Faculty of Behavioural and Movement Human Movement...
Transcript of Faculty of Behavioural and Movement Human Movement...
Applied Thermal Physiology
Hein Daanen Vrije Universiteit
Faculty of Behavioural and
Movement Sciences
Department Human Movement Sciences
Physiology Section
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Outline• My background
• Evolution of the thermal system
• Heat balance
• Cold strain (hypothermia, Injuries, dexterity, adaptation)
• Heat strain (exercise, WBGT)
• Preventing performance decrease in the heat
• Applications of thermal physiology
• Practical
Faculty of Behavioural and Movement Sciences
Human Movement Sciencesprof. dr. Jaap van Dieen
Experimental and Applied Psychologyprof. dr. Jan Theeuwes
Biological Psychologyprof. dr. Dorret Boomsma
Clinical, Neuro- and Developmental Psychologyprof. dr. Pim Cuijpers
Educational and family studiesprof. dr. Doret de Ruyter
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Human Movement Sciences
Section Coördinatiedynamics
Section Physiology
Section Motor learning & performance
Section Neuromechanics
Section Education
Section Sensorimotor control
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Physiology - Staffrehabilitation sport muscle
Dr. Karin Gerrits
Prof.Dr. Thomas Janssen
Dr. Martin Truijens
Dr. Jo de Ruiter
Dr. Jos de Koning
Dr. Willem Hoogaars
Dr. Richard Jaspers
Prof. Dr. Hein Daanen
head secretary postdocs
Stefan de Graaf
Dr. Koen Levels
Dr. Dionne Noordhof
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Background
Specialized in thermal physiology
and 3D anthropometry
1990- 2016: TNO - Applied
Scientific Research
2013 – 2016: Fashion Research &
Technology – Amsterdam
University of Applied Sciences
2003 – 2016:Thermal Physiology –
VU University
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Human surroundings
-89.5°C (July 1983)57.8°C (September 1922)
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Evolution of the thermal control system
Congregation of paramecia at a preferred temperature of 24-28°C (Mendelssohn, 1895)
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Evolution of the thermal control system
Cell specialisation
Sensor1 Communication Heat production
1Copyright (c) 2005, GIUNTI PUBLISHING GROUP
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Poikilothermia versus Homeothermia
Poikilothermia (exotherm)
Homeothermia (endotherm)
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Mechanisms to cope with thermal extremes
Heat: vasodilation
sweat loss
(max. 3.7 l/hr = 2458 W)
POWERFUL ACCLIMATIZATION
Cold: vasoconstriction
shivering
fur coat
brown fat
POOR ACCLIMATIZATION
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Surface to area distribution
Latitude (absolute degrees)
Bod
y su
rface area / m
ass (cm2/k
g)
Bod
y su
rface area / m
ass (cm2/k
g)
Source: Lewin&Foley, Principles of human evolution, Blackwell Publ.
