Alessandra Adami

Effects of priming exercise on the speed of adjustment of muscle oxidative metabolism at the onset of moderate-intensity step transitions in older adults.

Aging is associated with a functional decline of the oxidative metabolism due to progressive limitations of both O(2) delivery and utilization. Priming exercise (PE) increases the speed of adjustment of oxidative metabolism during successive moderate-intensity transitions. We tested the hypothesis that such improvement is due to a better matching of O(2) delivery to utilization within the working muscles. In 21 healthy older adults (65.7 ± 5 yr), we measured contemporaneously noninvasive indexes of the overall speed of adjustment of the oxidative metabolism (i.e., pulmonary Vo(2) kinetics), of the bulk O(2) delivery (i.e., cardiac output), and of the rate of muscle deoxygenation (i.e., deoxygenated hemoglobin, HHb) during moderate-intensity step transitions, either with (ModB) or without (ModA) prior PE. The local matching of O(2) delivery to utilization was evaluated by the ΔHHb/ΔVo(2) ratio index. The overall speed of adjustment of the Vo(2) kinetics was significantly increased in ModB compared with ModA (P < 0.05). On the contrary, the kinetics of cardiac output was unaffected by PE. At the muscle level, ModB was associated with a significant reduction of the overshoot in the ΔHHb/ΔVo(2) ratio compared with ModA (P < 0.05), suggesting an improved O(2) delivery. Our data are compatible with the hypothesis that, in older adults, PE, prior to moderate-intensity exercise, beneficially affects the speed of adjustment of oxidative metabolism due to an acute improvement of the local matching of O(2) delivery to utilization.

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

PurposeMorton (J Sport Sci 29:307–309, 2011) proposed a model of the peak power attained in ramp protocol (

Changes in whole tissue heme concentration dissociates muscle deoxygenation from muscle oxygen extraction during passive head-up tilt

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Cardiac output, O2 delivery and V˙O2 kinetics during step exercise in acute normobaric hypoxia

w·peak) that included critical power (CP) and anaerobic capacity as constants, and mean ramp slope (S) as variable. Our hypothesis is that

The Q˙−V˙O2 diagram: An analytical interpretation of oxygen transport in arterial blood during exercise in humans

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Dynamics of the RR-interval versus blood pressure relationship at exercise onset in humans

w·peak 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.MethodsSixteen men performed six ramp tests with 25xa0W increments. Step duration was: 15, 30, 60, 90, 120 and 180xa0s. Maximal oxygen consumption (