Short bursts of exercise at home good for the heart

reposted from: http://www.nhs.uk/news/2013/February/Pages/Short%20bursts-of-exercise-good-for-heart.aspx

crabsallover highlights, key points, comments / links.

Short bursts of exercise, such as raking the lawn and climbing the stairs, are an excellent way of warding off health problems such as high blood pressure, high cholesterol and diabetes, the Daily Mirror and many global media outlets reported.

The news is based on the results of a cross-sectional study which suggested that even less than 10 minutes of moderate or vigorous activity, such as climbing stairs, ‘count’ and may be as beneficial as longer periods of exercise.

This useful and well-conducted study measured the physical activity of more than 6,000 adults, in addition to measuring various health markers such as blood fats, blood sugar and blood pressure, that are known to be risk factors for chronic conditions including diabetes and heart disease.

The study found that performing moderate or vigorous activity of any duration – either short bursts of less than 10 minutes or for longer – was associated with improved measurements of several cardiovascular risk factors.

The study suggests that even people who do not have time to go to the gym or an exercise class can get many of the health benefits of exercise from adopting an ‘active’ lifestyle.

While the study cannot directly prove cause and effect, it would suggest that any moderate or vigorous exercise you can fit in during the course of a day, benefits your health.

10-minute exercise programmes

NHS Choices has produced a series of 10-minute exercise programmes you can do in the comfort of your own home:

• 10-minute home cardio workout
• 10-minute legs, bums and tums home workout
• 10-minute home toning workout

Don’t forget to warm up before, and then cool down after, exercising.

Where did the story come from?

The study was carried out by researchers from Bellarmine University and Oregon State University. The source of funding for this study was not declared.

The study was published in the peer-reviewed American Journal of Health Promotion.

This study was covered by the Daily Mirror and the Mail Online. Although the gist of the story is correct, the researchers looked at short bursts of moderate and vigorous physical activity, rather than the ‘light exercise’ reported in the Mail Online.

How active should I be?

To stay healthy, adults aged 19-64 should try to be active daily and should do:

• at least 150 minutes (2 hours and 30 minutes) of moderate-intensity aerobic activity such as cycling or fast walking every week, and
• muscle-strengthening activities on two or more days a  week that work all major muscle groups (legs, hips, back, abdomen, chest, shoulders and arms)

Read more about physical activity guidelines for adults

What kind of research was this?

This cross-sectional study aimed to determine whether short bursts of physical activity were associated with a decreased risk of metabolic syndrome.

Metabolic syndrome is a term used to describe a combination of related risk factors for chronic conditions such as heart disease and type 2 diabetes – these factors include high waist circumference, blood fats, blood sugar and blood pressure.

The researchers also looked at some additional biological markers known to be risk factors for cardiovascular disease.

They looked at whether there were any differences in risk factors for short bursts of activity versus more prolonged bursts.

Cross-sectional studies have a inherent limitation as they cannot prove causation (a direct cause and effect), they can only highlight possible associations.

So in this case, the researchers cannot conclude that it is the short bursts of activity directly affecting the biological markers measured.

Also, because participants aren’t followed over time we don’t know what came first, so we don’t know:

• if people who exercise a certain way are healthier
• if people who are healthier exercise a certain way

What did the research involve?

The researchers used data collected as part of the US National Health and Nutrition Examination Survey, which collects annual health and nutrition data on a random sample of US citizens. For this study, data from 6,321 non-pregnant adults with data on physical activity from the 2003-2004 and 2005-2006 cycles was used.

A participant’s physical activity was determined by collecting data using an accelerometer. Accelerometers measure the participant’s change in velocity over time (acceleration) allowing the intensity of physical activity to be measured, as well as the duration.

Participants had data on physical activity for at least four days, and at least 10 hours each day. The researchers classified the intensity of physical activity into moderate or vigorous using cut-offs for accelerometry readings.

