Archive for category Primate Physiology
It would be great if an acclaimed — and more importantly, extremely widely read — U.S. newspaper could boast “Health” and “Science” sections that boasted consistently impressive articles. This one is getting a lot of attention, and with good reason: something like two-thirds of adult Americans are considered overweight, millions of them are trying to shed pounds, and Gina Kolata’s article in effect conveys the message that they are screwed.
I’m going to assume that anyone reading this has read the article and the study it draws from or at least has tabs open to these, because I am not going to review it in depth.
A couple of very quick, seemingly obvious, and (perhaps deliberately) underemphasized or omitted points:
Not because I’ve done anything good but because others keep doing things that are impressively bad.
In doing some research for a desultory LIVESTRONG piece on energy supplements and heart rate, I came across perhaps one of the worst articles of its type in the history of the Internet, with “its type” being anything purporting to offer science-based health information on a widely read site. Or, if you prefer, anything posted anywhere. The writing itself hits all of the low notes of the craft–hyperbole, repetition, gratuitous capitalization, subject-verb mismatching etc.–but even worse is the amount of extraneous, wonky, and flat-out erroneous content. This section is my “favorite”:
Energy drinks and alcohol is a popular combination, but can be dangerous as well. The trouble is this: energy drinks are an upper. They dilate your pupils and increase your heart rate. They make you ready to spring into action. Alcohol is a depressant, or a downer. It makes your pupils constrict, and lowers your heart rate. Thus, when you combine an upper and a downer, as you do when you mix an energy drink with alcohol, your heart doesn’t know what to do. It goes back and forth between increasing and decreasing in BPM. This is not only unhealthy, but can also be dangerous. You are essentially throwing off the rhythm of you heartbeat. Once again, low levels are fine, but it is dangerous when moderation is thrown out the window.
First of all, ethyl alcohol may cause bradycardia at high levels, but is proximate effect is tachycardia. Combining stimulants such as caffeine and alcohol can have an additive effect on cardiac conduction and lead to things like atrial fibrillation in susceptible people. As far as the heart not “knowing” what to do, there are no “decisions” when it comes to drugs with potentially antagonistic effects. The heart will not “choose” methamphetamine over hypothermia and jack itself up to 160 beats per minute or “opt for” the reverse and sink to a pulse of 40. I’m also skeptical of the idea that booze and energy drinks are a popular combination, but if that’s the case among anyone reading this article with a nodding head, maybe that’s why they’re on a site with “fat chicks” in its name.
Three Fat Chicks apparently gets about 35,000 page views a day, or over a million a month. Maybe, though its support forums and so on, it’s a valuable resource for people wanting to lose weight or become fitter, and articles need not be written in masterful prose in order to convey meaningful information. But this kind of shit is a reminder than on the Internet, even high-traffic and superficially slick-looking sites often lack any sort of quality control or oversight and that when something as important as health is involved, it’s a good idea to check sources–and “Are Energy Drinks Safe on Heart Rate?” doesn’t have any.
One of the medical feeds I subscribe to included an article yesterday about the increased benefits endurance athletes enjoy when using a replacement drink containing a mixture of protein and carbohydates instead of one containing carbs alone (e.g., Gatorade, All-Sport, countless others).
I found this blurb (and the study itself) noteworthy for two reasons.
Those of you who run, bike, swim, or otherwise engage in aerobic exercise have probably noticed that in spite of burning scads of calories during your chosen activity, the last thing you feel when you’re finished is hungry. Now, researchers at Loughborough University in the United Kingdom may have discovered exactly why this is.
In a study published in the November issue of the American Journal of Physiology’s Regulatory, Integrative and Comparative Physiology, David J. Stensel and his colleagues demonstrated that 60 minutes of treadmill exercise and 90 minutes of weight training have different effects on the levels of the hormones peptide YY, which suppresses appetite, and ghrelin, the only hormone known to increase it.
The researchers discovered that aerobic exercise produces increased peptide YY levels while lowering ghrelin, leading to decreased appetite. Weight training was associated with a decrease in ghrelin, but no change in peptide YY, meaning that there was a net suppression of appetite, but not to the same degree as observed with treadmill training. In both cases, changes in appetite lasted for about two hours.
The study included only eleven subjects, and the results are subjective in that subjects were asked to rate their own hunger (not that a better means of assessing appetite exists). These subjects were all male, young (21.1 +/- 0.3 years), and fit (VO2 Max of 62.1 +/- 1.8 ml/kg/min; BMI of 23.1 +/- 0.4), so it’s not necessarily true that their subjective feelings of hunger or even their physiological responses can be extrapolated to the general population.
If there’s a practical application here, people who want to lose weight and get stronger might be advised to save the “cardio” portion of their gym work until the end of the workout in order to maximally suppress appetite.
Then again, I have a problem with the idea of working out for an hour or more and avoiding nourishment in the immediate aftermath, since this period is when carbohydrate (glycogen) replenishment in muscle can be most efficiently achieved. Whether you’re hungry or not, you should make every effort to take in 200-400 kcal worth of carbohydrates (the equivalent of a banana and a 16-ounce sports drink) as soon as you roll off the last bench or wind up your five-miler. Then, if need be, you can let your hormones go to work for you.