Faculty of Behavioural and Movement Human Movement Sciencesmembers.ziggo.nl/daanen/vu/vu-college2016.pdf · running. 19 Retain heat: * Behaviour * Vasoconstriction ... • Cardiovascular

Applied Thermal Physiology

Hein Daanen Vrije Universiteit

Faculty of Behavioural and

Movement Sciences

Department Human Movement Sciences

Physiology Section

2

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

4

Human Movement Sciences

Section Coördinatiedynamics

Section Physiology

Section Motor learning & performance

Section Neuromechanics

Section Education

Section Sensorimotor control

5

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

6

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

7

Human surroundings

-89.5°C (July 1983)57.8°C (September 1922)

8

Evolution of the thermal control system

Congregation of paramecia at a preferred temperature of 24-28°C (Mendelssohn, 1895)

9

Evolution of the thermal control system

Cell specialisation

Sensor1 Communication Heat production

1Copyright (c) 2005, GIUNTI PUBLISHING GROUP

10

Poikilothermia versus Homeothermia

Poikilothermia (exotherm)

Homeothermia (endotherm)

11

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

12

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.

13

The heat balance

Heat storage

Heat lossHeat production

14

M ± S ± R ± C - E = 0:

* M: Metabolism

* S: Storage

* R: Radiation

* C: Convection (conduction)

* E: Evaporation

37°Chot cold

15

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

16

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

17

Heat balanceClimate

Clothing

Metabolism

Individual

factors

The heat balanceThermal balance

18

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

19

Retain heat:

* Behaviour

* Vasoconstriction

Maintaining Thermal Balance in the cold

20

Increased heat production:

*shivering

(Benzinger)

Shivering thermogenesis

21

Non-shivering

Thermogenesis

(Claessens, 2008)

Non-Shivering thermogenesis

22

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

36

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

Applied Thermal Physiology35

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


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


• 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


• 14 males

• 14°C water immersion

• 35.5°C / 170 min


• 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


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.


• 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


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


Cooling during task performance

Two hours of flight

35ºC with and without cooling

Bron: Reffeltrath e.a., 2002


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

*

* *


Pre-cooling

• Eight male subjects

• Four cooling conditions (40 min):

N CC WC CW• Followed by 40 min exercise at 60%

VO2max


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


Pacing strategies

Does it help to adjust the pacing strategy when it is hot?

Tools to pace become more and more popular


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


Applications of thermal physiology

Sports



clothing



Prevention of cold injuries



Thermometry



Labour



Clinical applications


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)


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


Praktical 2016

Forms : - explanation

- informed consent

- score form subject

- score form experiment

- score form (thermal) comfort

Web: http://members.ziggo.nl/daanen/VU


Praktical

Where: TNO Soesterberg

Exclusion: Pregnancy or lactation

Exercise intolerance


Practical

* Please take sport equipment, swimming gear, towel

* Location: Kampweg 5 Soesterberg

* Please be in time – be careful – have fun


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


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

[email protected]

Documents

Faculty of Behavioural and Movement Human Movement Sciencesmembers.ziggo.nl/daanen/vu/vu-college2016.pdf · running. 19 Retain heat: * Behaviour * Vasoconstriction ... • Cardiovascular