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Archive for August, 2011

Cardio vs weights for visceral and liver fat

August 30th, 2011

A new study in the American Journal of Physiology revisits a very familiar topic — cardio versus weights — to determine which is better for reducing dangerous visceral and liver fat. A total of 155 subjects completed one of three eight-month training programs:

  1. Aerobic (AT): ~12 miles per week at 75% VO2max;
  2. Resistance(RT): 3 days a week, 8 exercises, 3 sets of 8-12;
  3. Aerobic/resistance (AT/RT): both the above programs combined.

At the end of the eight months, they used some pretty sophisticated tools to measure the outcomes, including CT scans to measure levels of visceral and liver fat. Here are some of the key outcomes:

And here’s how the researchers sum up the findings:

First, a resistance training program–even a very substantial one–did not significantly reduce body mass, visceral fat, liver fat or ALT liver enzyme levels. RT also did not reduce total abdominal fat, nor did it improve fasting insulin resistance. Second, in contrast to RT, a typical vigorous AT program resulted in significant reductions in visceral fat, liver fat and abdominal subcutaneous fat, and also led to improvements in circulating ALT and HOMA (fasting insulin resistance).

The results aren’t too surprising: as the researchers note, this particular aerobic training program likely burned about 67% more calories than the resistance program. It does seem a bit strange to me that adding resistance training to the aerobic training seems to make things worse rather than better — but the overall analysis in the paper says that AT and AT/RT are statistically indistinguishable. In other words, the weights add nothing. Don’t get me wrong: weights are useful for a lot of things, and this study was only testing a few specific outcomes. But on those outcomes — and they’re very important ones, particularly if you’re overweight — cardio trumps weights.

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Post-exercise refuelling: all at once, or spread out?

August 29th, 2011

We’ve all heard about the post-exercise “window” for refuelling to maximize recovery and adaption: you need to take in carbs and protein with 0.5-2 hours. But does the timing really matter for building muscle? A new study from Stuart Phillips’ group at McMaster University compared two tactics for post-workout protein intake. Once group took 25 grams of whey protein immediately after a set of leg-extension exercises; the other group received the same 25 grams of whey protein in 10 2.5-gram doses every 20 minutes for 200 minutes. They measured “muscle protein synthesis” — basically a very accurate way of assessing how well you’re stimulating muscle growth after a single bout rather than having to run the experiment for several months to actually see muscle growth — and found that it was much higher in the group that took their protein all at once. After six hours, protein synthesis was elevated by 193% in the single-shot group and just 121% in the prolonged group.

The question this study was seeking to answer actually relates to the difference between whey protein (which is absorbed quickly) and casein (which is absorbed more slowly: the 2.5 grams of whey every 20 minutes was chosen to mimic the absorption pattern of casein). The problem is that if you compare two different proteins in a study, then you’re changing a bunch of different factors at once — the absorption timing, but also factors like the amount of leucine, a branched-chain amino acid thought to be key for muscle growth. Since both groups received 25 grams of whey (and thus identical amounts of leucine), this shows that absorption rate is key.

Practical takeaway: this was a muscle protein synthesis study, not a training study, so you have take the results cautiously. But it does suggest that if you’re trying to build muscle, taking in a big dose (i.e. 25 grams) of protein as soon as possible is preferable to snacking over the course of a few hours. It also confirms previous findings suggesting that whey (found in dairy products) has some advantages over other protein sources.

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Timing of baking soda loading, and the future of fatigue research

August 28th, 2011

I spent three days last week at a conference called “The Future of Fatigue in Exercise,” hosted by Frank Marino and Rob Duffield at Charles Sturt University in Bathurst, Australia. Lots of interesting presentations and discussions, which I’ll be writing about in various forms over the next few months. To start, I thought I’d share a couple of short “practical” tidbits of research-in-progress that were presented at the conference. First: the timing of baking soda loading.

The practice of taking baking soda to buffer acid-base balance in the blood for short-duration exercise has been around for at least 30 years. It’s commonly used by athletes in events lasting around 2:00 (like 800-metre running), and may also help with repeated-sprint ability. Does it work? The research isn’t clear-cut, but most sports scientists believe that it works to some degree. The problem is that it also messes with your stomach, causing diarrhea and other lovely effects that aren’t conducive to great performance. (Random aside: I actually got my “big break” in university when one of my teammates had to bail out of the 4x800m relay team at the conference championships because he’d taken too much baking soda. I was inserted as a last-minute sub and ran a breakthrough race, earning a spot on the team at nationals. But I digress…)

Anyway, Jason Siegler of the University of Western Sydney presented some data looking at the timing of soda loading. Usually athletes take soda about an hour before competition, so that levels of of bicarbonate in the blood peak roughly when you’re competing. This also happens to be when gastrointestinal symptoms peak. What Siegler and his colleagues had noted in previous experiments was that bicarbonate levels actually stay high for several hours, while stomach problems tend to subside after a few hours.

