Jack M. Goodman

Favorable left ventricular remodeling following large myocardial infarction by exercise training. Effect on ventricular morphology and gene expression.

Continued adverse remodeling of myocardium after infarction may lead to progressive ventricular dilation and heart failure. We tested the hypothesis that exercise training in a healed myocardial infarction-dysfunction rat model can favorably modify the adverse effects of ventricular remodeling including attenuation of abnormal myosin gene expression. Sprague-Dawley rats were subjected to either proximal LAD ligation or sham operation. At 5 wk after the operation, animals were randomly assigned to sedentary conditions or 6 wk of graduated swim training, creating four experimental groups: infarct sedentary (IS), infarct exercise (IE), sham sedentary (SS), and sham exercise (SE). At 11 wk all rats were sacrificed and analyzed. Compared to sedentary infarct controls, exercise training attenuated left ventricular (LV) dilation and allowed more hypertrophy of the non infarct wall. The exercise-trained hearts also showed a reduction in the estimated peak wall tension. Northern blot analysis showed an increase in beta-myosin heavy chain expression in the hearts of the sedentary infarction group soon after infarction when compared to sham controls. However, with exercise training, there was a significant attenuation of the beta-myosin heavy chain expression in the myocardium. Exercise training in a model of left ventricular dysfunction after healed myocardial infarction can improve the adverse remodeling process by attenuating ventricular dilation and reducing wall tension. The abnormal beta-myosin expression was also attenuated in the exercise trained group. This is evidence that abnormal gene expression following severe myocardial infarction dysfunction can be favorably modified by an intervention.

Quantitating the capillary supply and the response to resistance training in older men

Abstract Resistance training (RT) has been shown to increase aerobic power in older humans. To determine the effects of RT on the capillary supply in this population, nine older men (65–74 y) engaged in 9 weeks RT of the lower body. Following RT, peak O2 uptake (V.O2,peak) increased by 7% (P<.01). Needle biopsies (vastus lateralis muscle) revealed significant increases (mean ± SE) in fibre area (3,874 ± 314 μm2 to 4,778 ± 309 μm2), fibre perimeter (P, 262 ± 11 μm to 296 ± 11 μm), capillary contacts (3.7 ± .2 to 4.3 ± .3) and the individual capillary-to-fibre ratio (C:Fi, 1.33 ± .32 to 1.61 ± .37, P<.005). To evaluate the potential for blood-tissue exchange, both fibre area-based and perimeter-based measures of the capillary supply were compared. While the area-based measures were maintained, C:Fi/P was increased, consistent with an increase in the size of the fibre-capillary interface and thus, an increased potential for oxygen flux following RT. Of the measurements of capillary supply, V.O2,peak correlated best with C:Fi/P (r = 0.69, P<.005). These results indicate a significant increase in the capillary supply relative to the perimeter, but not the cross-sectional area, of the muscle fibres following RT in older men, and that C:Fi/P is strongly correlated to the V.O2,peak in this population.

Aerobic and Resistance Training in Coronary Disease: Single versus Multiple Sets

PURPOSE The purpose of this study was to compare resistance training (RT) (one set vs three sets) combined with aerobic training (AT) versus AT alone in persons with coronary artery disease. METHODS Subjects (n = 72) were randomized to AT (5 d x wk(-1)) or combined AT (3 d x wk(-1)) with either one set (AT/RT1) or three sets (AT/RT3) of RT performed 2 d x wk(-1). VO2peak, ventilatory anaerobic threshold (VAT), strength and endurance, body composition, and adherence were measured before and after 29 wk of training. RESULTS Fifty-three subjects (mean +/- SEM age 61 +/- 2) completed the training. The increase from baseline in VO2peak (L x min(-1)) averaged 11% for AT (P < 0.05), 14% for AT/RT1 (P < 0.01), and 18% for AT/RT3 (P < 0.001), however, the difference between groups was not significant. VAT improved significantly in the AT/RT3 group only (P < 0.05). The AT/RT3 group gained more lean mass than the AT group (1.5 versus 0.4 kg, P < 0.01), yet gains between AT/RT1 and AT were similar (P = 0.2). Only AT + RT groups demonstrated a reduction in body fat (P < 0.05). Strength and endurance increased more in the AT + RT groups than AT alone (P < 0.05). Adherence to number of sets performed was lower in AT/RT3 than AT/RT1 (P < 0.02). CONCLUSIONS Combined AT + RT yields more pronounced physiological adaptations than AT alone and appears to be superior in producing improvements in VO2peak, muscular strength and endurance, and body composition. The data support the use of multiple set RT for patients desiring an increased RT stimulus which may further augment parameters that affect VO2peak, VAT, lower body endurance, and muscle mass in a cardiac population.

