Oxygen pulse is not predictive of stroke volume in heart failure.

AIM: Stroke volume (SV) is the major cardiovascular discriminator between those that are exercise trained versus untrained individuals and healthy individuals versus those with pathologic left ventricular dysfunction. Furthermore, since the increase in oxygen pulse (O(2)P) (O(2)P=VO(2)/HR?oxygen uptake/heart rate) that occurs with exercise is a function of SV and the arterial-venous oxygen difference (a-vO(2)), O(2)P has been demonstrated a reliable indicator of SV for healthy individuals. Although commonly used as a physiological and clinical marker of SV, the validity of O(2)P as an indicator of SV in patients with heart failure has not been investigated. METHODS: Thirty-one (23 men, 8 women) patients (age: 64+/-7.9; ejection fraction: 24+/-7.8) with chronic heart failure had cardiac output measured during steady-state workloads (25 watts and 75% VO(2peak)) upon entry and again at completion of 12 weeks of exercise training. Four patients were excluded due to clinical complications and 3 because of non-compliance; therefore, 24 patients completed the study. RESULTS: The relationships between SV and O2P are: 1) baseline: SV=11.1+4(O2P), SEE=11.8; r(2)=0.39 and 2) study completion: SV=25.1+2.3(O2P), SEE=12.7; r(2)=0.21. While SV did not increase after 25 watts, O2P continued to increase by 17%, respectively. In addition, there were no training effects on SV or O(2)P. As SV increased, O(2)P underpredicted measured SV. CONCLUSIONS: In patients with heart failure and poor left ventricular function, O(2)P is not recommended as a marker of the SV during exercise.

Body fat distribution's impact on physiologic outcomes during cardiac rehabilitation.

BACKGROUND: High waist-to-hip ratios (WHRs) predispose individuals to metabolic syndromes that may affect outcome responses to cardiac rehabilitation programs. METHODS: A total of 101 male patients who had undergone coronary artery revascularization surgery and completed 12 weeks of cardiac rehabilitation were divided into lower (LOWHR, n = 51) and higher (HIWHR, n = 50) waist-to-hip groups. Outcomes were measured at week 1 and week 12 of cardiac rehabilitation. RESULTS: Waist-to-hip ratio and body weight were greatest for HIWHR (P < 0.001) with no between-group differences in the amount of change from week 1 to 12. Triceps and subscapular skin-folds were greater for HIWHR (P < 0.001) with no difference in the amount of change between groups. Caloric expenditure during exercise class was higher for LOWHR (P = 0.022). Daily caloric expenditure was greater for LOWHR (P = 0.034) as was daily caloric intake (P < 0.001). There were no group differences for VO2peak and ventilatory anaerobic threshold (VAT) with nonsignificant trends for greater increases in LOWHR. CONCLUSIONS: Cardiac rehabilitation patients with greater WHRs expend less calories during exercise classes. To enhance overall caloric expenditure and obtain positive outcomes, cardiac rehabilitation professionals must emphasize greater activity with less sedentary time throughout the patients normal daily routine. The validity of using self-reported caloric intake and expenditure values in the cardiac rehabilitation population is questionable.

Exercise tolerance, body composition and blood lipids in obese African-American women following short-term training.

BACKGROUND: The purpose of this investigation was to examine the exercise tolerance, body composition and blood lipids in African-American women, possessing greater than or equal to 30% body fat, following six weeks of endurance training. METHODS: Oxygen consumption (VO2), central hemodynamics, blood lipids, body weight, body fat, and the body mass index of seven subjects (21.0 +/- 0.8 yrs) were studied. Heart rate (HR), blood pressure (BP), exercise duration, rating of perceived exertion (RPE), blood lactate (bLA) and VO2 were obtained in response to a maximal exercise tolerance test on a motorized treadmill. Subjects trained three times per week for 50 minutes per session (30 minutes at 70% maximal oxygen consumption (VO2max). RESULTS: Dependent "t"-tests revealed significant (p < 0.05) increases in VO2max, 27%; exercise duration, 31%; as well as peak HR, systolic blood pressure (SBP), and bLA. Values for submaximal HR, SBP, RPE during the post-training test were lower. In addition, body weight, body fat and the body mass index decreased 2.2%, 1.3% and 3.4% respectively. There were no changes in blood lipids. CONCLUSIONS: These findings suggest short-term training at 70% VO2max provides the necessary stimulus for obese women to improve exercise tolerance and body composition. However, the training stimulus is insufficient to alter lipid profiles.