Laura Banks

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.

Promoting positive body image among university students: A collaborative pilot study.

The purpose of the present study was to pilot a prevention program designed to promote positive body image among university students. Thirty-seven undergraduate students from three Canadian universities were recruited to participate in the study. They were selected from a pool of students enrolled in a peer health education program facilitated by the university-based health promotion staff. Borrowing from the tenets of the non-specific vulnerability stressor model and the disease-specific social cognitive theory, the intervention focused on media literacy, self-esteem enhancement strategies, stress management skills and ways to recognize healthy versus unhealthy relationships. Separate ANOVAs revealed that participants reported significant improvements in body satisfaction and reductions in the internalization of media stereotypes between the baseline and post-program period. The program received a favorable response from the participating students, who appreciated the face-to-face format of the intervention, and from the university staff who expressed interest in embedding the strategies into their routine peer mentoring training activities. Limitations of the study and suggestions for future research are discussed.

Blood pressure reduction following prolonged exercise in young and middle-aged endurance athletes

Background: Previous studies examining the relationship between exercise dose and post-exercise hypotension (PEH) have employed a limited range of exercise duration and subject age. We extended the dose–response curve by studying two intensities of prolonged exercise that may produce a greater magnitude of PEH and reveal age differences in the exercise dose–response relationship for PEH. Methods: Two groups of healthy recreational endurance athletes were studied: Young (n = 17; age 28 ± 1.1 years) and middle-aged participants (n = 18; 52 ± 0.90 years). They performed on separate occasions, 120 min of prolonged exercise (running) at moderate (60% VO2max) and high intensities (80% VO2max). Results: PEH after 1 hour of recovery was similar within each age group for either exercise intensity, but was significantly greater in the middle-aged group (moderate intensity, −12.3 ± 1.6 mmHg; high intensity, −15.1 ± 1.7 mmHg) compared with the young group (moderate intensity, −1.2 ± 1.7 mmHg; high intensity, −5.7 ± 2.5 mmHg; p < 0.05). Stepwise regression showed that baseline blood pressure but not age was significantly related to the degree of PEH. Thus, the greater PEH seen in the middle-aged group is attributed to their higher baseline blood pressure (124 ± 3.0/79 ± 2.0 mmHg) than the young group (111 ± 2.0/69 ± 1.8 mmHg). A reduced total peripheral resistance following exercise was the primary contributor to PEH across both age groups and exercise intensities. Conclusions: We conclude that prolonged exercise induces a significant PEH regardless of exercise intensity.

The Acute Risks of Exercise in Apparently Healthy Adults and Relevance for Prevention of Cardiovascular Events.

BACKGROUND Increased physical activity (PA) is associated with improved quality of life and reductions in cardiovascular (CV) morbidity and all-cause mortality in the general population in a dose-response manner. However, PA acutely increases the risk of adverse CV event or sudden cardiac death (SCD) above levels expected at rest. We review the likelihood of adverse CV events related to exercise in apparently healthy adults and strategies for prevention, and contextualize our understanding of the long-term risk reduction conferred from PA. METHODS A systematic review of the literature was performed using electronic databases; additional hand-picked relevant articles from reference lists and additional sources were included after the search. RESULTS The incidence of adverse CV events in adults is extremely low during and immediately after PA of varying types and intensities and is significantly lower in those with long-standing PA experience. The risk of SCD and nonfatal events during and immediately after PA remains extremely low (well below 0.01 per 10,000 participant hours); increasing age and PA intensity are associated with greater risk. In most cases of exercise-related SCD, occult CV disease is present and SCD is typically the first clinical event. CONCLUSIONS Exercise acutely increases the risk of adverse CV events, with greater risk associated with vigorous intensity. The risks of an adverse CV event during and immediately after exercise are outweighed by the health benefits of vigorous exercise performed regularly. A key challenge remains the identification of occult structural heart disease and inheritable conditions that increase the chances of lethal arrhythmias during exercise.