The Relationship between Vigorous Physical Activity and Juvenile Delinquency: A Mediating Role for Self-Esteem?

Many policy-related reviews of the potential social value of sport and physical activity list the prevention of juvenile delinquency. We examined the relationships among vigorous physical activity, self-esteem, and delinquent behavior among adolescents in a large cross-sectional survey of Ontario adolescents. Data are based on questionnaires from 3,796 students (range 11–20 years) derived from the 2005 Ontario Student Drug Use Survey. Negative binominal regression methods were used to estimate both additive and interactive models predicting delinquent behavior. Vigorous physical activity was positively associated with delinquent behavior; however, this pattern of association was observed only among male adolescents. There was no evidence of a mediating role for self-esteem. Our findings suggest that physical activity is not the solution for reducing juvenile delinquency.

Evidence-based risk assessment and recommendations for physical activity clearance: established cardiovascular disease 1

Physical activity is an effective lifestyle therapy for patients at risk for, or with, documented cardiovascular disease (CVD). Current screening tools--the Physical Activity Readiness Questionnaire (PAR-Q) and the Physical Activity Readiness Medical Evaluation (PARmed-X)--require updating to align with risk/benefit evidence. We provide evidence-based recommendations to identify individuals with CVD at lower risk, intermediate risk, or higher risk of adverse events when participating in physical activity. Forms of exercise and the settings that will appropriately manage the risks are identified. A computer-assisted search of electronic databases, using search terms for CVD and physical activity risks and benefits, was employed. The Appraisal of Guidelines for Research and Evaluation were applied to assess the evidence and assign a strength of evidence rating. A strength rating for the physical activity participation clearance recommendation was assigned on the basis of the evidence. Recommendations for physical activity clearance were made for specific CVD groups. Evidence indicates that those who are medically stable, who are involved with physical activity, and who have adequate physical ability can participate in physical activity of lower to moderate risk. Patients at higher risk can exercise in medically supervised programs. Systematic evaluation of evidence indicates that clinically stable individuals with CVD may participate in physical activity with little risk of adverse events. Therefore, changes in the PAR-Q should be undertaken and a process of assessment and consultation to replace the PARmed-X should be developed. Patients at lower risk may exercise at low to moderate intensities with minimal supervision. Those at intermediate risk should exercise with guidance from a qualified exercise professional. Patients at higher risk should exercise in medically supervised programs.

Impaired left and right ventricular function following prolonged exercise in young athletes: influence of exercise intensity and responses to dobutamine stress

