ASSESSMENT OF PHYSICAL ACTIVITY

IN NUTRITIONAL EPIDEMIOLOGY

Present by:Sajjad Moradi

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Present by:Sajjad Moradi-MS Student

Department of Community Nutrition, School of Nutritional Sciences and Dietetics, Tehran

University of Medical Sciences (TUMS), Tehran, Iran

Why is physical activity important?

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Introduction

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Energy expenditure Control for confounder

factor in dietary associations

Special Features

Complex behavior Strong parallels with

assessment dietary composition

TERMINOLOGIES AND DEFINITION

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Terminologies and definition

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What is physical activity?any body movement produced by muscle skeletal calorie expenditure

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Terminologies and definition

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What is Exercise? planned or

structured physical activity

Target

What is physical fitness?a set of attributes that people have or achieve ability to perform physical activity

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Terminologies and definition

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physical activity VS physical fitness physical activity is behavior

physical fitness is functional attribute

What is physical inactivity?

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Terminologies and definition

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not engaging in any regular pattern of physical activity

bodily movement is minimalSuch as:

•Watching television•Reading•Working on computer

Measurement of physical activity type intensity

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Measurem

ent of physical activity

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physical activity categories :• Occupational• Transportation• Household• Leisure-time

Exercise categories :

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Aerobic (with oxygen)→continues motion→ walking , hiking, running, cycling, rowing, swimming , skating

Resistant training (without oxygen)→ weight lifting→ use to increase muscular size and strength

Measurem

ent of physical activity

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physical activity intensityAbsoluteRelative

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Absolute intensity:•Metabolic equivalent tasks(METs)• Oxygen consumption• Rate of energy expenditure• 1MET =3.5ml/kg/min or 1ml/kg/h

Levels of MET:•Light-intensity 3>MET•Moderate-intensity 3 <MET<6•Vigorous-intensity MET>6

Measurem

ent of physical activity

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Measurem

ent of physical activity

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Measurem

ent of physical activity

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Measurem

ent of physical activity

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Measurem

ent of physical activity

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تکراردر 3) بار

(هفته

زمان(2

(ساعتبدن وزن

(کیلوگرم70)

زمان مدتکل

ساعت 6هفته در

METشدت ) 5(× ××

شده مصرف انرژی30 MET/h/Week30 Kcal/Kg/W

2100 Kcal

Relative intensity: The relative percentage of maximal aerobic power that is maintained during exerciseOxygen uptake(VO2 MAX) → maximum amount of oxygen uptake in milliliters (minute/kg body Weight) during exercise

Maximum heart rat(HR MAX) → linear relationship between increase in oxygen uptake and increase in heart rateRating of Perceived Exertion(RPE) → based on scale from 6 to 20

Physical Activity Ratio (PAR) → energy expend in activity /BMR for selected time unitPhysical Activity level(PAL) → TEE/BEE for 24h

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Measurem

ent of physical activity

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Physical activity assessment methodsEnergy expenditure Physical Activity level(PAL) Physical fitness

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Physical activity assessment

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Reference measures of energy expenditure

Physical activity assessment

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Doubly Labeled Water(DLW)

Indirect calorimetry

Motion sensors

Doubly Labeled Water(DLW)• Free-living subject• Oral administration of weighted water • Isotopes deuterium (2H) and oxygen-18(18O)• Highly accurate and reference method• expensive and time consuming

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Physical activity assessment

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Physical activity assessment

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Indirect calorimetry• Advance gas exchange (safer and easier)

• Face mask• Short time• Oxygen uptake• Carbon dioxide production•Highly accurate

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Motion sensors for physical activity assessment

Physical activity assessment

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Accelerometers Pedometer

Physical activity assessment

Taster Accelerometers• Frequency• Duration• Intensity

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• Reliability→ higher dynamic activity :running, walking• Strong correlation → criterion measures: DLW and oxygen uptake• Aquatic activities → cannot usually capture energy expenditure

Physical activity assessment

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Disadvantage: large number participants, Cannot guarantee accurate monitor placement on participants during long, Lack of field base equations to accurately estimate energy expenditure ,Inaccurate assessment of a large rang of activity SAJJAD MORADI 22

• Advantage: portable, light weight, non invasive and allow for extended period of recording without interfering in usual activity, remove of shelf report errors, provide minute by minute Information, ease data collection and analysis

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Physical activity assessment

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Physical activity assessment

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Accelerometers usage:• Track physical activity• Validating physical activity

questionnaire• Validation studies in both adult

and children• Evaluate intervention programs• Monitor adherence• large scale epidemiology studies