L-Arginine Affects Aerobic Capacity and Muscle Metabolism in MELAS (Mitochondrial Encephalomyopathy, Lactic Acidosis and Stroke-Like Episodes) Syndrome

Objective To study the effects of L-arginine (L-Arg) on total body aerobic capacity and muscle metabolism as assessed by 31Phosphorus Magnetic Resonance Spectroscopy (31P-MRS) in patients with MELAS (Mitochondrial Encephalomyopathy with Lactic Acidosis and Stroke-like episodes) syndrome. Methods We performed a case control study in 3 MELAS siblings (m.3243A>G tRNAleu(UUR) in MTTL1 gene) with different % blood mutant mtDNA to evaluate total body maximal aerobic capacity (VO2peak) using graded cycle ergometry and muscle metabolism using 31P-MRS. We then ran a clinical trial pilot study in MELAS sibs to assess response of these parameters to single dose and a 6-week steady-state trial of oral L-Arginine. Results At baseline (no L-Arg), MELAS had lower serum Arg (p = 0.001). On 31P-MRS muscle at rest, MELAS subjects had increased phosphocreatine (PCr) (p = 0.05), decreased ATP (p = 0.018), and decreased intracellular Mg2+ (p = 0.0002) when compared to matched controls. With L-arginine therapy, the following trends were noted in MELAS siblings on cycle ergometry: (1) increase in mean % maximum work at anaerobic threshold (AT) (2) increase in % maximum heart rate at AT (3) small increase in VO2peak. On 31P-MRS the following mean trends were noted: (1) A blunted decrease in pH after exercise (less acidosis) (2) increase in Pi/PCr ratio (ADP) suggesting increased work capacity (3) a faster half time of PCr recovery (marker of mitochondrial activity) following 5 minutes of moderate intensity exercise (4) increase in torque. Significance These results suggest an improvement in aerobic capacity and muscle metabolism in MELAS subjects in response to supplementation with L-Arg. Intramyocellular hypomagnesemia is a novel finding that warrants further study. Classification of Evidence Class III evidence that L-arginine improves aerobic capacity and muscle metabolism in MELAS subjects. Trial Registration ClinicalTrials.gov NCT01603446.

Enhanced Physiology for Submaximal Exercise in Children after the Fontan Procedure.

PURPOSE After the Fontan procedure, children exhibit reduced peak exercise capacity, yet their submaximal exercise response remains unclear. This study sought to determine the relationship between submaximal and peak exercise capacity and physical activity in Fontan patients. METHODS This cross-sectional study recruited 50 Fontan patients (59% males) with a median age of 9 yr (range = 6-12 yr). The median age at Fontan procedure was 2.9 yr (range = 1.6-9.1 yr). Study assessments included medical history, exercise testing, and accelerometry. RESULTS Significantly lower submaximal oxygen consumption (V˙O2) and HR in response to a standardized workload than published values for healthy children (mean ± SD) of -1.72 ± 5.24 (P < 0.001) and -1.45 ± 1.98 (P < 0.001), respectively, suggest enhanced submaximal work efficiency in this group of patients after Fontan. Higher submaximal V˙O2 z-score was associated with higher submaximal HR z-score (P = 0.02) and lower body mass index z-score (P = 0.01). Higher V˙O2peak was associated with higher submaximal V˙O2 z-score (P < 0.01), male sex (P = 0.03), higher RER (P = 0.02), lower submaximal HR z-score (P < 0.01), and higher chronotropic responsiveness (P < 0.0001). Exercise test duration z-score was associated with lower submaximal HR z-score (P = 0.02) and higher chronotropic responsiveness (P = 0.02). CONCLUSIONS Fontan patients exhibited a lower submaximal V˙O2 and HR responsiveness at a given workload than healthy controls did during standardized exercise testing. Thus, they may be better adapted to perform submaximal exercise. Although peak exercise capacity is limited, Fontan patients are able to perform submaximal physical activities at the same level as their healthy peers.

Factors associated with low physical activity levels following pediatric cardiac transplantation

Banks L, Dipchand AI, Manlhiot C, Millar K, McCrindle BW. Factors associated with low physical activity levels following pediatric cardiac transplantation.

Cardiac energy metabolism is positively associated with skeletal muscle energy metabolism in physically active adolescents and young adults

