SIST EN ISO 8996:2022
(Main)Ergonomics of the thermal environment - Determination of metabolic rate (ISO 8996:2021)
Ergonomics of the thermal environment - Determination of metabolic rate (ISO 8996:2021)
This document specifies different methods for the determination of metabolic rate in the context of
ergonomics of the thermal working environment. It can also be used for other applications, e.g. the
assessment of working practices, the energetic cost of specific jobs or sport activities and the total
energy cost of an activity. The methods are classified in four levels of increasing accuracy: level 1,
Screening, with a table giving examples of activities with low, moderate and high metabolic rates; level
2, Observation, where the metabolic rate is estimated by a time and motion study; level 3, Analysis,
where the metabolic rate is estimated from heart rate recordings or accelerometers measurements;
and level 4, Expertise, where more sophisticated techniques are described. The procedure to put into
practice these methods is presented and the uncertainties are discussed.
Ergonomie der thermischen Umgebung - Bestimmung des körpereigenen Energieumsatzes (ISO 8996:2021)
Der (körpereigene) Energieumsatz bzw. die körpereigene Energieerzeugung, als Umwandlung von chemischer in mechanische und thermische Energie, ist ein Maß für den Energieaufwand der Muskelarbeit und ermöglicht es, die Tätigkeiten quantitativ abzuschätzen. Der Energieumsatz ist eine wichtige Größe bei der Bestimmung des Wohlbefindens oder der Belastung, die sich durch ein warmes Umgebungsklima ergeben können. Besonders in einem sehr warmen Umgebungsklima wird die Wärmebelastung durch das bei der Muskelarbeit auftretende hohe Maß an körpereigener Wärmeerzeugung erhöht, da große Mengen an Wärme hauptsächlich durch das Verdunsten von Schweiß abgegeben werden müssen. Im Gegensatz dazu unterstützt ein hohes Maß an körpereigener Wärmeerzeugung in einem kaltem Umgebungsklima den Ausgleich übermäßiger Wärmeverluste über die Haut und verringert so die Kältebelastung.
Diese Internationale Norm legt unterschiedliche Verfahren für die Bestimmung des Energieumsatzes im Bereich der Ergonomie der thermischen Arbeitsumgebung fest. Die Internationale Norm kann auch für andere Anwendungsgebiete, zum Beispiel für die Bewertung von Arbeitsverfahren, des Energieaufwands für spezielle Aufgaben oder Sportaktivitäten sowie des Gesamtenergieaufwands einer Tätigkeit usw., angewendet werden.
Die in dieser Internationalen Norm enthaltenen Abschätzungen, Tabellen und anderen Daten beziehen sich auf die allgemeine Arbeitsbevölkerung. Die Anwender sollten in Bezug auf besondere Gruppen, Kinder, ältere Personen, Personen mit Körperbehinderungen usw. entsprechende Korrekturen vornehmen. Persönliche Merkmale, z. B. Körpermasse, können verwendet werden, wenn der Körper durch Laufen oder Steigen bewegt wird (Anhang A und Anhang B). Geschlecht, Alter und Körpermasse sind in Anhang C für die Bestimmung des Energieumsatzes auf Grundlage der Herzfrequenz berücksichtigt.
Ergonomie de l'environnement thermique - Détermination du métabolisme énergétique (ISO 8996:2021)
Le présent document spécifie différentes méthodes visant à déterminer le métabolisme énergétique dans le domaine de l’ergonomie de l’environnement de travail thermique. Il peut cependant être également utilisé en vue d’autres applications, par exemple l’évaluation des pratiques de travail, le coût énergétique de travaux ou d’activités sportives spécifiques et le coût énergétique global d’une activité. Les méthodes sont classées en quatre niveaux de précision croissante: niveau 1, Typologies, avec un tableau donnant des exemples d’activités avec métabolismes énergétiques faibles, modérés et élevés; niveau 2, Observation, où le métabolisme énergétique est estimé par une étude des temps et des mouvements; niveau 3, Analyse, où le métabolisme énergétique est estimé à partir d’enregistrements de la fréquence cardiaque ou de mesures d’accéléromètres; et niveau 4, Expertise, où des techniques plus sophistiquées sont décrites. Le mode opératoire pour mettre en pratique ces méthodes est indiqué et les incertitudes sont examinées.
Ergonomija toplotnega okolja - Ugotavljanje presnovne toplote (ISO 8996:2021)
Ta dokument določa različne metode za ugotavljanje presnovne toplote v kontekstu ergonomije toplotnega delovnega okolja. Primeren je tudi za druge vrste uporabe, npr. ocenjevanje delovnih praks, energetskih stroškov za posamezno delovno mesto ali športno dejavnost in skupnih energetskih stroškov posamezne dejavnosti. Metode so razvrščene v štiri stopnje povečanja natančnosti: stopnja 1 – presejanje, s preglednico primerov dejavnosti z nizko, zmerno in visoko prenosno toploto; stopnja 2 – opazovanje, pri čemer se presnovna toplota oceni na podlagi študije časa in gibanja; stopnja 3 – analiza, pri čemer se presnovna toplota oceni na podlagi zapisov srčnega utripa ali meritev merilnikov pospeška; ter stopnja 4 – strokovno znanje, pri čemer so opisane kompleksnejše tehnike. Predstavljen je postopek uporabe teh metod v praksi in obravnavane so negotovosti v zvezi s tem.
