Cardiac and respiratory muscle responses to dietary N-acetylcysteine in rats consuming a high-saturated fat, high-sucrose diet.

NEW FINDINGS: What is the central question of this study? This study addresses whether a high-fat, high-sucrose diet causes cardiac and diaphragm muscle abnormalities in male rats and whether supplementation with the antioxidant N-acetylcysteine reverses diet-induced dysfunction. What is the main finding and its importance? N-Acetylcysteine attenuated the effects of high-fat, high-sucrose diet on markers of cardiac hypertrophy and diastolic dysfunction, but neither high-fat, high-sucrose diet nor N-acetylcysteine affected the diaphragm. These results support the use of N-acetylcysteine to attenuate cardiovascular dysfunction induced by a 'Western' diet. ABSTRACT: Individuals with overweight or obesity display respiratory and cardiovascular dysfunction, and oxidative stress is a causative factor in the general aetiology of obesity and of skeletal and cardiac muscle pathology. Thus, this preclinical study aimed to define diaphragmatic and cardiac morphological and functional alterations in response to an obesogenic diet in rats and the therapeutic potential of an antioxidant supplement, N-acetylcysteine (NAC). Young male Wistar rats consumed ad libitum a 'lean' or high-saturated fat, high-sucrose (HFHS) diet for ∼22 weeks and were randomized to control or NAC (2 mg/ml in the drinking water) for the last 8 weeks of the dietary intervention. We then evaluated diaphragmatic and cardiac morphology and function. Neither HFHS diet nor NAC supplementation affected diaphragm-specific force, peak power or morphology. Right ventricular weight normalized to estimated body surface area, left ventricular fractional shortening and posterior wall maximal shortening velocity were higher in HFHS compared with lean control animals and not restored by NAC. In HFHS rats, the elevated deceleration rate of early transmitral diastolic velocity was prevented by NAC. Our data showed that the HFHS diet did not compromise diaphragmatic muscle morphology or in vitro function, suggesting other possible contributors to breathing abnormalities in obesity (e.g., abnormalities of neuromuscular transmission). However, the HFHS diet resulted in cardiac functional and morphological changes suggestive of hypercontractility and diastolic dysfunction. Supplementation with NAC did not affect diaphragm morphology or function but attenuated some of the cardiac abnormalities in the rats receiving the HFHS diet.

Role of Cross-training in Orthopaedic Injuries and Healthcare Burden in Masters Swimmers.

We determined whether the incidence of injuries would increase with advancing age and whether the participation in cross-training would be related to a decreased rate of injuries and healthcare costs in Masters swimmers. A total of 499 swimmers (55±14 years of age) belonging to US Masters Swimming completed a comprehensive questionnaire that included questions regarding their medical history as well as their training history. In average, swimmers had been training for 13±12 years, and 35, 40, and 47% participated in running, cycling, and dryland resistance training, respectively. According to the logistic regression, prevalence of injuries increased significantly but modestly with advancing age (p<0.05). Linear regression analysis showed that for every 1 month increase in the length of injury, healthcare costs increased by 7.4% (p<0.05). Linear regression and logistic regression analyses determined that overall volume of swimming training was not related to age or incidence of injuries, respectively. Multinomial logistic regression analyses using age and sex as predictors demonstrated that the odds of reporting a swim-related injury were significantly lower for individuals who participated in any number of cross-training activities compared with those who do not cross-train (p<0.05). Regular participation in any cross-training modality was inversely related to age (p<0.05). We concluded that the diversification of the overall training program by incorporating cross-training may be an important strategy to reduce sport-specific injuries among Masters athletes.

Age-related Changes in Training Stimuli and Performance in Masters Swimmers.

Age-related decreases in performance are thought to be driven by decreases in exercise training stimuli. We determined the influence of changes in training stimuli with advancing age on swimming performance using cross-sectional and longitudinal data analyses. Totals of 692 and 98 competitive swimmers belonging to the US Masters Swimming Association were analyzed in cross-sectional and longitudinal analyses. Swimming times increased with advancing age, and age was the strongest predictor of swimming performance, followed by training volume, in both the cross-sectional and longitudinal analyses. In the cross-sectional data analyses, an increase in training volume by 10 km/month, was associated with improved performance by 0.69 s regardless of age. In the longitudinal analyses, training volume was not a significant predictor for younger swimmers. In middle-aged swimmers, however, increases in training volume resulted in faster swimming times, and its effect was more pronounced in older swimmers. We concluded that there was a graded positive relationship between yearly increases in training volume and improved swimming performance, and that such effects were greater with advancing age.

Effects of sleep deprivation on endothelial function in adult humans: a systematic review.

