This is the summary of an article published in the last issue of the JAP. I think is interesting for us:
Cardiovascular and respiratory responses to apneas with and without face immersion in exercising humans
Johan P. A. Andersson,1 Mats H. Linér,2 Anne Fredsted,1 and Erika K. A. Schagatay3
1Department of Cell and Organism Biology, Lund University, SE-223 62 Lund; 2Department of Anesthesiology and Intensive Care, Lund University Hospital, SE-221 85 Lund; and 3Department of Natural and Environmental Sciences, Mid Sweden University, SE-851 70 Sundsvall, Sweden
Submitted 18 November 2002 ; accepted in final form 21 October 2003
The effect of the diving response on alveolar gas exchange was investigated in 15 subjects. During steady-state exercise (80 W) on a cycle ergometer, the subjects performed 40-s apneas in air and 40-s apneas with face immersion in cold (10°C) water. Heart rate decreased and blood pressure increased during apneas, and the responses were augmented by face immersion. Oxygen uptake from the lungs decreased during apnea in air (-22% compared with eupneic control) and was further reduced during apnea with face immersion (-25% compared with eupneic control). The plasma lactate concentration increased from control (11%) after apnea in air and even more after apnea with face immersion (20%), suggesting an increased anaerobic metabolism during apneas. The lung oxygen store was depleted more slowly during apnea with face immersion because of the augmented diving response, probably including a decrease in cardiac output. Venous oxygen stores were probably reduced by the cardiovascular responses. The turnover times of these gas stores would have been prolonged, reducing their effect on the oxygen uptake in the lungs. Thus the human diving response has an oxygen-conserving effect.
diving reflex; bradycardia; vasoconstriction; oxygen and carbon dioxide stores; breath holding
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Address for reprint requests and other correspondence: J. P. A. Andersson, Dept. of Cell and Organism Biology, Lund Univ., Helgonav. 3 B, SE-223 62 Lund, Sweden (E-mail: Johan.Andersson@cob.lu.se).
Cardiovascular and respiratory responses to apneas with and without face immersion in exercising humans
Johan P. A. Andersson,1 Mats H. Linér,2 Anne Fredsted,1 and Erika K. A. Schagatay3
1Department of Cell and Organism Biology, Lund University, SE-223 62 Lund; 2Department of Anesthesiology and Intensive Care, Lund University Hospital, SE-221 85 Lund; and 3Department of Natural and Environmental Sciences, Mid Sweden University, SE-851 70 Sundsvall, Sweden
Submitted 18 November 2002 ; accepted in final form 21 October 2003
The effect of the diving response on alveolar gas exchange was investigated in 15 subjects. During steady-state exercise (80 W) on a cycle ergometer, the subjects performed 40-s apneas in air and 40-s apneas with face immersion in cold (10°C) water. Heart rate decreased and blood pressure increased during apneas, and the responses were augmented by face immersion. Oxygen uptake from the lungs decreased during apnea in air (-22% compared with eupneic control) and was further reduced during apnea with face immersion (-25% compared with eupneic control). The plasma lactate concentration increased from control (11%) after apnea in air and even more after apnea with face immersion (20%), suggesting an increased anaerobic metabolism during apneas. The lung oxygen store was depleted more slowly during apnea with face immersion because of the augmented diving response, probably including a decrease in cardiac output. Venous oxygen stores were probably reduced by the cardiovascular responses. The turnover times of these gas stores would have been prolonged, reducing their effect on the oxygen uptake in the lungs. Thus the human diving response has an oxygen-conserving effect.
diving reflex; bradycardia; vasoconstriction; oxygen and carbon dioxide stores; breath holding
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Address for reprint requests and other correspondence: J. P. A. Andersson, Dept. of Cell and Organism Biology, Lund Univ., Helgonav. 3 B, SE-223 62 Lund, Sweden (E-mail: Johan.Andersson@cob.lu.se).