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Stunning new research on the impact of exercise intensity on our biology: Wisdom Wednesdays · Hardiness with Dr Paul Taylor

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  Speaker 1: Hey everybody, welcome to another edition of Wisdom Wednesdays. Now
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  Speaker 1: today I want to talk about a couple of different
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  Speaker 1: papers on a similar theme that I think really does
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  Speaker 1: change how we think about exercise. Now, most of you
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  Speaker 1: will know the exercise recommendations are typically in minutes in Australia, UK,
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  Speaker 1: and also New Zealand and the States are very, very similar.
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  Speaker 1: 75 to 150 minutes of vigorous or 150 to 300
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  Speaker 1: minutes of moderate. But some fascinating research is beginning to
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  Speaker 1: suggest that our bodies don't simply count minutes. They also
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  Speaker 1: respond very, very much to the strength of the signal
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  Speaker 1: or the intensity. And it turns out that intensity is
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  Speaker 1: a very different biological signal to time. So there was
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  Speaker 1: a new paper published in Cell Reports Medicine recently that
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  Speaker 1: produced a pretty tremendous result, a pretty extraordinary result. They
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  Speaker 1: did three minutes of actual sprinting. So this was six
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  Speaker 1: 30-second all-out efforts. Actually, when they measured the impact in
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  Speaker 1: the body, caused significant and immediate changes in 714 different
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  Speaker 1: proteins in the blood. And a 90-minute moderate cycling session
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  Speaker 1: changed seven. You heard that right. Seven were changed from
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  Speaker 1: 90 minutes of moderate and 714 proteins were changed from
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  Speaker 1: just three minutes of all-out sprinting. Now, before you throw
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  Speaker 1: away your walking shoes and everybody starts doing Wingate sprints
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  Speaker 1: in the driveway... There are a couple of important qualifications
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  Speaker 1: to that finding, and we'll get into them. So the
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  Speaker 1: typical headline that would generally be generated in newspapers from
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  Speaker 1: this research paper is that sprinting produced 100 times more protein.
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  Speaker 1: And that would actually be wrong. It didn't. What the
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  Speaker 1: researchers found was that roughly 100 times as many of
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  Speaker 1: the proteins they measured changed significantly immediately after the sprint session. Now,
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  Speaker 1: that's a subtle difference, but it is important. And they
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  Speaker 1: understand why it's interesting. We got to go back a
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  Speaker 1: few years. So in 2023, Michael May and College, they
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  Speaker 1: published a study in molecular and cellular proteomics, looking at
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  Speaker 1: what happens to protein circulating in our blood during acute exercise.
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  Speaker 1: And they studied 75 middle-aged adults, all doing a treadmill
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  Speaker 1: exercise stress test. and they measured a pretty extraordinary 4163
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  Speaker 1: different proteins in their blood before exercise at the peak
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  Speaker 1: of the exercise and then again an hour afterwards and
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  Speaker 1: at peak exercise now remember this is a stress test
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  Speaker 1: so it's a graded exercise test that gets pretty high
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  Speaker 1: in intensity so at peak exercise 765 proteins had changed
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  Speaker 1: significantly that's pretty similar to the The three minutes of
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  Speaker 1: all out sprinting. Right. But an hour later, only 128
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  Speaker 1: were significantly different than baseline. So there was a big
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  Speaker 1: change initially and then back to baseline. So exercise produced
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  Speaker 1: this enormous, rapid and pretty transient molecular wave through the bloodstream.
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  Speaker 1: And that takes us into the really interesting area of exerkines.
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  Speaker 1: And I've actually had a professor on talking about exerkines before.
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  Speaker 1: But to explain this, we used to think about muscle
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  Speaker 1: primarily as mechanical tissue. It contracts, it produces force, it
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  Speaker 1: moves bones, and it consumes glucose and fat, and it
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  Speaker 1: allows us to move. But it's also an endocrine organ.
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  Speaker 1: You may have heard me talk about this. It produces
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  Speaker 1: its own hormones. We typically call them myokines or exokines.
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  Speaker 1: So when we exercise, muscle communicates chemically with the rest
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  Speaker 1: of our body. So do fat tissues, the liver, blood vessels,
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  Speaker 1: and immune cells. They all release proteins, peptides, and metabolites
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  Speaker 1: into circulation, which can travel to completely different tissues and
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  Speaker 1: alter or influence what those tissues do. So collectively, these
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  Speaker 1: exercise responsive signaling molecules are often referred to as exokines.