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN ISO 8996:2022
01-maj-2022
Nadomešča:
SIST EN ISO 8996:2005
Ergonomija toplotnega okolja - Ugotavljanje presnovne toplote (ISO 8996:2021)
Ergonomics of the thermal environment - Determination of metabolic rate (ISO
8996:2021)
Ergonomie der thermischen Umgebung - Bestimmung des körpereigenen
Energieumsatzes (ISO 8996:2021)
Ergonomie de l'environnement thermique - Détermination du métabolisme énergétique
(ISO 8996:2021)
Ta slovenski standard je istoveten z: EN ISO 8996:2021
ICS:
13.180 Ergonomija Ergonomics
SIST EN ISO 8996:2022 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
---------------------- Page: 1 ----------------------
SIST EN ISO 8996:2022
---------------------- Page: 2 ----------------------
SIST EN ISO 8996:2022
EN ISO 8996
EUROPEAN STANDARD
NORME EUROPÉENNE
December 2021
EUROPÄISCHE NORM
ICS 13.180 Supersedes EN ISO 8996:2004
English Version
Ergonomics of the thermal environment - Determination
of metabolic rate (ISO 8996:2021)
Ergonomie de l'environnement thermique - Ergonomie der thermischen Umgebung - Bestimmung
Détermination du métabolisme énergétique (ISO des körpereigenen Energieumsatzes (ISO 8996:2021)
8996:2021)
This European Standard was approved by CEN on 3 December 2021.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2021 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 8996:2021 E
worldwide for CEN national Members.
---------------------- Page: 3 ----------------------
SIST EN ISO 8996:2022
EN ISO 8996:2021 (E)
Contents Page
European foreword . 3
2
---------------------- Page: 4 ----------------------
SIST EN ISO 8996:2022
EN ISO 8996:2021 (E)
European foreword
This document (EN ISO 8996:2021) has been prepared by Technical Committee ISO/TC 159
"Ergonomics" in collaboration with Technical Committee CEN/TC 122 “Ergonomics” the secretariat of
which is held by DIN.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by June 2022, and conflicting national standards shall be
withdrawn at the latest by June 2022.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 8996:2004.
Any feedback and questions on this document should be directed to the users’ national standards
body/national committee. A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the
United Kingdom.
Endorsement notice
The text of ISO 8996:2021 has been approved by CEN as EN ISO 8996:2021 without any modification.
3
---------------------- Page: 5 ----------------------
SIST EN ISO 8996:2022
---------------------- Page: 6 ----------------------
SIST EN ISO 8996:2022
INTERNATIONAL ISO
STANDARD 8996
Third edition
2021-12
Ergonomics of the thermal
environment — Determination of
metabolic rate
Ergonomie de l'environnement thermique — Détermination du
métabolisme énergétique
Reference number
ISO 8996:2021(E)
© ISO 2021
---------------------- Page: 7 ----------------------
SIST EN ISO 8996:2022
ISO 8996:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2021
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
© ISO 2021 – All rights reserved
---------------------- Page: 8 ----------------------
SIST EN ISO 8996:2022
ISO 8996:2021(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 The units . 1
5 The four levels of methods for estimating the metabolic rate . 1
6 Level 1, Screening: classification of metabolic rate by categories .3
7 Level 2, Observation .3
7.1 E valuation of metabolic rate for a given activity . 3
7.2 E valuation of the mean metabolic rate over a given period of time . 4
7.3 Accuracy . 4
8 Level 3, Analysis. 4
8.1 E valuation of metabolic rate using heart rate . 4
8.1.1 Principle of the method . 4
8.1.2 Determination of the (HR–M) relationship for purely dynamic muscular
work . 5
8.1.3 E valuation of the metabolic rate as a function of HR in real situations . 6
8.2 E valuation of metabolic rate by accelerometry. 7
9 Level 4, Expertise . 8
9.1 E valuation of metabolic rate by measurement of oxygen consumption rate . 8
9.1.1 Partial and integral method . 8
9.1.2 Evaluation of metabolic rate from oxygen consumption rate. 10
9.1.3 E valuation of oxygen uptake . 11
9.1.4 Calculation of metabolic rate . . 13
9.2 E valuation of metabolic rate by the doubly labelled water method for long term
measurements.13
9.3 E valuation of metabolic rate by direct calorimetry — Principle . 14
Annex A (informative) Evaluation of the metabolic rate at level 1, Screening .15
Annex B (informative) Evaluation of the metabolic rate at level 2, Observation .17
Annex C (informative) Evaluation of the metabolic rate at level 3, Analysis .21
Annex D (informative) Evaluation of the metabolic rate at level 4, Expertise .23
Annex E (normative) Correction of the heart rate measurements for thermal effects .25
Bibliography .27
iii
© ISO 2021 – All rights reserved
---------------------- Page: 9 ----------------------
SIST EN ISO 8996:2022
ISO 8996:2021(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to
the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see
www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 159, Ergonomics, Subcommittee
SC 5, Ergonomics of the physical environment, in collaboration with the European Committee for
Standardization (CEN) Technical Committee CEN/TC 122, Ergonomics, in accordance with the
Agreement on technical cooperation between ISO and CEN (Vienna Agreement).
This third edition cancels and replaces the second edition (ISO 8996:2004), which has been technically
revised.
The main changes to the previous edition are as follows:
— The metabolic rate associated with a given task and estimated using the methods described in this
document is expressed in watts.
— At level 1, Screening, the method classifying metabolic rate according to occupation has been
removed, and revised procedures are provided for the evaluation of metabolic rate for given
activities (level 2, Observation) and when using heart rate (level 3, Analysis).
