1
00:00:09,560 --> 00:00:13,399
Speaker 1: Here everyone, Welcome to another edition of Wisdom Wednesdays, and

2
00:00:13,440 --> 00:00:15,720
Speaker 1: today I want to do a bit of a deep

3
00:00:15,800 --> 00:00:19,320
Speaker 1: dive into heat. Now, many of us think of hate

4
00:00:19,360 --> 00:00:23,160
Speaker 1: therapies as a bit of a luxury, a sauna after

5
00:00:23,200 --> 00:00:25,400
Speaker 1: a workout, a hot bath at the end of the day,

6
00:00:25,840 --> 00:00:28,400
Speaker 1: and probably something that we do to relax. But the

7
00:00:28,480 --> 00:00:32,000
Speaker 1: research coming out lately paints a very different picture. And

8
00:00:32,159 --> 00:00:35,360
Speaker 1: heat isn't just comfort, It's a training stimulus. And I've

9
00:00:35,400 --> 00:00:38,960
Speaker 1: talked a little bit before about the benefits of saunas,

10
00:00:39,000 --> 00:00:41,200
Speaker 1: but I really want to do a deep dive into

11
00:00:41,240 --> 00:00:45,199
Speaker 1: the idea that heat is a stressor that can literally

12
00:00:45,320 --> 00:00:48,239
Speaker 1: change how your body functions all the way down to

13
00:00:48,320 --> 00:00:52,520
Speaker 1: gene expression. And the question and I want to explore

14
00:00:52,600 --> 00:00:58,720
Speaker 1: today is does a sauna outperform a hot bath or

15
00:00:58,760 --> 00:01:01,440
Speaker 1: the other way around. So let's start with a few

16
00:01:01,560 --> 00:01:05,640
Speaker 1: really interesting studies, very recent studies. One done it just

17
00:01:05,680 --> 00:01:10,039
Speaker 1: this year by Takeida and colleagues. They ran a pretty

18
00:01:10,120 --> 00:01:15,760
Speaker 1: interesting experiment. They put people through five high intensity resistance

19
00:01:15,800 --> 00:01:18,480
Speaker 1: training sessions over two weeks. So high intensity when it

20
00:01:18,520 --> 00:01:21,160
Speaker 1: comes to resistance training, it just means heavy loads, right,

21
00:01:21,720 --> 00:01:25,560
Speaker 1: and after each workout, the participants were randomly assigned to

22
00:01:25,720 --> 00:01:31,000
Speaker 1: either soaking their legs in a forty degrees centigrade hot

23
00:01:31,040 --> 00:01:35,000
Speaker 1: bath for ten minutes. That's about forty degrees apologies for

24
00:01:35,040 --> 00:01:38,440
Speaker 1: our American friends, but forty degrees centigrade. That's a kind

25
00:01:38,480 --> 00:01:40,959
Speaker 1: of a hot what you would describe as a hot bath.

26
00:01:41,080 --> 00:01:44,320
Speaker 1: Not ridiculously hot, but a hot bath. And the other

27
00:01:44,360 --> 00:01:48,040
Speaker 1: guys took a forty degree hot shore, so they had

28
00:01:48,080 --> 00:01:51,120
Speaker 1: the same water temperature and for the same amount of time.

29
00:01:51,280 --> 00:01:53,960
Speaker 1: They did the hot shore for ten minutes. The only

30
00:01:54,000 --> 00:01:56,560
Speaker 1: difference is that one group was immersed in the hot

31
00:01:56,600 --> 00:01:59,480
Speaker 1: water and the other one wasn't. And the results were

32
00:01:59,520 --> 00:02:03,760
Speaker 1: really interesting. The guys who took the hot baths almost

33
00:02:04,000 --> 00:02:08,959
Speaker 1: doubled the strength training games of the guys who took

34
00:02:09,000 --> 00:02:13,080
Speaker 1: the shore. They had a nine point three percent increase

35
00:02:13,120 --> 00:02:16,880
Speaker 1: in maximum leg strength for the hot bath group, and

36
00:02:16,919 --> 00:02:19,680
Speaker 1: it was only a four point five percent increase in

37
00:02:19,720 --> 00:02:23,160
Speaker 1: the hot shot group. And the difference really comes down

38
00:02:23,200 --> 00:02:28,079
Speaker 1: to heat load how deeply the body actually absorbs the heat.

39
00:02:28,600 --> 00:02:33,560
Speaker 1: So it turns out that hot water immersion actually reduces

40
00:02:33,680 --> 00:02:38,000
Speaker 1: peripheral fatigue, or did in this study, and improved neuromuscular

41
00:02:38,080 --> 00:02:42,880
Speaker 1: recovery far more than a simple hot sho and even

42
00:02:42,960 --> 00:02:45,960
Speaker 1: adding light movement in the bath didn't enhance the effect.

