Stig A. Slørdahl

Superior Cardiovascular Effect of Aerobic Interval Training Versus Moderate Continuous Training in Heart Failure Patients A Randomized Study

Background— Exercise training reduces the symptoms of chronic heart failure. Which exercise intensity yields maximal beneficial adaptations is controversial. Furthermore, the incidence of chronic heart failure increases with advanced age; it has been reported that 88% and 49% of patients with a first diagnosis of chronic heart failure are >65 and >80 years old, respectively. Despite this, most previous studies have excluded patients with an age >70 years. Our objective was to compare training programs with moderate versus high exercise intensity with regard to variables associated with cardiovascular function and prognosis in patients with postinfarction heart failure. Methods and Results— Twenty-seven patients with stable postinfarction heart failure who were undergoing optimal medical treatment, including &bgr;-blockers and angiotensin-converting enzyme inhibitors (aged 75.5±11.1 years; left ventricular [LV] ejection fraction 29%; &OV0312;o2peak 13 mL · kg−1 · min−1) were randomized to either moderate continuous training (70% of highest measured heart rate, ie, peak heart rate) or aerobic interval training (95% of peak heart rate) 3 times per week for 12 weeks or to a control group that received standard advice regarding physical activity. &OV0312;o2peak increased more with aerobic interval training than moderate continuous training (46% versus 14%, P<0.001) and was associated with reverse LV remodeling. LV end-diastolic and end-systolic volumes declined with aerobic interval training only, by 18% and 25%, respectively; LV ejection fraction increased 35%, and pro-brain natriuretic peptide decreased 40%. Improvement in brachial artery flow-mediated dilation (endothelial function) was greater with aerobic interval training, and mitochondrial function in lateral vastus muscle increased with aerobic interval training only. The MacNew global score for quality of life in cardiovascular disease increased in both exercise groups. No changes occurred in the control group. Conclusions— Exercise intensity was an important factor for reversing LV remodeling and improving aerobic capacity, endothelial function, and quality of life in patients with postinfarction heart failure. These findings may have important implications for exercise training in rehabilitation programs and future studies.

Aerobic Interval Training Versus Continuous Moderate Exercise as a Treatment for the Metabolic Syndrome A Pilot Study

Background— Individuals with the metabolic syndrome are 3 times more likely to die of heart disease than healthy counterparts. Exercise training reduces several of the symptoms of the syndrome, but the exercise intensity that yields the maximal beneficial adaptations is in dispute. We compared moderate and high exercise intensity with regard to variables associated with cardiovascular function and prognosis in patients with the metabolic syndrome. Methods and Results— Thirty-two metabolic syndrome patients (age, 52.3±3.7 years; maximal oxygen uptake [&OV0312;o2max], 34 mL · kg−1 · min−1) were randomized to equal volumes of either moderate continuous moderate exercise (CME; 70% of highest measured heart rate [Hfmax]) or aerobic interval training (AIT; 90% of Hfmax) 3 times a week for 16 weeks or to a control group. &OV0312;o2max increased more after AIT than CME (35% versus 16%; P<0.01) and was associated with removal of more risk factors that constitute the metabolic syndrome (number of factors: AIT, 5.9 before versus 4.0 after; P<0.01; CME, 5.7 before versus 5.0 after; group difference, P<0.05). AIT was superior to CME in enhancing endothelial function (9% versus 5%; P<0.001), insulin signaling in fat and skeletal muscle, skeletal muscle biogenesis, and excitation-contraction coupling and in reducing blood glucose and lipogenesis in adipose tissue. The 2 exercise programs were equally effective at lowering mean arterial blood pressure and reducing body weight (−2.3 and −3.6 kg in AIT and CME, respectively) and fat. Conclusions— Exercise intensity was an important factor for improving aerobic capacity and reversing the risk factors of the metabolic syndrome. These findings may have important implications for exercise training in rehabilitation programs and future studies.

High intensity aerobic interval exercise is superior to moderate intensity exercise for increasing aerobic capacity in patients with coronary artery disease

Background Increased aerobic exercise capacity appears to reduce both all-cause mortality and cardiovascular disease mortality. Physical exercise to improve peak oxygen uptake (VO2peak) is thus strongly recommended, however evidence regarding the most efficient training intensity for patients with coronary artery disease (CAD) is still lacking. The purpose of this randomized study was therefore to assess the effects of high intensity aerobic interval exercise compared to moderate intensity exercise, representing the same total training load, for increasing VO2peak in stable CAD-patients. Methods Twenty-one stable CAD-patients were randomized to supervised treadmill walking at either high intensity (80–90% of VO2peak) or moderate intensity (50–60% of VO2peak) three times a week for 10 weeks. Results After training VO2peak increased by 17.9% (P = 0.012) in the high intensity group and 7.9% (P = 0.038) in the moderate intensity group. The training-induced adaptation was significantly higher in the high intensity group (P = 0.011). Conclusions High intensity aerobic interval exercise is superior to moderate exercise for increasing VO2peak in stable CAD-patients. As VO2peak seems to reflect a continuum between health and cardiovascular disease and death, the present data may be useful in designing effective training programmes for improved health in the future.

