Claude Lajoie

Female Rats Fed a High-Fat Diet Were Associated with Vascular Dysfunction and Cardiac Fibrosis in the Absence of Overt Obesity and Hyperlipidemia: Therapeutic Potential of Resveratrol

It remains presently unknown whether vascular reactivity is impaired and whether maladaptive cardiac remodeling occurs before the onset of overt obesity and in the absence of hyperlipidemia. Normal female rats were fed a high-fat diet for 8 weeks and were associated with a modest nonsignificant increase of body weight (standard diet, 300 ± 10, versus high-fat diet, 329 ± 14 g) and a normal plasma lipid profile. In rats fed a high-fat diet, systolic (171 ± 7 mm Hg) and diastolic blood pressures (109 ± 3) were increased compared to a standard diet (systolic blood pressure, 134 ± 8; diastolic blood pressure, 96 ± 5 mm Hg), and acetylcholine-dependent relaxation of isolated aortic rings (high-fat diet, 22 ± 5%, versus standard diet, 53 ± 8%) was significantly reduced. Furthermore, perivascular fibrosis was detected in the heart of rats fed a high-fat diet. The exogenous addition of resveratrol (trans-3,5,4′-trihydroxystilbene) (0.1 μM) to aortic rings isolated from rats fed a high-fat diet restored acetylcholine-mediated relaxation (47 ± 9%). The administration of resveratrol (20 mg/kg/day for 8 weeks) to rats fed a high-fat diet prevented the increase in blood pressure and preserved acetylcholine-dependent relaxation of isolated aortic rings. However, resveratrol therapy failed to attenuate the perivascular fibrotic response. These data have demonstrated that a high-fat diet fed to normal female rats can elicit a hypertensive response and induce perivascular fibrosis before the development of overt obesity and in the absence of hyperlipidemia. Resveratrol therapy can prevent the hypertensive response in female rats fed a high-fat diet but is without effect on the progression of perivascular fibrosis.

Greater physical fitness is associated with better air ventilation efficiency in firefighters.

Firefighting is a hazardous task associated with a heavy workload where task duration may be limited by air cylinder capacity. Increased fitness may lead to better air ventilation efficiency and task duration at a given heavy work intensity. This study compared performance, air ventilation and skeletal muscle oxygen extraction during a maximal graded walking test (GWT), a 10 METS (metabolic equivalent) treadmill test (T10) and a simulated work circuit (SWC). Participants (n = 13) who performed the SWC in a shorter time had significantly lower air cylinder ventilation values on the T10 (r = -0.495), better peak oxygen consumption (r = -0.924) during the GWT and significantly greater skeletal muscle oxygen extraction during the SWC (HbDiff, r = 0.768). These results demonstrate that the fastest participants on the SWC had better air ventilation efficiency that could prolong interventions in difficult situations requiring air cylinder use.

Energy expenditure at work in physical education teachers

The objective of this study was to quantify work energy expenditure (EE) in physical education (PE) teachers. Sixty-four (64) physical educators (49 men, 15 women) had their individualized linear function between heart rate (HR) and oxygen consumption measured by laboratory testing. HR was then recorded on 2 different days at work to estimate EE, correlated with a diary of daily tasks. Average absolute EE was low-to-moderate (2.7 ± 1.4 to 4.6 ± 2.5 kcal·min(-1)) and low when expressed in relative values (15.3 ± 6.1% to 24.8 ± 7.6% of VO2max). However, these physical educators often reached very high intensities (from 7.5 ± 7.9% to 23.8 ± 22.3% of work time at 100 bpm and more). PE teaching requires a light-to-moderate EE with more intense periods of physical activity. The variety of tasks performed (office work, supervision and monitoring, mixed participation and active participation) significantly influenced EE.