43
00:02:46,080 --> 00:02:50,000
Speaker 1: It was really the heat stimulus alone that drove the

44
00:02:50,080 --> 00:02:54,359
Speaker 1: increased adaptation, and that's the first clue that immersion maybe

45
00:02:54,360 --> 00:02:57,880
Speaker 1: doing something unique. Then there was another study that added

46
00:02:57,960 --> 00:03:02,680
Speaker 1: to this also this year, and the researcher lead researcher

47
00:03:02,840 --> 00:03:08,400
Speaker 1: was at Tenkio and they compared three forms of passive

48
00:03:08,400 --> 00:03:10,760
Speaker 1: heat and this was very interesting. I've been waiting for

49
00:03:10,800 --> 00:03:14,320
Speaker 1: somebody to do this today. They compared time in a

50
00:03:14,520 --> 00:03:18,560
Speaker 1: far infrared sauna and then they had a traditional sauna

51
00:03:18,720 --> 00:03:22,079
Speaker 1: at eighty degrees centigrade that's what a lot of the

52
00:03:22,480 --> 00:03:26,000
Speaker 1: research used. And then they had hot water immersion in

53
00:03:26,040 --> 00:03:30,480
Speaker 1: a hot tub for forty point five degrees centigrade and

54
00:03:30,600 --> 00:03:33,000
Speaker 1: all of them for forty five minutes, and there were

55
00:03:33,120 --> 00:03:37,200
Speaker 1: twenty healthy adults. They completed all three conditions, which is

56
00:03:37,320 --> 00:03:40,840
Speaker 1: really cool when they do all of them. So if

57
00:03:40,880 --> 00:03:45,440
Speaker 1: you follow longevity research or influencers, there's lots to talk

58
00:03:45,480 --> 00:03:48,880
Speaker 1: about the benefits of sauna, and most people will say

59
00:03:48,880 --> 00:03:51,600
Speaker 1: traditional sauna is better than far infra red and there

60
00:03:51,680 --> 00:03:56,080
Speaker 1: is more research around it. But what they actually find

61
00:03:56,640 --> 00:03:59,480
Speaker 1: and they looked at increases in core body temperature, which

62
00:03:59,480 --> 00:04:01,440
Speaker 1: is important for reasons they're getting too in. A second

63
00:04:02,240 --> 00:04:05,880
Speaker 1: is that the far infrared sauna and barely moved core

64
00:04:06,000 --> 00:04:10,800
Speaker 1: temperature at all. The traditional sauna increased it by about

65
00:04:11,120 --> 00:04:15,520
Speaker 1: zero point four degrees centigrade, but the hot water immersion

66
00:04:15,640 --> 00:04:20,320
Speaker 1: group increased their core temperature by one point one degree centigrade.

67
00:04:20,839 --> 00:04:25,080
Speaker 1: Now this is really interesting to me because all of

68
00:04:25,160 --> 00:04:27,920
Speaker 1: the research that I have seen suggests that you need

69
00:04:28,000 --> 00:04:32,320
Speaker 1: to increase core body temperature by one degree in order

70
00:04:32,440 --> 00:04:35,440
Speaker 1: to activate heat chock proteins. And heat chock proteins are

71
00:04:35,440 --> 00:04:41,000
Speaker 1: a special class of stress response proteins that drive these

72
00:04:41,200 --> 00:04:45,919
Speaker 1: cellular pathways that actually improve our health and are strongly

73
00:04:46,000 --> 00:04:50,800
Speaker 1: tied into longevity as well. So the bath that warm

74
00:04:51,080 --> 00:04:56,320
Speaker 1: soothing relatively gentle bath produced almost three times the thermal

75
00:04:56,400 --> 00:05:01,279
Speaker 1: load of the sauna, and interestingly, cardiac got pout also

76
00:05:01,480 --> 00:05:05,159
Speaker 1: jumped dramatically during the immersion by three point seven leaders

77
00:05:05,200 --> 00:05:08,240
Speaker 1: per minute, and that was about sixty percent more than

78
00:05:08,320 --> 00:05:12,080
Speaker 1: the traditional finish sauna. But the most interesting part for

79
00:05:12,200 --> 00:05:15,480
Speaker 1: me was that it was only the hot bath that

80
00:05:15,680 --> 00:05:19,520
Speaker 1: provoked a measurable immune response, and the guys who did

81
00:05:19,600 --> 00:05:22,520
Speaker 1: when they did the hot bath, they are interlooking six

82
00:05:23,080 --> 00:05:26,599
Speaker 1: levels increased, their natural killer sales increase, which are important

83
00:05:26,720 --> 00:05:31,360
Speaker 1: immune sales, and CD eight plus T sales also increased

84
00:05:31,360 --> 00:05:33,960
Speaker 1: twenty four to forty eight hours later and the sauna.

