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Wisdom Wednesdays: Exercise and heat exposure - are there beneficial effects? · Hardiness with Dr Paul Taylor

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  Speaker 1: Hey everyone, welcome to another edition of Wisdom Wednesdays. Before
• 0:12
  Speaker 1: we get into the podcast, quick announcement. My new book,
• 0:15
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• 0:39
  Speaker 1: a bit of a discount. Now onto the podcast. Today,
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  Speaker 1: we are going to talk about the interaction between exercise
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  Speaker 1: and heat exposure. So some of you may know or
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  Speaker 1: may have heard that getting in a sauna after doing
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  Speaker 1: particularly resistance training can spike growth hormone by a significant
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  Speaker 1: amount three to four fold increase, and some studies have
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  Speaker 1: shown and a new study just out followed a bunch
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  Speaker 1: of cyclists, male cyclists who were pretty fit. They had
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  Speaker 1: an average VO two max of sixty middle leaders per
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  Speaker 1: kilogram per minute, which is pretty damn fit. But it
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  Speaker 1: was a randomized control trial and they all performed high
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  Speaker 1: intensity interval training for three weeks and then did hot
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  Speaker 1: water immersion after exercise. Now, some of the research has
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  Speaker 1: suggested that getting into a hot bath for at about
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  Speaker 1: forty degrees for twenty minutes can actually mimic the effects
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  Speaker 1: of the sauna and spike growth hormone and lead to
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  Speaker 1: better performance games after exercise. So let's dig into this study.
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  Speaker 1: So they did nine high intensity interval training sessions over
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  Speaker 1: three weeks, so that was three sessions per week, and
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  Speaker 1: immediately after exercise, they took a thirty minute bath in
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  Speaker 1: either hot water at forty two degrees centigrade which is
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  Speaker 1: one hundred and eight degrees firenheit or thermonutral kind of
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  Speaker 1: body temperature ish so thirty four degrees centigrade or seventy
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  Speaker 1: five degrees fahrenheit. And before and after the interventions, the
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  Speaker 1: researchers collected muscle biopsies. So these guys are pretty game.
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  Speaker 1: I don't know if you've ever seen a muscle biopsy
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  Speaker 1: or had a muscle biopsy, but they basically use a massive,
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  Speaker 1: thick needle like device and take a pinch of your muscle.
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  Speaker 1: That's about the size of a rice crispy or rice
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  Speaker 1: bubble depending on what country you're in, So it's pretty
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  Speaker 1: dam sore. But anyway, so these guys were donating a
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  Speaker 1: little bit of their muscles to science, and what they
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  Speaker 1: wanted to look at was the adaptations in the mitochondria.
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  Speaker 1: And then the performed a time to exhaustion test and
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  Speaker 1: a twenty kilometer time trial on a cycle orgometer, and
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  Speaker 1: the time trial performance improved to a similar degree in
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  Speaker 1: both the hot water and the thermal neutral water groups
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  Speaker 1: during the study, whereas the mitochondrial adaptations were unchanged in
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  Speaker 1: both groups. So this is a bit of a damp
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  Speaker 1: squid in terms of this idea that going into a
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  Speaker 1: sauna or exposing yourself to heat and can improve exercise adaptations.
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  Speaker 1: But a couple of things to dig into. So firstly,
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  Speaker 1: let's look at a big picture. So repeated heat exposure
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  Speaker 1: that is sufficiently stressful to elevate core temperature and that's
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  Speaker 1: critical actually results in a number of physiological adaptations, so
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  Speaker 1: you get overall heat acclimation. But what actually happened is
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  Speaker 1: there's their plasma volume. The amount of plasma increases or expands,
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  Speaker 1: you get reduced heart rate and core temperature at rest,
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  Speaker 1: and during exercise you get higher sweat output earlier onset
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  Speaker 1: of sweating and increased amounts of hemoglobin or hemoglobin mass.
