Cardiac output and oxygen uptake relationship during physical effort in men and women over 60 years old

This study investigated the relationship between oxygen uptake (VO 2 ), cardiac output (Q), stroke volume (SV), and heart rate (HR) in 54 men and 77 women (age = 69 ± 5 years) during incremental effort. Subjects performed a maximal cycle-ergometer test and VO 2 was directly measured. HR and SV were assessed by ECG and cardiograph impedance. Regression equations were calculated for Q–VO 2 , HR–VO 2 , and Q–HR relationships. The equations obtained for women were (a) Q (l min −1 ) = 2.61 + 4.67 VO 2 (l min −1 )( r 2 = 0.84); (b) HR (bpm) = 62.03 + 46.55 VO 2 (l min −1 ) ( r 2 = 0.72); (c) ( r 2 = 0.41); (d) HR (bpm) = 41.48 + 9.24 Q (l min −1 ) ( r 2 = 0.73). Equations for men were (a) Q (l min −1 ) = 2.52 + 5.70 VO 2 (l min −1 ) ( r 2 = 0.89); (b) HR (bpm) = 66.31 + 32.35 VO 2 (l min −1 ) ( r 2 = 0.72); (c) ( r 2 = 0.47); (d) HR (bpm) = 56.33 + 5.25 Q (l min −1 ) ( r 2 = 0.69). The intercepts for Q–VO 2 and HR–VO 2 equations were similar for both genders, but the slopes were different ( P 0.05). A significant difference between men and women was observed for both slopes and intercepts in the Q–HR relationship ( P