabalism. So strength training can be component of healthy weight control. A secondary and possibly overlooked benefit is that when human muscle works hard as in strength requiring activities, it stimulates the production of NO perhaps even more than in endurance exercise. It has been suggested that this NO production may be part of the blood pressure drop observed after strength exercises.

The bottom line is that endurance ( walking, running, general activity) is key health promoter. However, this doesn't mean that strength exercises don't play also a role, and can't also be helpful in hypertension control.

Interesting side effect is that vitamin A and Vitamin C may play a role in helping to maintain NO levels in the blood. Thus some of that vegetables effect may also be better ability to hang unto the NO consumed and produced by exercise.

http://psychologytoday.com/articles/pto-20050208-000001.html

Another interesting article is this one
http://www.notes.co.il/dina/32099.asp

Some key points from it is that relaxation and mediation promote NO production, as does heat, ( hot relaxing bath). It also suggests that periods of lower stress (noise reduction, lower anxiety, less information processing, peace, etc.) promote the buildup of NO capability so that the body is better able to then handle the stress it does face.

In this context - one could then think of resperate sessions as recharging periods. We are recharging our biological systems with chemicals and reserves to handle the daily stress of life.