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negative symptoms do not manifest. In a research paper, Wenger and Bagchi noted that the pattern of heart rate, finger temperature and pulse volume were different during kapalbhati than during normal hyperventilation. Kuvalayananda and Karambelkar also noted that mean carbon dioxide concentrations of alveolar air after kapalbhati were similar to resting levels, not lower as occurs with hyperventilation. In a study conducted by YRF at Munger in 2004, it was found that when 21 healthy adults practised bhastrika (five rounds in progressive stages for five weeks) the postpractice pulse rate and BP readings showed a downward trend. This was especially true when bhastrika was performed with external retention and bandhas.
Frostell, Pande and Hedenstiernalo found that the average arterial carbon dioxide partial pressure was slightly (14%) reduced but within the normal range during a predominantly thoracic variation of bhastrika. All research indicates average tidal volumes during kapalbhati of about 35 to 55 percent of the average resting tidal volume. It is concurred that carbon dioxide concentration in expired air is lower during yogic rapid breathing than during normal breathing because total ventilation increases more than carbon dioxide production.
It has also been found that the heart rate accelerates during the first 20 to 40 seconds of the yogic rapid breathing practices and then levels off at the faster rate. The degree of heart rate increase varies with the intensity and type of rapid breathing. For a healthy adult, bhastrika and kapalbhati provide significant exercise for the respiratory muscles with only a mild to moderate overall body work output. The average oxygen consumption rates during kapalbhati have been 1.1 to 1.8 times higher than while sitting quietly. It has also been reported that average oxygen consumption increases as duration of rapid breathing increases from one to five minutes. Research found that bhastrika at about 4 breaths per second, maintained continuously for 30 to 60 minute periods, increased oxygen uptake compared to sitting quietly by a factor of three, which was about 23 percent of
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