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Physical activity assessment

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•Measures steps in walking or running• walking speed high accuracy→ ambulatory activates low accuracy→ slow walking

• Inverse correlation → Over weight• Positive correlation → Fitness

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Physical activity assessment

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Disadvantage: inability to store data,possibility of participant tempering, are specifically designed to asses walking only

Advantage: inexpensive, noninvasive, potential for use in verity of setting(work pleases and schools), easy administer to large group, objective measure of common activity behavior

Physical fitness:

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• Heart rate• VO2 max

Aerobic fitness or cardiorespiratory fitness•Habitual physical fitness• Sex•Age•Genetics•Medical status

Physical activity assessment

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Golden standard measure of cardiorespiratory fitnessor exercise capacity:

•VO2 MAX→ maximum volume of oxygen that muscle can use While performing dynamic exercise

• Inverse association with cardiovascular disease and mortality

cardiorespiratory fitness rapid assessment:•Coopers 12 minute run• Step test• 2Km walk test• 20 minute shuttle run

Physical activity assessment

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Heart rate monitor

Advantage: easy and quick for data collection and analyses , good association with energy expenditure, low participant burden for limited recording periods

Describes:•Frequency• Duration• Intensity

Physical activity assessment

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Disadvantage:•Financial cost prohibit assessment of large number participants

• Stress changes heart rate

• Useful only for aerobic activities

• Heart rate characteristics and training state

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Physical activity assessment

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Physical activity assessment

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SELF REPORT METHODS

Self report methods

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Recording → Shortly after completion

Reference method Electric diary

system

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Self report methods

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Calibration physical activity question

• Type• Duration• Intensity

All physical activity performed in a day

• Short term• Long term

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Self report methods

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Short term recall Analogous to 24 hour diet recalls Time frames → 24 hour to 1 mount

Stanford seven day physical activity:•Moderate or vigorous exercise• work related• walking•Gardening• required to chapter long term

Disadvantage:•Tim consuming•Cognitive ability to recall• participants cooperation

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Self report methods

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Questionnaires are designed to elicit information:• Type• Average frequency• Duration• Intensity SAJJAD MORADI 36

Self report methods

Taster Habitual physical activity questionnaires Analogous to FFQS→ typically shorter than FFQS

Objective→ measurement of long term patterns Formats→ semi quantitative response categories Time frames→ several mount to one year Total energy expenditure calculate

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Self report methods

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Self report methods

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Advantage: assessing average long term activity pattern, inexpensive, low burden on participant

Disadvantage: cognitive challenge, random and systematic errors, participant tend to over report physical activity and under report sedentary behavior

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Validation

Taster Validation studies of physical activity questionnairesLack of true golden standard

DLW Indirect calorimetry Accelerometers Fitness measure• Heart rate• VO2 max

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Validation

Taster Validation studies of Habitual physical activity questionnairesPhysical activity diaries or records

• Advantage: actual behaviors, providing detailed information on multiple dimensions of physical activity

• disadvantage: not represent usual activity pattern, reporting biases, high burden on participant, many days of recording

In general: Validation studies→ low to moderate validityNot can capture all dimensions of physical activity non of the reference measure of physical activity are perfect

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Validation

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Random• Within-person variability tend to underestimate the strength of association between physical activity and health outcomesSystematic• Over and under reporting• Instrument tampering and defects• Recall bias

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Measurement error correctionAnalytic issues

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Dietary and other life style factors

Chorionic disease (revers causation)→ decline in physical activity• Heart disease

• Pulmonary disease

• Cancer

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Analytic issues

Taster Confounding and reverse causation

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Analytic issues

Taster Isotemporal analysisAnalogous energy substitution modelsTotal amount of time spent on physical activity Increasing time spend on one→ decreasing time in another Estimates replacing one type of activity by the same time in another is association with health outcomes

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Analytic issues

Taster Isotemporal analysis Weight change= (b1) slow walking

+(b2) brisk walking +(b3)jogging/running +(b4) other activates

+(b5)total activity +(b6) covariates

b1 to b6 → coefficients of respective activities or covariates

Isotemporal analysis Health effects of each physical activity type on body weightAdvantage: directly compare effect of different types of activity and different intensities of same activity and the effect of physical activity versus in inactivity practical recommendation on choice of physical activityDisadvantage: time in the isotemporal model reflected of activity component not included in the model→multicollinearity problem, not consider sleep duration

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Analytic issues

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THANK YOU FORYOUR ATTENTION