So they ran a test of repeated sprint ability where the subjects took baking soda either 60, 120 or 180 minutes prior. As expected, the levels of bicarbonate in the volunteers’ blood before exercise were essentially identical no matter when they took the baking soda. The incidence and severity of gastrointestinal symptoms peaked about 90 minutes after taking the soda, and returned to normal after 180 minutes. All three groups performed essentially the same in the sprint test.

I should point out that there was no control group, so this study doesn’t tell us anything about whether the intervention works or not. Also, the stomach problems don’t appear to have hurt performance in the actual sprints, despite reaching an average of 5-6 out of 10 of the scales of incidence and severity. Apparently the volunteers managed to grit their teeth, clench their cheeks, and get the job done despite the discomfort. Still, if I was a middle-distance athlete inclined to try my luck with baking soda (and, for the record, I never did try it — in fact, when I was competing in the 1990s it was briefly listed as a “banned technique” by doping authorities, though they obviously couldn’t make baking soda a “banned substance”) — anyway, if I was using it, these results would certainly encourage me to take it ~3:00 before competition to hopefully give my stomach a chance to settle down.

Cryosaunas, frostbite and Justin Gatlin

August 25th, 2011

Just last week, I posted about the first serious study on the use of “cryosaunas” for post-workout recovery. Now I have an important update for athletes considering using a cryosauna: make sure to take off any sweaty clothes before you enter the sauna! According to AP, Justin Gatlin, the 2004 Olympic champion sprinter (and convicted doper), has arrived in South Korea for the World Championships sporting a serious case of frostbite caused by wearing sweaty socks into a cryosauna:

“You wake up at 9 o’clock in the morning in Orlando and it’s already 90 degrees,” said the 29-year-old Gatlin, who lives and trains in Florida. “So we’re already hot, drenched with sweat. Get in the booth, socks were wet, socks froze to me instantly.”

[...] Gatlin said the pain from the frostbite had subsided and the injury hadn’t affected his stride. But it is still bothersome because the wounds on his heels are near the level where his socks sit and where the back of his running spikes touch.

“It’s better than it was. It was all pussed up and blistered. It bubbled up and it stayed bubbled up for a good four or five days,” Gatlin said, lifting up his sweat pants to reveal the scabby scars that resemble big blisters.

So there you go: using liquid nitrogen for post-workout recovery has some downsides. Who knew?

Can you trust the calorie counts on exercise machines?

August 23rd, 2011

After an interesting e-mail conversation with Dr. Yoni Freedhoff of the pull-no-punches Weighty Matters blog, I ended up writing a guest post about some of the factors you need to think about if you ever look at the calorie number that your treadmill (or elliptical or exercise bike or whatever) spits out. Without giving away too much, I’ll say this: if you’re not considering the difference between gross and net calorie burn, you’re kidding yourself! READ THE FULL POST HERE.

Does booze make your sleep better or worse?

August 22nd, 2011

Alcohol puts you to sleep — but how good is that sleep? A new study by Japanese researchers (abstract here; press release here) offers some interesting insights. Basically, it helps you get to sleep more quickly, and you sleep deeply for the first few hours, but once the “sedative and hypnotic effect of ethanol” wears off, it messes up the rest of the night and interferes with recovery.

The researchers studied 10 male university students. Each of them did three tests: one with a placebo, one with 0.5 grams of ethanol per kilogram of bodyweight, and one with 1.0 grams. The high dose corresponds to about four standard bottles of 5% beer for someone weighing 70 kg. They drank the beverages 100 minutes before bed, and then their sleep patterns were recorded.

Some background: your body is regulated by a balance between the “parasympathetic” nervous system (responsible for “rest-and-digest” functions) and the “sympathetic” nervous system (responsible for “fight-or-flight” functions). When you’re asleep, the parasympathetic system is supposed to take over and become dominant, helping your body to recover from the rigours of the day. What the Japanese study found for the first time (primarily by measuring heart rate and heart-rate variability) is that alcohol suppresses parasympathetic activity during sleep in a dose-dependent way (i.e. the higher dose of alcohol suppressed parasympathetic activity more strongly than the lower dose). The upshot:

These results suggest that ethanol disturbs the restorative effects of sleep, preventing the heart rate from decreasing and the parasympathetic nerves from becoming dominant. During the last half of the sleep period, when the sedative and hypnotic effect of ethanol wears off, the number of awakenings during sleep and Stage 1 increased under the [high dose] conditions.