The researchers also classified activity levels by duration, into two main groups:

• less than 10 minutes duration (‘nonbout’)
• more than 10 minutes duration (‘bout’)

Each period of activity was terminated if accelerometry readings fell below the cut off for three minutes or more.

The researchers also calculated whether a participant met physical activity guidelines, defined as engaging in 150 minutes of moderate-intensity activity or 75 minutes of vigorous-intensity activity or some combination of the two per week, and whether a participant met the criteria by only performing short, less than 10 minute duration ‘nonbout’ periods of activity.

The US National Health and Nutrition Examination Survey also collected data on a participant’s cardiovascular risk factors, including:

• metabolic syndrome – defined as having three or more of the following symptoms: a high waist circumference, a high level of triglycerides (a type of fat), low levels of high-density (‘good’) cholesterol, elevated blood pressure, elevated fasting blood sugar
• systolic and diastolic blood pressure
• blood levels of C-reactive protein (an inflammatory marker), high-density cholesterol, low-density (‘bad’) cholesterol, total cholesterol and blood sugar
• anthropometric measurements including waist circumference, skinfold thickness and body mass index (BMI)

The researchers also collected data on age, gender, smoking status, race/ethnicity, current health status, and whether the participant was taking any medication.

The researchers analysed whether there was an association between short ‘nonbout’ periods of activity and longer ‘bout’ periods of activity and cardiovascular risk factors.

They also looked at whether there was any difference in risk factors when physical activity guidelines were only met by performing short ‘nonbout’ periods of activity.

In these analyses, the researchers controlled for age, gender, smoking status, race/ethnicity, and current health status.

What were the basic results?

The researchers found that on average, participants performed 23.6 minutes of moderate-to vigorous-intensity physical activity per day in short, ‘nonbout’ bursts, and 6.6 minutes in 10 minutes or longer bursts (this rather confusing figure is due to some people not doing any moderate to vigorous physical activity in bouts of 10 minutes or longer, during some days).

A total of 42.9% of participants met physical activity guidelines if nonbout physical activity was included, but only 9.7% met guidelines if only 10 minutes or longer periods only were included.

Both ‘nonbout’ and ‘bout’ physical activity were associated with a reduction in cardiovascular risk factors. The associations were strongest when enough activity was performed to meet physical activity guidelines.

The strengths of associations were generally similar for ‘bout’ and ‘nonbout’ physical activity for all risk factors measured, with the exception of BMI.

To make sure the results weren’t due to the fact that people who performed the longer periods of activity were also performing the shorter periods of activity, the researchers repeated the analyses controlling for 10 minutes or longer periods of activity.

Short ‘nonbout’ physical activity was still associated with a reduced risk of metabolic syndrome; favourable levels of C-reactive protein, high density lipoprotein cholesterol, triglycerides; and favourable sized waist circumference, skinfold thickness and BMI.

Again, the associations were strongest when enough ‘nonbout’ physical activity was performed to meet the physical activity guidelines.

Finally, the researchers compared the mean levels of biological markers in people meeting the physical activity guidelines solely through performing short ‘nonbout’ periods of physical activity and those meeting guidelines by performing longer periods of activity.

There was no statistical difference between the level of any marker except for BMI. Participants who met guidelines through longer periods of activity had significantly lower body mass indices (25.85) than those meeting guidelines through short periods of activity (27.49, p<0.0001).

How did the researchers interpret the results?

The researchers conclude that these results show that “with the exception of BMI, meeting physical activity guidelines using an ‘active lifestyle’ approach (nonbout activity) as opposed to a more structured exercise approach (bout activity) resulted in similar health outcomes.”

They suggest that “to reduce levels of adult adiposity (body fatness), adults are encouraged to engage in bouts of physical activity of at least 10 minutes in duration; however, for other health outcomes, an active lifestyle approach (for example, climbing a flight of stairs vs. taking the elevator), particularly of vigorous intensity, may be beneficial for initiating physical activity behaviour among inactive adults as well as being sufficient to elicit improvements in health parameters.”

