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Canadian Cardiovascular Society (CCS) Poster PREVENTION POSTER SESSION II Monday, October 27, 2014 489 AN EXAMINATION OF ACCELEROMETER CUT-POINTS FOR QUANTIFYING PHYSICAL ACTIVITY IN CARDIAC POPULATIONS
Canadian Journal of Cardiology Volume 30 2014
recommendations. Caution should be applied when deciding on the appropriate cut-points to use in a clinical population with lower cardiorespiratory fitness. CIHR, HSF
SA Prince, JL Reed, AE Mark, C Blanchard, S Grace, R Reid
490 HIGH INTENSITY AEROBIC INTERVAL EXERCISE IN HEALTHY YOUNG AND OLDER ADULTS: HEMODYNAMIC AND SKELETAL MUSCLE SUBSTRATE USE
Ottawa, Ontario
J Larouche, E Thorin, M Juneau, M Gayda, A Nigam
BACKGROUND:
Montréal, Québec
Accurate measurement of physical activity (PA) is necessary to monitor trends, assess relations with health and measure adherence to PA guidelines. While accelerometers provide accurate measures of PA they rely on validated cut-points to quantify time spent in light, moderate and vigorous intensities. Cut-points have largely been established using healthy populations; however, accelerometer output can differ based on cardiorespiratory fitness, suggesting that among individuals with compromised functioning such as those with coronary artery disease (CAD); these cut-points may lead to a misclassification of intensity. The objective of this study was to compare well-known and widely used cut-points (Sasaki) derived from healthy adults with those developed in a CAD population (Mark). METHODS: Two-hundred and thirty-one adults with CAD (mean SD: 63.7 9.2 years) wore an ActiGraph GT3X accelerometer for a minimum of 4 consecutive days and 10 hours/day. Daily time spent in moderate-to-vigorous PA (MVPA) was compared using two cut-point definitions: Mark (58.3 10.7 years, mean vO2peak ¼ 29.5 7.6 mL/kg/min) and Sasaki (28.0 9.0 years, vO2peak 31.5 mL/kg/min). Vector magnitude was used to quantify time spent in light (Mark: 151-1799, Sasaki: 151-2689cpm), moderate (1800-3799, 26906166cpm) and vigorous (3800, 6167cpm) PA. Paired t-tests, linear regression and Bland-Altman analyses assessed mean differences and agreement between cut-points at each PA level. Spearman correlation assessed relations between MVPA from each cut-point with vO2peak, waist circumference, BMI, blood pressure, triglycerides, total cholesterol, HDL and LDL. RESULTS: Daily minutes of MVPA were highly correlated between the cut-points (r¼0.90, p<0.0001). Average minutes/day spent in MVPA was significantly greater using the Mark rather than Sasaki cut-points (86.3 40.4 vs. 44.1 26.0, p<0.0001). The 95% limits of agreement ranged from 1.8 to 82.5 minutes/ day and indicated a systematic difference with greater positive mean differences with increasing amounts of MVPA. MVPA from both cut-points were similarly correlated with vO2peak (Mark: r¼0.37, Sasaki: r¼0.43; p<0.0001). MVPA was significantly associated with diastolic blood pressure, total cholesterol, and LDL for the Mark cut-points only (p0.05). CONCLUSION: CAD-specific cut-points classify greater quantities of MVPA compared to those developed in a healthy adult population and show better correlation with some cardio-metabolic outcomes. Large limits of agreement suggest that differences in cut-points will have a significantly large effect on the number of individuals who meet daily PA ̇ ̇
BACKGROUND:
Hemodynamic responses and skeletal muscle substrate use during high-intensity interval exercise (HIIE) compared to during moderate-intensity continuous exercise (MICE) are poorly documented in healthy young (YA) and older adults (OA). METHODS: Twenty young healthy subjects (285 years) and twenty older healthy subjects (617 years) performed a maximal cardiopulmonary exercise test, HIIE and MICE sessions with gas exchange and hemodynamic measurements. HIIE consisted of two blocks of 10 minutes of 15-second intervals at 100% of maximal aerobic power (MAP) interspersed with15-second passive recovery intervals. MICE consisted of two 10-minute blocks of continuous exercise at 60% of MAP. RESULTS: Cardiac Index and SVi were significantly higher in YA vs. OA (CI and SVi: p<0.01) in both sessions. Glucose oxidation was higher in YA vs. OA in HIIE (41.068.89 vs. 35.139.17, mg/min/LBM; p<0.001) and MICE (44.566.68 vs. 36.796.6, p<0.001). Higher CHO oxidation (p<0.05) was found in the MICE session for both groups. Energy expenditure (cal/min/LBM) was higher in YA vs. OA for both exercise mode (p<0.0001). CONCLUSION: Healthy aging is associated with a reduced hemodynamic function and ability to oxidize glucose during exercise. Exercise modality has an influence on glucose oxidation, this oxidation being lower during high-intensity interval exercise with passive recovery. High-intensity interval exercise is more efficient; a similar energy expenditure and half the pedaling time.