— The accuracy of the methods for estimating the metabolic rate has been reevaluated in light of
the recent literature and consequently the integral method is no longer recommended at level 4,
Expertise.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
iv
© ISO 2021 – All rights reserved
---------------------- Page: 10 ----------------------
SIST EN ISO 8996:2022
ISO 8996:2021(E)
Introduction
The metabolic rate, as a conversion of chemical into mechanical and thermal energy, measures the
energetic cost of muscular load and gives a quantitative estimate of the activity. Metabolic rate is an
important determinant of the comfort or the strain resulting from exposure to a thermal environment.
In particular, in hot climates, the high levels of metabolic heat production associated with muscular
work aggravate heat stress, as large amounts of heat need to be dissipated, mostly by sweat evaporation.
On the contrary, in cold environments, high levels of metabolic heat production help to compensate for
excessive heat losses through the skin and therefore reduce the cold strain.
The estimations, tables and other data included in this document concern the general working
population. Corrections can be needed when dealing with special populations, including children, aged
persons or people with physical disabilities. Personal characteristics, such as body mass, may be used if
the body is moved due to walking or climbing (Annex B). Gender, age and body mass are considered in
Annex C for the evaluation of the metabolic rate from heart rate.
v
© ISO 2021 – All rights reserved
---------------------- Page: 11 ----------------------
SIST EN ISO 8996:2022
---------------------- Page: 12 ----------------------
SIST EN ISO 8996:2022
INTERNATIONAL STANDARD ISO 8996:2021(E)
Ergonomics of the thermal environment — Determination
of metabolic rate
1 Scope
This document specifies different methods for the determination of metabolic rate in the context of
ergonomics of the thermal working environment. It can also be used for other applications, e.g. the
assessment of working practices, the energetic cost of specific jobs or sport activities and the total
energy cost of an activity. The methods are classified in four levels of increasing accuracy: level 1,
Screening, with a table giving examples of activities with low, moderate and high metabolic rates; level
2, Observation, where the metabolic rate is estimated by a time and motion study; level 3, Analysis,
where the metabolic rate is estimated from heart rate recordings or accelerometers measurements;
and level 4, Expertise, where more sophisticated techniques are described. The procedure to put into
practice these methods is presented and the uncertainties are discussed.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
4 The units
The metabolic rate associated with a given task and estimated using the methods described in this
document shall be expressed in watts.
If the task does not involve displacements, the metabolic rate will not vary as a function of the size and
the weight of the subject. If it involves displacements, then the weight of the person shall be taken into
account (see Annex B).
As the heat associated to this metabolic rate and produced inside the body leaves it essentially through
−2
the skin, thermophysiologists usually express the metabolic rate per unit of body surface area in W⋅m
and the estimations of thermal comfort and thermal constraints described in ISO 7243, ISO 7730,
−2
ISO 7933 and ISO 11079 are done using metabolic rates in W⋅m .
5 The four levels of methods for estimating the metabolic rate
The mechanical efficiency of muscular work – called the ‘useful work’ – is low. In most types of industrial
work, it is so small (a few per cent) that it is assumed to be nil. This means that the energy spent while
working is assumed to be completely transformed into heat. For the purposes of this document, the
metabolic rate is assumed to be equal to the rate of heat production.
Table 1 lists the different approaches presented in this document for determining the metabolic rate.
1
© ISO 2021 – All rights reserved
---------------------- Page: 13 ----------------------
SIST EN ISO 8996:2022
ISO 8996:2021(E)
These approaches are structured following the philosophy exposed in ISO 15265 regarding the
assessment of exposure. Four levels are considered:
— Level 1, Screening: a method simple and easy to use is presented to quickly classify as light, moderate,
high or very high the mean workload according to the kind of activity.
— Level 2, Observation: a time and motion study is presented for people with full knowledge of the
working conditions but without necessarily a training in ergonomics, to characterize, on average, a
working situation at a specific time:
A procedure is described to successively record the activities with time, estimate the metabolic
rate of each activity using formulae and data presented in Annex B and compute the time-weighted
average metabolic rate.
— Level 3, Analysis: one method is addressed to people trained in occupational health and ergonomics
of the thermal environment. The metabolic rate is evaluated from heart rate recordings over a
representative period. This method for the indirect evaluation of metabolic rate is based on its
relationship with heart rate under defined conditions. Another method at this level is based on the
use of accelerometery to record body movement.
— Level 4, Expertise: three methods are presented. They require very specific measurements made by
experts:
— Method 4A: the oxygen consumption measured over short periods (10 min to 20 min);
— Method 4B: the so-called doubly labelled water method aiming at characterizing the average
metabolic rate over much longer periods (1 week to 2 weeks);
— Method 4C: a direct calorimetry method.
Table 1 — Levels for the evaluation of the metabolic rate
Level Method Uncertainty Inspection of the work place
1 Rough information
Classification according to
Not required
activity
Screening Very great risk of error
2 High error risk
Time and motion study Required
Observation Uncertainty: ± 20 %
3A: Heart rate measure-
Medium error risk
3
ment under defined condi-
Study required to determine a rep-
Uncertainty: ± 10 to 15 %
tions
resentative period
Analysis
3B: Accelerometry High risk of error
4A: Measurement of oxygen Errors within the limits of
Time and motion study necessary
consumption the accuracy of the meas-
urement or of the time and
motion study, if assumptions Inspection of work place not re-
4B: Doubly labelled water
(9.1.1, 9.1.4) are met quired, but leisure activities shall
method
4 be evaluated.