Conclusion

The results of this study suggests that even short periods of physical activity ‘count’ and are associated with improved levels of several risk factors for cardiovascular disease. The study found that the strength of this association was generally as strong for short periods of activity as longer periods of activity.

This study has strengths and weaknesses. The strengths are that both physical activity and the levels of the biological markers were measured objectively, and did not rely on self-reporting, and that it was performed using a large sample of US adults.

However, it was a cross-sectional study, and cross-sectional studies have the limitation that they cannot show causation, in this case, the researchers cannot conclude whether it is the short bursts of activity that affect the biological markers measured.

Also, because participants aren’t followed over time we don’t know what came first, so we don’t know if people who exercise a certain way are healthier or if people who are healthier exercise a certain way.

However, overall this study supports the suggestion that any level of physical activity is better than no activity.

Even if you don’t feel ready to join your local gym, you can still begin making changes to your lifestyle today to improve your activity levels – read more about how you can get fitter without the gym.

Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter.

Links to the headlines

Well, I'll go to the foot of the stairs! Light exercise around the house is as good for your heart as workout. Daily Mirror, January 31 2013

Forget the gym and try the stairs! Short bursts of exercise are just as beneficial as a regular workout. Daily Mail, January 31 2013

Taking the Stairs, Raking Leaves May Have Same Health Benefits as a Trip to the Gym. Sciencedaily.com, published online January 28 2013

Links to the science

Loprinzi PD, Cardinal BJ. Association Between Biologic Outcomes and Objectively Measured Physical Activity Accumulated in >10-Minute Bouts and <10-Minute Bouts. American Journal of Health Promotion. Published online January 2013

Forget BMI, your waist size predicts early death

Crabsallover says 'the study strongly suggests that a high waist circumference WC increases chances of early death, irrespective of whether one has normal, overweight or obese BMI. Excess fat inside the belly (visceral fat) surrounds organs within the abdominal cavity and can more than double chances of death from respiratory diseases, other causes, cardiac diseases and cancers:-

• a male with WC of 120cm (47") or more compared to WC of less than 90cm (35") increases chance of death by 2.02 times.
• a female with WC of 110cm (43") or more compared to WC of less than 75cm (29") increases chance of death by 2.36 times. 
• WC may be a better predictor of death risk than BMI.  
• A large waist WC is linked to higher rates of type 2 diabetes, abnormal lipid levels, measures of inflammation and heart disease.
• WC was positively associated with mortality within all categories of BMI. 
• In men, a 10-cm increase in WC was associated with increased relative risks of 1.16, 1.18 and 1.21 within normal (18.5 to 25), overweight (25 to 30), and obese (30) BMI categories, respectively. 
• In women, corresponding relative risks were 1.25, 1.15, and 1.13.
• "Even if you have a normal BMI and a big tummy then you are just as much at risk as someone who is classified as obese with a large tummy."

The following article by NHS Choices is unedited except for my emphasis.

NHS Choices Tue Aug 10 2010 12:22:00 GMT+0100 (GMT Daylight Time) Share

A large gut may mean fat is stored
around your organs

Waist Size 'predicts early death'

“Men and women with large waists are at increased risk of dying young,” BBC News has reported. The article said that people with a large gut all have the same risk of early death, regardless of whether their body mass index (BMI) is healthy.

The research behind the news tracked more than 100,000 men and women aged 50 and over for nine years. It found that people with very large waists – 47 inches (120cm) or more for men and 42 inches (110cm) or more in women – were about twice as likely to die during the follow-up period compared to thinner people. These deaths were not just from weight-related problems.

It has long been thought that fat collecting around the tummy puts people at greater risk than weight put on elsewhere. The strengths of this study lie in its large size and the collection data on the participants over time rather than their consulting records alone. It may eventually lead to guidance that both BMI and waist circumference need monitoring by people trying to maintain or regain a healthy weight. Regardless of overall weight, people should avoid becoming too big around the middle.

Where did the story come from?