Or, from the press release:

“It is generally believed that having a nightcap may aid sleep, especially sleep initiation,” said Nishino. “This may be true for some people who have small amounts of alcohol intake. However, it should be noted that large amounts of alcohol intake interfere with sleep quality and the restorative role of sleep and these negative consequences may be much larger during chronic alcohol intake.”

Bottom line: much like the effects of alcohol on muscle recovery, a few drinks isn’t likely to hurt you (and plenty of evidence suggests that a drink or two a night will improve your health). But more than that can affect your health in subtle ways that you probably don’t even notice.

The benefits of coaching for recreational runners

August 21st, 2011

Instead of a Jockology column this week, my editors at the Globe and Mail asked me to write about the phenomenon of recreational runners hiring elite distance runners to coach them. I spoke to a bunch of runners ranging from beginners to veterans road warriors, working with coaches like Marilyn Arsenault, Jerry Ziak and Brandon Laan, to find out why they decided to get coaching and what they’re learning from it:

As she recovered from a hysterectomy last year, Dee Ogden was eager to resume running but nervous about the post-surgical impact on her running form. So she did something that surprisingly few runners do: She hired a coach.

“When you learn tennis, you learn about your stroke and form,” says Ms. Ogden, 44, a registered nurse in Victoria. “Why wouldn’t you do that with running?” [READ ON...]

 

For nitrate boost, stick to beet juice and avoid supplements

August 20th, 2011

I’ve blogged a bunch of times this year about the incredible performance-boosting effects of juice; studies showing that it’s the nitrates in beet juice that are responsible; and further studies exploring how nitrate from beets is converted (by bacteria in your mouth) to nitrite, and then to nitric oxide, which is where all the magic happens. This has led to all sorts of questions, like (a) aren’t nitrates, as found in hot dogs and so on, really bad for you?, and (b) can I just take a nitrate supplement instead of drinking all that beet juice that turns the toilet a funny colour?

The answer to the first question is, well, I don’t know — but scientists are definitely rethinking the idea that nitrates are a big villain. Stephan Guyenet had a good blog post that explored some of this change in thinking.

As for the second question, there’s a series of letters to the editor in the current issue of the Journal of Applied Physiology that should make you think twice before considering supplementing. The first is from a group of Swedish researchers who have pioneered some of the research into the health benefits of nitrates. They basically suggest that direct supplementation of nitrate (in the form of nitrate salt) is probably okay (it’s “nontoxic even in higher doses”), because the body can only convert it slowly to nitrite through the help of friendly mouth bacteria. But taking nitrite supplements directly has a toxicity comparable to cyanide — and there’s great potential for confusion, according to the researchers:

A case of unintentional ingestion of nitrite by an athlete was recently reported on a runners’ internet forum. The subject had taken a nitrite salt before exercise in the belief that it was nitrate, and he developed symptoms suggestive of methemoglobinemia.

They also point out that “organic nitrates and nitrites, for example nitroglycerine and amyl nitrite” can be fatal at too high a dose. The bottom line, they say:

In summary, at this time we advise athletes to refrain from the uncontrolled use nitrate and nitrite salts as dietary supplements. While the acute toxicity of nitrate is very low or absent, any confusion leading to a large unintentional intake of nitrite or organic nitrates and nitrites is potentially life threatening. In contrast, with natural sources of nitrate such as whole vegetables or vegetable juices, we do not foresee any acute risks.

There are a couple of letters in response from beet juice researchers, and they’re basically in agreement. To paraphrase very roughly, they basically say “Yes, taking nitrites would be a really dumb thing to to do, so stick with whole fruits and vegetables as a nitrate source.”

Having read all of that, it’s still not entirely clear to me if there’s a problem with taking nitrate salt. However, my confusion on that point is precisely the point, I guess: if nitrites and organic nitrates are potentially very dangerous, it’s best not to mess around if you’re not absolutely sure you’ve got the right stuff. Stick with the beets.

Genetics vs. practice for athletic performance

August 19th, 2011

Over the last few years, we’ve seen a big shift toward the important of practice — “deliberate practice,” to use the term coined by Florida State psychologist Anders Ericsson — in achieving greatness in pretty much any field of human endeavour, including sports. Books by people like Malcolm Gladwell, Daniel Coyle and Matthew Syed have advanced this “nurture over nature” argument. It’s an empowering message, and perhaps important to counter the idea of genetic predestination.

