Trine Moholdt

Cardiovascular risk of high-versus moderate-intensity aerobic exercise in coronary heart disease patients

Background— Exercise performed at higher relative intensities has been found to elicit a greater increase in aerobic capacity and greater cardioprotective effects than exercise at moderate intensities. An inverse association has also been detected between the relative intensity of physical activity and the risk of developing coronary heart disease, independent of the total volume of physical activity. Despite that higher levels of physical activity are effective in reducing cardiovascular events, it is also advocated that vigorous exercise could acutely and transiently increase the risk of sudden cardiac death and myocardial infarction in susceptible persons. This issue may affect cardiac rehabilitation. Methods and Results— We examined the risk of cardiovascular events during organized high-intensity interval exercise training and moderate-intensity training among 4846 patients with coronary heart disease in 3 Norwegian cardiac rehabilitation centers. In a total of 175 820 exercise training hours during which all patients performed both types of training, we found 1 fatal cardiac arrest during moderate-intensity exercise (129 456 exercise hours) and 2 nonfatal cardiac arrests during high-intensity interval exercise (46 364 exercise hours). There were no myocardial infarctions in the data material. Because the number of high-intensity training hours was 36% of the number of moderate-intensity hours, the rates of complications to the number of patient-exercise hours were 1 per 129 456 hours of moderate-intensity exercise and 1 per 23 182 hours of high-intensity exercise. Conclusions— The results of the current study indicate that the risk of a cardiovascular event is low after both high-intensity exercise and moderate-intensity exercise in a cardiovascular rehabilitation setting. Considering the significant cardiovascular adaptations associated with high-intensity exercise, such exercise should be considered among patients with coronary heart disease.

Aerobic exercise intensity assessment and prescription in cardiac rehabilitation: a joint position statement of the European Association for Cardiovascular Prevention and Rehabilitation, the American Association of Cardiovascular and Pulmonary Rehabilitation and the Canadian Association of Cardiac Rehabilitation

Aerobic exercise intensity prescription is a key issue in cardiac rehabilitation, being directly linked to both the amount of improvement in exercise capacity and the risk of adverse events during exercise. This joint position statement aims to provide professionals with up-to-date information regarding the identification of different exercise intensity domains, the methods of direct and indirect determination of exercise intensity for both continuous and interval aerobic training, the effects of the use of different exercise protocols on exercise intensity prescription and the indications for recommended exercise training prescription in specific cardiac patients’ groups. The importance of functional evaluation through exercise testing prior to starting an aerobic training program is strongly emphasized, and ramp incremental cardiopulmonary exercise test, when available, is proposed as the gold standard for a physiologically comprehensive exercise intensity assessment and prescription. This may allow a shift from a ‘range-based’ to a ‘threshold-based’ aerobic exercise intensity prescription, which, combined with thorough clinical evaluation and exercise-related risk assessment, could maximize the benefits obtainable by the use of aerobic exercise training in cardiac rehabilitation.

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.

Physical activity and mortality in men and women with coronary heart disease: a prospective population-based cohort study in Norway (the HUNT study):

Background Patients with established coronary heart disease (CHD) are encouraged to be physically active to prevent disease progression and to prolong life. The amount and intensity of exercise required for risk reduction in patients with CHD is not yet fully resolved. Design Population-based prospective cohort study with 18 years of follow-up. Methods A linkage between a Norwegian population-based study (Nord-Trøndelag health study) and the Cause of Death Registry at Statistics Norway. Exercise amount and intensity were measured at baseline (1984–1986) in 2137 men and 1367 women with CHD. Results During 18 years of follow-up, 1741 (81.6%) men and 1100 (80.5%) women died. Compared with the reference category (no activity), one weekly exercise session was associated with a lower all-cause mortality, both in men (relative risk 0.80, 95% confidence interval 0.68–0.94) and women (relative risk 0.68, 95% confidence interval 0.55–0.83). This inverse association became stronger with increasing frequency (P ≤ 0.001 for men and women). Those who reported moderate or high-intensity exercise had a somewhat lower risk of death than those who exercised with low intensity. Conclusion Exercise training reduced all-cause and cardiovascular mortality in men and women with CHD. This study adds significantly to the sparse literature regarding prospective data on physical activity, exercise intensity and mortality in CHD patients. Eur J Cardiovasc Prev Rehabil 15:639–645