491 CEREBRAL OXYGENATION/PERFUSION, CARDIOPULMONARY AND HEMODYNAMIC RESPONSES DURING MAXIMAL INCREMENTAL EXERCISE IN HEART TRANSPLANT RECIPIENTS VS. HEALTHY CONTROL SUBJECTS A Desjardins, A Nigam, M Juneau, G Lapierre, M White, V Gremeaux, M Gayda Montréal, Québec BACKGROUND:
VO2 peak is one of the best predictors of mortality and is the best criteria in heart transplantation for identifying patients likely to derive a survival benefit from this intervention.VO2 peak has been shown to be positively correlated with cerebral perfusion.
Abstracts
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Objective: 1) To compare VO2 peak, cardiac output (CO) and cerebral oxygenation/perfusion (COP) in heart transplant recipients (HTR) and age-matched controls (AMC) during maximal exercise (ME), 2) to study the relationships between VO2 peak, CO, COP in HTR and AMC. 27 AMC and 26 HTR were recruited. VO2 peak and cardiac hemodynamic (impedance cardiography) were measured during a ME. COP (O2Hb, tHb) was measured using near-infrared spectroscopy (NIRS). RESULTS: Compared to AMC, HTR had a lower VO2 peak (ml/min/kg of lean body mass), maximal (max) cardiac index (CImax), max ventilation, max tidal volume and max respiratory frequency vs. AMC (P<0,0001). End-systolic volume index and systemic vascular resistance index were higher in HTR (P<0,05). At 50% and 75% of peak, O2Hb was lower in HTR (P<0,05). At 100% of peak, tHb was lower in HTR (P<0,05). At recovery, O2Hb and tHb were lower in HTR (P<0,05). VO2 peak (ml/ min/kg) and CImax were correlated to DO2Hb (R¼0,33 and 0,36, P<0,05) and DtHb (R¼0,35 and 0,44, P<0,01). CONCLUSION: VO2 peak is reduced in HTR because of central, ventilator, peripheral factors and medication. Lower VO2 peak and CImax in HTR does not seem to really affect COP during exercise. During exercise, our results suggest a lower O2 saturation in HTR. In HTR, the lower tHb at ME could be due to a better physical capacity in AMC. In HTR, differences in COP during recovery could be explained by the absence of cardiac overshoot phenomenon, medication and/or endothelial dysfunction.
end-diastolic volume indexes (P<0.05), but the DHHb was lower in OB (P<0.05). Cognitive function was similar between groups when defining obesity as % body fat. VO2 peak was related to cognitive functions (short term-working memory, processing speed, inhibition and mental flexibility: R¼-0.32 to 0.43, P<0.05) but not cardiac index (CI). CONCLUSION: 1) OB subjects have a lower VO2 peak (including VO2 peak adjusted for lean body mass) compared to AMCH, indicating lower cardiorespiratory fitness. 2) Cognitive function was similar between groups when defining obesity as % body fat. However, visceral adiposity defined by % of trunk fat mass correlated significantly with short-term memory(Forward Empan), inhibition and mental flexibility (stroop 3 and stroop 4). 3) Because of similar DO2Hb during exercise between groups and because DHHb (mM) was significantly reduced in OB, these results suggest a reduced O2Hb extraction in OB. However, reduced DHHB in OB was not associated with impaired cognitive function. 4) In all subjects, parameters assessing the main executive functions were correlated to VO2 peak but not the CO or CI.