Sleep deprivation is highly prevalent and is associated with increased cardiovascular disease (CVD) morbidity and mortality. Age-related alterations in sleep and chronobiology may exaggerate CVD susceptibility in older individuals. The mechanisms responsible for the association between sleep deprivation and CVD are not fully understood, but endothelial dysfunction may play a central role. Our objective was to conduct a systematic literature review to evaluate the evidence on the effects of sleep deprivation on endothelial function (EF). This review adhered to the PRISMA guidelines and was pre-registered with PROSPERO (#CRD42020192485, 07/24/2020). We searched PubMed, Web of Science, Embase, and Cochrane Library for articles published through May 1, 2020. Eligibility criteria included publication in English and use of well-established EF methodologies in adult humans. Two investigators independently performed the literature search, study selection, data extraction, risk-of-bias assessment, and qualitative data synthesis. Out of 3571 articles identified, 24 articles were included in the systematic review. Main findings include the following: (1) shorter sleep duration is associated with lower macrovascular EF; (2) not sleeping 7-9 h/night is linked with impaired microvascular EF; (3) sleep restriction impairs micro- and macrovascular EF; (4) acute total sleep deprivation impairs micro- and macrovascular EF but data on macrovascular EF are less consistent; and (5) shift work impairs macrovascular EF. In conclusion, sleep deprivation impairs EF, which may explain the link between insufficient sleep and CVD. Future investigations should fully elucidate the underlying mechanisms and develop strategies to combat the adverse endothelial effects of sleep deprivation across the lifespan.

Effects of full-fat dairy products on subclinical vascular function in adults with elevated blood pressure: a randomized clinical trial.

BACKGROUND: High consumption of low- and non-fat dairy products improves vascular dysfunction associated with elevated arterial blood pressure (BP). Currently, it is unknown if conventional full-fat dairy products improve vascular functions. OBJECTIVES: To determine if adding whole milk and full-fat dairy products to the normal routine diet improves vascular function in adults with elevated BP. DESIGN: Sixty adults (age ± SEM; 58 ± 2 years) with elevated BP (systolic/diastolic; 120-159/ < 99 mmHg) were randomized into a controlled crossover intervention trial consisting of two 4-week dietary periods. The high dairy condition consisted of adding four daily servings of whole milk or full-fat dairy products to the normal diet and eliminated all dairy intake during the control (no dairy) condition. A 2-week washout period separated the dietary conditions. RESULTS: Carotid-femoral pulse wave velocity (cfPWV) did not differ significantly between high dairy (11.3 ± 0.3 versus 10.9 ± 0.3 m/sec) and no dairy conditions (11.2 ± 0.3 versus 11.0 ± 0.3 m/sec). The results were consistent when ultrasound-derived vascular distension measures (arterial compliance, beta-stiffness index, and elastic modulus) were evaluated. Cardiovagal baroreceptor sensitivity (via Valsalva maneuver) demonstrated no significant difference for either dietary condition. Brachial arterial flow-mediated dilation (FMD) did not differ significantly during the high dairy (5.7 ± 0.5 versus 5.4 ± 0.6%) and no dairy conditions (6.5 ± 0.5 versus 5.6 ± 0.6%). CONCLUSIONS: The solitary addition of whole milk and full-fat dairy products has no effect on subclinical vascular function in adults with elevated BP.

Effects of mirthful laughter on pain tolerance: A randomized controlled investigation.

INTRODUCTION: Chronic pain is a debilitating condition that affects many people. Currently, there is no single treatment known to cure or assure relief from chronic pain. Accordingly, the management of patients' discomfort is an integral part of treating chronic pain. Such treatment, however, is not effective for many patients. We investigated whether mirthful laughter provided by comic relief can influence pain tolerance and muscle soreness in young healthy participants. METHODS: Forty participants underwent a randomized controlled cross-over designed experiment. Each participant was exposed to a comedy video eliciting mirthful laughter and an uninteresting documentary. Delayed onset muscle soreness was induced in one leg at a time by eccentric exercise. Pain tolerance was tested using blunt force application and assessed subjectively using a visual analog scale. RESULTS: Watching the comedy video elicited a significantly greater irregular breathing pattern compared with watching the documentary video (p < 0.001). After watching the comedy, the participants' positive affect was increased (Δ2 ±â€¯1) while it was largely decreased (Δ-11 ±â€¯2) after watching the documentary video (p < 0.001). Pain tolerance was decreased by 17 ±â€¯5 N after viewing the documentary video (p < 0.001), but did not change significantly after watching the comedy. CONCLUSIONS: Thirty minutes of watching a comedy eliciting laughter favorably influenced pain tolerance in healthy humans. CLINICAL TRIAL NO.: #NCT02896075.