Cardiovascular responses to dry resting apnoeas in elite divers while breathing pure oxygen.

Purpose: We hypothesized that the third dynamic phase (ϕ3) of the cardiovascular response to apnoea requires attainment of the physiological breaking point, so that the duration of the second steady phase (ϕ2) of the classical cardiovascular response to apnoea, though appearing in both air and oxygen, is longer in oxygen.

Methods: Nineteen divers performed maximal apnoeas in air and oxygen. We measured beat-by-beat arterial pressure, heart rate (fH), stroke volume (SV), cardiac output (Q˙).

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

Purpose: Cardiovascular responses during resting apnoea include three phases: (1) a dynamic phase of rapid changes, lasting at most 30 s; (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.

Effects of step duration in incremental ramp protocols on peak power and maximal oxygen consumption.

Purpose: Morton (J Sport Sci 29:307-309, 2011) proposed a model of the peak power attained in ramp protocol ([Formula: see text]) that included critical power (CP) and anaerobic capacity as constants, and mean ramp slope (S) as variable. Our hypothesis is that [Formula: see text] depends only on S, so that Morton's model should be applicable in all types of ramps. The aim of this study was to test this hypothesis by validating Morton's model using stepwise ramp tests with invariant step increment and increasing step duration.

Exercising fasting or fed to enhance fat loss? Influence of food intake on respiratory ratio and excess postexercise oxygen consumption after a bout of endurance training.

Exercise and nutrition are often used in combination to lose body fat and reduce weight. In this respect, exercise programs are as important as correct nutrition. Several issues are still controversial in this field, and among them there are contrasting reports on whether training in a fasting condition can enhance weight loss by stimulating lipolytic activity.