Uncertainty: ± 5 %
Expertise
Errors within the limits of
the accuracy of the meas-
Inspection of work place not
urement or of the time and
4C: Direct calorimetry
required.
motion study
Uncertainty: ± 5 %
The uncertainty of each method is provided in Table 1 as coefficient of variation (CV), i.e. the percentage
ratio of the standard deviation to the mean, and should be understood as indicative values, which can
increase due to non-controlled influences discussed as follows. The accuracy at each level is discussed
in describing the methods in Clauses 6 to 9. It increases from level 1 to level 4 and, as far as possible, the
most accurate method should be used.
2
© ISO 2021 – All rights reserved
---------------------- Page: 14 ----------------------
SIST EN ISO 8996:2022
ISO 8996:2021(E)
Attention should be drawn to various sources of variations:
— For a person trained in the activity, the variation is about 5 % under laboratory conditions.
— Under field conditions, i.e. when the activity to be measured is not exactly the same from test to test,
a variation of up to 20 % can be expected.
— In cold conditions, an increase of up to 400 W can be observed when shivering occurs.
— Heavy clothing can also increase the metabolic rate by 20 % or more, by increasing the weight
carried by the subject and decreasing the subject's ease of movement.
The accuracy depends also upon the following:
— The representativeness of the time period observed.
— The possible disturbance of the normal activity by the observer and/or the procedure. In this
regard, the method based on heart rate recordings appears to be one that interferes the least with
the activity.
— The number of measurements: repetition is one method to reduce random measurement error.
2
Based on the CV of an unbiased estimate, the formula (actual CV/requested CV) approximates
the required number of repetitions (Vogt et al., 1976). This implies that in order to achieve a 10 %
uncertainty level, two measurements would be necessary with a method actually providing 14 %,
while four repetitions would be needed with 20 % uncertainty, and nine with 30 %. Of course,
this improvement will only work if no systematic errors are inherent. It is recommended that the
metabolic rate from all the samples is evaluated and the mean value adopted as the metabolic rate
of the condition studied.
6 Level 1, Screening: classification of metabolic rate by categories
The metabolic rate can be estimated approximately using the classification given in Annex A. Table A.1
defines five classes of metabolic rate: resting, low, moderate, high and very high. For each class, a range
of metabolic rate values is given as well as a number of examples. These activities are supposed to
include short rest pauses.
An inspection of the work place is not necessary.
The examples given in Table A.1 illustrate the classification.
As the method provides only a rough estimate of the metabolic rate with considerable possibilities
for error, it should only be used for classification purposes without interpolation between the four
categories.
7 Level 2, Observation
7.1 Evaluation of metabolic rate for a given activity
Annex B gives mean values or formulae for estimating the metabolic rate in watts in the following cases:
— at rest;
— for activities with displacements:
−1
— when walking with or without load at < 6 km⋅h ;
−1
— when running with or without load at ≥ 6 km⋅h ;
3
© ISO 2021 – All rights reserved
---------------------- Page: 15 ----------------------
SIST EN ISO 8996:2022
ISO 8996:2021(E)
— when going up or down stairs and ladders;
— for activities without displacement
— when lifting or lowering loads without displacement;
— from the observation of the body segment involved in the work: both hands, one arm, two arms,
the entire body, taking into account the body posture: sitting, kneeling, crouching, standing,
standing stooped;
7.2 E valuation of the mean metabolic rate over a given period of time
To evaluate the average metabolic rate over a given period of time, it is necessary to carry out a detailed
study of the work. This involves:
— determining the list of activities performed during this period of time;
— estimating the metabolic rate for each of these activities, taking account of their characteristics
and using the data in Annex B, e.g. speed of displacement, heights climbed, weights manipulated,
number of actions carried out;
— determining the time spent at each activity over the whole period of time considered.
The time-weighted average metabolic rate for the time period can then be evaluated using Formula (1):
n
1
M= Mt (1)
ii
∑
T
i=1
where
M is the average metabolic rate for the work cycle, W;
M is the metabolic rate for activity i, W;
i
t is the duration of activity i, min;
i
T is the total duration, min, of the period of time considered, and is equal to the sum of the partial
durations t .
i
The procedure of this time and activity evaluation is further described in Annex B.
The time and duration of the study shall be representative of the activity in all its possible variations:
the duration may be rather short if the work cycle is short and repetitive, and very long when the
activities change permanently.
7.3 Accuracy
The accuracy of the time and activity procedure depends upon the accuracy of the formulas used (see
Annex B), but mostly upon the level of training of the observers and their knowledge of the working
conditions: the possibility for errors is high.
8 Level 3, Analysis
8.1 E valuation of metabolic rate using heart rate
8.1.1 Principle of the method
In the case of pure dynamic work using major muscle groups, with no static muscular, thermal and
mental loads, the metabolic rate may be estimated by measuring the heart rate while working. Under
4
© ISO 2021 – All rights reserved
---------------------- Page: 16 ----------------------
SIST EN ISO 8996:2022
ISO 8996:2021(E)
such conditions, a linear relationship exists between the metabolic rate and the heart rate. If the above-
mentioned restrictions are taken into account, this method can be more accurate than the level 1 and
level 2 methods of evaluation (see Table 1) and is considerably less complex than the methods listed in
level 4. In that case, the relationship between heart rate and metabolic rate is shown in Formula (2):
M = a + b HR (2)
where
M is the metabolic rate, W;
HR is the heart rate measured, beats⋅per min;
a and b are coefficients
The heart rate may be recorded continuously, for example by the use of telemetric equipment, or, with a
reduction in accuracy, measured manually by counting the arterial pulse rate.
