Stability of relative oxygen pulse curve during repeated maximal cardiopulmonary testing in professional soccer players

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&#8226;kg-1&#8226;min-1), HR (190 ± 1 vs188 ± 1 bpm) and relative O2 pulse (32.9 ± 0.6 vs 32.6 ± 0.6 mL O2&#8226;beat-1&#8226;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

The slope of the oxygen pulse curve does not depend on the maximal heart rate in elite soccer players

“…In this context, HR continues to increase throughout the entire CPET duration, whereas VO 2 follows a less steep pattern or even keeps constant, resulting in a plateau of the relative O 2 pulse. Because the O 2 pulse can be considered a surrogate for SV, this finding corroborates the observations described in other studies15,16,21-23 that suggest a trend of continuously increasing SV in high-performance athletes during a maximal CPET. For example, Gledhill et al15 reported a continuous increase in SV in elite cyclists during a maximum CPET.…”

“…Therefore, to avoid the influence of body dimension variability on O 2 pulse values, we analyzed this variable relative to body weight (mLO 2 ·beat -1 ·kg -1 ), as was recently done in other studies of our group. 7 , 23 , 32 Therefore, our reported relative O 2 pulse values allow the extrapolation of the results to a wider range of individuals and situations. Our results indicate that relative O 2 pulse is quasi-linear throughout a CPET.…”

“…Thus, although two individuals may have the same maximum O 2 pulse, their functional capacity (measured by maximum running speed) can vary significantly. Therefore, to avoid the influence of body dimension variability on O 2 pulse values, we analyzed this variable relative to body weight (mLO 2 ·beat -1 ·kg -1 ), as was recently done in other studies of our group 7,23,32. Therefore, our reported relative O 2 pulse values allow the extrapolation of the results to a wider range of individuals and situations.…”

A Pre-season Comparison of Aerobic Fitness and Flexibility of Younger and Older Professional Soccer Players

“…A maximal treadmill (ATL Master, Inbrasport, Brazil) cardiopulmonary exercise test (CPX) was performed according to the following protocols: after 1 min at 5.5 km • h − 1 , speed was increased to 8 km • h − 1 and thereafter increased by 0.1 km • h − 1 every 7.5 s (0.8 km • h − 1 per minute) until exhaustion. Immediately after achieving the maximum tolerated speed -individually recorded -with strong verbal encouragement, a cool-down period of walking for 2 min at 5.5 km • h − 1 was performed [ 23 ] . Based on the conditions experienced while playing the sport (fl at terrain), the treadmill slope was kept constant at 0 % during the CPX.…”

“…From the ratio between ventilation and VO 2 , the ventilatory equivalent (VE/ VO 2 ) was obtained for each minute of CPX, and the minimum value was identifi ed. VO 2 max was considered to be the highest value obtained after averaging the 6 10-s measurements at each minute [ 23 ] .…”