85
00:05:34,000 --> 00:05:37,839
Speaker 1: Both of the saunas didn't even come close. So it's

86
00:05:38,000 --> 00:05:41,560
Speaker 1: pretty rare that we find a very simple practice like

87
00:05:41,640 --> 00:05:45,000
Speaker 1: a hot bath beating a finish sauna in terms of

88
00:05:45,040 --> 00:05:49,200
Speaker 1: physiological impact. Anybody who's followed the researchers will know that

89
00:05:49,480 --> 00:05:52,440
Speaker 1: there's a hayper research coming out of Finland that shows

90
00:05:52,520 --> 00:05:57,920
Speaker 1: that regular sauna actually improves health and longevity. But it

91
00:05:57,960 --> 00:05:59,880
Speaker 1: would appear, at least from this study, that you need

92
00:06:00,120 --> 00:06:02,360
Speaker 1: spend a lot more time in the sauna than you

93
00:06:02,400 --> 00:06:07,000
Speaker 1: would do in hot bath. And let's explore why it's

94
00:06:07,080 --> 00:06:11,560
Speaker 1: really it's all about heat transfer, because water conducts heat

95
00:06:12,120 --> 00:06:16,760
Speaker 1: twenty five times more effectively than our That's why getting

96
00:06:16,839 --> 00:06:20,880
Speaker 1: in cold water at ten degrees centigrade is a shitload

97
00:06:20,960 --> 00:06:25,160
Speaker 1: worse than being in colder at ten degrees centigrade. So

98
00:06:25,440 --> 00:06:28,880
Speaker 1: even if the temperature is lower in the bath, the

99
00:06:28,960 --> 00:06:33,600
Speaker 1: body is absorbing much more heat, and that leads us

100
00:06:33,600 --> 00:06:36,480
Speaker 1: into the whole idea about heat shock proteins. These are

101
00:06:37,160 --> 00:06:41,320
Speaker 1: the bodies internal repair squad and much more. And we

102
00:06:41,480 --> 00:06:43,800
Speaker 1: know there's a bucket load of research around heat shock

103
00:06:43,839 --> 00:06:48,919
Speaker 1: proteins and particularly heat chock protein seventy that is produced

104
00:06:48,960 --> 00:06:51,920
Speaker 1: when your body senses thermal stress, whether that's being in

105
00:06:52,080 --> 00:06:54,920
Speaker 1: the sauna, being in a hot bath, or exercising in

106
00:06:55,000 --> 00:06:58,600
Speaker 1: the heat. And what these heat shok proteins do. They

107
00:06:58,640 --> 00:07:02,920
Speaker 1: get activated and they repair damage proteins within our cells,

108
00:07:03,320 --> 00:07:08,000
Speaker 1: but they also support mitochondrial function. They improve the resilience

109
00:07:08,080 --> 00:07:11,000
Speaker 1: of your cells, and they play a role in a

110
00:07:11,160 --> 00:07:15,640
Speaker 1: number of different longevity pathways. And as I said earlier,

111
00:07:15,680 --> 00:07:18,760
Speaker 1: a rise of around one degree centigrade and core body

112
00:07:18,800 --> 00:07:22,760
Speaker 1: temperature is enough to activate heat shock proteins. So this

113
00:07:22,920 --> 00:07:26,360
Speaker 1: recent research is backed up by other research, a whole

114
00:07:26,400 --> 00:07:29,440
Speaker 1: heap of it around heat shock proteins. So, for instance,

115
00:07:29,840 --> 00:07:32,960
Speaker 1: a really interesting twenty eleven paper by Coon and an

116
00:07:33,000 --> 00:07:35,680
Speaker 1: at All that showed that was the one that first

117
00:07:35,720 --> 00:07:39,920
Speaker 1: showed that core body increases of roughly one degree centigrade

118
00:07:40,280 --> 00:07:43,800
Speaker 1: triggered a heat shark protein expression during heat stress. Then

119
00:07:43,880 --> 00:07:48,560
Speaker 1: in twenty nineteen Gibson and colleagues they demonstrated activation of

120
00:07:48,720 --> 00:07:53,320
Speaker 1: protective genes after heat stress sufficient to raise core body

121
00:07:53,360 --> 00:07:57,560
Speaker 1: temperature above the baseline Horowitz. In two thousand and seven,

122
00:07:57,720 --> 00:08:03,440
Speaker 1: they reviewed how repeated heat exposure actually induces cross tolerance,

123
00:08:03,560 --> 00:08:09,120
Speaker 1: the cross stress or effect enhancing overall stress resilience by

124
00:08:09,440 --> 00:08:13,480
Speaker 1: activating heat shark protein pathways, so making the body more

125
00:08:13,600 --> 00:08:17,960
Speaker 1: resilient at a cellular level. And the Gucci and colleagues

126
00:08:17,960 --> 00:08:21,040
Speaker 1: in twenty twelve they showed that sauna exposure this was

127
00:08:21,080 --> 00:08:25,640
Speaker 1: a longer duration, increases circulating stress hormones and heat shark proteins.

