Matt Metzgar

Aerobic Capacity and the Metabolic Syndrome

This news release talks about an intriguing study between aerobic capacity and heart disease.  Over 11 generations, researchers bred rats with either low or high aerobic capacity.  The group of low aerobic capacity rats scored higher on risk factors related to the metabolic syndrome, suggesting a strong link between the two.

I dug deeper and got the full-text of the original study.  First, there was some good news for the low capacity rats: there were able to significantly increase their aerobic capacity through training.  The high capacity group was able to increase their fitness through training as well, and a sizeable gap remained, but at least the low capacity group maintained the ability to improve their capacity.

Next, the authors looked at longitudinal changes in both groups of rats.  They noticed that at five weeks old, both groups of rats weighed the same and had the same amounts of visceral fat.  Therefore, the authors believed that the low aerobic capacity of the one group of rats (before training) preceded and may have actually led to the metabolic problems this group encountered.

This is quite interesting as it shows that the metabolic syndrome may be prevented by achieving a high aerobic capacity (or as high as a person can get, given their genetics).  Other lines of thought suggest that a poor diet leads to metabolic problems, which leads to diminshed activity and ultimately a diminished aerobic capacity.  This new line of thinking starts from the other end and suggests that a low aerobic capacity may be the starting point for a downward metabolic cascade.  Of course, diet can cause metabolic dysfunction, but little research has focused on the possibility that aerobic capacity may be the more important and ultimate regulator of the metabolism.

But what about the conventional wisdom that aerobic capacity unavoidably declines with age?  Personally, I think this "normal" decline has been greatly overstated.  This article shows that if a person continues with high-intensity aerobic interval training, their aerobic capacity will not drop off much over time.  And this is great news for anyone wanting to stay healthy and avoid the metabolic syndrome as they age.

Abdominal Fat and Aerobic Capacity

In this post, I mentioned how just segmenting a group by aerobic capacity showed large differences in waist measurements.  Since then, I've found a slew of studies that connects abdominal fat with aerobic capacity.

Here's one study that shows men with lower aertobic fitness had higher levels of visceral fat.  Here's another study that shows aerobic fitness is an independent predictor of wasit circumference in youths.  And here I think is the best study on the subject.  For a given body mass index (BMI) or waist circumference, subjects with lower aerobic fitness had higher levels of abdominal fat.

So what's the relationship between aerobic fitness and abdominal fat?  I have my ideas in this next post.

Interval Training: State of the Art

I recently ordered this paper, which turned out to be a very good review of interval training.  The review was concerned with which types of interval training elicited the greatest improvements in VO2max, or aerobic capacity.

In order to maximize the effects of interval training, the recommendations are as follows:

• The work interval should be between 90% and 105% of VO2max
• The work interval should last between 15 and 30 seconds
• The relief interval should be between 15 and 30 seconds
• Cumulative work interval time should total at least 6 minutes
• There should be no break between the warm-up period and the intervals

These are sound recommendations which can be used to build an effective interval training program.

Activity versus Fitness

Most people know that staying active is important for general health.  The government recommends certain minimum amounts of activity for children and adults.  But unfortunately, less emphasis is placed on achieving a high level of cardiovascular fitness.

This study examines both total activity and aerobic fitness in children.  The study concludes that both total physical activity and cardiorespiratory fitness have separate and independent effects on metabolic syndrome.  In other words, both are necessary for optimal health.

Other studies, which I plan to dig up soon, have looked at the optimal amount of total physical activity (total energy expenditure) per week.  In this study, for both total activity and cardiovascular fitness, it showed the more of each, the better.  The highest quintiles for these two variables showed the lowest risk for the metabolic syndrome.

Keeping active and expending a minimum number of calories per week is a vital part of staying of healthy.  However, part of this activity should be spent at higher intensities in order to develop a high level of aerobic fitness.

Trans Fats are Fattening

Not only are trans fat terrible for your health, research suggests they lead to more abdominal fat than other types of fats.  As discussed in this article, a recent study compared monkeys on a diet with trans fat to those on a diet with monosaturated fat.  Even though total calories consumed were the same, the trans fat monkeys had a 7.2 percent increae in body weight and much more abdominal fat than the other group of monkeys.

