Sweat Science

The idea that popping antioxidant supplements doesn’t help — and may even counteract — some of the benefits of exercise and training is something I’ve written about several times, most recently here. So I’m duty-bound to point out the latest study, due in a future issue of Medicine & Science in Sports & Exercise (abstract available here).

The gist: 12 weeks of strenuous, supervised bicycle training, five days a week. Supplement with vitamins C and E or placebo, double-blinded. A whole bunch of physiological parameters were measured as outcomes (maximal oxygen consumption, maximal power output, workload at lactate threshold, glycogen concentration, citrate synthase, [beta]-hydroxyacyl-CoA dehydrogenase activity, if you’re interested in the details). The result:

[T]here were no differences between the two groups with regard to any of the physiological and metabolic variables measured… Our results suggest that administration of vitamins C and E to individuals with no prior vitamin deficiencies has no effect on physical adaptations to strenuous endurance training.

Of course, there are many other purported benefits to these vitamins, such as on immune function. But chalk this up as another data point in an ongoing story.

supplements

A few eyebrows were raised when NASCAR champ Jimmie Johnson was named AP Athlete of the Year last month. Johnson defended his athleticism, saying:

So to anyone who wants to go head-to-head with me in athletic ability, let’s go. I talked a lot with Jason Sehorn about this, and I don’t know how exactly you measure athletic ability, but I know my five-mile run time [of 34 minutes, 55 seconds] will destroy most NFL players.

Anyway, that debate popped to mind when I noticed this paper among the list accepted for future publication in Medicine & Science in Sports & Exercise: “The Physiological Demands of Off-Road Vehicle Riding.” Researchers measured strength and oxygen consumption of 56 ATV drivers and 72 off-road motorcyclists during a 48-minute ride. They found that ATV drivers were breathing hard enough to indicate they were getting a workout about 14% of the time; the motorcyclists were puffing 38% of the time. Also, their muscles got tired, particularly in the upper body. The conclusion:

Based on the measured metabolic demands, evidence of muscular strength requirements, and the associated caloric expenditures with off-road vehicle riding, this alternative form of activity conforms to recommended physical activity guidelines and could be effective for achieving beneficial changes in health and fitness.

What to say about this? Well, given that one of the other papers accepted was yet another examination of whether active video games count as exercise, at least the ATVers are getting outside for their “exercise”!

cardio, sports technology

I generally try not to get too excited about mouse studies, because there’s so much uncertainty about how the results will translate to humans. Still, I was very interested in a new study on fat-burning from Australian researchers at the Garvan Institute of Medical Research. I’ve always been skeptical about the various ways people suggest trying to convince your body to burn fat rather than carbohydrates, whether it’s by keeping your heart rate in a certain zone (usually by going slower than you would otherwise go, which seems silly to me) or by taking some sort of pill.

Anyway, there’s a very good press release describing the new study and providing context, but allow me to quote the key section:

Sydney scientists have demonstrated that mice genetically altered to burn fats in preference to carbohydrates, will convert the unburned carbohydrates into stored fat anyway, and their ultimate weight and body composition will be the same as normal mice.

The research related to an enzyme called ACC2 (acetyl-CoA carboxylase) that controls whether cells burn fats or carbohydrates. There’s no doubt that this is still a very complicated area of research, so I’m certainly not claiming this is the “last word” on this topic. But it reinforces my impression that our primary focus should be on burning (or avoiding) calories, not burning fat.

weight loss

Gina Kolata has another debunking-conventional-wisdom Personal Best column in the New York Times, this time taking on physical therapy (or physiotherapy, as it’s known here in Canada). I’ve really appreciated some of her previous articles on stretching, cool-downs, massage, lactic acid, and so on. This one, I was less impressed by. She writes:

When I’ve gone to physical therapy, the treatments I’ve had — ice and heat, massage, ultrasound — always seemed like a waste of time. I usually went once or twice before stopping.

To me, this is sort of like saying “Yeah, I’ve tried antibiotics several times, but it never seems to work for me, so I always just take the pills for a day or two and then throw the rest away.” Any successes I’ve had with physical therapy tend not to be the “fix pain in two weeks” category, but more like “spend six months correcting some subtle weaknesses and imbalances in order to avoid repeating the injury you just had.” It’s a long-term investment.

That being said, the article has some interesting information about which treatment and recovery modalities actually have solid evidence behind them (not many). I’ve written about heat and ice and massage before — the fact is, if we limited ourselves to the modalities that have solid peer-reviewed evidence, we’d all just be lying in bed for a few weeks every time we got injured. So much as I like evidence-based medicine, I think we have to be realistic about the current state of knowledge.

injuries, recovery

In the comments section of yesterday’s post, John Lofranco raised the topic of a subject that has been popping online and in newspapers over the past few days. You may have seen the headlines: “Running shoes are more dangerous than high heels” and so on. Here’s the press release, and here’s the full text of the study itself, “The Effect of Running Shoes on Lower Extremity Joint Torques,” by researchers at the University of Virginia. Here’s the key part of the press release:

In a study published in the December 2009 issue of PM&R: The journal of injury, function and rehabilitation, researchers compared the effects on knee, hip and ankle joint motions of running barefoot versus running in modern running shoes. They concluded that running shoes exerted more stress on these joints compared to running barefoot or walking in high-heeled shoes.