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The heat balance
Heat storage
Heat lossHeat production
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M ± S ± R ± C - E = 0:
* M: Metabolism
* S: Storage
* R: Radiation
* C: Convection (conduction)
* E: Evaporation
37°Chot cold
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Rest:
Equilibrium between heat
production and heat loss
Diet induced thermogenesis
Exercise:
Heat Production exceeds heat loss
Core temperature increase
Performance decrement
Heat balance in rest and exercise
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M ± R ± C - E = ± S:
* M: Metabolism
* S: Storage
* R: Radiation
* C: Conv+Cond
* E: Evaporation
(Marino et al., EJAP, 2000)
S
-1400
-1200
-1000
-800
-600
-400
-200
0
200
400
15°C 25°C 35°C
Wet
Dry
Storage
Thermal balance - 8 km run
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Heat balanceClimate
Clothing
Metabolism
Individual
factors
The heat balanceThermal balance
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Required clothing for thermal neutrality (ISO/TR 11079)
0
1
2
3
4
5
6
-30 -20 -10 0 10 20Temp. (°C)
Re
qu
ired
clo
thin
g (
Clo
)
rest
sitting
standing
walking
running
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Retain heat:
* Behaviour
* Vasoconstriction
Maintaining Thermal Balance in the cold
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Increased heat production:
*shivering
(Benzinger)
Shivering thermogenesis
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Non-shivering
Thermogenesis
(Claessens, 2008)
Non-Shivering thermogenesis
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Cold related problems
•Discomfort of hands and feet
•Reduced dexterity
•Increased risk for accidents
•Cold injuries
•Hypothermia
Applied Thermal Physiology
Hypothermia
Initial increase in Tcore
Slow drop thereafter
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36,2
36,4
36,6
36,8
37
37,2
0 20 40 60 80 100 120
minutes
bo
dy
co
re t
em
pe
ratu
re (
°C)
core shell
Physical Afterdrop
Time in minutes
Esophageal te
mpera
ture
(°C
)
Pow
er
(W)
-10
10
30
50
70
90
36.3
36.4
36.5
36.6
36.7
36.8
36.9
37.0
37.1
37.2
0 6 12 18 24 30 36
Physiological Afterdrop
Subjects were
cooled to 35°C
Comparison of rewarming methods
1 warm bath2 bath without extremities
Bath rewarming
3 through hands & feet
4 shivering thermogenesis
Other rewarming methods
Results Afterdrop
Rewarming speed Manual dexterity
• Cold exposure leads to decreased
peripheral tissue temperature
• This leads to decreased dexterity, increases risk for accidents
cold warm
Methods – measurementsDexterity score
Finger skin temperature (Tfi)
Toe temperature (Ttoe)
Rectal temperature (Tre)
Mean skin temperature (Tsk)
Mean body temperature (Tb)
Thermal sensation
Exclusion: T<5°C
Results – finger skin temperature
Drop in dexterity below about 14°C
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IR-image:
12
2
1
0
5
10
15
20
25
30
35
0 5 10 15 20 25 30
Time (min)
fin
ge
r s
kin
te
mp
era
ture
(°C
)
Protection against cold injuries
Applied Thermal Physiology36
0
10
20
30
40
-10 0 10 20 30
Time (min)
fin
ge
r s
kin
tem
pe
ratu
re (
°C)
Warm core
Cold core
Neutral core
Protection depends on core temperature
Arterio-Venous
Anastomoses
coldCIVD
CIVD - background Acclimatization vs Acclimation
Acclimatization: adaptation in
natural settings
Acclimation: adaptation in
artificial settings
Acclimatization can be risky
The Dutch soccer team training in Portugal
Adaptation to cold - general
• Metabolic – higher
MHP, higher Tsk
• Insulative – lower Tsk, MHP unchanged
• Hypothermic – lower Tc, MHP unchanged
• Insulative hypothermic – lower Tsk, Tc
Mainly based on population studies
Non-Shivering adaptations
• 9 females, 10 males
• 10 days mild cold exposure
(15 °C, 6 hr / day)
• 4% increase of NST
• equals < 1 W
Adaptation to cold - general
• Pre/post in 12°C water until 35°C/ 90 min
• 7 subjects core cooling (5 days, 45 min, 12°C)
• 7 skin cooling (5 days, 5 min, 12°C)
• 7 control
• Hypometabolic adaptation to mild core cooling
Adaptation to cold - general
• 14 males
• 14°C water immersion
• 35.5°C / 170 min
Adaptation to cold - general
• quicker cooling
• feeling less cold
• hypometabolic
acclimation
Adaptation to cold – generalDoes it improve performance
in the cold?• Pre/Post 60 min in 18ºC
water + 30 min cycling
(1W/kg)
• 15 days 90 min in 18ºC
water
• Again hypometabolic
adaptation
• No effect on metabolism
during exercise Stocks et al., 2001
Local cold adaptations
Astrand et al.: when a person, whether an arctic native or otherwise, allows his or her hands to be repeatedly exposed to cold for about ½ h daily for a few weeks, this
cold stress increases the blood flow through the hands, so that they remain warmer and are not so apt to become numb when exposed to cold.