The study was carried out by researchers from the Epidemiology Research Programme at the American Cancer Society in Atlanta, Georgia. No funding sources were reported. The study was published in the peer-reviewed medical journal, Archives of Internal Medicine.

BBC News reported this study fairly and included a quote from the National Obesity Forum saying that the research “underlines the message that fat inside the belly is dangerous”.

What kind of research was this?

The data for this study came from a large US cohort study designed to identify causes of cancer and prevent cancer that ran from 1997 and 2006. This subsequent study looked at waist circumference (WC), a measure of abdominal obesity and linked to higher rates of death independently of other measures of obesity such as body mass index (BMI). The researchers wanted to explore this link further as they say few studies have looked at WC in relation to sub-categories of BMI or the effect of  very high waist circumferences, which are becoming increasingly common.

The researchers were able to sub-divide the large population into men and women and eight different waist circumference categories, with sufficient data in each to examine links between weight circumference, BMI and risk of mortality in a meaningful way. 

This well-designed study also corrected for many of the other factors that could have been influencing the results, such as race, educational level, marital status, smoking status, alcohol use, height and physical activity.

What did the research involve?

The researchers explain that a large waist circumference (WC) is linked to higher rates of type 2 diabetes, abnormal lipid levels, measures of inflammation and heart disease. The theory is that WC may be associated with these conditions because it indicates “visceral fat”, a collection of fatty tissue surrounding the organs within the abdominal cavity. 

A person does not necessarily have to be obese or overweight to have high levels of visceral fat, which means that a simple waist measurement might be a better predictor of death risk than BMI alone.

The data was analysed for 48,500 men and 56,343 women who were all over 50 and enrolled in the Cancer Prevention Study II Nutrition Cohort. In the original cancer study participants had completed a 10-page questionnaire sent to them during 1992/3. This included information on things such as age, sex, medical history and behavioural lifestyle information on smoking and physical activity. WC was first measured by the participants themselves in 1997: they were sent a tape measure and asked to measure their WC just above the navel to the nearest quarter inch while standing, and to avoid measuring over bulky clothing.

The BMI of each participant was calculated from weight reported in the 1997 survey and height reported in the 1982 survey. They excluded participants with missing, extreme or implausible values for BMI or WC, or plus those with unknown smoking status. They also excluded a relatively large number of people (7,997 men and 7,482 women) who had shown a weight loss of 4.5kg or more between 1992 and 1997, on the basis that their weight loss may have been related to unknown or unrecorded disease. Deaths were recorded in the usual way on death certificates and the researchers were automatically notified of any deaths among the participants. The researchers then looked at how WC related to specific causes of death..

Results were analysed appropriately and presented as the relative risk of death adjusted for age, race, educational level, marital status, smoking status, alcohol use, height, and physical activity. Analyses of women were also adjusted for hormone therapy. An additional separate analysis was done adjusting for BMI.

What were the basic results?

Over a nine-year follow-up period, 9,315 men (19.2%) and 5,332 (9.4%) women died. When the researchers analysed the data with the adjustments for BMI and other risk factors they found that in both men and women a very high WC carried about twice the risk of mortality than those in the lowest WC group:

• 2.02 times greater for male WC of 120cm or more compared to WC of less than 90cm (Relative Risk [RR] 2.02, 95% confidence interval [CI], 1.71 to 2.39)
• 2.36 times greater for female WC of 110cm or more compared to WC of less than 75cm (Relative Risk [RR] 2.36, 95% CI 1.98 to 2.82)

Increasing waist circumference was associated with increasing mortality across all categories of BMI (normal, overweight, and obese). In contrast, when analysed by categories of WC, mortality rates did not increase with increasing levels of BMI.

Increased WC was associated with increased risk of mortality for all specific causes of death they analysed; cancer, cardiovascular, respiratory and all other causes. The strength of the association was strongest for respiratory disease and all other causes of death, followed by cardiovascular disease and then cancer as a cause of death.

How did the researchers interpret the results?

The researchers conclude that their results emphasise the importance of waist circumference as a risk factor for mortality in older adults, regardless of BMI.