The mean heart rate may be computed over fixed time intervals, for example 1 min, over a given period
of time or over the whole shift time.
The accuracy of this estimation of the metabolic rate depends upon:
— the accuracy and validity of the relation in Formula (2);
— the magnitude of the HR components not linked to the dynamic muscular load.
8.1.2 Determination of the (HR–M) relationship for purely dynamic muscular work
The (HR–M) relation can be determined by different methods of decreasing accuracy:
a) The most accurate method consists of recording the heart rate and corresponding oxygen
consumption at different effort levels during a cardiac stress test, for example on an ergometer or
a treadmill in a thermically neutral environment. The (HR−M) relation can be used provided the
durations of the efforts at each level are such that stable HR and oxygen consumption values are
reached.
Studies showed that when the cardiac test consists of manual crank efforts, instead of cycling on
a bicycle or walking on a treadmill the metabolic rate for the same HR value is 23 % to 30 % lower
and the validity of (HR−M) will be limited to activities involving only the upper body and limbs.
Conversely, the (HR–M) relation derived from tests on an ergometer or treadmill will mainly be
valid for activities involving the lower limbs and the entire body.
This method of determination of the (HR–M) relationship is very strenuous and may only be
p
...
SLOVENSKI STANDARD
oSIST prEN ISO 8996:2021
01-januar-2021
Ergonomija toplotnega okolja - Ugotavljanje presnovne toplote (ISO/DIS
8996:2020)
Ergonomics of the thermal environment - Determination of metabolic rate (ISO/DIS
8996:2020)
Ergonomie der thermischen Umgebung - Bestimmung des körpereigenen
Energieumsatzes (ISO/DIS 8996:2020)
Ergonomie de l'environnement thermique - Détermination du métabolisme énergétique
(ISO/DIS 8996:2020)
Ta slovenski standard je istoveten z: prEN ISO 8996
ICS:
13.180 Ergonomija Ergonomics
oSIST prEN ISO 8996:2021 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
---------------------- Page: 1 ----------------------
oSIST prEN ISO 8996:2021
---------------------- Page: 2 ----------------------
oSIST prEN ISO 8996:2021
DRAFT INTERNATIONAL STANDARD
ISO/DIS 8996
ISO/TC 159/SC 5 Secretariat: BSI
Voting begins on: Voting terminates on:
2020-10-26 2021-01-18
Ergonomics of the thermal environment — Determination
of metabolic rate
Ergonomie de l'environnement thermique — Détermination du métabolisme énergétique
ICS: 13.180
THIS DOCUMENT IS A DRAFT CIRCULATED
This document is circulated as received from the committee secretariat.
FOR COMMENT AND APPROVAL. IT IS
THEREFORE SUBJECT TO CHANGE AND MAY
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS
ISO/CEN PARALLEL PROCESSING
BEING ACCEPTABLE FOR INDUSTRIAL,
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
Reference number
NATIONAL REGULATIONS.
ISO/DIS 8996:2020(E)
RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
©
PROVIDE SUPPORTING DOCUMENTATION. ISO 2020
---------------------- Page: 3 ----------------------
oSIST prEN ISO 8996:2021
ISO/DIS 8996:2020(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2020
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved
---------------------- Page: 4 ----------------------
oSIST prEN ISO 8996:2021
ISO/DIS 8996:2020(E)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 The units . 1
5 The 4 levels of methods for estimating the metabolic rate . 2
6 The accuracy of the estimation of the metabolic rate . 3
7 Level 1, Screening: Classification of metabolic rate by categories.4
8 Level 2, Observation . 4
8.1 E valuation of metabolic rate for a given activity . . 4
8.2 E valuation of the mean metabolic rate over a given period of time . 5
9 Level 3, Analysis . 5
9.1 E valuation of metabolic rate using heart rate . 5
9.1.1 Principle of the method . 5
9.1.2 Accuracy of the (HR − M) relationship . 6
9.1.3 Validity of the (HR − M) relationship . 6
9.1.4 HR components not linked to the dynamic muscular load . 7
9.2 E valuation of metabolic rate by accelerometry . 7
10 Level 4, Expertise . 8
10.1 E valuation of metabolic rate by measurement of oxygen consumption rate . 8
10.1.1 Partial and integral method. 8
10.1.2 Evaluation of metabolic rate from oxygen consumption rate .11
10.1.3 Evaluation of oxygen uptake .11
10.1.4 Calculation of metabolic rate.13
10.2 E valuation of metabolic rate by the doubly labelled water method for long term
measurements .13
10.3 E valuation of metabolic rate by direct calorimetry — Principle .14
Annex A (informative) Evaluation of the metabolic rate at level 1, Screening.15
Annex B (informative) Evaluation of the metabolic rate at level 2, Observation .17
Annex C (informative) Evaluation of the metabolic rate at level 3, Analysis .21
Annex D (informative) Evaluation of the metabolic rate at level 4, Expertise .23
Annex E (normative) Correction of the heart rate measurements for thermal effects .25
Annex F (informative) Uncertainties of the integral method .27
Bibliography .29
© ISO 2020 – All rights reserved iii
---------------------- Page: 5 ----------------------
oSIST prEN ISO 8996:2021
ISO/DIS 8996:2020(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following
URL: www .iso .org/ iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 159, Ergonomics, Subcommittee SC 5,
Ergonomics of the physical environment, Work Group WG 1, Ergonomics of the thermal environment.