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  Speaker 1: And this potentially helps explain one of the great things
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  Speaker 1: about exercise. You can track the muscles in your legs,
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  Speaker 1: yet somehow you get changes in your brain, your liver,
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  Speaker 1: your pancreas, your blood vessels and your immune system. So
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  Speaker 1: there has to be communication occurring between those tissues. And
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  Speaker 1: the study by me and colleagues showed that just how
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  Speaker 1: extensive that communication can actually be. Hundreds of plasma proteins
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  Speaker 1: changed during a relatively brief bout of hard exercise. And
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  Speaker 1: some of the proteins that remained elevated after exercise were
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  Speaker 1: associated with things such as improved cardiorespiratory fitness, improved glucose metabolism,
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  Speaker 1: body composition, And their blood lipid profiles. Now, that doesn't
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  Speaker 1: prove that the proteins caused the benefits. Some of the
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  Speaker 1: immediate changes could simply reflect blood flow changes, tissue stress
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  Speaker 1: or proteins leaking into circulation during hard exercise. But it
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  Speaker 1: did raise a really interesting question. And that is, does
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  Speaker 1: the intensity of exercise change the message? And that is
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  Speaker 1: what Luke Olson and colleagues have now investigated. So they
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  Speaker 1: compared two very different exercise stimulus, or stimuli, in young, active,
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  Speaker 1: metabolically healthy men. So one group did six 30-second all-out
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  Speaker 1: sprints on a bike. It's called the Wingate Test, and
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  Speaker 1: it's freaking horrible, especially the last 10 seconds. But those
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  Speaker 1: six 30-second spins were separated by four minutes of recovery.
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  Speaker 1: So that's three minutes of genuine all-out work. Although importantly,
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  Speaker 1: the entire session obviously lasts much longer because you got
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  Speaker 1: the recovery periods, right? But the other group did 90
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  Speaker 1: minutes of continuous moderate intensity cycling. And they measured 2,884
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  Speaker 1: proteins in the blood before exercise, immediately afterwards, and three
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  Speaker 1: hours later, And this is where the things became really interesting.
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  Speaker 1: So immediately after the sprint session, 714 proteins had changed significantly,
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  Speaker 1: as I said earlier on. That's almost a quarter of
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  Speaker 1: everything they measured. And more than 98% of those proteins increased.
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  Speaker 1: And then, as I said earlier, the 90-minute moderate cycling session,
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  Speaker 1: that changed seven. Seven proteins immediately afterwards versus 714 proteins.
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  Speaker 1: in the sprint session. And that is a pretty remarkable difference.
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  Speaker 1: But the bit that gets lost in the headlines is
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  Speaker 1: that the moderate exercise wasn't doing nothing. Its response was slower.
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  Speaker 1: Three hours later, more proteins had changed after the moderate
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  Speaker 1: session and the metabolite data showed something similar. So sprinting
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  Speaker 1: created this enormous immediate metabolic disturbance that involved lactate, pyruvate
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  Speaker 1: and other metabolites related to carbohydrate metabolism that you get
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  Speaker 1: from high intensity exercise. While during recovery from moderate exercise,
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  Speaker 1: there was more of a delayed fatty acid response. So
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  Speaker 1: if you only took a blood sample at the minute
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  Speaker 1: the exercise stops, you're naturally going to go, hey, the
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  Speaker 1: sprinting is way, way better than the moderate stuff, right?
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  Speaker 1: But the researchers here did something really interesting. They took
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  Speaker 1: the plasma after the exercise sessions and exposed human fat cells,
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  Speaker 1: which are called adipocytes, to that plasma. And the plasma
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  Speaker 1: collected after the sprinting produced broad changes in gene expression
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  Speaker 1: in those fat cells. with more than 1,600 genes changing
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  Speaker 1: their activity. The plasma following the moderate exercise session produced
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  Speaker 1: changes in only a few dozen of them, right? So
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  Speaker 1: in other words, something circulating in the blood following the
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  Speaker 1: sprint session was capable of sending a remarkably powerful message
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  Speaker 1: to fat tissue. And that reinforces the idea of this
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  Speaker 1: inter-organ communication. Your legs do the sprinting, but the chemical
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  Speaker 1: consequences don't stay in your legs. Now, one possibility that
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  Speaker 1: they discussed in the paper is a process called ectodermian shedding.