Aerobic interval training reduces cardiovascular risk factors more than a multitreatment approach in overweight adolescents

The aim of the present study was to compare the effects of a multidisciplinary approach (MTG) and aerobic interval training (AIT) on cardiovascular risk factors in overweight adolescents. A total of 62 overweight and obese adolescents from Trøndelag County in Norway, referred to medical treatment at St Olavs Hospital, Trondheim, Norway, were invited to participate. Of these, 54 adolescents (age, 14.0 +/- 0.3 years) were randomized to either AIT (4 x 4 min intervals at 90% of maximal heart rate, each interval separated by 3 min at 70%, twice a week for 3 months) or to MTG (exercise, dietary and psychological advice, twice a month for 12 months). Follow-up testing occurred at 3 and 12 months. VO(2max) (maximal oxygen uptake) increased more after AIT compared with MTG, both at 3 months (11 compared with 0%; P<0.01) and 12 months (12 compared with -1%; P<0.01). AIT enhanced endothelial function compared with MTG at both 3 months (absolute change, 5.1 compared with 3.9%; P<0.01) and 12 months (absolute change, 6.3 compared with 1.0%; P<0.01). AIT was favourable compared with MTG in reducing BMI (body mass index), percentage of fat, MAP (mean arterial blood pressure) and increasing peak oxygen pulse. In addition, AIT induced a more favourable regulation of blood glucose and insulin compared with MTG. In conclusion, the novel findings of the present proof-of-concept study was that 3 months of twice weekly high-intensity exercise sessions reduced several known cardiovascular risk factors in obese adolescents more than that observed after a multitreatment strategy, which was initiated as hospital treatment. Follow-up at 12 months confirmed that AIT improved or maintained these risk factors to a better degree than MTG.

Strength training versus aerobic interval training to modify risk factors of metabolic syndrome

Metabolic syndrome is characterized by central obesity, elevated blood pressure, high fasting glucose and triglyceride levels, and low HDL levels. Regular physical activity can improve the metabolic profile and reduce the risks of cardiovascular diseases and premature mortality. However, the optimal training regime to treat metabolic syndrome and its associated cardiovascular abnormalities remains undefined. Forty-three participants with metabolic syndrome were randomized to one of the following groups: aerobic interval training (AIT; n = 11), strength training (ST; n = 11), a combination of AIT and ST (COM; n = 10) 3 times/wk for 12 wk, or control (n = 11). Risk factors comprising metabolic syndrome were evaluated before and after the intervention. Waist circumference (in cm) was significantly reduced after AIT [95% confidence interval (CI): -2.5 to -0.04], COM (95% CI: -2.11 to -0.63), and ST (95% CI: -2.68 to -0.84), whereas the control group had an increase in waist circumference (95% CI: 0.37-2.9). The AIT and COM groups had 11% and 10% increases in peak O2 uptake, respectively. There were 45% and 31% increases in maximal strength after ST and COM, respectively. Endothelial function, measured as flow-mediated dilatation (in %), was improved after AIT (95% CI: 0.3-3), COM (95% CI: 0.3-3), and ST (95% CI: 1.5-4.5). There were no changes in body weight, fasting plasma glucose, or HDL levels within or between the groups. In conclusion, all three training regimes have beneficial effects on physiological abnormalities associated with metabolic syndrome.

A single weekly bout of exercise may reduce cardiovascular mortality: how little pain for cardiac gain? ‘The HUNT study, Norway’

Background The observation that exercise training reduces cardiovascular mortality is robust and consistent, but the amount and intensity of exercise that is required for risk reduction is not yet resolved. Methods We studied the association between the amount and intensity of exercise and cardiovascular mortality in 27 143 men and 28 929 women who were free from known cardiovascular disease at the beginning of follow-up between 1984 and 1986. The relative risk of death was calculated as the rate of death among participants within a given physical activity category compared with the rate of death in the reference category (no physical activity). We used Cox regression analysis to adjust for age and other potentially confounding factors. Results After 16 years (SD 4 years) of follow-up, 2946 men (10.8%) and 2486 women (8.6%) had died from ischaemic heart disease or stroke. A single weekly bout of exercise of high intensity reduced the risk of cardiovascular death, both in men [relative risk (RR) 0.61, 95% confidence interval (CI) 0.49–0.75], and women (RR 0.49, 95% CI 0.27–0.89), compared with those who reported no activity. There was no additional benefit from increasing the duration or the number of exercise sessions per week. The risk reduction related to exercise increased with increasing age in men, but not in women. Conclusion These results challenge the current recommendation that expenditure of at least 1000 kcal per week is required to achieve exercise-induced protection against premature cardiovascular mortality.

