Abstract
During cardiopulmonary exercise testing (CPET), stroke volume can be indirectly assessed by O2 pulse profile. However, for a valid interpretation, the stability of this variable over time should be known. The objective was to analyze the stability of the O2 pulse curve relative to body mass in elite athletes. VO2, heart rate (HR), and relative O2 pulse were compared at every 10% of the running time in two maximal CPETs, from 2005 to 2010, of 49 soccer players. Maximal values of VO2 (63.4 ± 0.9 vs 63.5 ± 0.9 mL O2•kg-1•min-1), HR (190 ± 1 vs188 ± 1 bpm) and relative O2 pulse (32.9 ± 0.6 vs 32.6 ± 0.6 mL O2•beat-1•kg-1) were similar for the two CPETs (P > 0.05), while the final treadmill velocity increased from 18.5 ± 0.9 to 18.9 ± 1.0 km/h (P < 0.01). Relative O2 pulse increased linearly and similarly in both evaluations (r² = 0.64 and 0.63) up to 90% of the running time. Between 90 and 100% of the running time, the values were less stable, with up to 50% of the players showing a tendency to a plateau in the relative O2 pulse. In young healthy men in good to excellent aerobic condition, the morphology of the relative O2 pulse curve is consistent up to close to the peak effort for a CPET repeated within a 1-year period. No increase in relative O2pulse at peak effort could represent a physiologic stroke volume limitation in these athletes.
Highlights
During a maximum cardiopulmonary exercise testing (CPET), known as ergospirometry [1], an integrated evaluation of the cardiorespiratory responses is possible through the quantification of expired volume and analysis of gas fractions
ANOVA indicated that the values for relative VO2, heart rate (HR), and relative O2 pulse progressively increased, essentially every 20% of the CPET duration (P < 0.01)
The present study sought to determine the stability of the relative O2 pulse curves in a group of elite professional soccer players who were reevaluated after an average interval of 1 year
Summary
During a maximum cardiopulmonary exercise testing (CPET), known as ergospirometry [1], an integrated evaluation of the cardiorespiratory responses is possible through the quantification of expired volume and analysis of gas fractions. Different investigators using distinct populations and/or clinical and sports settings have proposed that the O2 pulse can indirectly reflect stroke volume, so that both the maximum value and the curve shape, which are a function of CPET duration, will be directly associated with cardiac inotropism and lusitropism [4,5,6,7,8,9,10] In this context, several studies have shown that relatively low maximum O2 pulse values are associated with a lower survival rate among middle-aged individuals as well as patients with heart failure [11,12], most likely reflecting impaired inotropic and/or lusitropic capacity and disturbing the stroke volume response to exercise. Recent evidence has pointed to a role for O2 pulse data as an important clinical tool to detect severe myocardial ischemia [10,14,15]
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