Effects of aging and endurance exercise training on cardiorespiratory fitness and cardiac structure and function in healthy midlife and older women.

Cardiovascular disease (CVD) remains the leading cause of morbidity and mortality in women in developed societies. Unfavorable structural and functional adaptations within the heart and central blood vessels with sedentary aging in women can act as the substrate for the development of debilitating CVD conditions such as heart failure with preserved ejection fraction (HFpEF). The large decline in cardiorespiratory fitness, as indicated by maximal or peak oxygen uptake (V̇o2max and V̇o2peak, respectively), that occurs in women as they age significantly affects their health and chronic disease status, as well as the risk of cardiovascular and all-cause mortality. Midlife and older women who have performed structured endurance exercise training for several years or decades of their adult lives exhibit a V̇o2max and cardiac and vascular structure and function that are on par or even superior to much younger sedentary women. Therefore, regular endurance exercise training appears to be an effective preventative strategy for mitigating the adverse physiological cardiovascular adaptations associated with sedentary aging in women. Herein, we narratively describe the aging and short- and long-term endurance exercise training adaptations in V̇o2max, cardiac structure, and left ventricular systolic and diastolic function at rest and exercise in midlife and older women. The role of circulating estrogens on cardiac structure and function is described for consideration in the timing of exercise interventions to maximize beneficial adaptations. Current research gaps and potential areas for future investigation to advance our understanding in this critical knowledge area are highlighted.

The utility and safety of hypoxia experiences for rebreather divers.

BACKGROUND: Aircrew training often includes an hypoxic experience aimed at improving symptom recognition and self-rescue in a subsequent hypoxic event. Similar training has been advocated for rebreather divers. We investigated the effect of a prior hypoxic experience on actual and perceived cognitive function during subsequent hypoxia and measured the physiological responses to severe progressive hypoxia. METHODS: Twenty-five subjects underwent two hypoxic hypoxia experiences (trials one and two) approximately five weeks apart. Subjects breathed 5.5% oxygen whilst performing a playing card recognition test. The primary endpoint was the time taken to make three consecutive errors in the card recognition test (time of useful consciousness, TUC). Secondary endpoints were the total number of errors made, accuracy of error recollection and physiological variables. RESULTS: Mean (SD) TUC was 166 seconds (37) and 169 s (35), and subjects made 8.9 (2.4) and 7.8 (2.0) errors in trials one and two respectively. Error recall was identical between trials with participants failing to recall 6 (3) and 6 (2) errors made in trials one and two respectively. Across both trials mean nadir arterial blood and cerebral oxygen saturations were 52% and 49% respectively. The mean (SD) increase in heart rate was 42 (16) beats·min⁻¹. CONCLUSION: An hypoxic experience did not improve cognitive performance or subject insight into performance in a second exposure five weeks later. Hypoxia imposes a significant physiological stress which may be hazardous in unscreened, non-medically supervised subjects. Hypoxia experience training is not recommended for rebreather divers at this time.

Parent's Cardiorespiratory Fitness, Body Mass, and Chronic Disease Status Is Associated with Metabolic Syndrome in Young Adults: A Preliminary Study.

We sought to determine if there was an intergenerational association between parental weight, cardiorespiratory fitness (CRF), and disease status, with the prevalence of metabolic syndrome (MetSyn) in their young adult offspring. Young adults (n = 270, 21 ± 1 years, 53.3% female) were assessed for MetSyn and self-reported parent's CRF, body mass status, and disease status. MetSyn was present in 11.9% of participants, 27.4% had one or two components, and 58.5% had no components. A significantly higher percentage (93.9%) of young adults with MetSyn identified at least one parent as being overweight or obese, 84.8% reported low parental CRF and 87.9% reported a parent with disease (all p < 0.017). MetSyn in offspring is more likely when parents are perceived to have low CRF, increased body mass, and a diagnosis of disease. Evaluating the offspring of people with low CRF, elevated body mass, or who have a history of cardiovascular disease (CVD) or diabetes should be considered to promote early identification and treatment of young adults to reduce future premature CVD in these at-risk individuals.

Prevalence of metabolic syndrome and metabolic syndrome components in young adults: A pooled analysis.

