Association among cardiopulmonary and metabolic rehabilitation, arrhythmias, and myocardial ischemia responses of patients with HFpEF or HFmrEF

There's limited evidence of the potential benefits of cardiopulmonary and metabolic rehabilitation (CPMR) in patients with heart failure with preserved ejection fraction (HFpEF) or mildly reduced ejection fraction (HFmrEF) and coronary artery disease (CAD). The aim of this study was to investigate the impact of CPMR on the myocardial ischemia response (MIR), exercise-induced arrhythmias (EIA), New York Heart Association (NYHA) functional class, heart rate recovery (HRR), Borg CR10 perceived symptoms, and the SF-36 physical and mental health summary scores. A prospective cohort study was conducted with 106 patients undergoing 12 weeks of CPMR who completed two exercise tests pre- and post-CPMR: 1) maximum incremental test (CPX) and 2) submaximal constant load test (SUB). After CPMR, the effects on MIR, EIA, NYHA functional class, and HRR during both tests were analyzed. There was a significant change in NYHA functional classes after CPMR, with 96% of the patients in class I (vs 62% pre-CPMR, P<0.0001), 4% in class II (vs 32%), and none in class III (vs 6%). There was a significant reduction in the frequency of EIA (P<0.05) and MIR (P<0.001) and a significantly improved performance on both CPX and SUB tests (P<0.0001). Lastly, there was significant progress in the recovery metrics like HRR (P<0.0001), the Borg CR10 (P<0.0001), and the SF-36 summary scores (P<0.0001). The CPMR resulted in a significant decrease in EIA, delayed ischemia threshold in CPX and SUB tests, increased functional capacity, and improved quality of life.

Effect of three caffeine doses on plasma catecholamines and alertness during prolonged wakefulness

OBJECTIVE

Determine the relationship between caffeine, catecholamines, and alertness during prolonged wakefulness.

METHODS

Following 49 h of prolonged wakefulness, each of 50 healthy males (18-32 years) orally ingested either a placebo or one of three doses of caffeine, 2.1 (low), 4.3 (medium), or 8.6 mg kg-1 body weight (high), in a randomized double-blind design. Wakefulness continued for an additional 12 h during which venous blood samples were collected for catecholamine and caffeine analysis [determined using high-performance liquid chromatography (HPLC)]. A sleep latency test, the Stanford sleepiness scale, and a choice reaction time test were administered periodically during the post-dosing period and served as measures of alertness (physiological, subjective, and behavioral, respectively).

RESULTS

Caffeine had no significant effect on noradrenaline, but adrenaline was significantly increased between 1 h and 4 h post-dosing in the high dose group compared with a placebo group. Following caffeine administration, responses to sleep latency, sleepiness scores, and reaction time scores showed dose-related changes that were exhibited by significant correlation coefficients.

CONCLUSION

The results indicate that high doses of caffeine have a significant and beneficial effect on alertness during prolonged wakefulness.

Hemostatic responses to maximal exercise in oral contraceptive users

OBJECTIVE

This study examined the effect of exercise on markers of fibrinolysis and coagulation in users and nonusers of oral contraceptives.

STUDY DESIGN

Fourteen oral contraceptive users and 14 nonusers performed a maximal exercise test on a cycle ergometer. Blood samples were collected before and immediately after the completion of the test. A repeated-measures analysis of variance was used for statistical analysis with values considered significant at P =.05.

RESULTS

Acute maximal exercise resulted in significant increases in tissue plasminogen activator activity in both groups. There was a trend toward a smaller increase in tissue plasminogen activator activity in oral contraceptive users, but the difference between groups was not statistically significant. Plasminogen activator inhibitor 1 activity was reduced with exercise in both groups but with a significantly greater decrease observed in the nonusers (P <.0001). Prothrombin fragment 1+2 was significantly higher (P <.0001) in the oral contraceptive group but did not change with exercise. Epinephrine levels before and after exercise were similar between the 2 groups, but postexercise norepinephrine concentrations were significantly lower (P =.026) in the oral contraceptive users.