Long-term follow-up after cardiac rehabilitation: A randomized study of usual care exercise training versus aerobic interval training after myocardial infarction☆

due to discontinuedtraining.The design and methods of this randomized controlled trial havebeen prescribed in detail earlier [5]. Briefly, patients with an MI2–12 weeks ago were included and did either AIT as 4 times 4 minof treadmill walking at about 90% of individual heart rate maximum,or usual care continuous aerobic exercise for 60 min, twice weekly for12 weeks. The intensity during usual care was set to be moderate-to-high, and controlled by subjective ratings of perceived exertion.Datawascollectedat4timepoints;beforeandaftertraining,andat6and 30 months follow-up (Fig. 1). The primary outcome measure wasVO

The higher the better? Interval training intensity in coronary heart disease

OBJECTIVES Peak oxygen uptake (VO2 peak) increases more after high intensity interval training compared to isocaloric moderate exercise in patients with coronary heart disease (CHD). We assessed the impact of exercise intensity during high intensity intervals on the increase in VO2 peak. DESIGN/METHODS We included 112 patients with coronary heart disease who had participated in randomized trials of interval training consisting of four times four minutes intervals at 85-95% of heart rate maximum (HRmax) for 12 weeks. Exercise intensity was calculated for each patient using HR during the two last minutes of each interval, expressed as percentage of HRmax. We used a univariate general linear model with VO2 peak increase as the dependent variable and percentage of HRmax, age, number of exercise sessions, and baseline VO2 peak as covariates. Exercise intensity was also divided into three categories; <88%, 88-92%, and >92% of HRmax, and these categories were used as a fixed factor in the model. RESULTS VO2 peak increased by 3.9 (SD 3.1) mL kg(-1)min(-1), equal to 11.9% after 23.4 exercise sessions. Percentage of HRmax had a significant effect on increase in VO2 peak, both as a continuous (p=0.019) and categorical variable (p=0.020). The estimated marginal means and 95% confidence intervals of the increase in VO2 peak for the three intensity categories were 3.1 (2.0, 4.2), 3.6 (2.8, 4.4), and 5.2 (4.1, 6.3) for the <88%, the 88-92%, and the >92% category, respectively. CONCLUSIONS Even within the high intensity training zone, exercise intensity was an important determinant for improving VO2 peak in patients with coronary heart disease.

Home-Based Aerobic Interval Training Improves Peak Oxygen Uptake Equal to Residential Cardiac Rehabilitation: A Randomized, Controlled Trial

Aerobic capacity, measured as the peak oxygen uptake, is a strong predictor of survival in cardiac patients. Aerobic interval training (AIT), walking/running four times four minutes at 85–95% of peak heart rate, has proven to be effective in increasing peak oxygen uptake in coronary heart disease patients. As some patients do not attend organized rehabilitation programs, home-based exercise should be an alternative. We investigated whether AIT could be performed effectively at home, and compared the effects on peak oxygen uptake with that observed after a standard care, four-week residential rehabilitation. Thirty patients undergoing coronary artery bypass surgery were randomized to residential rehabilitation or home-based AIT. At six months follow-up, peak oxygen uptake increased 4.6 (±2.7) and 3.9 (±3.6) mL·kg−1 min−1 (both p<0.005, non-significant between-group difference) after residential rehabilitation and AIT, respectively. Quality of life increased significantly in both groups, with no statistical significant difference between groups. We found no evidence for a different treatment effect between patients randomized to home-based AIT compared to patients attending organized rehabilitation (95% confidence interval −1.8, 3.5). AIT patients reported good adherence to exercise training. Even though these first data indicate positive effects of home-based AIT in patients undergoing coronary artery bypass surgery, more studies are needed to provide supporting evidence for the application of this rehabilitation strategy. Trial Registration ClinicalTrials.gov NCT00363922

Letter to the EditorLong-term follow-up after cardiac rehabilitation: A randomized study of usual care exercise training versus aerobic interval training after myocardial infarction☆

due to discontinuedtraining.The design and methods of this randomized controlled trial havebeen prescribed in detail earlier [5]. Briefly, patients with an MI2–12 weeks ago were included and did either AIT as 4 times 4 minof treadmill walking at about 90% of individual heart rate maximum,or usual care continuous aerobic exercise for 60 min, twice weekly for12 weeks. The intensity during usual care was set to be moderate-to-high, and controlled by subjective ratings of perceived exertion.Datawascollectedat4timepoints;beforeandaftertraining,andat6and 30 months follow-up (Fig. 1). The primary outcome measure wasVO

Exercise Training in Pregnancy for obese women (ETIP): study protocol for a randomised controlled trial