492 CEREBRAL OXYGENATION/PERFUSION, CARDIAC HEMODYNAMICS DURING EXERCISE AND COGNITIVE FUNCTIONS IN OBESE PATIENTS
P Sosner, M Gayda, G Mitchell, J Lalongé, M Juneau, J Tardif, A Nigam
METHODS:
G Lapierre, O Dupuis, S Frazer, L Bherer, V Labelle, M Juneau, V Gremeaux, M Gayda Montréal, Québec BACKGROUND:
Obesity is associated with an accelerated rate of cognitive decline in memory, attention, processing speed and executive functions resulting in a higher risk of dementia and Alzheimer’s disease (AD) in later life. In cardiac patients showing mild cognitive impairments, cerebral O2Hb correlates with VO2 peak and left ventricular ejection fraction, reflecting a link between cardiac output and cerebral O2Hb during maximal exercise. METHODS: Objectives:1) To compare cerebral oxygenation/ perfusion (COP), central hemodynamics, VO2 peak and cognitive functions in obese patients (OB) and age-matched healthy controls (AMHC) 2) to study the relationships between VO2 peak, cardiac output (CO),cognitive functions in OB. 21 AMHC and 33 OB subjects were recruited. VO2 peak (ml/min/ LBM), cardiac hemodynamics (impedance cardiography) and COP (near-infrared spectroscopy) were measured during a maximal incremental ergocycle test. Cognitive function assessments (standard battery, paper-pen tests) included: short termworking memory, perceptual abilities, processing speed, inhibition and mental flexibility and long-term verbal memory. RESULTS: Compared to AMHC, OB had a lower VO2 peak, lower ejection fraction (EF%), and higher end-systolic and
493 STATIN THERAPY DECREASES VO2PEAK WITHOUT AFFECTING EXERCISE ENDURANCE, ENDOTHELIAL FUNCTION OR ARTERIAL STIFFNESS AMONG SUBJECTS WITH PRIMARY UNTREATED HYPERCHOLESTEROLEMIA
Montréal, Québec BACKGROUND: Statin therapy may have beneficial effects on conduit vessel compliance and endothelial function. We sought to study the effect of statin therapy on endothelial function, aortic stiffness, and its potential impact on VO2peak and submaximal exercise endurance. METHODS: In this double-blind, placebo-controlled trial, 20 patients with primary untreated hypercholesterolemia and free of cardiovascular disease (5610 years, 12 men, BMI: 274 kg/m2, blood pressure: 126/7812/5 mm Hg) were randomized 1:1 to pravastatin 40 mg daily or placebo for 12 weeks. Endothelial function (flow mediated dilatation (FMD)), aortic stiffness (carotid-femoral pulse wave velocity (cfPWV)), VO2peak on a maximal exercise test and submaximal endurance time were measured. RESULTS: In pre/post comparisons in statin group, we observed a decrease in LDL-cholesterol (4.490.34 vs. 3.030.73 mmol/L, P¼0.01, g¼0.79), no change in FMD (7.03.7 vs. 10.14.7 %, P¼0.12, g¼-0.34), cfPWV (7.691.87 vs. 8.282.17 m/s, P¼0.17, g¼-0.14) or submaximal exercise duration (1326649 vs. 1230862 sec, P¼0.67, g¼0.06), but a decrease in VO2peak that was unchanged in placebo group (Figure 1). CONCLUSION: In patients with previously untreated hypercholesterolemia, 12-weeks of statin therapy had deleterious effects on cardiorespiratory fitness assessed by VO2peak.