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  Speaker 1: And that heat acclimation is something that athletes do, that
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  Speaker 1: military guys do as well, and it can it has
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  Speaker 1: been shown quite unequivocally to improve aerobic exercise performance in
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  Speaker 1: hot environments, especially performance on time to exhaustion tests. Now,
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  Speaker 1: on the other hand, and some studies have shown mixed
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  Speaker 1: results with respect as to whether heat acclimation improves aerobic
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  Speaker 1: exercise performance in normal environments, so when it's not too hot,
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  Speaker 1: and according to a meta analysis, heat acclamation can improve
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  Speaker 1: vot max to a small degree when testing occurs in
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  Speaker 1: a temperate environment, so not that hot, and the magnitude
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  Speaker 1: of improvement is greater when VO two max is tested
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  Speaker 1: in a hot environment, which kind of makes sense because
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  Speaker 1: you're adapting to the heat. Now, alow, VO two max
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  Speaker 1: is a strong predictor of aerobic exercise performance, Several other
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  Speaker 1: physiological factors also play a role, such as your lactate threshold.
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  Speaker 1: So there's a whole heap of stuff of adaptations that
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  Speaker 1: actually go on in a number of these different studies.
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  Speaker 1: And you can induce this heat acclamation by either exercising
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  Speaker 1: in the heat or exercising in a thermal neutral environment
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  Speaker 1: and wearing a heat suit or thermal clothing. And it
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  Speaker 1: can also be induced, and this is where this study
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  Speaker 1: comes in through passive methods like sona bailing or hot
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  Speaker 1: water immersion. So some of these adaptations occur pretty quickly,
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  Speaker 1: such as plasma volume expansion that can take only three
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  Speaker 1: or four days, but we know that some longer interventions,
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  Speaker 1: generally about five weeks or so, are needed to increase
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  Speaker 1: your red blood cell volume and hemoglobin mass. Now, although
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  Speaker 1: it has been suggested that the different protocols whether you
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  Speaker 1: do sauna post exercise, hot water post exercise, or you
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  Speaker 1: exercise in the heat, although some of the previous research
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  Speaker 1: has suggested that they stimulate similar adaptations, Ultimately, this study
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  Speaker 1: didn't find a beneficial effect of the hot water immersion
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  Speaker 1: on exercise performance. And one potential reason for this is
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  Speaker 1: that the exercise tests were performed in a temperate environment,
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  Speaker 1: and as discussed above, those adaptations and generally have the
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  Speaker 1: biggest impact when you're exercising in hot environments. But there's
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  Speaker 1: another thing that's really important here, and I think why
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  Speaker 1: this study didn't enhance the exercise adaptations, and it's probably
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  Speaker 1: because the protocol wasn't stressful enough. During the last five
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  Speaker 1: minutes of hot water immersion, core temperature was approximately thirty
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  Speaker 1: seven point eight degrees, which is about one hundred degrees fahrenheit. Now,
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  Speaker 1: the evidence suggests that core temperature should be raised to
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  Speaker 1: at least thirty eight point five degrees that's one hundred
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  Speaker 1: and one point three degrees fahrenheit. So it was almost
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  Speaker 1: a one degree centigrade, almost one degree centigrade lower than
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  Speaker 1: it needed to be to maximize heat acclimation adaptations. And
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  Speaker 1: here's the thing. Why all of this happens, or why
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  Speaker 1: a lot of this happens, and particularly the changes are
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  Speaker 1: the increased adaptations are because of stress response proteins, and
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  Speaker 1: a lot of the research around SONA bathing is shown
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  Speaker 1: that we get a lot of the positive adaptations, not
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  Speaker 1: all of them, but we certainly get a lot of
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  Speaker 1: positive adaptations because that heat can activate these stress response proteins.
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  Speaker 1: These are my favorite proteins in the body, and they
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  Speaker 1: are nature's agents of hardiness. So when you exercise vigorously,
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  Speaker 1: or you are in the heat enough to increase your
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  Speaker 1: core body temperature by about one degree, or you have
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  Speaker 1: significant amounts of cold exposure, you will release these stress
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  Speaker 1: response proteins, and in cold exposure you get both heat
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  Speaker 1: shok proteins and cold shock proteins, whereas in the heat
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  Speaker 1: you only get heat shock proteins. But these proteins actually
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  Speaker 1: stimulate lots of different adaptations, and it's basically nature's way
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  Speaker 1: of going Jesus, this is a stressful environment, so we
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  Speaker 1: had better toughen up the body in case we encounter
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  Speaker 1: this environment again. And I think this is probably why
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  Speaker 1: this study didn't show the improvement that other studies have,
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  Speaker 1: because they didn't increase the core body temperature. And I'm
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  Speaker 1: not sure how quickly they got into the water, but
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  Speaker 1: I certainly know. So to add a bit of color
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  Speaker 1: onto this, when I was deciding whether or not to
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  Speaker 1: have when I got my sauna, whether or not to
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  Speaker 1: have a traditional finish sauna or an infrared sauna, what
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  Speaker 1: I was really interested in. I did a whole heap
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  Speaker 1: of research on the heat shot proteins and find that
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  Speaker 1: generally you need to stimulate or increase your core body
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  Speaker 1: temperature by about one degree or to that threshold of
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  Speaker 1: thirty and a half degrees in order to stimulate those
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  Speaker 1: heat chock proteins. And I find that actually the infrared
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  Speaker 1: sauna did increase my core body temperature by one degree
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  Speaker 1: if I was in it for at least twenty minutes,
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  Speaker 1: and it was on seventy degrees and especially it did
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  Speaker 1: it quicker after exercise. I won't go into too much
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  Speaker 1: detail about how I worked, how much my core body
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  Speaker 1: temperature was increasing. I will just leave that to the imagination.