The problem is that, in many cases, they’re arguing against a straw man. To show that practice — lots of it, perhaps even 10,000 hours — is utterly crucial to the making of a champion is not the same as showing that genetics don’t matter! It seems utterly trivial to argue that you need to be tall to be a great basketball centre, and that no amount of practice will make you taller. And it’s just as inane to argue that height is the only attribute that’s strongly influenced by genetics and also contributes to athletic success. But people like Syed seem to be arguing just that.

Anyway, if you’re interested in the topic, Ross Tucker of the Science of Sport blog has an excellent two-part look at why we can’t ignore the role of genes in sports, and why that role is so complicated that we shouldn’t expect to find a “speed gene” or an “endurance gene,” despite the promises of genetic screening companies (part 1 here, part 2 here).

My only criticism of Ross’s series is that, in the second part, he makes a brief hypothetical digression about the role of genetics in the dominance of Kenyan distance runners. Leaving aside the question of whether it’s true or not, it’s not a hypothesis that follows from the rest of the discussion. He presents powerful evidence that genes must play a role in the ultimate potential of any given individual — but that says nothing about what distribution of genetic variations we’d expect to find in different population groups. If I’d had to wager money, I’d guess that his hypothesis is probably correct. But (as the comments below the blog entry show) by going there he left his arguments open to some quite reasonable criticism, which makes it seem like the whole question is up for debate — when in reality, most of what he says is so irrefutable that only someone trying to sell a “contrary to conventional wisdom” book could ignore it.

Speaking of books — but rigorous academic books rather than pop science — York University’s Joe Baker has co-edited a new book called “Talent Identification and Development in Sport” that was launched this week (press release here). If you’re interested in the actual science on these topics — the role of genetics; secondary factors like birth date, cultural context and population size; perceptual motor skill acquisition and expertise; and so on — then this is place to go.

Decision fatigue and workout planning

August 19th, 2011

John Tierney has an interesting article in New York Times Magazine about the concepts of “decision fatigue” and “ego depletion” — the idea that the simple act of making decisions, no matter how seemingly trivial, uses of a finite store of willpower. The idea seems intuitively obvious, but the studies he describes are fascinating and unexpected.

For example, prisoners appearing before Israeli parole boards have a 70 percent chance of getting parole if they appear first thing in the morning, but just a 10 percent chance if they appear late in the day: the judges are tired of making decisions, and react unconsciously by sticking to the default option. Lots of different factors affect decision fatigue, including glucose levels in the brain — so the chance of parole drops to 20 percent by midmorning, then rises to 65 percent after the midmorning break, during which sandwich and fruit is served to the judges. Just before lunch, probability is back down to 10 percent, then back up to 60 percent immediately after lunch, and so on.

It’s a long article, and I don’t want to oversimplify by summing up — but this is the passage, near the end, that I found interesting in the context of exercise:

“Good decision making is not a trait of the person, in the sense that it’s always there,” Baumeister says. “It’s a state that fluctuates.” His studies show that people with the best self-control are the ones who structure their lives so as to conserve willpower. They don’t schedule endless back-to-back meetings. They avoid temptations like all-you-can-eat buffets, and they establish habits that eliminate the mental effort of making choices. Instead of deciding every morning whether or not to force themselves to exercise, they set up regular appointments to work out with a friend. Instead of counting on willpower to remain robust all day, they conserve it so that it’s available for emergencies and important decisions.

I think this is a really important point. Strangely, I’ve found it’s much easier for me to stick to a routine where I run every day than to run six or five or four days a week. In terms of my current fitness goals, six days would be plenty and possibly even preferable to seven — but as soon as you introduce that element of choice, every morning suddenly gets much more complicated. Should I take my day off this morning? How tired am I? Is it going to rain? How do I expect to feel later in the week?

When I was training more seriously, a periodic rest day was much more important in order to get adequate recovery — but even then, I found it much easier to schedule a regular rest day (I took every second Monday off) than to make those decisions on a day-to-day basis. It wasn’t a question of being too obsessive to take an unplanned day off — it was simply too much mental effort to have to decide every morning “Am I running today?” There’s a great passage in Once a Runner about that idea (unfortunately I don’t have my copy here, or I’d quote it), how you have to make the decision about what you’re going to do, then close the book and just do it, rather than revisiting the decision every time it gets hard, or every time you wake up in the morning. (Of course, you still have to allow a certain amount of flexibility: sometimes it really is smarter to take an unplanned day off — but that’s different from having a regular weekly day off that can be taken any day of the week.)

When people ask me for advice about planning an exercise program, that’s one of the things I emphasize. Being flexible and fitting in exercise when it’s convenient may sound good in theory. But for me, at least, my will power isn’t strong enough to do that on a regular basis. Better to make the decision in advance, then just follow my own orders when it’s time to workout.