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Compression gear during interval workouts: a new possibility

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My new Sweat Science columns are being published at www.outsideonline.com/sweatscience. Also check out my new book, THE EXPLORER'S GENE: Why We Seek Big Challenges, New Flavors, and the Blank Spots on the Map, published in March 2025.

- Alex Hutchinson (@sweatscience)

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An interesting wrinkle in the debate over whether compression garments do anything during exercise to improve performance, from a new Australian study just posted in the Journal of Strength & Conditioning Research. The situation so far:

  • Every time you take a step while running, the flexing of your calf muscle operates something called the “calf muscle pump” — basically, your calf literally squeezes the blood vessels in your lower leg, helping to shoot oxygen-depleted blood back toward the heart.
  • Graduated compression of the lower leg (i.e. tighter at the ankle, looser at the knee) is thought to enhance the action of this calf muscle pump, by helping it to squeeze harder. This should reduce the load on your heart and speed the circulation of blood through your body, possibly enhancing performance.
  • One argument against the idea that compression garments boost performance is that, when you’re running hard, the action of the calf muscle pump is already maxed out, so adding more compression doesn’t help. You can’t squeeze more blood from a stone!

The new study put 25 rubgy players through a form of interval workout: basically 5:00 easy, 5:00 medium, 5:00 hard, 5:00 easy, 5:00 hard, 5:00 easy. They each did the test twice, once in running shorts and once in full-leg graduated compression bottoms. The researchers measured a bunch of variables (heart rate, oxygen consumption, lactate levels, blood pH) during each stage of the workout. There were basically only two elements where the data was significantly different between shorts and tights: in the fourth and sixth intervals (i.e. the easy recovery intervals), heart rate and lactate levels were both significantly lower in compression tights.

On the surface, this fits nicely with the ideas above. The tights don’t help when you’re running fast, since the calf muscle pump is maxed out; but during the easy recovery, the compression does help, resulting in lower lactate and heart rate — and, in theory, better performance on the subsequent hard section.

This is the problem, though: the study didn’t actually measure performance. The pace during each interval was predetermined, so we don’t know whether this difference in physiological parameters actually translates into better real-world performance. That’s a point that was highlighted in another Australian compression study that I blogged about back in August. That study also found physiological “improvements” from compression — but in that case, they also measured performance and found no difference. As the researchers wrote:

However, the magnitude of this improved venous flow through peripheral muscles appears trivial for athletes and coaches, as it did not improve [time-to-exhaustion] performance. This would suggest that any improvement in the clearance of waste products is insufficient to negate the development of fatigue.

Bottom line: I remain skeptical that wearing compression during a run will allow you to run faster. (Note that this is entirely separate from the question of whether wearing compression during and after a run will allow you to avoid or recover more quickly from muscle soreness, a claim that has somewhat better support.) This new study raises the intriguing possibility that compression might boost active recovery during interval workouts — but until it’s directly tested in a performance context, it’s just a hypothesis.

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The case against antioxidant vitamin supplements

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My new Sweat Science columns are being published at www.outsideonline.com/sweatscience. Also check out my new book, THE EXPLORER'S GENE: Why We Seek Big Challenges, New Flavors, and the Blank Spots on the Map, published in March 2025.

- Alex Hutchinson (@sweatscience)

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The December issue of Sports Medicine has an enormous, detailed review of research on the effect of antioxidant (i.e. vitamin C, vitamin E, coenzymeQ10, etc.) supplements on training. To most people, this seems like a no-brainer: what could be smarter than popping a multivitamin as “insurance” in case your diet isn’t giving you all the vitamins you need? But (as I’ve blogged about before) there’s an emerging school of thought arguing that taking antioxidants can actually block some of the gains you’d otherwise get from training. Here’s how I explained the debate back in April:

The traditional theory goes like this: strenuous exercise produces “reactive oxygen species” (ROS), which cause damage to cells and DNA in the body. Taking antioxidant supplements like vitamins C and E helps to neutralize the ROS, allowing the body to recover more quickly from workouts.

The new theory, in contrast, goes like this: strenuous exercise produces ROS, which signal to the body that it needs to adapt to this new training stress by becoming stronger and more efficient. Taking antioxidant supplements neutralizes the ROS, which means the body doesn’t receive the same signals telling it to adapt, so you make smaller gains in strength and endurance from your training.

The new paper comes down firmly on the side of the latter view:

The aim of this review is to present and discuss 23 studies that have shown that antioxidant supplementation interferes with exercise training-induced adaptations. The main findings of these studies are that, in certain situations, loading the cell with high doses of antioxidants leads to a blunting of the positive effects of exercise training and interferes with important [reactive oxygen species]-mediated physiological processes, such as vasodilation and insulin signalling.

So is this definitive? Far from it. As the review notes, there have been a few studies that found beneficial effects of antioxidant supplements on exercise performance, tons that have found no effect, and a few (23, to be exact) that have found negative effects. What most of the studies have in common:

As commonly found in sports nutrition research, the vast majority do not adhere to all the accepted features of a high-quality trial (e.g. placebo-controlled, double-blind, randomized design with an intent-to-treat analysis). Indeed, most studies fail to provide sufficient detail regarding inclusion and exclusion criteria, justification of sample size, adverse events, data gathering and reporting, randomization, allocation and concealment methods, and an assessment of blinding success. The poor quality of the majority of studies in this field increases the possibility for bias and needs to be always considered when evaluating the findings.

This is a really important point to bear in mind, and not just when it comes to sports nutrition. Whatever the supplement, training method, or piece of equipment you’re talking about, there’s nearly always a crappy, poorly executed study that seems to “prove” that it works. So where does that leave us? On this topic, I’m in agreement with the authors:

We recommend that an adequate intake of vitamins and minerals through a varied and balanced diet remains the best approach to maintain the optimal antioxidant status in exercising individuals.