This third edition cancels and replaces the second edition (ISO 8996:2004), which has been technically
revised.
The main changes compared to the previous edition are as follows:
— The metabolic rate associated with a given task and estimated using the methods described in this
document is expressed in watts.
— At Level 1, Screening, the method classifying metabolic rate according to occupation was removed,
and revised procedures are provided for the evaluation of metabolic rate for given activities (Level
2, Observation), and when using heart rate (Level 3, Analysis).
— The accuracy of the methods for estimating the metabolic rate was re-evaluated in light of the recent
literature, and consequently the integral method is no longer recommended at Level 4, Expertise.
iv © ISO 2020 – All rights reserved
---------------------- Page: 6 ----------------------
oSIST prEN ISO 8996:2021
DRAFT INTERNATIONAL STANDARD ISO/DIS 8996:2020(E)
Ergonomics of the thermal environment — Determination
of metabolic rate
1 Scope
The metabolic rate, as a conversion of chemical into mechanical and thermal energy, measures the
energetic cost of muscular load and gives a quantitative estimate of the activity. Metabolic rate is an
important determinant of the comfort or the strain resulting from exposure to a thermal environment.
In particular, in hot climates, the high levels of metabolic heat production associated with muscular
work aggravate heat stress, as large amounts of heat need to be dissipated, mostly by sweat evaporation.
On the contrary, in cold environments, high levels of metabolic heat production help to compensate for
excessive heat losses through the skin and therefore reduce the cold strain.
This International Standard specifies different methods for the evaluation of metabolic rate in the
context of ergonomics of the thermal working environment. It can also be used for other applications —
for example, the assessment of working practices, energetic cost of specific jobs or sport activities, the
total energy cost of an activity, etc.
The estimations, tables and other data included in this International Standard concern the general
working population. Users should make appropriate corrections when they are dealing with special
populations including children, aged persons, people with physical disabilities, etc. Personal
characteristics, e.g. body mass, may be used if the body is moved due to walking or climbing (Annex A
and B). Gender, age and body mass are considered in Annex C for the evaluation of the metabolic rate
from heart rate.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 9886, Ergonomics — Evaluation of thermal strain by physiological measurements
ISO 13731, Ergonomics of the thermal environment — Vocabulary and symbols
ISO 15265, Ergonomics of the thermal environment — Risk assessment strategy for the prevention of stress
or discomfort in thermal working conditions
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http:// www .electropedia .org/
— ISO Online browsing platform: available at https:// www .iso .org/ obp
4 The units
The metabolic rate associated with a given task and estimated using the methods described in this
document shall be expressed in watts.
© ISO 2020 – All rights reserved 1
---------------------- Page: 7 ----------------------
oSIST prEN ISO 8996:2021
ISO/DIS 8996:2020(E)
If the task does not involve displacements, the metabolic rate will not vary as a function of the size and
the weight of the subject. If it involves displacements, then the weight of the person must be taken into
account (see Annex B).
As the heat associated to this metabolic rate and produced inside the body must leave it essentially
through the skin, thermophysiologists usually express the metabolic rate per unit of body surface
−2
area (in W⋅m ) and the estimations of thermal comfort and thermal constraints described in other
−2
standards of this series are always done using metabolic rates in W⋅m .
5 The 4 levels of methods for estimating the metabolic rate
The mechanical efficiency of muscular work — called the ‘useful work’ — is low. In most types of
industrial work, it is so small (a few percent) that it is assumed to be nil. This means that the energy
spent while working is assumed to be completely transformed into heat. For the purposes of this
International Standard, the metabolic rate is assumed to be equal to the rate of heat production.
Table 1 lists the different approaches presented in this International Standard for determining the
metabolic rate.
These approaches are structured following the philosophy exposed in ISO 15265 regarding the
assessment of exposure. Four levels are considered:
— Level 1, Screening: a method simple and easy to use is presented to quickly classify as light,
moderate, high or very high the mean workload according to the kind of activity.
— Level 2, Observation: a time and motion study is presented for people with full knowledge of the
working conditions but without necessarily a training in ergonomics, to characterize, on average, a
working situation at a specific time:
A procedure is described to successively record the activities with time, estimate the metabolic rate of
each activity using formulas and data presented in Annex B and compute the time weighted average
metabolic rate.
— Level 3, Analysis: one method is addressed to people trained in occupational health and ergonomics
of the thermal environment. The metabolic rate is evaluated from heart rate recordings over a
representative period. This method for the indirect evaluation of metabolic rate is based on the
relationship between oxygen uptake and heart rate under defined conditions. Another method at
this level is based on the use of accelerometry to record body movement.
— Level 4, Expertise: 3 methods are presented. They require very specific measurements made by
experts:
— Method 4A: the oxygen consumption measured over short periods (10 min to 20 min);
— Method 4B: the so-called doubly labelled water method aiming at characterizing the average
metabolic rate over much longer periods (1 to 2 weeks);
— Method 4C: a direct calorimetry method.