(31)Phosphorus Magnetic Resonance Spectroscopy ((31)P MRS) is a well-validated, noninvasive magnetic resonance imaging technique that has been used to determine cardiac and skeletal muscle energy metabolism in vivo. Few studies have documented cardiac energy metabolism in adolescents and young adult cohorts. This cross-sectional study sought to explore the association among cardiac energy metabolism, skeletal muscle energy metabolism, moderate-to-vigorous physical activity (MVPA), and age in adolescents and young adults. Ten healthy, active participants (40% male) with a mean ± SD age of 18.6 ± 4.9 years, body mass index of 21.1 ± 2.4 kg·m(-2), and median MVPA level of 83 min per weekday (lower quartile: 45 min per weekday; upper quartile: 114 min per weekday) completed the following study assessments: a (31)P MRS scan to determine cardiac and skeletal muscle energy metabolism, cardiopulmonary exercise testing to determine aerobic power, and accelerometry to determine MVPA over 7 days. Resting cardiac energy metabolism, as measured by the ratio of phosphocreatine to adenosine triphosphate (PCr/ATPβ, mean ± SD: 2.76 ± 0.65), was positively associated with skeletal muscle aerobic oxidative function (Estimate (SE): -0.1(0.01), p < 0.001), as measured by PCr recovery half-time following 60 s of exercise (34 ± 9 s). This association, which was adjusted for peak aerobic power, MVPA, age, and sex, suggests the development of an association between cardiac and skeletal muscle health at any early age. Larger studies are needed to establish normative data for both physically active and sedentary males and females that may be used for comparison in future studies involving clinical cohorts.

Factors Associated With Low Moderate-to-Vigorous Physical Activity Levels in Pediatric Patients With Kawasaki Disease

Background/Methods We sought to determine functional health status and physical activity determinants in 27 patients with Kawasaki disease (KD; 20 males, 11 ± 3 years old). Patient physical activity data were compared with a population-based study of healthy children (Canadian Health Measures Survey). Results KD patients performed less moderate-to-vigorous physical activity (MVPA) than healthy children (males, 27 vs 61 min/d, P < .001; females, 10 vs 47 min/d, P < .001). Male KD patients performed more MVPA than female KD patients (median = 27; quartiles [Q1 15, Q3 26] min/d vs 10 [Q1 7, Q3 11] min/day, P = .009). Lower MVPA in KD patients was significantly associated with female gender; lower child self-efficacy score; lower Child Health Questionnaire (CHQ-PF50) scores for role functioning behavioral issues, physical functioning, and family cohesion; and higher CHQ-PF50 scores for self-esteem and family activity limitations. Conclusion Physical activity counseling should be a focus of management for children with a history of KD.

Cardiac function following prolonged exercise: influence of age

This study sought to determine the influence of age on the left ventricular (LV) response to prolonged exercise (PE; 150 min). LV systolic and diastolic performance was assessed using echocardiography (ECHO) before (pre) and 60 min following (post) exercise performed at 80% maximal aerobic power in young (28 ± 4.5 years; n = 18; mean ± SD) and middle-aged (52 ± 3.9 years; n = 18) participants. LV performance was assessed using two-dimensional ECHO, including speckle-tracking imaging, to determine LV strain (LV S) and LV S rate (LV SR), in addition to Doppler measures of diastolic function. We observed a postexercise elevation in LV S (young: -19.5 ± 2.1% vs. -21.6 ± 2.1%; middle-aged: -19.9 ± 2.3% vs. -20.8 ± 2.1%; P < 0.05) and LV SR (young: -1.19 ± 0.1 vs. -1.37 ± 0.2; middle-aged: -1.20 ± 0.2 vs. -1.38 ± 0.2; P < 0.05) during recovery in both groups. Diastolic function was reduced during recovery, including the LV SR ratio of early-to-late atrial diastolic filling (SR(e/a)), in young (2.35 ± 0.7 vs. 1.89 ± 0.5; P < 0.01) and middle-aged (1.51 ± 0.5 vs. 1.05 ± 0.2; P < 0.01) participants, as were conventional indices including the E/A ratio. Dobutamine stress ECHO revealed a postexercise depression in LV S in response to increasing dobutamine dose, which was similar in both young (pre-exercise dobutamine 0 vs. 20 μg·kg(-1)·min(-1): -19.5 ± 2.1 vs. -27.2 ± 2.2%; postexercise dobutamine 0 vs. 20 μg·kg(-1)·min(-1): -21.6 ± 2.1 vs. -23.7 ± 2.2%; P < 0.05) and middle-aged participants (pre: -19.9 ± 2.3 vs. -25.3 ± 2.7%; post: -20.8 ± 2.1 vs. -23.5 ± 2.7; P < 0.05). This was despite higher noradrenaline concentrations immediately postexercise in the middle-aged participants compared with young (4.26 ± 2.7 nmol/L vs. 3.00 ± 1.4 nmol/L; P = 0.12). These data indicate that LV dysfunction is observed following PE and that advancing age does not increase the magnitude of this response.