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Running “is so prone to these sorts of trends”

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My new Sweat Science columns are being published at www.outsideonline.com/sweatscience. Also check out my new book, THE EXPLORER'S GENE: Why We Seek Big Challenges, New Flavors, and the Blank Spots on the Map, published in March 2025.

- Alex Hutchinson (@sweatscience)

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I don’t mean to fixate on the topic of running form, but I just want to recommend Gina Kolata’s piece in today’s New York Times, which reads a lot like a response to Chris McDougall’s recent piece (and echoes much of what I wrote a couple of days ago). Her basic point: people are desperate for advice that will “explain” how to run, when in reality the biggest is barrier is simply that running is hard (especially for people who have been inactive for years) and takes more time to adapt to than most people expect.

Researchers who have no financial ties to running programs or shoe manufacturers say that most of those complications are unnecessary and some of the advice is even risky, because it can make running harder and can increase the chance of injury. […]

“There is good evidence that your body is exquisitely lazy and will find the easiest way for you to run,” said Carl Foster, professor of exercise and sports medicine at the University of Wisconsin-La Crosse. […]

Running form is just one example of the confusions buffeting beginning runners. Running, said John Raglin, professor of kinesiology at Indiana University, “is so prone to these sorts of trends.”

People “will latch onto anything,” he added, and an anecdote or two about what is supposed to be an ideal running form often passes for evidence.

Kolata’s articles can sometimes seem a little nihilistic, as she writes about the surprising lack of evidence for very common treatments in sports medicine and physiotherapy, and common practices like warming up. The point isn’t that we shouldn’t do anything that isn’t “evidence-based” — life is complicated, and we inevitably have to make lots of decisions armed only with imperfect knowledge. But we should be aware of that, and not mistake our current guesses and hypotheses for “the one true way.”

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Marathons and the female heart

THANK YOU FOR VISITING SWEATSCIENCE.COM!

My new Sweat Science columns are being published at www.outsideonline.com/sweatscience. Also check out my new book, THE EXPLORER'S GENE: Why We Seek Big Challenges, New Flavors, and the Blank Spots on the Map, published in March 2025.

- Alex Hutchinson (@sweatscience)

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Is marathon running good or bad for your heart? That question has become a hot topic over the past few years thanks to a few studies showing negative effects like heart scarring and artery hardening in veteran marathon runners. One of those studies was a conference presentation last year that looked at 25 male runners who had each completed the Twin Cities marathon 25 years in a row. Compared to matched controls, the runners had greater plaque volume in their coronary arteries.

Now the same group of researchers has followed up with a similar study of 25 female runners who have run a marathon each year for the past 10 years. In this case, the result (as presented at the American Health Association conference) is exactly the opposite: the runners have fewer coronary plaques than matched controls.

So what to make of this? Neither study has been published in a journal yet, so it’s difficult to analyze the results in detail. It’s possible that the conflicting results are simply a result of the fact that the male marathoners were older, on average, that the female marathoners. Or it may be a physiological gender difference. Or it may have something to do with training history. Or it may be a complete fluke: in the male group, the key difference in the plaque volume was 274±176 vs. 169±170. Those are rather large ranges of uncertainty.

But the real question is none of the above: it’s whether these findings about elevated risk factors translate into compromised health. So far, I’m not aware of any study that links marathon running, or any form of endurance exercise, to elevated risk of death (or any other serious ailment) from any cause. That doesn’t mean such risks don’t exist (they could easily be hidden by the overall positive effect of exercise’s other health benefits). Still, as I wrote in the Globe and Mail a few months ago (and probably reflecting my “wishful thinking” bias), I can’t bring myself to get too worried about these apparent risks in the absence of any direct evidence. As Amby Burfoot wrote, “show me the bodies in the streets.”

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Exercise -> serotonin -> antidepressant

THANK YOU FOR VISITING SWEATSCIENCE.COM!

My new Sweat Science columns are being published at www.outsideonline.com/sweatscience. Also check out my new book, THE EXPLORER'S GENE: Why We Seek Big Challenges, New Flavors, and the Blank Spots on the Map, published in March 2025.

- Alex Hutchinson (@sweatscience)

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It’s well-established that exercise can be a powerful tool against depression (as Gretchen Reynolds wrote about in the New York Times a few months ago). What’s less clear is how and why it might help. A new study in  Medicine & Science in Sports & Exercise, from researchers at the University of Sherbrooke, offers some evidence for the theory that exercise can boost serotonin levels in the brain. This, of course, is pretty much the same as what the most common antidepressants (SSRIs: selective serotonin reuptake inhibitors) do.

The study was pretty straightforward. They had 19 men with an average age of 64 perform a 60-minute bout of exercise at moderate intensity (average HR 129 beats per minute, 68% VO2max). Then they measured several proxies of serotonin production, since it’s very difficult to directly measure neurotransmitters in the brain. The result: levels of tryptophan — the key precursor which is converted into serotonin — roughly doubled.

Is this a surprise? There was previous evidence in studies of rodents and younger humans that exercise boosted tryptophan availability, but it wasn’t clear whether the same effect would occur in older adults. This is particularly important because we become increasingly susceptible to depression as we age, suggesting that some of the mechanisms that help us ward off depression stop working quite as well.

Of course, one of the problems with “prescribing” exercise as a depression treatment (as Reynolds notes) is that once you’re depressed, it can be extremely difficult to summon the motivation needed to maintain a regular exercise program. Still, this study suggests that exercise might help to prevent depression in the first place, particularly as you get older.