Conclusion

This large, prospective cohort study was well-conducted and analysed. The new finding is that, after making appropriate adjustments for BMI, increasing levels of WC were associated with higher risk of mortality in men and women. Although this was suspected before, this is the first study that has analysed such a large number or participants in so many sub-categories of waist size and within the three standard clinical categories of BMI (normal, overweight, and obese).

Other points worth noting are that:

• Waist circumference was measured and reported by the participants, which may have introduced some error.
• As this is an observational study, the link between WC and mortality might be overestimated because of confounding by unmeasured or unknown factors associated with both larger WC and higher mortality.
• As all study participants were 50 years or older and nearly all white. The results may not apply to younger populations or those of other racial or ethnic backgrounds.

Overall, this large, well-conducted study emphasises the importance of considering obesity in different ways. In any of the standard clinical groups of BMI, (normal, overweight and obese) it appears that avoiding excessive abdominal obesity can reduce risk of premature death.

Links To The Headlines

Large waist size linked to 'higher risk of death'. BBC News, August 10 2010

Links To Science

Jacobs EJ, Newton CC, Wang Y, et al. Waist Circumference and All-Cause Mortality in a Large US Cohort. Archives of Internal Medicine 2010;170(15):1293-1301

WAIST SIZES - MEN*

• Small - up to 78cm (30")
• Medium - 82.5-87.5cm (32"-34")
• Large - 90-94cm (35"-37")
• X Large - 96.5-101.5cm (38"-40")
• XX Large - 104-109cm
• XXX Large - 112-117cm
• All sizes according to M&S*

Which BMI gives the lowest risk of death? Why the pot belly is a killer.

source: New Scientist, 12 November 2008

An expanding waistline could double your risk of death
(Image: Wikimedia commons)

Updated: 8/8/10.
Crabsallover Notes: Among male participants who had never smoked, the risk of death was lowest:

1. at a BMI of 24.5 (supplementary Figure 2)
2. 85cm waist circumference (supplementary Figure 3)
3. 0.88 waist to hip ratio.(supplimentary Figure 3).

22:00 12 November 2008 by David Robson

Having trouble slipping into those jeans? That expanding belly could as much as double your risk of premature death, even if your weight is considered healthy.

While obesity is a well-known predictor of diabetes, heart disease and some kinds of cancer, a major new study shows that a paunch poses its own particular risks, independently of fat stored elsewhere in the body. This suggests that the size of someone's waistline as well as their body mass index should be taken into account in assessing their health.

The team behind the study, including researchers from Imperial College London and the German Institute of Human Nutrition in Potsdam-Rehbrücke, followed the health of 359,387 people from nine European countries over roughly 10 years. They wanted to examine a link between waistline and health that had been found in earlier smaller-scale studies. Previous animal studies had also suggested that visceral fat around the belly has more negative effects on health than fat in the thighs of the hind legs.

After controlling for factors such as overall obesity, the team found that the risk of premature death among subjects with a waist exceeding 120cm (47.2in) for men and 100cm (39.4in) for women was twice that for those whose waists were under 80cm (31.5in) for men and 65cm (25.6in) for women.

For a given BMI, a 5cm increase in waistline increased the risk of premature death by 17% in men and 13% in women.

A simple predictor of risk

"There aren't many simple individual characteristics that can increase a person's risk of premature death to this extent, independently from smoking and drinking," says Elio Riboli from Imperial College London, who was part of the team.

The ratio of waist size to hip measurement also appears to be an important predictor of the risk of premature death. Most waist-to-hip ratios for men ranged from 0.78 and 1.10 for men, and for a given ratio, an increase by 0.1 increased the chance of premature death by a whopping 34%. Most female waist-to-hip ratios were in the 0.66-0.98 range, and (again for a given ratio) an increase of 0.1 resulted in a 24% jump in risk.

The team speculate that fatty deposits around the waist could secrete elevated levels of hormones and other signalling proteins called cytokines that lead to chronic illnesses like heart disease and cancer.