We examined the effect of intensity during prolonged exercise (PE) on left (LV) and right ventricular (RV) function. Subjects included 18 individuals (mean +/- SE: age = 28.1 +/- 1.1 yr, maximal aerobic power = 55.1 +/- 1.6 ml . kg(-1) . min(-1)), who performed 150 min of exercise at 60 and 80% maximal aerobic power on two separate occasions. Transthoracic echocardiography assessed systolic and diastolic performance, and blood sampling assessed hydration status and noradrenaline levels before (pre), during (15 and 150 min), and 60 min following (post) PE. beta-Adrenergic sensitivity pre- and post-PE was assessed by dobutamine stress. High-intensity PE (15 vs. 150 min) induced reductions in LV ejection fraction (69.3 +/- 1.3 vs. 63.5 +/- 1.3%, P = 0.000), LV strain (-23.5 +/- 0.6 vs. -22.3 +/- 0.6%, P = 0.034), and RV strain (-26.3 +/- 0.6 vs. -23.0 +/- 0.6%, P < 0.01). Both exercise intensities induced diastolic reductions (pre vs. post) in the ratio of septal early wave of annular tissue velocities to late/atrial wave of annular tissue velocities (2.15 +/- 0.15 vs. 1.62 +/- 0.09; 2.21 +/- 0.15 vs. 1.48 +/- 0.10), ratio of lateral early wave of annular tissue velocities to late/atrial wave of annular tissue velocities (3.84 +/- 0.42 vs. 2.49 +/- 0.20; 3.56 +/- 0.32 vs. 2.08 +/- 0.18), ratio of early to late LV strain rate (2.42, +/- 0.16 vs. 1.97 +/- 0.13; 2.30 +/- 0.15 vs. 1.81 +/- 0.11), and ratio of early to late RV strain rate (2.03 +/- 0.17 vs. 1.51 +/- 0.09; 2.16 +/- 0.16 vs. 1.44 +/- 0.11) (P < 0.001). Evidence of beta-adrenergic sensitivity was supported by a decreased strain, strain rate, ejection fraction, and systolic pressure-volume ratio response to dobutamine (P < 0.05) with elevated noradrenaline (P < 0.01). PE-induced reductions in LV and RV systolic function were related to exercise intensity and beta-adrenergic desensitization. The clinical significance of exercise-induced cardiac fatigue warrants further research.

Scope and nature of sudden cardiac death before age 40 in Ontario: A report from the Cardiac Death Advisory Committee of the Office of the Chief Coroner

BACKGROUND Understanding sudden cardiac death in the young may inform prevention strategies. OBJECTIVE To determine the scope and nature of sudden death in a geographically defined population. METHODS We performed a retrospective population-based cohort study in Ontario, Canada, of all sudden cardiac death cases involving persons aged 2-40 years identified from the 2008 comprehensive Coroner database. Of 1741 Coroners cases, 376 were considered potential sudden cardiac death cases and underwent review. RESULTS There were 174 cases of adjudicated sudden cardiac death from a population of 6,602,680 persons aged 2-40 years. Structural heart disease was present in 126 cases (72%), 78% of which was unrecognized. There was no identifiable cause of death in 48 cases (28%), representing primary arrhythmia syndromes. The majority of decedents were men (76%) over the age of 18 (90%). The overall incidence of sudden cardiac death increased with age from 0.7/100,000 (2-18 years) to 2.4/100,000 (19-29 years) to 5.3/100,000 (30-40 years) person-years. Persons experiencing sudden cardiac death before age 30 were more likely to have a primary arrhythmia syndrome (odds ratio 2.97; P<.001). The majority of events occurred in the home (72%); 33% of the events in children/adolescents and 9% of the events in adults occurred during reported moderate or vigorous exercise (P = .002). There were no pediatric deaths during organized competitive sports. CONCLUSIONS The incidence of sudden cardiac death increases with age, typically occurring in a man at rest in the home with unrecognized underlying heart disease or a primary arrhythmia syndrome. Prevention strategies should consider targeting identification of unrecognized structural heart disease and primary arrhythmia syndromes.

Interval and continuous exercise elicit equivalent postexercise hypotension in prehypertensive men, despite differences in regulation

Equicaloric bouts of interval (IE: 5 × 2:2 min at 85% and 40% maximal oxygen uptake) and steady state (SS: 21 min at 60% maximal oxygen uptake) exercise were performed by 13 older prehypertensive males on separate days, at equivalent times of day, to assess the influence of exercise mode on postexercise hypotension (PEH). Exercise conditions were compared with a control session. Cardiovascular measures were collected for 30 min prior to, and 60 min following exercise. PEH, as measured by mean postexercise systolic blood pressure (SBP) decrease (IE: -4 ± 6 mm Hg; SS: -3 ± 4 mm Hg; control: 4 ± 4 mm Hg), area under the SBP curve (IE: -240 ± 353 mm Hg·min; SS: -192 ± 244 mm Hg·min), and minimum SBP achieved (IE: -15 ± 7 mm Hg; SS: -13 ± 7 mm Hg), was equivalent after both conditions. Stroke volume was significantly reduced (IE: -14.6 ± 16.0 mL; SS: -10.1 ± 14.2 mL, control -1.7 ± 2.2 mL) and heart rate was significantly elevated (IE: 13 ± 8 beats·min⁻¹; SS: 7.9 ± 8 beats·min⁻¹; control: -2 ± 3 beats·min⁻¹) postexercise after both conditions. Cardiac output and total peripheral resistance were nonsignificantly decreased and increased postexercise, respectively. Baroreflex sensitivity (BRS) was reduced following IE (p < 0.05) and heart rate variability (HRV) parameters were reduced after both conditions, with IE eliciting larger and longer reductions in some indices. The results from the current study indicate that older prehypertensive adults experience similar PEH following equicaloric bouts of IE and SS exercise despite larger alterations in HRV and BRS elicited by IE.