CONCLUSION

These data suggest that oral contraceptive use blunts the fibrinolytic response to exercise. This, together with increased coagulation activation in oral contraceptive users, may alter the hemostatic balance during exercise.

The effect of the menstrual cycle on the pharmacokinetics of caffeine in normal, healthy eumenorrheic females

OBJECTIVE

Hormonal fluctuations of estrogen and progesterone in eumenorrheic women may be capable of altering the pharmacokinetics of certain agents. The objective of this study was to determine the effect of the luteal, ovulatory and follicular phases of the menstrual cycle on the pharmacokinetics of caffeine, a low clearance, flow-independent drug.

METHODS

Subjects were ten healthy, non-smoking, eumenorrheic females who were not pregnant and had not used oral contraceptives for a minimum of 3 months prior to the study. Blood samples were collected during one menstrual cycle for the determination of estradiol and progesterone concentrations during the follicular (days 2-6 post-onset of menses), ovulatory (days 13-16 post-onset of menses) and luteal (days 22-26 post-onset of menses) phases. Caffeine was administered over a single menstrual cycle during the follicular, ovulatory and luteal phases. Each subject was administered a single oral dose of caffeine (300 mg) in 100 ml of lemonade during each phase of the menstrual cycle. A venous catheter was used to collect blood samples at pre-dose and at the following time points: 0.25, 0.5, 0.75, 1, 1.5, 2, 4, 6, 8, 10, 12 and 24 h. Plasma caffeine concentrations were determined using a validated ultraviolet high-performance liquid chromatography method.

RESULTS

There were no significant (P < 0.05) differences in the pharmacokinetic parameters of caffeine across the menstrual cycle phases. The average area under the plasma concentration-time curve (AUCinf) was 93.01 mg 1(-1) x h and the absorption rate constant (ka) was 2.88 h(-1) during the ovulatory phase, 83.0 mg 1(-1) h and 2.06 h(-1), respectively, during the luteal phase and 84.7 mg 1(-1) x h and 1.84 h(-1), respectively, during the follicular phase.

CONCLUSIONS

These findings suggest that the menstrual cycle does not significantly alter the pharmacokinetics of caffeine.

Gender effect on beta-endorphin response to exercise

PURPOSE

Twelve healthy men (26.4 yr) and women (26.8 yr) were compared at rest and after cycling for 25 min at 60 and 80% VO2max to determine whether gender and menstrual cycle influenced circulating beta-endorphin concentration (BE).

METHODS

VO2max was determined on a cycle ergometer, and subjects completed the exercise in a randomized order. Women were tested in both the luteal (L) and follicular (F) phases of their menstrual cycle, which was confirmed by their blood estrogen levels. All tests were conducted in the morning after a 30-min rest (12-h postabsorptive). An indwelling venous catheter placed in a forearm vein enabled blood sampling at rest, 25 min of cycling, and 25 min of recovery.

RESULTS

Resting BE was similar for men before both 60 and 80% intensities of exercise, 5.27 +/- 0.43 and 5.30 +/- 0.33 pmol.mL-1, respectively. BE was not significantly changed at 60% VO2max (6.54 +/- 0.33 pmol.mL-1) but significantly increased at 80% VO2max (11.90 +/- 1.98 pmol.mL-1). Women tended to have slightly lower BE during the L compared with F, but this did not reach significance (L = 4.40 +/- 0.22, F = 4.73 +/- 0.30 pmol.mL-1). Cycling at 60% VO2max did not significantly increase BE in the L (5.41 +/- 0.42 pmol.mL-1) nor the F (5.35 +/- 0.40 pmol.mL-1). Cycling at 80% VO2max increased BE to a similar extent in both the L and F phase, respectively (10.44 and 10.96). Although the BE concentrations tended to be slightly lower in women compared with men at 80% VO2max, this did not reach statistical significance.

CONCLUSIONS

These data suggest that women cycling at 80% VO2max will have a similar BE response to men independent of their menstrual cycle. BE in women at rest and who exercise at lower exercise intensities may have slightly lower BE levels then men independent of the time of the women's menstrual cycle.