cardiorespiratory fitness

Exercise gives older men a better brain boost

Men have stronger positive correlation between fitness and brain function

February 13, 2019

Science Daily/American Physiological Society

New research suggests that the relationship between physical and brain fitness varies in older adults by virtue of their sex.

 

Cardiorespiratory fitness is the measure of how much -- and how well -- oxygen is delivered to the muscles during exercise. Fitness level has also been associated with changes in the brain's nerve-rich tissue, called gray matter, and better cognitive function in later life. Previous studies have also found cardiorespiratory fitness to be related to how the brain functions during periods of rest. Nerve connectivity in the brain during rest changes with age. These changes can negatively affect cognitive function. However, "the neural basis of sex differences in the relationship between fitness and brain function in older adults has not been directly explored," wrote researchers from York University and McGill University in Canada.

 

The research team studied one group of men and one of women, both with an average age of 67. The volunteers self-reported their typical daily physical activity level. The research team recorded the participants' height, weight, age, sex and resting heart rate to determine their cardiorespiratory fitness. They also administered imaging tests of the brain to record nerve function both within specific brain networks (local efficiency) and among all networks (global efficiency).

 

The men were found to have higher cardiorespiratory fitness levels than the women. However, the women had higher local network efficiency and lower global network efficiency than the men. This pattern of connectivity was more robust in the women and has been positively associated with executive function, which are skills that contribute to being able to focus, pay attention and manage time. Fitness levels, however, were more strongly associated with improving this brain efficiency pattern for men than women.

 

"Our findings that [cardiorespiratory fitness] is associated with brain function in a sex-dependent manner underscore the importance of considering sex as a factor when studying associations between exercise and brain health in older adulthood," the researchers wrote.

https://www.sciencedaily.com/releases/2019/02/190213124408.htm

Healthy? Stay fit to avoid a heart attack

Low cardiorespiratory fitness could be a warning sign of future problems, even in the fit and healthy

November 28, 2018

Science Daily/European Society of Cardiology

Even if you are a fit and healthy person with no signs of any heart or blood vessel disease, low cardiorespiratory fitness could be a warning sign of future problems, according to a new study.

 

Cardiorespiratory fitness refers to the ability of the blood circulation and respiratory systems to supply adequate oxygen to muscles during sustained physical activity. The main measure of it is VO2max -- the maximum rate of oxygen consumption during exercise that increases with intensity.

 

In the study published today, 4527 fit and healthy men and women with no history of cardiovascular or lung disease, cancer or raised blood pressure, had their cardiorespiratory fitness assessed when they joined a large, population-based health study in Norway (the HUNT3 study) between 2006-2008. Wearing a face mask and a heart rate monitor, they warmed up for ten minutes on a treadmill before running faster and faster. Their oxygen intake was measured to establish their VO2max. The researchers also gathered information on tobacco use, alcohol consumption, family history of cardiovascular disease, physical activity, weight, height and waist circumference, blood pressure and cholesterol levels.

 

After an average follow-up time of nearly nine years, the researchers found that greater cardiorespiratory fitness was linked to a lower risk of cardiovascular disease, such as heart attacks. Only 147 participants (3.3%) were diagnosed with heart disease or died from it, or required intervention to unblock clogged arteries during this period.

 

"We found a strong link between greater fitness and reduced risk of a coronary event during the nine years of follow-up in a very healthy sample of adults," said Dr Bjarne Nes, a researcher at the Norwegian University of Science and Technology (NTNU). "In fact, the participants who were in the 25% of those with the highest cardiorespiratory fitness had nearly half the risk compared to those in the 25% with the lowest fitness levels."

 

The researchers found that, in both men and women, the risk of cardiovascular problems fell by 15% for every extra unit of measurement of cardiorespiratory fitness -- metabolic equivalents (METs). METs measure the oxygen required for the energy expended on physical activity, with one MET being the amount needed if a person is sitting quietly (3.5 mL of oxygen per kg of body weight per minute), while high exertion such as running would use about eight METs.

 

"This indicates that greater cardiorespiratory fitness protects against both chronic and acute heart and blood vessel problems," said Dr Nes. "Even a small increase in fitness could have a large impact on health."

 

The lead author of the study, Dr Jon Magne Letnes, who is a medical doctor and research fellow in the Cardiac Exercise Research Group at NTNU, said: "Our results should encourage the use of exercise as preventive medicine. A few months of regular exercise may be an efficient way of reducing the cardiovascular risk."

 

A strength of the study is that cardiorespiratory fitness was measured with a gold-standard maximal exercise test of peak oxygen uptake (VO2peak) -- the first to do this in a healthy sample of the general population. Previous studies that have linked fitness to disease risk in healthy populations are mainly based on self-report or less accurate estimates.

 

A limitation of the study is that participating in voluntary exercise testing introduces the possibility that more active people might choose to join the study, which might reduce its applicability to the general population.