Launay & Savourey: This local cold adaptation is probably the most interesting cold adaptation from professional
activities point of view as it is easy to get with limited equipment.
Local cold adaptationsAbstract: The duration of vasoconstriction and
magnitude of cold vasodilatation of 11 experienced fish filleters was compared with 9 controls by immersion of the left hand in stirred ice and water mixtures. Vasodilatation occurred significantly earlier in the filleters, whose hand skin temperatures were significantly higher during immersion, in both the initial vasoconstriction and after vasodilatation. .. The difference is considered to show the characteristics of acclimatization, and the fact that the filleters are accustomed to working with their hands in very cold water is considered to be the stress producing the acclimatization response.
But it is not unlikely that you only become a fish filleter when you always have warm hands..
Nelms and Soper, 1961
Local cold adaptations
Experiment:
9 male and 7 female subjects
immersed their right (trained) hand and foot simultaneously
in 8ºC water; 30 min daily; for 15 days.
During the pre and post-test (days 1 and 15, respectively) the left (untrained) hand and foot were immersed as well.
Local cold adaptations
• Toe temperature: 9.5 to 10.0ºC
• Finger temperature: 9.3 to 8.9ºC
• No changes for non-immersed hands and feet
• Drop in pain score over time
• Colder fingers with less pain -> higher risk for injuries
Local cold adaptations
Mekjavic et al., 2008
‘..repeated local cold exposure does not alter
circulatory dynamics in the peripheries’
Cold adaptations - conclusion
• General cold adaptation:
• people cool faster
• generate less heat
• feel less cold
• Local cold acclimation:
• fingers colder and less sensitive
Not really great adaptations...
Risc factors:
* High Temperature
* High Humidity
* No wind
* Solar radiation
* Insulation
* Exercise
Exercise in impermeable suits is a combination of most risk factors
Heat strain WBGT
Temperature (temp.)
Black Bulb (temp., radiation, wind)
Wet bulb (temp., radiation, wind, humidity)
WBGT = 0.7 Tnwb + 0.3 Tgl
In sun: WBGT = 0.7 Tnb + 0.2 Tgl + 0.1 Tdb
WBGT – limits WBGT – clothing correction
Heat Stress and Exercise
• Fatigue from a variety of
mechanisms:
• Cardiovascular collapse
• Hydration & fluid imbalance
• Neurotransmitters
• Psychological
Multiple Triggers of Fatigue
Cheung and Sleivert 2004a
Cheung & McLellan 1998
MF HF
EU HY EU HY
38.77 38.69 39.15 39.20
38.79 38.63 39.14 39.21
• Similarity of endpoint Tre with fatigue.
• Systematic differences with fitness.
Effects of hydration, fitness, & heat acclimation on heat tolerance during uncompensable heat stress
Human EvidenceTcore(end) with different Tcore(start)
Tcore(end) with different Tcore(rise)
Gonzalez-Alonso et al. 1999
Exercise and heat transfer
0
100
200
300
400
500
600
700
800
900
1000
0 50 100 150 200 250Cycling power (W)
Hea
t tr
an
sfer
(W
)
Heat production
Heat loss
Sweat
Dry heat loss
Performance decrease in the heat
Ely et al., MSSE, 2007
0
1
2
3
4
5
6
7
8
5-10 10-15 15-20 20-25
WBGT
% s
low
er
than
co
urs
e r
eco
rd
Performance decrease related to WBGT for 7 marathons in
US/Canada
Performance decrease in the heat -physiology
Reduced gross efficiency (at cell level?)