Metabolic syndrome (MetSyn) represents a clustering of different metabolic abnormalities. MetSyn prevalence is present in approximately 25% of all adults with increased prevalence in advanced ages. The presence of one component of MetSyn increases the risk of developing MetSyn later in life and likely represents a high lifetime burden of cardiovascular disease risk. Therefore we pooled data from multiple studies to establish the prevalence of MetSyn and MetSyn component prevalence across a broad range of ethnicities. PubMed, SCOPUS and Medline databases were searched to find papers presenting MetSyn and MetSyn component data for 18-30 year olds who were apparently healthy, free of disease, and MetSyn was assessed using either the harmonized, National Cholesterol Education Program Adult Treatment Panel III (NCEP-ATPIII), American Heart Association/National Heart, Blood and Lung Institute (AHA/NHBLI), or International Diabetes Federation (IDF) definitions of MetSyn. After reviewing returned articles, 26,609 participants' data from 34 studies were included in the analysis and the data were pooled. MetSyn was present in 4.8-7% of young adults. Atherogenic dyslipidaemia defined as low high density lipoprotein (HDL) cholesterol was the most prevalent MetSyn component (26.9-41.2%), followed by elevated blood pressure (16.6-26.6%), abdominal obesity (6.8-23.6%), atherogenic dyslipidaemia defined as raised triglycerides (8.6-15.6%), and raised fasting glucose (2.8-15.4%). These findings highlight that MetSyn is prevalent in young adults. Establishing the reason why low HDL is the most prevalent component may represent an important step in promoting primary prevention of MetSyn and reducing the incidence of subsequent clinical disease.

Can certified health professionals treat obesity in a community-based programme? A quasi-experimental study.

OBJECTIVE: To test the effectiveness of a non-pharmaceutical programme for obese participants in a rural Eastern Canadian Province using certified health professionals. DESIGN: A prospective quasi-experimental design with repeated premeasure and postmeasure. PARTICIPANTS: 146 participants with obesity (body mass index >30 kg/m(2)) from rural and urban communities in an Eastern Canadian Province were divided into four groups. INTERVENTION: A 6-month intensive active community-based lifestyle intervention (InI) delivered by Certified Exercise Physiologists, Certified Personal Trainers and Registered Dietitians, followed by 6 months of self-management. A second intervention (InII) was nested in InI and consisted of group-mediated cognitive-behavioral intervention (GMCBI) delivered by an exercise psychologist to two of the four InI groups. OUTCOMES: (1) Improving health outcomes among the participants' preactive and postactive 6-month intervention and self-management period, (2) Documenting the impact of InII (GMCBI) and location of the intervention (urban vs rural). RESULTS: The 6-month active InI significantly improved cardiovascular health for participants who completed the intervention. InII (GMCBI) significantly lowered the attrition rate among the participants. The self-management period was challenging for the participants and they did not make further gains; however, most were able to maintain the gains achieved during the active intervention. The location of the intervention, urban or rural, had little impact on outcomes. CONCLUSIONS: A community-based programme utilising healthcare professionals other than physicians to treat obese patients was effective based on premeasure and postmeasure. During the self-management phase, the participants were able to maintain the gains. Psychological support is essential to participant retention.

Evaluation of Children Playing a New-Generation Motion-Sensitive Active Videogame by Accelerometry and Indirect Calorimetry.

OBJECTIVE: New-generation active videogames (AVGs) use motion-capture video cameras to connect a player's arm, leg, and body movements through three-dimensional space to on-screen activity. We sought to determine if the whole-body movements required to play the AVG elicited moderate-intensity physical activity (PA) in children. A secondary aim was to examine the utility of using accelerometry to measure the activity intensity of AVG play in this age group. SUBJECTS AND METHODS: The PA levels of boys (n=26) and girls (n=15) 5-12 years of age were measured by triaxial accelerometry (n=25) or accelerometry and indirect calorimetry (IC) (n=16) while playing the "Kinect Adventures!" videogame for the Xbox Kinect (Microsoft(®), Redmond, WA) gaming system. The experiment simulated a typical 20-minute in-home free-play gaming session. RESULTS: Using 10-second recording epochs, the average (mean±standard deviation) PA intensity over 20 minutes was 4.4±0.9, 3.2±0.7, and 3.3±0.6 metabolic equivalents (METs) when estimated by IC or vertical axis (Crouter et al. intermittent lifestyle equation for vertical axis counts/10 seconds [Cva2RM]) and vector magnitude (Crouter et al. intermittent lifestyle equation for vector magnitude counts/10 seconds [Cvm2RM]) accelerometry. In total, 16.9±3.2 (IC), 10.6±4.5 (Cva2RM), and 11.1±3.9 (Cvm2RM) minutes of game playing time were at a 3 MET intensity or higher. CONCLUSIONS: In this study, children played the Xbox Kinect AVG at moderate-intensity PA levels. The study also showed that current accelerometry-based methods underestimated the PA of AVG play compared with IC. With proper guidance and recommendations for use, video motion-capture AVG systems could reduce sedentary screen time and increase total daily moderate PA levels for children. Further study of these AVG systems is warranted.