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  Speaker 1: So there's a couple of other three week studies, and
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  Speaker 1: it's important to compare the time that looked at post
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  Speaker 1: exercise sauna building. And one had male football players in
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  Speaker 1: Spain that did their usual training program and then performed
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  Speaker 1: three forty minutes ona sessions a week, and it was
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  Speaker 1: four bouts of ten minutes each with a little break
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  Speaker 1: in between, at a temperature of a undred degrees centigrade
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  Speaker 1: or two hundred and twelve degrees firenheat, which is pretty
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  Speaker 1: damn hot. And they had that as I said, they
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  Speaker 1: did ten minutes and the end a few minutes of
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  Speaker 1: recovery and then ten minutes again and at the end
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  Speaker 1: of the study there are time to exhaustion and their
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  Speaker 1: VO two max improved more in the solar group than
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  Speaker 1: the control group. And another study which has a crossover design,
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  Speaker 1: which is what you do that the first, whether it's
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  Speaker 1: the control group some one group does that first and
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  Speaker 1: the other does the intervention and then they switch over.
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  Speaker 1: This is probably the best design that there is that
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  Speaker 1: had meal distance runners and triathletes sit in the sauna
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  Speaker 1: at ninety degrees centigrade or one hundred and ninety degrees
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  Speaker 1: fahrenheit immediately after exercise for about thirty minutes, result in
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  Speaker 1: a total of about thirteen SAW sessions during the study
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  Speaker 1: and the end of the study their performance on a
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  Speaker 1: time to exhaustion test was better when they incorporated the
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  Speaker 1: SAWA sessions. And there are actually numerous studies that show
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  Speaker 1: that you get improvements in our increased stimulation from strength
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  Speaker 1: training if you then get into the sauna afterwards. But
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  Speaker 1: it would appear in all of these studies that you
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  Speaker 1: need to increase your core body temperature by about one degree. Now,
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  Speaker 1: if you are working out intensely and then you get
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  Speaker 1: straight into the sauna, you're going to have a quicker
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  Speaker 1: impact on your core body temperature. So, particularly if you've
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  Speaker 1: worked out to the point where you're sweating and you're hot,
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  Speaker 1: and then you just jump into the sauna, some of
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  Speaker 1: the research shows that about twenty minutes in there at
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  Speaker 1: any degree centigrade. Now that's in a traditional sauna, and
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  Speaker 1: I think you get away with less in a near
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  Speaker 1: infrared sona because, as you may be aware, that heats
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  Speaker 1: you from the inside as well, and I certainly sweat
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  Speaker 1: much more at the same temperature on an infrared song
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  Speaker 1: than I do on a traditional finished sona. But anyway,
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  Speaker 1: it would appear to be that you gotta increase that
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  Speaker 1: core body temperature by one degree in order to get
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  Speaker 1: those real additional effects on a muscle mass and muscle
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  Speaker 1: stimulation from strength training, but on this one improvements and
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  Speaker 1: exercise performance if you're doing cardiovascular training. So the take
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  Speaker 1: on with all of this is that if you want
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  Speaker 1: to optimize your adaptations to exercise, whether that's through strength
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  Speaker 1: training or cardiovascular training, both sauna and hot baths would
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  Speaker 1: appear to be a good way to actually do that
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  Speaker 1: if you have access to them and you have the
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  Speaker 1: time to be able to do that. That's it for
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  Speaker 1: this week, folks, Catch you next time.