Thank goodness many companies are removing trans fat from their offerings.  The obesity epidemic doesn't need any more help in the form of trans fats.

The Importance of Aerobic Capacity

heI was looking at the full-text of this study earlier.  The study was loooking at the effects of a single exercise session on inflammation, but that wasn't what caught my eye.

Subjects were separated into two groups based only on their VO2max.  The baseline characteristics of each group were then listed.  Here's a few of the characteristics:

	Highly Fit	Moderately Fit
Body Fat %	13.5	22
Waist (cm)	81.2	90.1
VO2max	53.9	39.3
Average Caloric Intake	3,016	2,395

These are huge differences in fatness among the two groups.  Of course, the difference in VO2max didn't happen by magic, the highly fit group most likely trained harder. Also note that the fit group consumed significantly more calories on average.  But I still think it's pretty amazing that just one variable, aerobic capacity, is so closely related to body fat measures.

Inflammation and Depression

I have been following a line of research that links inflammation and depression.  For example, it has been shown that levels of inflammation can be 40% to 50% higher in depressed people compared to non-depressed people.  In fact, some researchers believe that inflammation the primary cause of depression.  It is now a matter of finding out what physical and mental stressors activiate inflammation in certain people.

This is interesting to me because diet and exercise play a large role in regulating the body's level of inflammation.  Other studies have shown that exercise can often treat depression.  Could the link be through exercises beneficial effects on inflammation?

As I talked about in this post, intermittent fasting can help reduce inflammation as well.  And of course, eating more along the lines of a Paleo diet will help to reduce inflammation as well.

Researchers are now looking at anti-inflammatory medicines as a way to treat depression.  Hopefully, they will not overlook the power of diet and exercise to lower inflammation as well.

Simpsons Fun

As part of the promotions for the upcoming Simpsons movie, 7-Eleven has made over 12 stores nationwide into "Kwik-E-Marts", the fictional stores on the show.  More information about the promotion is available in this article.

It turns out that one of the Kwik-E-Marts is a couple miles up the road from where I live.  I don't watch the Simpsons, but I thought it would be fun to check out the promotion.  Below are a few photos I took, including one with the manager in his Kwik-E-Mart uniform.

Sketches

For reasons described in this post, I've been doing a few sketches for fun lately.  To help organize things, I've created a new blog category for these sketch posts.

Creativity and Aging

I've been doing a lot of thinking about the relationship between creativity and aging.  A couple of years ago, I read some papers by Professor Geoffrey Miller (http://www.unm.edu/~psych/faculty/lg_gmiller.html) that looked at the function of creativity.  He concludes that creativity is a tool in the mating game, and shows that creative output generally peaks in the 20s.

Initially, this was a bit depressing to me since I've always enjoyed creative activites.  I started to think, "why bother to create if I'm past my peak?"  But then I started thinking about how athletic ability changes throughout the lifetime.  Generally, people reach their physical peak in their 20s as well (though of course, not always).  So does mean it's futile to exercise when you're older? Of course not.

I think evolution changes the default setting on the body from "growth" to "decay" sometimes in the 30s.  This is when people start to lose muscle mass if they aren't strength training.  Aerobic capacity also starts to decline.

But science has shown that if you continually challenge the body through strength and aerobic exercise, you can keep the body young.  A person may not be able to roll the clock back 100% to their 20s, but you can do pretty well.  And of course, exercise has many side benefits, such as feeling better and functioning better on a daily basis.

So I thought, "why not apply the same principle to creativity?"  I definitely think there is a default switch for creativity as well, and that it turns off in the 30s.  But again, if you can challenge the mind with youthful creative challenges, then maybe this helps the mind "stay young" as well. 

I've been testing this theory by brushing off the pencils and doing some sketches.  So far, my theory is holding up as I definitely feel more creative "juice" on a day-to-day basis. 

There's no reason to think that both mental and physical aging can't be postponed/minimized by utilizing challenges.  Challenges keep us young by signaling the body and mind to grow instead of decay.