Stroke volume responses may be related to the gap between peak and maximal O-2 consumption

BACKGROUND: Although several studies have focused on maximal O-2 uptake ((V) over dotO(2max)) measured by a verification phase following the determination of peak O-2 uptake ((V) over dotO(2peak)) by a graded exercise test, an explanation for the underlying mechanisms of the difference between (V) over dotO(2peak) and confirmed (V) over dotO(2max) is scant. OBJECTIVE: To explore the hypothesis that when the difference between (V) over dotO(2peak) and (V) over dotO(2max) (Delta(V) over dotO(2)) increases, the gap between peak stroke volume (SVpeak) and SV level corresponding to (V) over dotO(2peak) velocities (Delta SV) grows. METHODS: Nine moderately to well-trained male athletes ((V) over dotO(2max): 60.2 +/- 7 mL.min(-1).kg(-1)) volunteered to take part in the study. Following familiarization session, volunteers were asked to perform submaximal and maximal graded exercise tests. Then, constant-loading SVpeak tests (using wattages in a range from 40-100% of (V) over dotO(2peak)) and verification phase (using wattages corresponding with 100-110% of (V) over dotO(2peak)) were conducted in a climatic chamber. RESULTS: The Delta(V) over dotO(2) was well correlated with Delta SV (Pearson r = 0.89; p <= 0.001). The mean SVpeak of participants corresponded to 60.3 +/- 18% of (V) over dotO(2peak). (V) over dotO(2max) was significantly greater (11.2%) than (V) over dotO(2peak) (60.2 +/- 7 vs. 54.2 +/- 8.1 mL.min(-1).kg(-1)) (p <= 0.01). CONCLUSIONS: (V) over dotO(2peak) and (V) over dotO(2max) differences may be related to the gap between SVpeak and SV at (V) over dotO(2peak).