Core temperature ( ºC)
Effic
iency (
%)
35.0 35.5 36.0 36.5 37.0 37.5 38.0 38.5
17.5
18.0
18.5
19.0
19.5
20.0
20.5
Daanen et al. IJSM 2006
Techniques to reduce performance decrease in the heat
Selection e.g. Africans versus Caucasians
Physiological adaptations - Acclimatization or acclimation
Physical training (cross acclimatisation)
Cooling (prior, during and after exercise)
Drinking
Pacing strategy
Selection
Difference in running speed
between 15°C en 35°C for 6 well
trained Africans and Caucasians
From: Marino et al., JAP 2004 Marino et al., EJAP 2000
Body mass (kg)
0
1
2
3
30 35 40 45 50 55Time (min)
Dif
fere
nce
in
ru
nn
ing
sp
eed
(km
/hr)
African Caucasian
Acclimatisation:
Core temperature ↓
Sweat rate ↑
Skin blood flow ↑
Metabolic rate ↓
Heart rate ↓
Stroke volume ↑
Fluid balance ↑
Thirst ↑
Electrolyte loss / litre sweat ↓
Total body water ↑
Plasma volume ↑
Heat Acclimatisation
Acclimation to heat
(Strydom et al., JAP 21(2): 636-642, 1966)
0
200
400
600
800
1000
1200
1400
1 2 3 4 5 6 7 8 9 10 11 12
day
Sw
eat
loss
(m
l/h
r)
Acclimation to heat
(Strydom et al., JAP 21(2): 636-642, 1966)
120
140
160
180
1 2 3 4 5 6 7 8 9 10 11 12
day
Hea
rt r
ate
(m
in-1)
Acclimation (Nadel)
0
0,2
0,4
0,6
0,8
37 37,5 38 38,5Tes (°C)
Ch
est
swea
t ra
tet
(mg
/min
.cm
²)
Normal
Trained
Acclimated
Heat acclimation for cold?
Lorenzo et al., 2010
Study Performance
parameters and
which effect (+ =
increase, - = no
increase)
Acclimatization type Training
participants
Lorenzo et al.
(2010)
VO2max +
TT work done +
Lactate threshold +
Heat acclimatization
protocol in heat chambers
(40˚C, 30% relative
humidity) with 2 bouts of
submaximal exercise.
Resume
‘normal
training’ in
moderate
conditions
Karlsen et al.
(2015)
VO2max -
TT power output -
Peak aerobic -
Exercise efficiency -
Heat acclimatization
protocol in Qatar (average
temperature 34.1 ˚C)
Training in
the heat. HI
part in
beginning of
the training
Keiser et al.
(2015)
VO2max –
TT average power
outpot -
Heat acclimatization in
heat chambers (38°C and
30% relative humidity)
Training in
the heat
chambers
Scriptie Timo vd Boogaard – 2016
Heat acclimation optimization
• It is recommended that athletes live in the heat, experience heat under the pressure of competition, acclimate for a specific climate and then undertake high-quality training in the cool (Taylor and Cotter, 2006).
• Controlled hyperthermia by exercise in the heat is optimal for thermal adaptation (> 2 hours, >5 days, >38ºC core)
• What happens if acclimation is too short andwhat if the recovery is insufficient?
Time too short..
• 5 days may work, but 3 days is too short
Daanen and Herweijer, 2014
8 females > 75 and 8 females 20-30
Insufficient recovery..