From what I can tell, this is solid research that suffered from the “broken telephone” effect, being successively distorted at each step. First, there’s the data they measured — useful stuff that sheds light on how our legs work. Then there’s the scientific paper, which in my opinion stretches the conclusions a little farther than the data currently warrant. Then there’s the press release, written by a PR person at the journal, which stretches things even further (the study, for instance, did not include any high-heeled shoes, and no direct comparisons between running shoes and high-heeled shoes were possible). Then there are the press articles, which rely on the press release… (There’s also this: “In July, [Kerrigan] left the University of Virginia to start her own company, JKM Technologies LLC, which will focus on developing her shoe in coming years.”)

Amby Burfoot of Runner’s World, in his Peak Performance blog, has written an excellent post in response to this study that is essential reading for anyone interested in running injuries and the role of shoes. As usual, it’s a nuanced point of view that neither praises nor buries the research. He points some of the leaps — the difference between measured torque in the knee and observing arthritis, the mismatched comparison between walking and running forces, the downplaying of the role of stride length. His main message is that this is a very complex field of research where little is known, so we should be open to new results but avoid gratuitous oversimplification. It’s definitely worth a read.

barefoot running, injuries, sports technology

Great article in the Wall Street Journal about Paul Williams’ National Runners’ Health Study. As I wrote last summer:

What Williams really emphasizes in his recent studies is the “dose-response” relationship between running and health: the farther and faster you run, the greater the benefits.

But this isn’t a very popular message among public-health advocates, who are struggling to convince people to do any exercise at all, let alone worry about how hard they go, according to WSJ’s Kevin Helliker:

In Dr. Williams’ study of more than 100,000 runners over nearly 20 years, stepped up exercise was found to have some powerful benefits. But his research is controversial. While Dr. Williams is well respected by other exercise scientists, he is shunned by those in the public-health field. Dr. Williams is routinely excluded from committees charged with formulating exercise guidelines, and his grant proposals are often rejected as irrelevant because few exercisers want to hear the word “more.” Public-health officials also worry that touting Dr. Williams’s research could discourage the sedentary from doing any exercise at all, or lure them off the couch with goals too lofty to engender success.

It’s an interesting dilemma, but ultimately I believe in simply telling the truth, even if it makes the message more “complicated.” More exercise is better, and if you’re simply meeting the standard exercise guidelines, you’re leaving a lot of potential benefits on the table:

A number of [Williams'] studies have taken direct aim at current exercise guidelines, by comparing the benefits of mere compliance with the benefits of running far beyond them. A Runners’ Health study published in the journal Stroke last spring found that men and women who ran more than eight kilometers a day had a 60% lower risk of stroke than those who ran at the guideline levels. An article published in September in the journal Atherosclerosis found that those Runners’ Health participants who exceeded guideline levels had a 26% lower risk of coronary heart disease than those who ran at guideline levels.

This week’s Jockology column takes a closer look at the idea that group exercise offers some benefits that solo sessions don’t.

The question

Will taking a class or finding training partners help me keep my exercise resolutions this year?

The answer

Consider the similarities between a modern exercise class and an ancient religious rite – the wise leader guiding the group through a series of ritualized movements, in perfect synchronization. If you’re struggling to keep faith with your fitness goals, this apparent coincidence might offer a solution.

New research suggests that group exercise unleashes a flood of chemicals in the brain, triggering the same responses that have made collective activities from dancing and laughter to religion itself such enduring aspects of human culture. For some (but not all) people, finding workout buddies could help turn fitness into a pleasant addiction. [read on...]

Obviously people have a lot of different reasons for working out in groups — or for working out on their own, for that matter. But I found the study of Oxford rowers described in the article to be one of the most interesting studies of 2009. In the running community, there’s a lot of debate about why so many athletes stop competing seriously after they finish university. Again, there are clearly many different reasons — but I’ve heard a lot of runners say that the training experience just isn’t the same once they’re no longer part of a group working out together and sharing common goals. Maybe this is really just a form of endorphin withdrawal!

sports psych

Here’s a mystery: Why is obesity still such a problem in the age of the magic zero-calorie sweetener? New Scientist has a great article on the latest brain-scanning research, which offers some hints about how these sweeteners may fool us on a conscious level, but don’t manage to trick our unconscious minds. These new studies suggest that “zero-calorie” options may really just lead to “deferred calories” that make us consume more than a full-sugar version would have.

For many years, there have been hints that people who drank sugar-free sodas ended up gaining more weight than those who didn’t. (Travis Saunders described some of this evidence at Obesity Panacea last year.) Guido Frank at the University of Colorado is one of the researchers whose studies help explain this. He fed drinks containing either sucrose (sugar) or sucralose (artificial sweetener) to subjects, who were unable to tell the difference between the two. However:

Sucrose produced stronger activation in the “reward” areas of the brain that light up in response to pleasurable activities such as eating and drinking. Sucralose didn’t activate these areas as strongly… Frank suggests that sucralose activates brain areas that register pleasant taste, but not strongly enough to cause satiation. “That might drive you to eat something sweet or something calorific later on,” he says.

This is still a developing area of research, but it seems highly likely that there’s no (calorie-)free lunch. You can’t have sweetness without (eventually) paying a caloric cost.

The obvious question, then, is whether you’re better off drinking diet soda or full-sugar soda. I’ll join with Travis Saunders in suggesting that you keep consumption of either to a minimum (though, as with most “bad” foods, it should be fine in moderation). But if I’m choosing between the two, now that I know that the overall caloric hit will be about the same for regular and diet soda, I’d rather drink the real thing.

[Thanks to Selam for the tip!]

hydration, nutrition, weight loss