 

In an accompanying editorial, Professor Sanjay Sharma, of St George's University of London (UK), who is medical director of the London Marathon and chair of the expert cardiology panel for the English Football Association, and Dr Aneil Malhotra, also of St George's, write: "This study adds to the current literature by demonstrating a similar benefit in an ostensibly healthy population with an incremental benefit that continues beyond 12 METS and suggests that there is no obvious upper threshold for the cardioprotective effects of exercise. Although the number of subjects is laudable, there are several points to note."

 

They highlight that there is an unavoidable but inherent selection bias towards participants who were motivated to take part and were probably more aware of lifestyle measures to avoid cardiovascular disease; and the participants were young and healthy, which explains the low number of cardiovascualar-related events during the follow-up period.

 

They conclude: "In an era where primary prevention is playing an increasingly significant role in society, this study helps highlight that improving CRF [cardiorespiratory fitness] is a pivotal factor in reducing CV [cardiovascular] risk and mortality. Regular physical activity and measures of CRF should be incorporated into clinical practice and CV risk models. All individuals should be encouraged to exercise to the minimal level recommended by the European guidelines for disease prevention, although the observations of Letnes and colleagues and several others suggest that substantially higher physical activity levels and CRF provide additional prognostic benefit. For those who are compromised due to comorbidities or functional status, there is overwhelming evidence that some physical activity is better than none."

https://www.sciencedaily.com/releases/2018/11/181128192147.htm

Vitamin D levels in the blood linked to cardiorespiratory fitness

October 30, 2018

Science Daily/European Society of Cardiology

Vitamin D levels in the blood are linked to cardiorespiratory fitness, according to a study published today in the European Journal of Preventive Cardiology, a publication of the European Society of Cardiology (ESC).

 

"Our study shows that higher levels of vitamin D are associated with better exercise capacity," said Dr Amr Marawan, assistant professor of internal medicine, Virginia Commonwealth University, Virginia, US. "We also know from previous research that vitamin D has positive effects on the heart and bones. Make sure your vitamin D levels are normal to high. You can do this with diet, supplements, and a sensible amount of sun exposure."

 

It is well established that vitamin D is important for healthy bones, but there is increasing evidence that it plays a role in other areas of the body including the heart and muscles.

 

Cardiorespiratory fitness, a reliable surrogate for physical fitness, is the ability of the heart and lungs to supply oxygen to the muscles during exercise. It is best measured as the maximal oxygen consumption during exercise, referred to as VO2 max. People with higher cardiorespiratory fitness are healthier and live longer.

 

This study investigated whether people with higher levels of vitamin D in the blood have improved cardiorespiratory fitness. The study was conducted in a representative sample of the US population aged 20-49 years using the National Health and Nutrition Survey (NHANES) in 2001-2004. Data was collected on serum vitamin D and VO2 max. Participants were divided into quartiles of vitamin D levels.

 

Of 1,995 participants, 45% were women, 49% were white, 13% had hypertension, and 4% had diabetes. Participants in the top quartile of vitamin D had a 4.3-fold higher cardiorespiratory fitness than those in the bottom quartile. The link remained significant, with a 2.9-fold strength, after adjusting for factors that could influence the association such as age, sex, race, body mass index, smoking, hypertension, and diabetes.

 

Dr Marawan said: "The relationship between higher vitamin D levels and better exercise capacity holds in men and women, across the young and middle age groups, across ethnicities, regardless of body mass index or smoking status, and whether or not participants have hypertension or diabetes."

 

Each 10 nmol/L increase in vitamin D was associated with a statistically significant 0.78 mL/kg/min increase in VO2 max. "This suggests that there is a dose response relationship, with each rise in vitamin D associated with a rise in exercise capacity," said Dr Marawan.

 

Dr Marawan noted that this was an observational study and it cannot be concluded that vitamin D improves exercise capacity. But he added: "The association was strong, incremental, and consistent across groups. This suggests that there is a robust connection and provides further impetus for having adequate vitamin D levels, which is particularly challenging in cold, cloudy places where people are less exposed to the sun."

 

On the other hand, Vitamin D toxicity can lead to excess calcium in the blood, which can cause nausea, vomiting, and weakness. "It is not the case that the more vitamin D, the better," said Dr Marawan. "Toxicity is caused by megadoses of supplements rather than diet or sun exposure, so caution is needed when taking tablets."

 

Regarding further research, Dr Marawan said: "We know the optimum vitamin D levels for healthy bones but studies are required to determine how much the heart needs to function at its best. Randomised controlled trials should be conducted to examine the impact of differing amounts of vitamin D supplements on cardiorespiratory fitness. From a public health perspective, research should look into whether supplementing food products with vitamin D provides additional benefits beyond bone health."

https://www.sciencedaily.com/releases/2018/10/181030091449.htm

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