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  Speaker 1: So rather than having to manufacture every signaling protein from scratch,
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  Speaker 1: which takes a lot of time, enzymes can actually cut
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  Speaker 1: parts of proteins already sitting on cell membranes and and
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  Speaker 1: then release them rapidly into circulation. And all this happens
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  Speaker 1: under the hood, which I find pretty fascinating. Now, the
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  Speaker 1: researchers didn't prove that this accounted for the whole response,
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  Speaker 1: and their technology couldn't definitively distinguish those little shared proteins,
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  Speaker 1: but they found changes consistent with the possibility that this
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  Speaker 1: was one of the ways very intense exercise created such
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  Speaker 1: a rapid signal. Then they cross-referenced their exercise-responsive proteins against
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  Speaker 1: data from more than 53,000 people. And they identified 33
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  Speaker 1: proteins associated with the lower risk of metabolic disorders, including
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  Speaker 1: obesity and type 2 diabetes. And of those 33 proteins,
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  Speaker 1: 32 of them were altered by the sprint exercise. Only
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  Speaker 1: three were altered by the moderate sessions. Now, again, we
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  Speaker 1: do have to be careful here. So this doesn't mean
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  Speaker 1: that sprinting has now been shown to prevent diabetes by
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  Speaker 1: altering these 32. proteins. That disease information came from an
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  Speaker 1: entirely different population. But all we can say is that
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  Speaker 1: the proteins that responded strongly to sprinting in one experiment
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  Speaker 1: were also associated with better overall health in another data set. Now,
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  Speaker 1: we all know association is not the same as causation,
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  Speaker 1: but this is certainly enough. And the way they did
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  Speaker 1: it is to make you sit up and pay attention.
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  Speaker 1: And another cool part of the study was that a
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  Speaker 1: smaller subset of participants trained for eight weeks and then
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  Speaker 1: repeated the experiment. And the acute sprint response was still there.
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  Speaker 1: suggesting this wasn't simply the molecular carnage of getting untrained
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  Speaker 1: people to do something pretty horrible for the first time.
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  Speaker 1: So we now have evidence that intense exercise can generate
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  Speaker 1: a very large acute molecular and metabolic signal. Now, the
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  Speaker 1: obvious next question is, does that signal actually lead to
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  Speaker 1: useful adaptations? And to answer that, we can actually go
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  Speaker 1: back to a paper about 20 years previously. So the
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  Speaker 1: paper in question is from a pretty famous physiology researcher
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  Speaker 1: called Marty Gabala. And in this study, they took 16
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  Speaker 1: young active men and they trained them six times over
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  Speaker 1: two weeks. One group did four to six 30-second all-out
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  Speaker 1: windgate sprints. the same one that I talked about in
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  Speaker 1: that original study, and they had four minutes of recovery.
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  Speaker 1: That's a typical protocol for that. The other group did
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  Speaker 1: 90 to 120 minutes of cycling at around 65% of
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  Speaker 1: VO2 peak, which kind of equates to that zone two
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  Speaker 1: that a lot of people talk about. Now, across the
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  Speaker 1: two weeks, the sprint group accumulated about two and a
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  Speaker 1: half hours of total training time, and that included their
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  Speaker 1: recovery periods. but the endurance group did about 10 and
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  Speaker 1: a half hours, right? So two and a half versus
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  Speaker 1: 10 and a half. Now the sprint group actually performed
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  Speaker 1: about 90% less total mechanical work. They basically burned about
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  Speaker 1: 630 kilojoules compared to 6,500 in the endurance group. And
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  Speaker 1: yet after only six training sessions, the two groups showed
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  Speaker 1: remarkably similar improvements in cycling performance and muscle oxidative capacity,
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  Speaker 1: muscle glycogen and buffering capacity. Now, there were eight people
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  Speaker 1: in the study and it lasted for only two weeks. Right.
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  Speaker 1: So it's not a massive study. But what it does
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  Speaker 1: show is that a surprisingly small dose of extremely intense work,
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  Speaker 1: can produce rapid physiological adaptation. And that's where this new
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  Speaker 1: paper becomes so interesting. So 20 years ago, Marty Gabala
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  Speaker 1: showed us the outcome. Very little intense work could produce
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  Speaker 1: a disproportionate adaptation. Now we're actually seeing the mechanisms, the
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  Speaker 1: molecular signaling that sits underneath it. So hard exercise appears
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  Speaker 1: to shout, Whereas moderate exercise appears to speak, but for
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  Speaker 1: a bit longer. And they're definitely not the same thing.
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  Speaker 1: This leads me nicely to the final paper I want
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  Speaker 1: to talk about by an author called Cobell and colleagues.
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  Speaker 1: And this was in 2026. And they took just over 3,000,
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  Speaker 1: nearly 3,300 American adults who were not trained. They reported
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  Speaker 1: doing no structured, moderate, or vigorous leisure time activity. So
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  Speaker 1: they were sedentary. And they put wrist accelerometers on them.