2 © ISO 2020 – All rights reserved
---------------------- Page: 8 ----------------------
oSIST prEN ISO 8996:2021
ISO/DIS 8996:2020(E)
Table 1 — Levels for the evaluation of the metabolic rate
Level Method Accuracy Inspection of the work place
1
Classification according to Rough information Very great
Not required
activity risk of error
Screening
2 High error risk
Time and motion study Required
Observation Accuracy: ± 20 %
Medium error risk
3A: Heart rate measurement
3
Study required to determine a rep-
under defined conditions
Accuracy: ± 10 %
resentative period
Analysis
3B: Accelerometry High risk of error
4A: Measurement of oxygen Errors within the limits of
Time and motion study necessary
consumption the accuracy of the measure-
ment or of the time and motion
study, if assumptions (10.1.1, Inspection of work place not re-
4B: Doubly labelled water
10.1.4) are met quired, but leisure activities must
4 method
be evaluated.
Accuracy: ± 5 %
Expertise
Errors within the limits of the
accuracy of the measurement
4C: Direct calorimetry Inspection of work place not required.
or of the time and motion study
Accuracy: ± 5 %
6 The accuracy of the estimation of the metabolic rate
The accuracy of the results are provided in Table 1 as coefficient of variation (CV), i.e. the percentage
ratio of the standard deviation to the mean, and should be understood as indicative values, which might
increase due to non-controlled influences discussed below. The accuracy increases from level 1 to
level 4 and, as far as possible, the most accurate method should be used.
— At level 1, Screening, the method provides only a rough estimate and there is considerable scope
for error. This limits its accuracy considerably. At this level, an inspection of the work place is not
necessary.
— At level 2, Observation, the accuracy of the time and motion study depends upon the accuracy of
the formulas used (see Annex B), but mostly upon the level of training of the observer and his/her
knowledge of the working conditions: the possibility for errors is high.
— At level 3, Analysis,
— the accuracy of the estimated metabolic rate is influenced by the accuracy of the (HR − M ) relationship
used, as other stress factors can influence the heart rate;
— the accuracy level of 10 %–15 % (Malchaire et al. 2017) will only be achieved in field situations
(Rodahl et al. 1974; Dubé et al. 2016), if the (HR − M) relationship is individually calibrated for each
subject during a cardiac stress test with activities that are representative for the type of work under
consideration (cf. 9.1.3), and if the estimates are corrected for the thermal HR component (Annex E)
(Vogt et al. 1973; Kampmann et al. 2001). Otherwise, the error when using (HR − M) relationships
defined for groups (Annex C) will rise dramatically and the accuracy level will fall behind level 2
methods (Bröde and Kampmann 2019);
— the accuracy of the evaluation using accelerometers is highly dependent upon the instruments used
as well as on the type of work, and the method appears to be more appropriate for long term than
short term evaluation.
© ISO 2020 – All rights reserved 3
---------------------- Page: 9 ----------------------
oSIST prEN ISO 8996:2021
ISO/DIS 8996:2020(E)
— At level 4, Expertise, the accuracy is determined as well by the measurement system (gas volume
and oxygen fraction) as by the dynamics of oxygen uptake.
It can be assumed that:
— For a person trained in the activity, the variation is about 5 % under laboratory conditions;
— Under field conditions, i.e. when the activity to be measured is not exactly the same from test to test,
a variation of up to 20 % can be expected;
— In hot conditions, an increase of metabolic rate by 7 % per degree rise in core temperature related
to the Q -effect with typical Q = 2 may be expected. This increase may vary largely between
10 10
different persons with Q values between 1 and 8 (Kampmann and Bröde 2015) and may occur
10
−1
well below an oxygen uptake of 1 l O ⋅min .
2
— In cold conditions, an increase of up to 400 W may be observed when shivering occurs.
— Heavy clothing might also increase the metabolic rate by 20 % or more, by increasing the weight
carried by the subject and decreasing the subject’s ease of movement.
Attention must be drawn to the fact that the accuracy depends also upon:
— the representativeness of the time period observed;
— the possible disturbance of the normal activity by the observer and/or the procedure. In this regard,
the method based on heart rate recordings appears to be one that interferes the least with the
activity;
— the number of measurements: repetition is one method to reduce random measurement error.
2
Based on the CV of an unbiased estimate, the formula (actual CV/requested CV) approximates the
required number of repetitions (Vogt et al. 1976). This implies that in order to achieve the 10 %
accuracy level, two measurements would be necessary with a method actually providing 14 %,
while four repetitions would be needed with 20 % accuracy, and even 9 with 30 %. Of course, this
improvement only will work if no systematic errors are inherent.
7 Level 1, Screening: Classification of metabolic rate by categories
The metabolic rate can be estimated approximately using the classification given in Annex A. Table A.1
defines five classes of metabolic rate: resting, low, moderate, high, very high. For each class, a range of
metabolic rate values is given as well as a number of examples. These activities are supposed to include
short rest pauses. The examples given in Table A.1 illustrate the classification.
As the accuracy of this method is low, it should only be used for classification purposes without
interpolation between the 4 levels.
8 Level 2, Observation
8.1 E valuation of metabolic rate for a given activity
Annex B gives mean values or formulas for estimating the metabolic rate in watts in the following cases:
— At rest;
−1
— When walking with/without load at < 6 km⋅h ;
−1
— When running with/without load at ≥ 6 km⋅h ;
— When going up or down stairs and ladders;
— When lifting or lowering loads without displacement;
4 © ISO 2020 – All rights reserved
---------------------- Page: 10 ----------------------
oSIST prEN ISO 8996:2021
ISO/DIS 8996:2020(E)
— For activities without displacement, from the observation of the body segment involved in the work:
both hands, one arm, two arms, the entire body;
— Taking into account the body posture: sitting, kneeling, crouching, standing, standing stooped;
8.2 E valuation of the mean metabolic rate over a given period of time
To evaluate the average metabolic rate over a given period of time, it is necessary to carry out a detailed
study of the work. This involves:
— Determining the list of activities performed during this period of time;
— Estimating the metabolic rate for each of these activities taking account of their characteristics and
using the data in Annex B: speed of displacement, heights climbed, weights manipulated, number of
actions carried out, etc.;
— Determining the time spent at each activity over the whole period of time considered.
