Yoga and Physical Health
The Sympathetic nervous system and the Parasympathetic nervous system constitute the autonomic nervous system, the branch of the nervous system that performs involuntary functions. The Sympathetic nervous system can be thought of as the “gas pedal” of the autonomic nervous system. It serves to accelerate the heart rate, constrict blood vessels, and raise blood pressure. The Parasympathetic nervous system can be thought of as the “brakes” of the autonomic nervous system. It controls salivation, lacrimation, urination, defecation and digestion and serves to slow the heart rate, increase the intestinal and gland activity, and relax the sphincter muscles. Yoga can act like a “cruise control.” The asanas (postures) in yoga help cleanse the cells of the nervous system, which then allow the nervous system to react calmly to stress. The muscles relax when tension and stress (produced by our adrenaline pouring into the system during “fight or flight”) are repressed.
The endocrine system is responsible for releasing hormones in the body. Yoga helps to improve the functioning of the different endocrine glands. Sirsasana (head stand) for example, has a direct effect on the pituitary gland. This gland, which is located inside your head, controls the functioning of all the other glands that comprise the endocrine system.
The cardiovascular system is responsible for transporting nutrients to cells and carrying waste away. Vinyasa style yoga increases cardiovascular health and expands lung capacity. Because vinyasa yoga typically links postures together, it increases the heart rate for a moderate aerobic effect. Vinyasa yoga also correlates movements with deep breathing, lessening fatigue while practicing.
Increased Oxygen Intake
The respiratory system is responsible for inspiration and expiration. Regular yoga practitioners have good oxygen intake levels because yoga expands the elasticity of the inner-rib muscles, and maximizes lung capacity. This is especially the case in forward bends (which stretch the posterior part of the lungs), and pranayama. Oxygen capacity usually diminishes with age as the ribs stiffen, but practicing yoga loosens these muscles, which can reverse some effects of aging.
The digestive system is responsible for converting ingested food into energy. Most of the time we just let our digestion work on its own. We can help by stretching and developing muscles in the stomach and internal organs. Back bends pull the stomach away from esophagus and the diaphragm, increasing tone and reducing the possibility of getting a hernia. By stretching our digestive system, the intestines get massaged and they can absorb more.
Sexuality and Libido
The reproductive system is responsible for healthy reproduction, procreation, and sexual arousal. There are many yoga postures and stances that benefit the reproductive system. These poses open up the area of the pelvis and the other areas that manage to stimulate pelvic circulation, increasing both sexual health and libido. Also, regularly practicing yoga allows people to feel more rested, possibly affecting fertility function.