To describe physical activity (PA) intensity across a school day and assess the percentage of girls and boys achieving recommended guidelines.
The authors measured PA via accelerometry in 380 ...children (8-11 years) and examined data representing (1) the whole school day, (2) regular class time, (3) recess, (4) lunch and (5) scheduled physical education (PE). Activity was categorised as sedentary (SED), light physical activity (LPA) or moderate to vigorous physical activity (MVPA) using age-specific thresholds. They examined sex differences across PA intensities during each time period and compliance with recommended guidelines.
Girls accumulated less MVPA and more SED than boys throughout the school day (MVPA -10.6 min; SED +13.9 min) recess (MVPA -1.6 min; SED +1.7 min) and lunch (MVPA -3.1 min; SED +2.9 min). Girls accumulated less MVPA (-6.2 min), less LPA (-2.5 min) and more SED (+9.4 min) than boys during regular class time. Fewer girls than boys achieved PA guidelines during school (90.9% vs 96.2%), recess (15.7% vs 34.1%) and lunch (16.7% vs 37.4%). During PE, only 1.8% of girls and 2.9% of boys achieved the PA guidelines. Girls and boys accumulated similar amounts of MVPA, LPA and SED.
The MVPA deficit in girls was due to their sedentary behaviour as opposed to LPA. Physical activity strategies that target girls are essential to overcome this deficit. Only a very small percentage of children met physical activity guidelines during PE. There is a great need for additional training and emphasis on PA during PE. In addition schools should complement PE with PA models that increase PA opportunities across the school day.
To systematically develop evidence-informed physical activity guidelines to improve physical fitness in people with spinal cord injury (SCI).
This study was conducted in Canada.
The Appraisal of ...Guidelines, Research and Evaluation II guideline development protocol was used to develop exercise guidelines to improve physical capacity and muscular strength. The evidence base for the guideline development process consisted of a systematic review and quality appraisal of research examining the effects of exercise on physical fitness among people with SCI. A multidisciplinary expert panel deliberated the evidence and generated the guidelines. Pilot testing led to refinement of the wording and presentation of the guidelines.
The expert panel generated the following guidelines: for important fitness benefits, adults with a SCI should engage in (a) at least 20 min of moderate to vigorous intensity aerobic activity two times per week and (b) strength training exercises two times per week, consisting of three sets of 8-10 repetitions of each exercise for each major muscle group.
People with SCI, clinicians, researchers and fitness programmers are encouraged to adopt these rigorously developed guidelines.
•We consider the order-up-to policy with a stochastic lead time and order crossovers.•We find the distribution of the number of open orders.•The inventory distribution when orders and ...work-in-progress are correlated is found.•We show minimal safety stock and inventory variance do not lead to minimum costs.
We study the impact of stochastic lead times with order crossover on inventory costs and safety stocks in the order-up-to (OUT) policy. To motivate our research we present global logistics data which violates the traditional assumption that lead time demand is normally distributed. We also observe that order crossover is a common and important phenomenon in real supply chains. We present a new method for determining the distribution of the number of open orders. Using this method we identify the distribution of inventory levels when orders and the work-in-process are correlated. This correlation is present when demand is auto-correlated, demand forecasts are generated with non-optimal methods, or when certain ordering policies are present. Our method allows us to obtain exact safety stock requirements for the so-called proportional order-up-to (POUT) policy, a popular, implementable, linear generalization of the OUT policy. We highlight that the OUT replenishment policy is not cost optimal in global supply chains, as we are able to demonstrate the POUT policy always outperforms it under order cross-over. We show that unlike the constant lead-time case, minimum safety stocks and minimal inventory variance do not always lead to minimum costs under stochastic lead-times with order crossover. We also highlight an interesting side effect of minimizing inventory costs under stochastic lead times with order crossover with the POUT policy—an often significant reduction in the order variance.
Preclinical studies have reported that a single treadmill session performed 24h prior to doxorubicin provides cardio-protection. We aimed to characterize the acute change in cardiac function ...following an initial doxorubicin treatment in humans and determine whether an exercise session performed 24h prior to treatment changes this response.
Breast cancer patients were randomized to either 30min of vigorous-intensity exercise 24h prior to the first doxorubicin treatment (n=13), or no vigorous exercise for 72h prior to treatment (control, n=11). Echocardiographically-derived left ventricular volumes, longitudinal strain, twist, E/A ratio, and circulating NT-proBNP, a marker of later cardiotoxicity, were measured before and 24–48h after the treatment.