Oxygen absorption by skin exposed to oxygen supersaturated water.

The present study tests the hypothesis that skin on the plantar surface of the foot absorbs oxygen (O(2)) when immersed in water that has a high dissolved O(2) content. Healthy male and female subjects (24.2 ± 1.4 years) soaked each foot in tap water (1.7 ± 0.1 mg O(2)·L(-1); 30.7 ± 0.3 °C) or O(2)-infused water (50.2 ± 1.7 mg O(2)·L(-1); 32.1 ± 0.5 °C) for up to 30 min in 50 different experiments. Transcutaneous oximetry and near infrared spectroscopy were used to evaluate changes in skin PO(2), oxygenated haemoglobin, and cytochrome oxidase aa(3) that resulted from treatment. Compared with the tap water condition, tissue oxygenation index was 3.5% ± 1.3% higher in feet treated for 30 min with O(2)-infused water. This effect persisted after treatment, as skin PO(2) was higher in feet treated with O(2)-infused water at 2 min (237 ± 9 vs. 112 ± 5 mm HG) and 15 min (131 ± 1 vs. 87 ± 4 mm HG) post-treatment. When blood flow to the foot was occluded for 5 min, feet resting in O(2)-infused water maintained a 3-fold higher O(2) consumption rate than feet treated with tap water (9.1 ± 1.4 vs. 3.0 ± 1.0 µL·100 g(-1)·min(-1)). We estimate that skin absorbs 4.5 mL of O(2)·m(-2)·min(-1) from O(2)-infused water. Thus, skin absorbs appreciable amounts of O(2) from O(2)-infused water. This finding may prove useful and assist development of treatments targeting skin diseases with ischemic origin.

Central role of TRPM4 channels in cerebral blood flow regulation.

BACKGROUND AND PURPOSE: The transient receptor potential channel TRPM4 is critically linked to the myogenic constrictor response of cerebral arteries that occurs when intravascular pressure increases. This myogenic behavior is thought to be fundamentally involved in the mechanisms of blood flow autoregulation. In this study, we tested the hypothesis that TRPM4 channels in cerebrovascular myocytes contribute to cerebral blood flow autoregulation in vivo. METHODS: In vivo suppression of cerebrovascular TRPM4 expression was achieved by infusing antisense oligodeoxynucleotides into the cerebral spinal fluid of 400- to 550-g Sprague-Dawley rats at 80 microg x day(-1) for 7 days using an osmotic pump that discharged into the lateral cerebral ventricle. Absolute cerebral blood flow measurements were obtained over a range of mean arterial pressures using fluorescent microsphere methods. RESULTS: Oligonucleotides infused into the cerebrospinal fluid were detected in the smooth muscle cells of pial arteries. Semi-quantitative RT-PCR indicated that the message for TRPM4 was decreased in the cerebral arteries of antisense-treated rats. Myogenic constriction was decreased by 70% to 85% in cerebral arteries isolated from TRPM4 antisense- compared with control sense-treated rats. Cerebral blood flow was significantly greater in TRPM4 antisense- versus sense-treated rats at resting and elevated mean arterial pressures, indicating that autoregulatory vasoconstrictor activity was compromised in TRPM4 antisense-treated animals. CONCLUSIONS: In vivo suppression of TRPM4 decreases cerebral artery myogenic constrictions and impairs autoregulation, thus implicating TRPM4 channels and myogenic constriction as major contributors to cerebral blood flow regulation in the living animal.

Potential interactions among vascular and muscular functional compartments during active hyperemia.

The increase in blood flow that accompanies the start of contractions (active hyperemia) is a complex phenomenon involving a fast phase in which blood flow increases quickly and then slows or decreases (seek phase) before stabilizing at a flow corresponding to the metabolic rate (matched phase). This pattern of blood flow change involves contributions from a flow-induced increase in flow, a response to short periods of occlusion or partial occlusion due to force generated by the muscle contraction, and metabolism. Even denervated, the vascular bed, which consists of endothelial cells, vascular smooth muscle cells, and an adventitial layer that has significant secretory potential, is able to coordinate the response pattern. Within the vascular wall, communication is possible bidirectionally across the wall and also along the wall in a retrograde or upstream direction. The signals involved, which range from endothelial cell products such as nitric oxide and endothelin to adenosine, a skeletal muscle metabolite, appear to be situation- and time-dependent. In addition to the communication potential within and along the vascular wall, signals from the vascular system are able to exert inotropic effects on mammalian skeletal muscle.