Breathing is one way to control your heart rate. Notice that when you run your breathing accelerates, but when you sit it slows. Although you may think that heart rate commands breath, by manipulating your breath you can gain power over your heart rate. Fast-paced breathing exercises will help you increase your heart rate, while slow-paced techniques will aid in decreasing the number of beats per minute.
Pranayama is a Sanskrit word that -- as noted by renowned yoga instructor B.K.S. Iyengar -- means rhythmic control of the breath. A study published in the "International Journal of Yoga" showed that slow Pranayama resulted in significant decreases in heart rate and blood pressure. Pranayama also has been shown to help cope with stress. Slow Pranayama works by stimulating your parasympathetic nervous system, which is the dominate system during rest and recuperation. Nadi Shodhana, Samavritti and Bhramari are all forms of slow Pranayama exercises.
Swami Niranjanananda Saraswati notes that Nadi Shodhana cleanses the energy channel, preparing you for the practice of other practices of Pranayama. It brings balance and harmony throughout your entire system. Sit in a comfortable position. Bring your right thumb to your right nostril. Inhale through your left nostril. Close off your left nostril with your index and middle finger. Exhale through your right nostril. Inhale through your right nostril. Continue slow and steady for one to three minutes, making your inhales and exhales longer each time.
Samavritti Pranayama means equal action. In other words, you are dividing your breath into an equal count of four for each part of the breath: the inhalation, retention and exhalation. This produces an even flow of breath, which calms the nervous system. Sit in a comfortable position. Place your hands on your thighs. Close your eyes. Inhale deeply for a count of four. Hold the breath in for a count of four. Exhale fully for a count of four. Hold the breath out for a count of four. This completes one round. Continue for 11 rounds.
Bhramari means "bee." This form of Pranayama is so called because it requires you to make the sound of a buzzing bee. Sit in a comfortable position with your eyes closed. Block your ears with your index fingers. Bring your focus to the point in between your eyebrows. Relax your jaw, slightly separating your teeth while keeping your lips together. Inhale long and deep. As you exhale, use your throat to make a humming sound like that of a bee. This completes one round. Continue for 11 rounds, gradually increasing to 21 rounds.