Following treatment in the control group, NT-proBNP, end-diastolic and stroke volumes, cardiac output, E/A ratio, strain, diastolic strain rate, twist, and untwist velocity significantly increased (all p≤0.01). Whereas systemic vascular resistance (p<0.01) decreased, and ejection fraction (p=0.02) and systolic strain rate (p<0.01) increased in the exercise group only. Relative to control, the exercise group had a significantly lower NT-proBNP (p<0.01) and a 46% risk reduction of exceeding the cut-point used to exclude acute heart failure.
The first doxorubicin treatment is associated with acutely increased NT-proBNP, echocardiographic parameters of myocardial relaxation, left ventricular volume overload, and changes in longitudinal strain and twist opposite in direction to documented longer-term changes. An exercise session performed 24h prior to treatment attenuated NT-proBNP release and increased systolic function. Future investigations should verify these findings in a larger cohort and across multiple courses of doxorubicin.
•Preclinical findings of exercise cardioprotection from doxorubcin are translated.•Aerobic exercise 24h prior to doxorubicin for breast cancer attenuated NT-proBNP.•The exercise session also increased systolic function.
A prevalent hypothesis concerning the cause of the rise in aneuploid conceptions with maternal age is that the changes that accompany normal ovarian aging increase the rate of meiotic errors in the ...oocyte. Biological aging of the ovary is accompanied by a decline in both the total oocyte pool and the number of antral follicles maturing per cycle, as well as changes in the levels of circulating reproductive hormones. The biological aging hypothesis predicts that aneuploidy rates should be higher in women with a prematurely reduced oocyte pool, and that women with trisomic conceptions should show signs of earlier ovarian aging than women of the same chronological age without trisomic conceptions. Comprehensive studies of aneuploidy in groups of women with known causes of premature ovarian failure remain to be done, though anecdotal evidence does suggest increased rates of pregnancy loss and aneuploidy. Smoking, which is a well-documented cause of earlier ovarian aging, is not associated with an increase in aneuploid conceptions. Evidence from women with unilateral ovariectomies is inconsistent. Support for the biological aging hypothesis was provided by one study showing that menopause occurred about a year earlier in women with a trisomic spontaneous abortion compared to women with chromosomally normal conceptions. Associations between high FSH and pregnancies with Down syndrome and chromosomally abnormal spontaneous abortions have also been reported. However, the most direct test of the hypothesis, which compared antral follicle counts and hormonal levels in women with trisomic pregnancies and those with chromosomally normal pregnancies, failed to find a difference in the expected direction. A prospective study of FSH levels in women with subfertility also failed to find an association with the rate of pregnancy loss. The bulk of evidence thus suggests that, if the processes of biological aging are indeed related to aneuploidy, they probably involve factors other than those measured by oocyte or antral follicle pool size and reproductive hormone levels.
Indigenous populations currently experience greater cardiovascular disease burdens. However, subclinical vascular structure and function among these populations is not well known. This investigation ...evaluated vascular structure and function among Canadian Indigenous populations. Blood pressure, body composition, pulse-wave velocity (PWV), baroreceptor sensitivity (BRS), arterial compliance and intima-media thickness (IMT) were measured. Vascular measures were evaluated across sexes and age groups. Vascular assessments were conducted among 55 Indigenous adults (38±18 years, 29 Female), including both First Nations (N=36) and Métis (N=19) individuals. Some differences in vascular measures were found between males and females, respectively (spectral BRS: 9.6±6.8 ms mm Hg(-1) vs 16.9±10.0 ms mm Hg(-1), P=0.01; small arterial compliance: 8.9±3.7 ml mm Hg(-1) × 100 vs 6.4±2.3 ml mm Hg(-1) × 100, P=0.004), with similar measures of overall IMT (0.61±0.14 mm vs 0.57±0.08 mm, P=0.19) and central PWV (5.7±2.5 m s(-1) vs 5.1±2.3 m s(-1), P=0.58). Greater IMT, and lower BRS and arterial compliance were identified among older adults. This relatively healthy population demonstrated healthy vascular measures, with poorer measures among older individuals.
