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A beat-by-beat analysis of cardiovascular responses to dry resting and exercise apnoeas in elite divers

Sivieri, Andrea ; Fagoni, Nazzareno ; Bringard, Aurélien ; Capogrosso, Michela ; Perini, Renza ; Ferretti, Guido

In: European Journal of Applied Physiology, 2015, vol. 115, no. 1, p. 119-128

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    Title
    • A beat-by-beat analysis of cardiovascular responses to dry resting and exercise apnoeas in elite divers
    Author
    • Sivieri, Andrea. Dipartimento di Scienze Cliniche E Sperimentali, Università di Brescia, Brescia, Italy
    • Fagoni, Nazzareno. Dipartimento di Scienze Cliniche E Sperimentali, Università di Brescia, Brescia, Italy
    • Bringard, Aurélien. Département des Neurosciences Fondamentales, Université de Genève, Geneva, Switzerland
    • Capogrosso, Michela. Dipartimento di Scienze Cliniche E Sperimentali, Università di Brescia, Brescia, Italy
    • Perini, Renza. Dipartimento di Scienze Cliniche E Sperimentali, Università di Brescia, Brescia, Italy
    • Ferretti, Guido. Dipartimento di Scienze Cliniche E Sperimentali, Università di Brescia, Brescia, Italy
    Document Type
    • Postprint
    Language
    • English
    Published in
    • European Journal of Applied Physiology, 2015, vol. 115, no. 1, p. 119-128. Springer Berlin Heidelberg
    Other Version
    OAI-PMH Identifier
    • oai:doc.rero.ch:331218
    Summary
    Purpose: Cardiovascular responses during resting apnoea include three phases: (1) a dynamic phase of rapid changes, lasting at most 30s; (2) a subsequent steady phase; and (3) a further dynamic phase, with a continuous decrease in heart rate (HR) and an increase in blood pressure. The interpretation was that the end of the steady phase corresponds to the physiological apnoea breaking point. This being so, during exercise apnoeas, the steady phase would be shorter, and the rate of cardiovascular changes in the subsequent unsteady phase would be faster than at rest. Methods: To test these hypotheses, we measured beat-by-beat systolic (SBP), diastolic, and mean blood pressures (MBP), HR, and stroke volume (SV) in six divers during dry resting (duration 239.4±51.6s) and exercise (30W on cycle ergometer, duration 88.2±20.9s) maximal apnoeas, and we computed cardiac output ( $$\dot{Q}$$ Q ˙ ) and total peripheral resistance (TPR). Results: Compared to control, at the beginning of resting (R1) and exercising (E1) apnoeas, SBP and MBP decreased and HR increased. SV and $$\dot{Q}$$ Q ˙ fell, so that TPR remained unchanged. At rest, HR, SV, $$\dot{Q}$$ Q ˙ , and SBP were stable during the subsequent phase; this steady phase was missing in exercise apnoeas. Subsequently, at rest (R3) and at exercise (E2), HR decreased and SBP increased continuously. SV returned to control values. Since $$\dot{Q}$$ Q ˙ remained unchanged, TPR grew. Conclusions: The lack of steady phase during exercise apnoeas suggests that the conditions determining R3 were already attained at the end of E1. This being so, E2 would correspond to R3.