Tag: sports technology

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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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A few months ago, I blogged about a placebo-controlled test of the “live high, train low” altitude training paradigm (here, and with a follow-up here). That test found no benefit to altitude training, which prompted some rather heated responses — including a comment from someone who works for an altitude tent company:

One bogus study cannot change the work that guys like David Martin and the Australia of Sport (AIS) have performed.

As it happens, the Australian Institute of Sport, working with Australia’s national swim team, has just published a massive new study of altitude training in the European Journal of Applied Physiology. They took 37 elite swimmers and divided them into three groups:

1. “Classic” altitude training: three weeks in Sierra Nevada, Spain (2,320 m) or Flagstaff (2,135 m);
2. LHTL, spending at least 14 hours a day for three weeks at simulated 3000 m at the Australian Institute of Sport in Canberra;
3. a control group that didn’t go to altitude.

To assess the effects of altitude training, they looked at blood parameters like total hemoglobin mass, and measured race performances 1, 7, 14 and 28 days after returning from altitude, as well as assessing season-long performance profiles (including performance at the World Championships).

Let’s start with the good news. Unlike the previous study, this study did find a clear increase in total hemoglobin mass, of about 4%, in both altitude groups. Here’s the individual scatter:

But what about performance? There, the results weren’t so good:

Or in words:

Swimming performance was substantially impaired for up to 7 days following 3 weeks of either Classic or LHTL altitude training. Despite ~4% increases in tHb resulting from both Classic and LHTL altitude training, there were no clear beneficial performance effects in the 28 days following altitude… A season-long comparison of two tapered performances at major championships also did not reveal a benefit for athletes who completed mid-season altitude training despite the substantial physiological changes associated with the altitude.

So does this “prove” that altitude training doesn’t help endurance performance? Of course not. But it’s a pretty interesting data point. This is the Australian swim team — one of the world’s powerhouses — supported by the Australian Institute of Sport, who have done lots of research into altitude training, and believe in it enough to construct an altitude house on their campus. They understand how it’s supposed to be done, and they executed it effectively enough to produce hemoglobin changes… but still, they didn’t manage to improve performance. If anything, they got worse.

If you’re doing altitude training, are you confident that you’re doing it better than they are?

[UPDATE: Sam McGlone and Paulo Sousa raised an important point on Twitter: the swim distances that they tested in this study were 100 or 200m. That’s pretty short – I don’t know the numbers for swimming, but maybe 50% aerobic at most? Here’s what the researchers say:

Based on the calculated aerobic contribution to energy production during competitive 100 and 200 m swimming races, the 3.8% increase in tHb we observed could elicit a 0.3–0.7% improvement in race time… Although improvements of this magnitude are equivalent to the smallest worthwhile change for swimming performance, detecting such changes can be difficult due to the variability associated with racing and the modest sample sizes available when targeting an elite athlete population.

Certainly something to keep in mind in interpreting this study.]

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)

***

I posted earlier this week about a study that found that the amount of lactate in your blood at threshold doesn’t predict endurance performance. This doesn’t mean that lactate measurements are useless, I pointed out:

It just means that a single lactate measurement in isolation is meaningless: you have to make repeated measurements and track your progress relative to your personal baseline, in order to eliminate the effects of individual variation.

Well, a new study in the British Journal of Sports Medicine actually calls that last statement into question. If you make repeated measurements of lactate threshold, are those measurements repeatable enough to detect small changes in fitness? Many, many studies have examined this question, with the general conclusion that “yes, they’re repeatable.” But most of these studies have only repeated the measurement twice or at most three times, which is hardly sufficient to look for variability.

So researchers from Massey University decided to run a study in which 11 fit subjects did at least six lactate tests each, to see how consistent the results were. The goal here was to make the measurements as identical as possible, so they strictly controlled diet, time of day, and training conditions, all which have been shown to influence lactate values. (Coaches: do you control these factors when you test your athletes?)