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  Speaker 1: And they were looking for these tiny bursts of what
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  Speaker 1: they called VILPAs, vigorous intermittent lifestyle physical activity. You might
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  Speaker 1: have heard me talking about this on a Wisdom Wednesday
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  Speaker 1: quite a long time ago. So this was things like
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  Speaker 1: quickly running up the stairs or carrying something quickly, rushing
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  Speaker 1: to get a bus, a bit of energetic play with
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  Speaker 1: your kids. are just those other little moments of ordinary
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  Speaker 1: life where you do a brief burst of physical activity
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  Speaker 1: that's actually quite vigorous. And the average time of those
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  Speaker 1: bouts were only about 10 seconds, right? Now, the median
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  Speaker 1: participant accumulated around five bouts a day, adding only one minute,
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  Speaker 1: just over a minute of vigorous physical activity per day
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  Speaker 1: in those little short bursts. And they followed these people
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  Speaker 1: for an average of nearly seven years. And during that time,
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  Speaker 1: nearly 300 of them died. And compared to those who
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  Speaker 1: did no vilpas, those doing the median of about just
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  Speaker 1: over five bouts per day had a 44% lower relative
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  Speaker 1: risk of all-cause mortality. Like that is massive. At just
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  Speaker 1: over a minute of vigorous activity a day, the relative
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  Speaker 1: risk was 39% lower, right? Interestingly, those what we call
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  Speaker 1: dose response curves, they flattened quite quickly at around eight
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  Speaker 1: bouts a day, approximately two minutes in total, seemed to
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  Speaker 1: give you a really massive benefit. Now that is pretty
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  Speaker 1: staggering for tiny amounts of physical activity. But we do
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  Speaker 1: need to remember that these were sedentary people, right? So
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  Speaker 1: in those sedentary people, just moving your body vigorously for
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  Speaker 1: little bursts can actually significantly reduce your risk of death.
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  Speaker 1: Now this is compared to sedentary people who do nothing
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  Speaker 1: or very, very little, right? So this is reason why
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  Speaker 1: you should when you're in the airport, get up the
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  Speaker 1: stairs rather than the escalator and do it as quickly
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  Speaker 1: as you possibly can, right? Running for the bus, don't
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  Speaker 1: be pissed off when you're running for the bus because
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  Speaker 1: it's actually doing a lot of good at a molecular level.
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  Speaker 1: So what do we make of all of this? I
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  Speaker 1: wanna pull this together now. Now, what is clear from this?
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  Speaker 1: There is an enormous amount of evidence behind the benefits
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  Speaker 1: of moderate exercise and it can be sustained for longer.
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  Speaker 1: It builds aerobic capacity and it generally burns up a
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  Speaker 1: lot of calories. It's got low injury risk and it
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  Speaker 1: produces molecular responses of its own, right? Some of which
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  Speaker 1: appear a little bit later for maybe hours afterwards, right?
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  Speaker 1: But what is now becoming very, very clear is that intensity,
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  Speaker 1: that has to be thought of as its own exercise variable.
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  Speaker 1: It's not just about time. It's about intensity. And this
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  Speaker 1: isn't just about squeezing the same workout into less time.
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  Speaker 1: it appears that the high intensity, the really vigorous stuff,
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  Speaker 1: is a completely different biological signal to moderate exercise. So
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  Speaker 1: perhaps instead of asking how many minutes of exercise did
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  Speaker 1: I do this week, There's another question we should ask.
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  Speaker 1: Did I give my body a reason to work really,
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  Speaker 1: really hard, even for a short period? If you've ever
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  Speaker 1: heard me in any corporate talks, you'll have heard me
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  Speaker 1: for years banging on about movement snacks. What the scientists
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  Speaker 1: now call vilpas, right? These little bursts of physical activity
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  Speaker 1: that you do throughout the day. And I do heaps
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  Speaker 1: of them. we have an exercise bag, I'll jump on
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  Speaker 1: and do a 20 second sprint. And then five minutes later,
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  Speaker 1: maybe do another 20 second sprint, or I'll get off
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  Speaker 1: my arse and do some kettlebell swings for 30 seconds.
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  Speaker 1: Those little bouts of particularly vigorous physical activity, it now
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  Speaker 1: appears that they are doing a lot more than we thought.
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  Speaker 1: And then when you package them into Six of those
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  Speaker 1: sprints with a four-minute recovery, that is a very, very
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  Speaker 1: effective exercise protocol. And it's very different from your zone
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  Speaker 1: two stuff. So I think that the optimal one involves
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  Speaker 1: a little bit of the moderate stuff, but also making
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  Speaker 1: sure that you're doing the vigorous. And also remember, you
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  Speaker 1: also got to lift some heavy shit. That's it for
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  Speaker 1: this week, folks. Catch you next time. Thank you.