Cardiovascular disease risk in female firefighters

Background Female firefighters are in the minority in the Québec firefighter population and worldwide. To our knowledge, no study has focused on cardiovascular risk factors in female firefighters, and further research in this area is needed to evaluate and reduce the risk of on-duty sudden cardiac death. Aims To evaluate the prevalence of cardiovascular disease (CVD) risk factors in female firefighters in Québec. Methods A cross-sectional study using an online questionnaire to evaluate lifestyle and CVD risk factors and symptoms. Results Forty-one female firefighters (age: 38.2 ± 9.9 years) participated in this study, representing ~7% of all female Québec firefighters. The prevalence of obesity (body mass index ≥ 30 kg/m2), hypertension, dyslipidaemia, type 2 diabetes mellitus, smoking and physical inactivity was 12% (95% confidence interval [CI] 4-26%), 5% (95% CI 0.6-19%), 5% (95% CI 0.6-19%), 3% (95% CI 0.1-14%), 14% (95% CI 5-29%) and 62% (95% CI 5-7%), respectively. Among survey participants, 76% (59-88%) had moderate to high CVD risk according to the 2013 American College of Sports Medicine guidelines. Eighty-two per cent of participants did not meet the National Fire Protection Associations required cardiorespiratory fitness standard of 12 metabolic equivalents. Conclusions A high proportion of female firefighters in this study were at moderate to high risk of CVD. These findings suggest that they would benefit from healthy lifestyle initiatives.

Physiological and Psychological Adaptations of Trained Cyclists to Spring Cycling Camps

Abstract The purpose of our study was to assess physiological adaptations and measure mood outcomes following a cycling training camp in competitive athletes. Fourteen competitive athletes (8 males, 6 females) performed 2 incremental tests to exhaustion before and after a training camp. Volume and intensity (load) of the training regimen were recorded. Submaximal and maximal metabolic data were analysed, as well as economy variables (gross mechanical efficiency and cycling economy). Skeletal muscle adaptations were assessed using near infrared spectroscopy (NIRS). For both genders (n = 14), peak power output, peak power output-W/kg ratio and peak power output-B[La] were significantly increased (p < 0.05) after the cycling training camp (p < 0.05). Significant increases occurred for gross mechanical efficiency measured at the lactate threshold (+4.9%) and at the same precamp lactate threshold power output (+2.9%). At the lactate threshold and Post Camp Lactate Threshold Power, cycling economy increased by 5.2 and 2.9%, respectively (p < 0.05). These power measurements were significantly correlated with individual fluctuations in deoxyhaemoglobin in the vastus lateralis for male cyclists only. Profile of Mood State questionnaire results showed that subcategories “Tension-Anxiety”, “Confusion”, “Fatigue” and “Total Global Score” significantly decreased after the training camp. Cycling training camps were associated with positive adaptations (increased cycling economy, gross mechanical efficiency and power output) as well as some mental benefits. This indicates that despite some significant physiological adaptations participants probably did not overreach during their CTC.

Cardiovascular Health Profile Among QuéBec Male And Female Police Officers

Abstract To document the cardiovascular health profile of Québec police officers (PO). Participants answered an online questionnaire evaluating the presence of cardiovascular disease (CVD) risk factors and symptoms. Two thousand, ninety-nine (2,099) male (age: 40.8 ± 9.2 years) and 756 female (age: 37.9 ± 7.9 years) PO participated in this study. The prevalence of obesity (body mass index ≥30 kg/m2) and diagnosed hypertension was respectively 21.1, and 14.3% in male and 7.3 and 4.1% in female PO. According to 2013 American College of Sports Medicine guidelines, 27.0 and 48.0% of male and 12.1 and 56.7% of female PO were categorized as being at moderate and high CVD risk, respectively. These findings suggest that Québec police departments should help PO to adopt and maintain a healthy lifestyle to decrease CVD risk.

Relationship between performance, air ventilation efficiency and muscle oxygenation in Firefighters

Firefighting is a hazardous task associated with a heavy workload where task duration may be limited by air cylinder capacity. Increased fitness may lead to better air ventilation efficiency and task duration at a given heavy work intensity.