Matt Metzgar

Intermittent Fasting

I found a couple recent papers of interest on intermittent fasting.  The first paper(pdf) appears in the American Journal of Clinical Nutrition and looks at intermittent fasting and calorie restriction.  It reviews both animal and human studies on the subject, concluding that intermittent fasting may be effective in treating chronic disease.

The second study is quite interesting because it looks at intermittent fasting and asthma.  In the study, subjects consumed 20% of their normal intake on one day, and then ate as much as they wanted on the next day.  They continued this alternate day calorie restriction for 8 weeks.  The authors hypothesized that this eating pattern would reduce oxidative stress and inflammation.  It appears to have worked as important markers of inflammation decreased in the subjects.

Snoopy

Just Me and the Birds

Today I walked down to the local soccer field to do some sprints.  And the whole time I was there, I didn't see another person out exercising or playing, even though there is park adjacent to the field.  I can't count the number of times this has happened to me here.  Hot or cold, early or late - I'm frequently the only person exercising outdoors.

The only consistent companion I have at the field are the birds.  Virtually every time I go down there, there is a pack of birds rummaging about.  When I start running, most of the flock leaves, but a few mellow birds stay behind and watch.  I try to at least put on a good show for them. 

Today was hot, around 105 degrees when I ran.  But a person can get adapted to hot or cold temperatures if he doesn't stay isolated indoors all the time.  I ran outside in single digits in Ohio and run outside in triple digits here.  I don't want to run a marathon in Death Valley or anything crazy, but a half hour in the hot or cold isn't that bad.

I watched today as parents were picking up their children from the elementary school near the field.  The kids were immediately swallowed up by giant SUVs with tinted windows and whisked away to another indoor location I'm sure.  No time for the kids to run on the field or play on the playground, there must be more important things to do.

The whole scene was a little sad.  I remember walking home from school as a kid, not taking the bus.  We'd run and play, throw snowballs, play football, etc.  It felt good to move around after sitting at desks all day.  It still does to me.  But now it's just me out there - me and the birds.

Cover of Immortal Iron Fist #4

Natural Parenting

Here's a great paper(pdf) that looks at parenting from an evolutionary, hunter-gatherer perspective.  It discusses approaches to child care that have been used successfully for thousands of years that are now being displaced by modern, often inferior methods.  The paper is fairly long, and so I wanted to present a summary here because I feel it's very important information.

Evolutionary Function of Crying

• Crying signals genuine needs of the infant
• Crying should be immediately attended to by the mother or caregiver
• Crying takes significant physical effort on the part of the infant
• The immediate response to crying should be to restore physical contact between the caregiver and the infant

Infants as Carried Young

• Hunter-gatherer women carried their infants in slings close to the body
• This increased beneficial skin-to-skin contact between the mother and the infant
• The common leg positions of babies suggest they are adapted for carrying

Cosleeping

• Cosleeping for the infant and mother has been the universal norm throughout most of human history
• Bedsharing is the environment to which the vulnerable newborn is best adapted
• Cosleeping may reduce some forms of SIDS

Breastfeeding

• No alternative to breast milk existed before the transition to a farming economy
• Therefore, infants have been breastfed for 99% of all human existence
• Artificial substitutes have been unable to replicate the complex structure of breast milk
• There is mounting evidence about the many benefits of breastfeeding on child development

Extrogestation

• Human infants are born in an exceptionally immature state
• The conditions for the early part of infant life should attempt to mimic that of the womb
• This includes close contact with the mother's body in a tight, warm embrace
• Heartbeat sounds are comforting to an infant; women tend to hold infants on the left side of their body, close to their hearts
• Rocking an infant provides a calming effect since it mimics the movement stimulation the infant received from the mother's normal daily movements
• Swaddling replicates the feeling of the womb and has been proven effective in calming infants

Toilet Training

• Infants were historically toilet trained much earlier than in modern times
• Natural toilet training depends on reading an infant's signals and responding appropriately
• Children trained in this way complete toilet training anywhere from 6 months to 2 years

Endurance Running and Testosterone

Here's a study I saw a few weeks ago that I've been meaning to post about. Researchers hypothesized that prenatal testosterone exposure would lead to differences in physical development, which would then lead to differences in adult endurance performance.

The study used a digit ratio, the ratio of the length of the second and fourth fingers, abbreviated as 2D:4D.  This 2D:4D ratio has been shown to be predictive of performance in other activities, such as soccer, skiing, and basketball.

The authors measured the digit ratio in men and women and then tested them over a series of 1 and 4-mile cross-country runs.  After analyzing the data, it turned out that the digit ratio explained 25% of the variation in running performance. 

This is quite a large amount of variation that's attributed to a single factor.  The authors believe that endurance running was an important part of human evolution, and that there were strong selection pressures on endurance performance and prenatal testosterone.

Muscles and Joints

I came across this article on osteoarthritis the other day.  It lists some key factors that increase the risk of arthritis over the years:

• Excess weight
• Inflammation
• Loss of muscle mass

All three of these factors can be largely controlled by diet and exercise.  A proper diet and exercise plan can minimize excess weight.  Inflammation is heavily influenced by diet, and a Paleo diet can reduce levels of inflammation.  Strength training can prevent/slow the loss of muscle mass.

Something else I found interesting in this article was the statement that muscle acts as a shock absorber, and that less muscle mass means more pounding on the joints.  Yet I wonder why I never see this discussed as it relates to running. 

For those people who run a lot (especially on pavement), they are placing a good deal of shock on the body.  It would then make sense that a runner would want to build up their lower-body muscles to help absorb some of this shock.  But I don't think I've ever seen this particular recommendation.  Many people recommend strength training for runners, but it's often for the reason of better performance, not better protection for the joints.  I also wonder whether the larger lower-body muscles of sprinters help protect their joints from damage. 

Woodstock

A quick sketch, just for fun.

Aging and Testosterone

I thought Clarence Bass had a nice article on testosterone and aging this month.  He points out that his testosterone levels are still normal despite his age (almost 70), and that his levels have probably not changed much over the years.

This goes against the thought of a "normal" decline in male reproductive hormones during aging.  But if you look deeper into this issue, you see that this decline is mostly due to poor eating and exercise habits.  Specificallly, it seems that abdominal fat is the real killer of testosterone levels in men.

Clarence has had low body fat for most of his adult life.  This factor, along with his eating and exercise habits, have apparently kept his hormones at youthful levels.  His example shows that the decline in male hormones is not inevitable; if a person takes care of their body, they can retain a youthful hormone profile throughout the years.

More Muscles, More Sex?

Today's USA Today had an article about muscularity and sex.  New research shows that well-muscled men are twice as likely to have more sex partners and flings than those with more slender physiques.  But when it comes to long-term relationships, slender men are more appealing to women because they are perceived as more faithful and romantic.

This is very interesting, and it shows that the strong desire of young men to gain muscle has evolutionary roots.