Automated analysis of myocardial deformation at dobutamine stress echocardiography: an angiographic validation.

OBJECTIVES We investigated the accuracy of automated analysis of myocardial deformation during dobutamine stress echocardiography (DSE). BACKGROUND The time required for segmental measurement of strain rate imaging (SRI) limits its feasibility for quantification of DSE. METHODS Myocardial deformation was assessed at DSE in 197 patients, 76 with and 61 without coronary artery disease (CAD) at angiography, and 60 at low risk of CAD. Automated deformation analysis was based on velocity gradient and segment length methods of measuring longitudinal motion within a region of interest tracked through the cardiac cycle. Results were compared with independent wall motion scoring (WMS). Patients were randomly divided; group A (n = 69) established optimal cutoffs for the parameters and group B (n = 68) tested their accuracy. RESULTS The feasibility of WMS exceeded that of both SRI methods at rest and at peak stress. In group A, the area under the receiver-operating characteristics curve of the peak systolic strain rate was 0.90 by both methods, and the optimal cutoffs for detection of CAD were -1.3 (velocity gradient) and -1.2 s(-1) (segment length). The areas under the receiver-operating characteristics curves for end-systolic strain were less (0.87) by both methods, with respective cutoffs of 9% and 8%. In group B, the velocity and segment length methods had respective sensitivities of 87% and 84% for SR, and 87% and 88% for end-systolic strain. Both significantly exceeded that of WMS in the same group (75%). CONCLUSIONS Automated analysis of myocardial deformation at DSE is feasible and accurate, and may increase the sensitivity of expert conventional reading.

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.

Regional myocardial long-axis strain and strain rate measured by different tissue Doppler and speckle tracking echocardiography methods: a comparison with tagged magnetic resonance imaging

AIMS Compare four different echocardiographic methods, based on tissue Doppler imaging (TDI) and speckle tracking (ST) separately or combined, for long-axis strain and strain rate (SR) measurements, using magnetic resonance imaging (MRI) tagging as a reference. METHODS AND RESULTS In 21 subjects (10 with myocardial infarction) peak systolic strain and systolic and early diastolic SR were measured by four different echo methods: (i) two-dimensional (2D) strain (B-mode); (ii) ST (custom software) of segment end-points (B-mode); (iii) similar to (ii), but combining ST with tissue Doppler tracking; (iv) strain from tissue Doppler velocity gradients (VG). Agreement with MRI tagging was better for strain than for SR. Ninety-five per cent limits of agreement were wider for the TDI-VG method, and 2D strain showed negative bias compared with MRI tagging and the other echo methods. Reproducibility was better for 2D strain than for MRI tagging and the other echo methods. CONCLUSION ST alone or combined with TDI seems to be suitable for automated measurements of regional myocardial deformation. The study gives important information on the strengths and weaknesses of the different methods, which is important for further development to increase accuracy and applicability.

Endothelial function in highly endurance-trained men : effects of acute exercise.

Exercise training reverses endothelial dysfunction, but the effect in young, healthy subjects is less clear. We determined the influence of maximal oxygen uptake (&OV0312;o2max) and a single bout of high-intensity exercise on flow-mediated dilatation (FMD), brachial artery diameter, peak blood flow, nitric oxide (NO) bioavailability, and antioxidant status in highly endurance-trained men and their sedentary counterparts. Ten men athletes (mean ± SEM age 23.5 ± 0.9 years, height 182.6 ± 2.4 cm, weight 72.5 ± 2.4 kg, &OV0312;o2max 75.9 ± 0.8 mL·kg−1·min−1) and seven healthy controls (age 25.4 ± 1.2 years, height 183.9 ± 3.74 cm, weight 92.8 ± 3.9 kg, &OV0312;o2max 47.7 ± 1.7 mL·kg−1·min−1) took part in the study. FMD, brachial artery diameter, and peak blood flow were measured using echo-Doppler before, 1 hour, 24 hours, and 48 hours after a single bout of interval running for 5 × 5 minutes at 90% of maximal heart rate. NO bioavailability and antioxidant status in blood were measured at all time points. Maximal arterial diameter and peak flow were 10-15% (P < 0.02) and 28-35% (P < 0.02) larger, respectively, in athletes vs. controls at all time points, and similar FMD were observed, apart from a transient decay of FMD in athletes 1 hour post exercise. NO bioavailability increased significantly after exercise in both groups and decreased to baseline levels after 24 hours in controls but remained increased 80% and 93% above baseline 24 and 48 hours post exercise in athletes. Antioxidant status was equal in the two groups at baseline and increased by approximately 10% 1 hour post exercise, an effect that lasted for 24 hours. Athletes had larger arterial diameter but similar FMD as untrained subjects, i.e., athletes had larger capacity for blood transport compared with their untrained counterparts. The observed FMD, bioavailability of NO, and antioxidant status in blood were highly dependent on the time elapsed after the exercise session.