BackgroundBoth maternal pre-pregnancy obesity and excessive gestational weight gain are increasing in prevalence and associated with a number of adverse pregnancy outcomes for both mother and child. Observational studies regarding physical activity in pregnancy have found reduced weight gain in active mothers, as well as reduced risk of adverse pregnancy outcomes. There is however a lack of high quality, randomized controlled trials on the effects of regular exercise training in pregnancy, especially those with a pre-pregnancy body mass index (BMI) at or above 30 kg/m2.MethodsWe are conducting a randomised, controlled trial in Norway with two parallel arms; one intervention group and one control group. We will enroll 150 previously sedentary, pregnant women with a pre-pregnancy BMI at or above 30 kg/m2. The intervention group will meet for organized exercise training three times per week, starting in gestation week 14 (range 12-16). The control group will get standard antenatal care. The main outcome measure will be weight gain from baseline to delivery. Among the secondary outcome measures are changes in exercise capacity, endothelial function, physical activity level, body composition, serum markers of cardiovascular risk, incontinence, lumbopelvic pain and cardiac function from baseline to gestation week 37 (range 36-38). Offspring outcome measures include anthropometric variables at birth, Apgar score, as well as serum markers of inflammation and metabolism in cord blood.DiscussionThe results of this trial will provide knowledge about effects of regular exercise training in previously sedentary, obese pregnant women. If the program proves effective in reducing gestational weight gain and adverse pregnancy outcomes, such programs should be considered as part of routine pregnancy care for obese women.Trial RegistrationClinicalTrials.gov: NCT01243554

Exercise Training and Weight Gain in Obese Pregnant Women: A Randomized Controlled Trial (ETIP Trial)

Background The effectiveness of exercise training for preventing excessive gestational weight gain (GWG) and gestational diabetes mellitus (GDM) is still uncertain. As maternal obesity is associated with both GWG and GDM, there is a special need to assess whether prenatal exercise training programs provided to obese women reduce the risk of adverse pregnancy outcomes. Our primary aim was to assess whether regular supervised exercise training in pregnancy could reduce GWG in women with prepregnancy overweight/obesity. Secondary aims were to examine the effects of exercise in pregnancy on 30 outcomes including GDM incidence, blood pressure, blood measurements, skinfold thickness, and body composition. Methods and Findings This was a single-center study where we randomized (1:1) 91 pregnant women with a prepregnancy body mass index (BMI) ≥ 28 kg/m2 to exercise training (n = 46) or control (standard maternity care) (n = 45). Assessments were done at baseline (pregnancy week 12–18) and in late pregnancy (week 34–37), as well as at delivery. The exercise group was offered thrice weekly supervised sessions of 35 min of moderate intensity endurance exercise and 25 min of strength training. Seventeen women were lost to follow-up (eight in the exercise group and nine in the control group). Our primary endpoint was GWG from baseline testing to delivery. The principal analyses were done as intention-to-treat analyses, with supplementary per protocol analyses where we assessed outcomes in the women who adhered to the exercise program (n = 19) compared to the control group. Mean GWG from baseline to delivery was 10.5 kg in the exercise group and 9.2 kg in the control group, with a mean difference of 0.92 kg (95% CI −1.35, 3.18; p = 0.43). Among the 30 secondary outcomes in late pregnancy, an apparent reduction was recorded in the incidence of GDM (2009 WHO definition) in the exercise group (2 cases; 6.1%) compared to the control group (9 cases; 27.3%), with an odds ratio of 0.1 (95% CI 0.02, 0.95; p = 0.04). Systolic blood pressure was significantly lower in the exercise group (mean 120.4 mm Hg) compared to the control group (mean 128.1 mm Hg), with a mean difference of −7.73 mm Hg (95% CI −13.23, −2.22; p = 0.006). No significant between-group differences were seen in diastolic blood pressure, blood measurements, skinfold thickness, or body composition in late pregnancy. In per protocol analyses, late pregnancy systolic blood pressure was 115.7 (95% CI 110.0, 121.5) mm Hg in the exercise group (significant between-group difference, p = 0.001), and diastolic blood pressure was 75.1 (95% CI 71.6, 78.7) mm Hg (significant between-group difference, p = 0.02). We had planned to recruit 150 women into the trial; hence, under-recruitment represents a major limitation of our results. Another limitation to our study was the low adherence to the exercise program, with only 50% of the women included in the intention-to-treat analysis adhering as described in the study protocol. Conclusions In this trial we did not observe a reduction in GWG among overweight/obese women who received a supervised exercise training program during their pregnancy. The incidence of GDM in late pregnancy seemed to be lower in the women randomized to exercise training than in the women receiving standard maternity care only. Systolic blood pressure in late pregnancy was also apparently lower in the exercise group than in the control group. These results indicate that supervised exercise training might be beneficial as a part of standard pregnancy care for overweight/obese women. Trial Registration ClinicalTrials.gov NCT01243554