"Abdominal fat is not a mere energy depot, but it also releases messenger substances that can contribute to the development of chronic diseases. This may be the reason for the link,"

says Tobias Pischon of the German Institute of Human Nutrition.

Review by Crabsallover

Journal reference: New England Journal of Medicine, vol 359, p 2105 (Full Text)
Table 1. Relative Risk of Death According to BMI among Men and Women in the European Prospective Investigation into Cancer and Nutrition.
Current guidelines with respect to obesity recommend the measurement of waist circumference in persons with a BMI between 25.0 and 34.9 and propose cutoff points for waist circumference of 102 cm in men and 88 cm in women (and cutoff points for waist-to-hip ratio of 1.0 in men and 0.85 in women) to define abdominal obesity and to identify persons at risk for disease.² However, less is known about the association of waist circumference or waist-to-hip ratio with the risk of death.

There was a significant nonlinear association of BMI with the risk of death, with the lowest risks at a BMI of 25.3 among men and 24.3 among women

and increased risks in the lower and upper BMI categories (Table 1 and Figure 1).
Figure 1. Adjusted Relative Risk of Death among Men and Women in the European Prospective Investigation into Cancer and Nutrition, According to BMI, Waist Circumference, and Waist-to-Hip Ratio.
The relative risk of death in association with body-mass index (BMI, the weight in kilograms divided by the square of the height in meters), waist circumference, and waist-to-hip ratio is shown in Panel A for men and in Panel B for women. Solid lines indicate relative risks, and dashed lines indicate 95% confidence intervals. The relative risks are plotted on a logarithmic scale.







Table 2. Relative Risk of Death According to Quintiles of Waist Circumference among Men and Women.
According to the Crude measure

the optimum waist measurement is 86-<91.5cm>

After further adjustment for BMI, waist circumference and waist-to-hip ratio showed a strong positive association with the risk of death (Table 2 and Figure 2, and Table 3 in the Supplementary Appendix). For a given BMI in men and women, a waist circumference that was 5 cm larger was associated with a risk of death that was increased by a factor of 1.17 among men and by a factor of 1.13 among women, and a waist-to-hip ratio that was 0.1 unit higher was associated with a risk that was increased by a factor of 1.34 among men and by a factor of 1.24 among women. In models that included waist circumference or waist-to-hip ratio, BMI remained significantly associated with the risk of death. Hip circumference was not significantly associated with the risk of death after adjustment for BMI.

Figure 2. Adjusted Relative Risk of Death among Men and Women, According to Waist Circumference and Waist-to-Hip Ratio after Adjustment for BMI.
The relative risk of death in association with waist circumference and waist-to-hip ratio, after adjustment for BMI, is shown in Panel A for men and in Panel B for women. Solid lines indicate relative risks, and dashed lines indicate 95% confidence intervals. The relative risks are plotted on a logarithmic scale.
Subgroup Analyses

Among participants who had never smoked, the risk of death was lowest at a BMI of 24.5 for men and 23.9 for women

Amongst Men who have never smoked (Supplimentary Figure 3) the lowest risk of death was with 85cm waist circumference / 0.88 waist to hip ratio.

(Figure 2 and Figure 3 in the Supplementary Appendix).

Waist Circumferance

A free tape measure from British Heart Foundation 'Heart Matters' waist measurement.

Crabsallover waist 99cm (at 12st 2 pounds) - increasing health risks according to the tape or according to table below "your health is at risk".

Sharon 37" - health at risk.

Click image below "how to measure your waist" and for measurements "your health is at risk" or "your health is at high risk".

Join Heart Matters from BHF - receive a free tape measure .... and a lot more.

WHO - Preventing the global obesity epidemic - 2000

Total report size: 253 pages
Summary 16 pages - click on Parts 1..2 etc, for additional pdf

Part 1: The problem of Overweight and Obesity

Part 2: Establishing the true costs of the problem of overweight and obesity