Left Atrial Volume, Cardiorespiratory Fitness, and Diastolic Function in Healthy Individuals: The HUNT Study, Norway.

Background Left atrial (LA) size and cardiorespiratory fitness (CRF) are predictors of future cardiovascular events in high-risk populations. LA dilatation is a diagnostic criterion for left ventricular diastolic dysfunction. However, LA is dilated in endurance athletes with high CRF, but little is known about the association between CRF and LA size in healthy, free-living individuals. We hypothesized that in a healthy population, LA size was associated with CRF and leisure-time physical activity, but not with echocardiographic indexes of left ventricular diastolic dysfunction. Methods and Results In this cross-sectional study from HUNT (Nord-Trøndelag Health Study), 107 men and 138 women, aged 20 to 82 years, without hypertension, cardiovascular, pulmonary, or malignant disease participated. LA volume was assessed by echocardiography and indexed to body surface area LAVI (left atrial volume index). CRF was measured as peak oxygen uptake (VO2peak) using ergospirometry, and percent of age- and-sex-predicted VO2peak was calculated. Indexes of left ventricular diastolic dysfunction were assessed in accordance with latest recommendations. LAVI was >34 mL/m2 in 39% of participants, and LAVI was positively associated with VO2peak and percentage of age- and-sex-predicted VO2peak (ß [95% CI], 0.11 [0.06-0.16] and 0.18 [0.09-0.28], respectively) and weighted minutes of physical activity per week (ß [95% CI], 0.01 [0.003-0.015]). LAVI was not associated with other indexes of left ventricular diastolic dysfunction. There was an effect modification between age and VO2peak/percentage of age- and-sex-predicted VO2peak showing higher LAVI with advanced age and higher VO2peak/percentage of age- and-sex-predicted VO2peak as presented in prediction diagrams. Conclusions Interpretation of LAVI as a marker of diastolic dysfunction should be done in relation to age-relative CRF. Studies on the prognostic value of LAVI in fit subpopulations are needed.

Aerobic interval training increases peak oxygen uptake more than usual care exercise training in myocardial infarction patients: a randomized controlled study.

OBJECTIVE: Exercise capacity strongly predicts survival and aerobic interval training (AIT) increases peak oxygen uptake effectively in cardiac patients. Usual care in Norway provides exercise training at the hospitals following myocardial infarction (MI), but the effect and actual intensity of these rehabilitation programmes are unknown. DESIGN: Randomized controlled trial. SETTING: Hospital cardiac rehabilitation. SUBJECTS: One hundred and seven patients, recruited two to 12 weeks after MI, were randomized to usual care rehabilitation or treadmill AIT. INTERVENTIONS: Usual care aerobic group exercise training or treadmill AIT as 4 × 4 minutes intervals at 85-95% of peak heart rate. Twice weekly exercise training for 12 weeks. MAIN MEASURES: The primary outcome measure was peak oxygen uptake. Secondary outcome measures were endothelial function, blood markers of cardiovascular disease, quality of life, resting heart rate, and heart rate recovery. RESULTS: Eighty-nine patients (74 men, 15 women, 57.4 ± 9.5 years) completed the programme. Peak oxygen uptake increased more (P = 0.002) after AIT (from 31.6 ± 5.8 to 36.2 ± 8.6 mL·kg(-1)·min(-1), P < 0.001) than after usual care rehabilitation (from 32.2 ± 6.7 to 34.7 ± 7.9 mL·kg(-1)·min(-1), P < 0.001). The AIT group exercised with significantly higher intensity in the intervals compared to the highest intensity in the usual care group (87.3 ± 3.9% versus 78.7 ± 7.2% of peak heart rate, respectively, P < 0.001). Both programmes increased endothelial function, serum adiponectin, and quality of life, and reduced serum ferritin and resting heart rate. High-density lipoprotein cholesterol increased only after AIT. CONCLUSIONS: AIT increased peak oxygen uptake more than the usual care rehabilitation provided to MI patients by Norwegian hospitals.

Aerobic interval training reduces blood pressure and improves myocardial function in hypertensive patients.

AIMS: Exercise is recommended as prevention, management, and control of all stages of hypertension. There are still controversies about the optimal training dose, frequency, and intensity. We aimed to study the effect of aerobic interval training on blood pressure and myocardial function in hypertensive patients. METHODS AND RESULTS: A total of 88 patients (52.0 ± 7.8 years, 39 women) with essential hypertension were randomized to aerobic interval training (AIT) (>90% of maximal heart rate, correlates to 85-90% of VO(2max)), isocaloric moderate intensity continuous training (MIT) (~70% of maximal heart rate, 60% of VO(2max)), or a control group. Exercise was performed on a treadmill, three times per week for 12 weeks. Ambulatory 24-hour blood pressure (ABP) was the primary endpoint. Secondary endpoints included maximal oxygen uptake (VO(2max)), mean heart rate/24 hour, flow mediated dilatation (FMD), total peripheral resistance (TPR), and myocardial systolic and diastolic function by echocardiography. Systolic ABP was reduced by 12 mmHg (p < 0.001) in AIT and 4.5 mmHg (p = 0.05) in MIT. Diastolic ABP was reduced by 8 mmHg (p < 0.001) in AIT and 3.5 mmHg (p = 0.02) in MIT. VO(2max) improved by 15% (p < 0.001) in AIT and 5% (p < 0.01) in MIT. Systolic myocardial function improved in both exercise groups, diastolic function in the AIT group only. TPR reduction and increased FMD were only observed in the AIT group. CONCLUSIONS: This study indicates that the blood pressure reducing effect of exercise in essential hypertension is intensity dependent. Aerobic interval training is an effective method to lower blood pressure and improve other cardiovascular risk factors.