Central and peripheral adaptations after 12 weeks of exercise training in post-coronary artery bypass surgery patients.

PURPOSE Training adaptations in patients with coronary artery disease (CAD) have been reported previously, but little is known about central and peripheral adaptations in those recovering from coronary artery bypass graft surgery (CABG). The purpose of this study was to examine the effects of 12 weeks of endurance exercise training on exercise performance and left ventricular and peripheral vascular reserve in a group of uncomplicated CABG patients. METHODS Thirty-one patients were recruited and began training 8 to 10 weeks after uncomplicated CABG. Patients underwent progressive exercise training consisting of walking and jogging, at 75% to 80% maximal oxygen intake (VO2max). Measures of left ventricular function included ejection fraction (EF), ventricular volumes, and the pressure volume ratio, an index of contractility. Peak ischemic exercise calf blood flow and vascular conductance was determined using strain-gauge plethysmography. Maximal oxygen intake and submaximal blood lactate concentration also was determined. RESULTS A significant improvement in VO2max (1497 +/- 60 mL/min versus 1691 +/- 71 mL/min) was observed after training. This change was accompanied by an increase in the EF during submaximal exercise (60 +/- 3% versus 63 +/- 2% at 40% VO2max; 61 +/- 3% versus 64 +/- 3% at 70% VO2max) (P < 0.05), and the change in EF from rest to exercise (delta EF). No changes were observed for ventricular volumes during exercise, although there was a trend for a higher stroke volume at 70% VO2max. A significant increase (18%) was observed for peak ischemic exercise calf blood flow and vascular conductance. In addition, submaximal blood lactate concentration was lower after training. CONCLUSIONS These data indicate that exercise training for 12 weeks in patients recovering from CABG can elicit significant improvements in functional capacity that, for the most part, are secondary to peripheral adaptations, with limited support for improvement in left ventricular function.

Exercise with a Twist: Left Ventricular Twist and Recoil in Healthy Young and Middle-Aged Men, and Middle-Aged Endurance-Trained Men

BACKGROUND The contribution of left ventricular (LV) twist and recoil in augmenting stroke volume during exercise is poorly understood, and few data are available describing the impact of endurance exercise on LV twist and recoil in middle-aged individuals. Therefore, the effects of chronic endurance training on these LV indices at rest and during submaximal exercise were examined in healthy, middle-aged untrained (MU) men and age-matched healthy, middle-aged endurance-trained (MT) men and in healthy, young untrained (YU) men as a healthy model. METHODS Two-dimensional echocardiography with speckle-tracking imaging was used to quantify LV twist and recoil in 11 YU (mean age, 24.0 ± 4.1 years), 9 MU (mean age, 54.8 ± 4.3 years), and 12 MT (mean age, 53.8 ± 4.1 years) subjects at supine rest and during submaximal supine cycle ergometry. RESULTS LV twist increased from rest to exercise in YU subjects (8.8 ± 3.8° to 12.8 ± 6.6°, P = .026) but not in MU subjects. LV twist also increased from supine rest to exercise in MT subjects (10.0 ± 3.1° to 13.1 ± 4.1°, P = .046). Time to peak untwisting velocity was significantly delayed in MU subjects during rest and exercise compared with both YU (P = .005 and P = .02, respectively) and MT (P = .018 and P = .045, respectively) subjects. No differences were detected in any of the timing indices of LV twist between YU and MT subjects. CONCLUSIONS This response pattern may help explain the mechanism underlying the training-induced augmentation in stroke volume during exercise, particularly the importance of the timing of key LV events that contribute to enhanced diastolic performance seen after endurance training.