• 15 male subjects
• 60 min bicycle exercise at 45% VO2max
• Followed by incremental max test of about 45 min
• 9 days HA in 35ºC, 29% RH; 3 days HA in 41ºC, 33% RH
• Retest in 35ºC, 29% RH after day 3, 7 and 18
Insufficient recovery
Adaptations occurred after HA period
De- and Re-acclimation
Only limited data available – more studies needed
Greater retention for dry heat
Greater retention when fit
Pandolf (1998): first review
Decay (%) 1 week 2 weeks 3 weeks
Rectal temp. 26 35 45
Heart rate 65 87 92
De- and Re-acclimation
16 male subjects
100 min treadmill exercise in 46ºC, 18% RH
10 days HA
Hereafter:
8 males reacclimatized after 12 days
8 males reacclimatized after 26 days
De- and Re-acclimation Heat acclimation - conclusions
• Acclimati(zati)on leads to impressive adaptations
• Heat acclimation is less risky than acclimatization
• Cool rest periods are necessary to have optimal
effect
• Once adaptation to heat has been attained, the
time that individuals may spend in cooler
conditions before returning to a hot environment
could be as long as one month, without the need
for extensive re-adaptation to heat
Heat acclimation - conclusions
• Review Daanen, Racinais, Periard in process
Applied Thermal Physiology78
Cooling during task performance
Two hours of flight
35ºC with and without cooling
Bron: Reffeltrath e.a., 2002
Applied Thermal Physiology79
Core temperature during flying
(Reffeltrath, 2002)
Tijd (min)
Kern
tem
pe
ratu
ur
toena
me (
ºC)
15 30 45 60 75 90 105 120-0,2
0,0
0,2
0,4
0,6
0,8
1,0
1,2
1,4
35ºC, geen koeling
35ºC, koeling door ingeblazen lucht
*
* *
Applied Thermal Physiology80
Pre-cooling
• Eight male subjects
• Four cooling conditions (40 min):
N CC WC CW• Followed by 40 min exercise at 60%
VO2max
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Pre-cooling – core temperature
37.0
37.5
38.0
38.5
39.0
39.5
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85
Time (min)
Co
re te
mp
. (°
C)
N
CC
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Pacing strategies
Does it help to adjust the pacing strategy when it is hot?
Tools to pace become more and more popular
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Power output during cycling
275
300
325
350
375
400
425
0 10 20 30Time (min)
Po
we
r O
utp
ut
(W)
32°C 23°C
Tatterson et al., JSMS, 2000
11 top cyclists – End lactate was lower in the heat => no metabolic
limitation
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Applications of thermal physiology
Sports
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Applications of thermal physiology
clothing
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Applications of thermal physiology
Prevention of cold injuries
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Applications of thermal physiology
Thermometry
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Applications of thermal physiology
Labour
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Applications of thermal physiology
Clinical applications
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Facilities in Thermal Physiology
* Climatic chambers (temp., wind,
sun, RH)
* Ergometry (arm, leg, tredmill,
work simulator)
* Physiological monitoring (temp., ventilation, blood flow)
* Clothing measures (insulation, humidity, ventilation)
* Anthropometry (body scanning)
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Praktical December 12-16, 2016
Goal: Heat balance
Settings: Climate: 35°C, 10°C
ergometry 1,5 W/kg (20% efficiency)
nude / no sun, nude / sun, clothed / no sun
4 subjects and 3-4 helpers per subject
Measures: temperature rectal, skin
thermal comfort
weight (wet heat loss)
Protocol: 30 min instr. – 30 min exercise – 10 min rest
Applied Thermal Physiology92
Praktical 2016
Forms : - explanation
- informed consent
- score form subject
- score form experiment
- score form (thermal) comfort
Web: http://members.ziggo.nl/daanen/VU
Applied Thermal Physiology93
Praktical
Where: TNO Soesterberg
Exclusion: Pregnancy or lactation
Exercise intolerance
Applied Thermal Physiology94
Practical
* Please take sport equipment, swimming gear, towel
* Location: Kampweg 5 Soesterberg
* Please be in time – be careful – have fun
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More info
Hein Daanen
TNO Human Factors
Postbus 23
3769 ZG Soesterberg
Tel. 0346 - 356402
Email: [email protected]
Web: www.tno.nl
http://members.ziggo.nl/daanen
Applied Thermal Physiology96
More info
Hein Daanen
TNO Human Factors
Postbus 23
3769 ZG Soesterberg
Tel. 0346 - 356402
Email: [email protected]
Web: www.tno.nl
http://members.ziggo.nl/daanen
Meer info