The time weighted average metabolic rate for the time period can then be evaluated using the equation:
n
1
M= Mt (1)
∑ ii
T
i=1
where
M is the average metabolic rate for the work cycle, W;
M is the metabolic rate for activity i, W;
i
t is the duration of activity i, min;
i
T is the total duration, min, of the period of time considered, and is equal to the sum of the partial
durations t .
i
The procedure of this time and activity evaluation is further described in Annex B.
9 Level 3, Analysis
9.1 E valuation of metabolic rate using heart rate
9.1.1 Principle of the method
In the case of dynamic work using major muscle groups, with only a small amount of static muscular
and mental loads, the metabolic rate may be estimated by measuring the heart rate while working.
Under such conditions, a linear relationship exists between the metabolic rate and the heart rate. If the
above mentioned restrictions are taken into account, this method can be more accurate than the level 1
and level 2 methods of evaluation (see Table 1 and Clause 6) and is considerably less complex than the
methods listed at level 4.
The relationship between heart rate and metabolic rate can be written as:
M = a + b HR (2)
where
© ISO 2020 – All rights reserved 5
---------------------- Page: 11 ----------------------
oSIST prEN ISO 8996:2021
ISO/DIS 8996:2020(E)
M is the metabolic rate, W;
−1
HR is the heart rate measured, beats⋅min ;
a and b are coefficients
The heart rate may be recorded continuously, for example by the use of telemetric equipment, or, with a
reduction in accuracy, measured manually by counting the arterial pulse rate.
The mean heart rate may be computed over fixed time intervals, for example 1 min, over a given period
of time or over the whole shift time.
The accuracy of this estimation of the metabolic rate depends upon:
— The accuracy and validity of the relation (2)
— The magnitude of the HR components not linked to the dynamic muscular load
9.1.2 Accuracy of the (HR − M) relationship
The relationship between heart rate and metabolic rate can be determined by different methods of
decreasing accuracy:
— The most accurate method consists of recording the heart rate and corresponding oxygen
consumption at different effort levels during a cardiac stress test, e.g. on an ergometer or a treadmill.
The (HR − M) relation can be used provided the durations of the efforts at each level are such that
stable HR and oxygen consumption values are reached. Such a procedure is very strenuous and is
usually performed in a medical environment.
— A simpler procedure consists of recording the stable heart rate during a few dynamic efforts
whose metabolic rates are known. The accuracy is then reduced as the oxygen consumption is not
measured.
— Expression (3) can be derived from evaluations of:
−1
— the heart rate at rest under neutral thermal conditions, HR , beats⋅min ;
0
— the metabolic rate at rest, M , W;
0
— the maximum working capacity, MWC, W;
−1
— the maximum heart rate HR , beats⋅min ;
max
— the increase in heart rate per unit of metabolic rate: RM = (HR − HR )/(MWC − M )
max 0 0
The (HR − M) relation is then given by:
M = M + (HR − HR)/RM (3)
0 0
The accuracy of this relation is a function of the validity of the measurements or estimations of HR , M ,
0 0
HR and MWC. Annex C proposes formulas for estimating these 4 parameters
max
Table C.1 provides direct evaluations of the (HR − M) relationship for women and men with ages ranging
from 20 years to 65 years and body masses ranging from 50 kg to 110 kg. The precision is then further
reduced.
9.1.3 Validity of the (HR − M) relationship
The question relates to the relevance of the (HR − M) relation directly or indirectly derived from a
cardiac stress test using the great muscular group of the legs, in the event of a work carried out with the
upper limbs. Studies showed that the V during manual crank efforts was 23 % to 30 % lower than
O2max
6 © ISO 2020 – All rights reserved
---------------------- Page: 12 ----------------------
oSIST prEN ISO 8996:2021
ISO/DIS 8996:2020(E)
that measured for the same HR value during a cardiac stress test on bicycle or treadmill. Using that
(HR − M) relation results therefore in an overestimation of the real energy expenditure.
9.1.4 HR components not linked to the dynamic muscular load
The heart rate at a given time may be regarded as the sum of several components:
HR = HR + ∆HR + ∆HR + ∆HR + ∆HR + ∆HR (4)
0 M S th N ε
where
HR is the heart rate, in beats per minute, at rest under neutral thermal conditions;
0
∆HR is the increase in heart rate, in beats per minute, due to dynamic muscular load, under neutral
M
thermal conditions;
∆HR is the increase in heart rate, in beats per minute, due to static muscular work (this component
S
depends on the relationship between the force used and the maximum voluntary force of the
working muscle group);
∆HR is the increase in heart rate, in beats per minute, due to heat stress (the thermal component
th
is discussed in ISO 9886);
∆HR is the increase in heart rate, in beats per minute, due to mental load;
N
∆HR is the change in heart rate, in beats per minute, due to other factors, for example respiratory
ε
effects, circadian rhythms, dehydration.
In the presence of static muscular work, dynamic work with small muscle groups and/or mental loads,
the slope of th
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.