128
00:08:25,960 --> 00:08:29,280
Speaker 1: And Faulkner and colleagues In twenty seventeen they did a

129
00:08:29,400 --> 00:08:34,120
Speaker 1: nice review summarizing how passive hating elevates tachhart protein levels

130
00:08:34,160 --> 00:08:38,760
Speaker 1: and influences inflammatory signaling. But the new studies that I

131
00:08:38,840 --> 00:08:42,600
Speaker 1: talked about right at the start, they're really important here

132
00:08:42,760 --> 00:08:48,240
Speaker 1: because hot water immersion was the only modality that reliably

133
00:08:48,400 --> 00:08:53,400
Speaker 1: pushed core body temperature above that critical one degree threshold.

134
00:08:53,720 --> 00:08:56,640
Speaker 1: So it's not saying that saunas are useless. It's just

135
00:08:56,760 --> 00:08:59,560
Speaker 1: that you need to spend more time in a sauna.

136
00:09:00,720 --> 00:09:03,520
Speaker 1: One little hack that you can do, And I have

137
00:09:03,640 --> 00:09:06,280
Speaker 1: trialed this before and I've done my own self experiment

138
00:09:06,400 --> 00:09:12,319
Speaker 1: on it is to exercise vigorously, but before you get

139
00:09:12,360 --> 00:09:15,199
Speaker 1: into the sauna, whether it's an infrared sona or a

140
00:09:15,280 --> 00:09:18,679
Speaker 1: normal sonar, because the exercise is going to boost your

141
00:09:18,720 --> 00:09:23,280
Speaker 1: core body temperature, and it's like having been in the

142
00:09:23,360 --> 00:09:26,440
Speaker 1: sauna without being in the sauna, So you probably need

143
00:09:26,640 --> 00:09:31,120
Speaker 1: less time if you're getting in straight after a workout. Right.

144
00:09:32,360 --> 00:09:37,360
Speaker 1: But the key takeover here is that heat works because

145
00:09:37,400 --> 00:09:41,160
Speaker 1: it's a stressor it's a hormetic stressor, that it's a

146
00:09:41,240 --> 00:09:44,319
Speaker 1: small dose of stress that forces the body to adapt

147
00:09:45,000 --> 00:09:48,520
Speaker 1: in many, many beneficial ways. You know, in the short

148
00:09:48,600 --> 00:09:51,720
Speaker 1: term physiologically or heart rate rises, your blood vessels dilate,

149
00:09:51,920 --> 00:09:54,280
Speaker 1: the blood flow to the muscles, and the brain increases.

150
00:09:54,920 --> 00:10:00,000
Speaker 1: Inflammation rises initially, then reduces and falls below baseline afterwards.

151
00:10:00,679 --> 00:10:04,880
Speaker 1: But importantly, immune sales are mobilized and heat chock proteins

152
00:10:05,520 --> 00:10:08,920
Speaker 1: actually repair cellular damage, so you get a net benefit

153
00:10:09,400 --> 00:10:12,600
Speaker 1: because of the hormetic stressor. And it's the same principle

154
00:10:12,640 --> 00:10:17,800
Speaker 1: as exercise. Stress plus recovery equals positive adaptation. And the

155
00:10:17,880 --> 00:10:22,000
Speaker 1: take on here is that hot water immersion getting into

156
00:10:22,040 --> 00:10:23,840
Speaker 1: the hot water in particular with it's a hot tub

157
00:10:23,920 --> 00:10:26,800
Speaker 1: or hot bath that seems to be the quickest way

158
00:10:26,920 --> 00:10:30,760
Speaker 1: to hit that one degree core body temperature consistently and safely.

159
00:10:31,040 --> 00:10:32,679
Speaker 1: And I guess the takeout here. Look, I'm a big

160
00:10:32,720 --> 00:10:37,080
Speaker 1: fan of sauna. It's not just for the health benefits

161
00:10:37,120 --> 00:10:40,679
Speaker 1: but also the relaxation benefits. But you know, if you're

162
00:10:40,880 --> 00:10:43,480
Speaker 1: flipping and flopping about should I spend a bucket load

163
00:10:43,480 --> 00:10:46,080
Speaker 1: of money on a sauna and much one should I get? Maybe?

164
00:10:46,120 --> 00:10:49,240
Speaker 1: Should just get a hot tub or have regular hot baths.

165
00:10:49,640 --> 00:11:00,360
Speaker 1: That's it for this week, folks, Catch you next time. Hey,