Summary
Physical activity is beneficial for many chronic conditions. However, activity levels of Native Americans are not well known. This systematic review investigated if Native American ...populations achieve the recommended physical activity levels, compared current and past activity levels, and assessed the ability of exercise training programmes to improve health outcomes among this population. Electronic databases (e.g. MEDLINE, EMBASE) were searched and citations were cross‐referenced. Included articles reported physical activity levels or investigations among Native Americans. This search identified 89 articles: self‐report (n = 61), accelerometry and pedometry (n = 10), metabolic monitoring (n = 10) and physical activity interventions (n = 17). Few adults were found to meet the physical activity recommendations (27.2% 95% confidence interval = 26.9–27.5% self‐report, 9% 4–14% accelerometry). Among children/youth, 26.5% (24.6–28.4%) (self‐report) to 45.7% (42.3–49.1%) (pedometry/accelerometry) met the recommendations. Adults and children/youth were generally identified as physically inactive (via doubly labelled water). Overall, Native American adults reported lower activity levels since 2000, compared to 1990s, although similar to 1980s. Few physical activity interventions employed strong methodologies, large sample sizes and objective outcome measures. There is a clear need to increase Native American populations' physical activity. Additional research is required to evaluate exercise training programmes among this population.
The purpose of this investigation was to characterize the arterial stiffness of male ultra-marathon runners (n = 9) using pulse wave velocity (cfPWV) and radial tonometry over the course of an ...ultra-marathon and during recovery. Measures were collected at rest, immediately following 45 km/75 km of running, then following 60 and 90 min of recovery. No statistical difference was found between baseline cfPWV and normative values. The cfPWV of ultra-endurance runners decreased at 45 km (3.4 ± 1.6 m/s, p=0.006), followed by an increase (1.6 ± 1.8 m/s, p = 0.04) toward baseline levels at the 75 km mark. Radial tonometry measures also indicated small artery stiffness was transiently increased after 75 km. The amount of training time (r = 0.82, p = 0.007) and the duration of a typical training session (r = 0.73, p = 0.03) were correlated strongly with persisting decrements in large artery compliance at 60 min of recovery. The finding that arterial stiffness decreased at the 45 km distance and then reverted back toward baseline levels with prolonged running, may indicate a role of exercise duration or accumulated stress for affecting vascular compliance. At present, it is premature to suggest that athletes should alter training or racing practices to protect vascular health.
Exercise hypertension is a common occurrence among individuals with aortic coarctation. Although exercise is known to be beneficial among the general population, the risks and benefits of exercise ...among those with aortic coarctation are less clear. This systematic review evaluates the benefits and risks of exercise for persons with aortic coarctation. Electronic databases were systematically searched (that is, MEDLINE and EMBASE) and key reviews cross-referenced to identify articles for inclusion. Original research articles reporting exercise among individuals with aortic coarctation were included. From 2608 individual citations, 68 eligible articles were identified. Aerobic exercise stress tests were found to be useful for determining exercise hypertension experiences post-surgical repair (N=5), and other long-term secondary findings (N=3). Experiences of exercise hypertension were associated with abnormal cardiac and/or aortic geometry and cardiac function (N=7). Exercise capacity was generally found to be similar to non-aortic coarctation controls post surgery (N=6). Exercise hypertension was experienced by 27% of participants, including 10% of adults and 43% of children/youth. Individuals who experience exercise hypertension experience greater increases in systolic blood pressure with exercise. No investigations identified evaluated forms of exercise other than aerobic stress tests and no exercise training programs have been conducted to date. Exercise stress tests can be valuable in this population for determining exercise hypertension, especially in the year post-surgical repair. Additional research is urgently needed to accurately assess the benefits and risks of exercise and exercise hypertension, and applicability of exercise restrictions for this population.
There is a growing interest in training for and competing in race distances that exceed the marathon; however, little is known regarding the vascular effects of participation in such prolonged ...events, which last multiple consecutive hours. There exists some evidence that cardiovascular function may be impaired following extreme prolonged exercise, but at present, only cardiac function has been specifically examined following exposure to this nature of exercise. The primary purpose of this study was to characterize the acute effects of participation in an ultra-marathon on resting systemic arterial compliance. Arterial compliance and various resting cardiovascular indices were collected at rest from 26 healthy ultra-marathon competitors using applanation tonometry (HDI CR-2000) before and after participation in a mountain trail running foot race ranging from 120-195 km which required between 20-40 continuous hours (31.2±6.8 h) to complete. There was no significant change in small artery compliance from baseline to post race follow-up (8.5±3.4-7.7±8.2 mL/mmHgx100, p=0.65), but large artery compliance decreased from 16.1±4.4 to 13.5±3.8 mL/mmHgx10 (p=0.003). Participation in extreme endurance exercise of prolonged duration was associated with acute reductions in large artery compliance, but the time course of this effect remains to be elucidated.
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