Of course, there are many different markers you can look for in lactate tests, so the researchers chose seven of the most common markers: Rest+1, 2.0 mmol/L, 4.0 mmol/L, D-max, nadir, lactate slope index, and visual turnpoint.

These results indicate that only the D-max marker has good reproducibility and that it alone can identify small but meaningful changes in training status with sufficient statistical power.

Expressed in terms of coefficient of variation (with is the standard deviation divided by the mean), the visual turnpoint was by far the worst, with a variation of 51.6%, while D-max has 3.8%. The other markers were between 5.9 and 12.6%. What does this mean in terms of cycling power? They run some numbers to show that even a fitness change corresponding to 70 watts (i.e. improving from 55 to 47 minutes in a 40 km time trial) wouldn’t be reliably detected by most lactate measures.

Tim Noakes, in his accompanying commentary, draws the following conclusions:

[T]hey conclude that unrealistically large changes in power output would have to occur before it can be claimed with certainty that training has produced a real change in an individual’s blood lactate concentrations during exercise. These findings should encourage sober reflection among that large group of exercise scientists who use blood lactate concentrations to guide athletes’ training.

I’m inclined to be a little less negative. After all, coaches and athletes can likely settle for somewhat less rigid definitions of what change can be considered “significant.” As long as they understand that the measurement is fallible and subject to variation, it might still be useful tool for monitoring fitness. (Is it useful for prescribing training paces? That’s a whole different question.)

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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Steve Magness has a fascinating post on his blog about a neat new study in the January issue of Journal of Applied Physiology. The researchers took a bunch of rats whose ancestors have been living at the Bolivian Institute for Altitude Biology, which is 3,600 metres above sea level. Half the rats were placed in a room with “enhanced oxygen” to mimic sea level from one day before birth to 15 days after birth; the other half simply grew up normally at 3,600 metres. Then the researchers followed the rats for the rest of their lives to see whether this “postnatal” exposure to low oxygen affected the rats’ development.

This study fits into the recent burst of research into epigenetics — the idea that early environmental influences can produce lasting changes in gene expression. And sure enough, there were significant differences between the rats who grew up at high altitude continuously (HACont) and those who got two weeks of sea-level oxygen (HApNorm):

As you can see, the high-altitude rats had higher hemoglobin and hematocrit long after the two-week exposure period (32 weeks is roughly middle-aged in rats). Among many other differences, the altitude babies also had a bigger heart, and used less oxygen. All of this sounds pretty good for endurance athletes — which is why Steve wrote:

I always joke with my friends that whenever I have kids, I’m going to stick them at altitude during pregnancy and right after just to develop super altitude adapted kids…

But there’s a caveat. Here’s the survival data for the two types of rat:

In fact, the researchers make the overall conclusion that low oxygen levels in the crucial weeks after birth are a bad thing:

We conclude that exposure to ambient hypoxia during postnatal development in [high altitude] rats has deleterious consequences on acclimatization to hypoxia as adults.

So you have to be careful what you wish for your kids. Either way, though, it’s clear that environment alone can produce profound, lifelong changes in physiology — producing group traits that we once might have mistakenly attributed to genetics.

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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I was at a conference on fatigue a few months ago where one of the speakers was Mike Lambert, a well-known sports science researcher from Tim Noakes’s group at the University of Cape Town. One of the questions at the end of his talk was about the use of lactate monitoring; his answer was something along the lines of “We refuse to measure lactate, because we don’t believe it offers any useful predictive information.” As a result, the UCT sports science unit doesn’t do much work with certain teams like the South African swim team, because the swim coaches are convinced that lactate testing offers important feedback.

A new paper just published online in the European Journal of Applied Physiology reminded me of that discussion. Researchers in Austria performed a whole series of difference incremental and maximal tests on 62 volunteers to look for patterns. The basic finding was that the amount of lactate in the blood at “maximal lactate steady state” (MLSS: the point where you’re producing and clearing lactate at the same rate) isn’t correlated with how fast or fit you are.

This isn’t the first study to make this observation. But previous studies have used relatively homogeneous groups, which makes it hard to determine whether lactate levels really have an effect. With VO2max, for example, you can safely bet the someone with a VO2max of 75 will perform better on any endurance task than someone with a VO2max of 35. But if you take a group of people who all have VO2max clustered between 60 and 70, then VO2max becomes a very poor predictor of performance.

In this case, the study subjects ranged from sedentary (with 0 hours per week of sports or exercise) to very fit athletes training up to 24.5 hours per week. Their power output on the bike at MLSS ranged from 100 to 302 watts. But despite this wide range, it was still impossible to predict anyone’s power levels by looking at their lactate levels at MLSS.

So does this mean Lambert is right and lactate is useless? Not necessarily. It just means that a single lactate measurement in isolation is meaningless: you have to make repeated measurements and track your progress relative to your personal baseline, in order to eliminate the effects of individual variation.

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)

***

Yesterday’s post about Carsten Lundby’s altitude study sparked some fantastic discussion in the comments section, on Twitter, and over e-mail. I really appreciate everyone who took time to share their thoughts and expertise, and I’d just like to follow up with a few thoughts of my own.

When a study like this comes along that contradicts the “conventional wisdom,” there are many possible ways to respond. One good response is to look for flaws in the study, to figure out if there’s some logical reason that it contradicts previous findings. At the other end of the spectrum, there are responses like this one, from the comments section of the previous post:

This study has a lot of holes in it, especially since some of the “best” physiologists state that LHTL works. One bogus study cannot change the work that guys like David Martin and the Australia of Sport (AIS) have performed.

With all due respect, the study “has holes in it” if there’s a problem with its methodology or design, not just because someone says it does. One study certainly can refute the work that others have done if the new study is correct and the others are flawed. That’s how science works: it doesn’t care what your name is or where you work. (Speaking of which, it’s no coincidence that this particular commenter works for a company that manufactures and sells altitude tents!)

Another commenter asked about individual (rather than average) responses. This is an excellent question, since it has long been hypothesized that there are “responders” and “non-responders” to altitude training. Here are the individual responses in hemoglobin mass for the altitude group:

On the surface, this looks to be exactly what we see: five “significant” (above the dashed line, which represents the typical error level of the measuring apparatus) responders, three who got significantly worse, and two basically unchanged. But let’s look also at the placebo group:

Once again (though with fewer subjects), we have some individuals responding “significantly” in both directions to the placebo stimulus, and some staying unchanged. Though the small sample size makes comparisons difficult, the scatter of individual results looks pretty similar in both cases (and was statistically indistinguishable).

So what do we conclude from this study? As I said in the previous post, this was an exquisitely careful study with an excellent design. That means we can place very high confidence (relative to previous altitude studies) in its evaluation of the specific conditions it tested. And this is the rub. They held certain conditions constant, such as oxygen levels, time exposed to hypoxia, and training stimulus. But what if the training stimulus was inappropriate (too hard? too easy?). What if the athletes had insufficiently high iron (despite being given daily iron supplements)? What if being confined to their rooms for 16 hours a day caused negative adaptations?

These are all possibilities — and they’re all possibilities considered by the researchers themselves in their discussion in the paper. No one — not me, not the researchers — is saying “altitude training is a scam.” But what they (and I) are saying is that, if you take a fairly conventional live-high-train-low paradigm as executed in the study (4 weeks, 3,000m/1,000m, continuing essentially the same training plan that you were doing at sea level, etc.), don’t assume that you’re automatically going to get the results you’re looking for. There are clearly some other variables at play that need to be controlled. Elite coaches and athletes have some pretty strong ideas about what these additional variables are. And if I worked for an altitude tent company, I’d spend a little less time mouthing off about “bogus studies,” and a little more time trying to nail down exactly what those variables are.