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Measuring Physical Activity. Physical activity is difficult to measure as it involves complex motions and provides different physiological stresses. Physical activity ranges from maximal exercise to fidgeting when at rest.

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measuring physical activity
Measuring Physical Activity
  • Physical activity is difficult to measure as it involves complex motions and provides different physiological stresses.
  • Physical activity ranges from maximal exercise to fidgeting when at rest.
  • You need to determine the frequency, intensity and duration of different activities to estimate a person’s daily or weekly physical activity.
  • The most common measure of physical activity is energy expenditure in kilocalories (kcal).
measuring physical activity1
Measuring Physical Activity
  • There is an inverse relationship between the accuracy of measuring physical activity and the ease and affordability of measuring physical activity.
  • Activity measurements using self-reports and activity logs are simple and easy to administer, but provide limited accurate data.
  • Scientific measures using techniques such as indirect calorimetry, and doubly labeled water, can accurately measure energy expenditure, but are expensive and not practical.
measuring physical activity2
Measuring Physical Activity
  • Physical activity is hard to measure as the type and amount of physical activity change from day to day, season to season, year to year.
  • Adults have less variation in their activity patterns compared to children.
  • Physical activity can be estimated using self-reports and activity logs.
  • More objective measures of physical activity include; indirect calorimetry, doubly labeled water, heart rate monitors, activity monitors, pedometers, GPS and direct observation.
measuring physical activity by self reports
Measuring Physical Activity by Self-Reports
  • Self-reports are a frequently used tool to measure the prevalence of physical activity in different populations.
  • Self-report questionnaires require the respondent to recall their activities over a specific time frame (1 day, 1 week, 1 year).
  • Self reports may be administered by:
    • telephone - mail
    • personal interview - computer
    • app
measuring physical activity by self reports1
Measuring Physical Activity by Self-Reports
  • Respondents may be asked to recall leisure time activities, occupational activities, structured exercise or all three.
  • In more detailed self-reports the respondent may be asked to recall the frequency, duration and intensity of each activity.
  • The Harvard Alumni Activity Survey is the best known self-report study.
  • The study is looking at the relationship between physical activity and heart attack.
  • The respondent sends in a report with all of the activity they completed in the last week. The activities are given an energy expenditure and classified based on intensity.
measuring physical activity by self reports2
Measuring Physical Activity by Self-Reports
  • Typical self-report studies ask respondents about their participation in a broad range of activities.
  • They are also asked to record their intensity and time spent doing each activity.
  • Intensity is usually reported as vigorous, moderate, low or sedentary and then converted to METS (the ratio of metabolic rate during an activity to a reference metabolic rate).
  • These 4 categories of activity can be correlated to indices for cardiovascular risk.
  • The researcher then totals the activity duration and intensity for a specific time frame.
  • This information can give an estimation of energy expenditure.
reliability and validity of self reports
Reliability and Validity of Self-Reports
  • Poorly administered self-reports may produce:
    • Inaccurate activity estimates
    • Incorrect conclusions about interventions
    • Inconclusive findings regarding activity and health
  • A good self-report will be:
    • Reliable
    • Valid
    • Sensitive to change
    • Will not influence the respondents behaviour
    • Reasonable administration cost
reliability and validity of self reports1
Reliability and Validity of Self-Reports
  • Even the best self-reports have a considerable amount of error (usually overestimate).
  • Even with the associated error, self-reports are still able to show a strong correlation between physical activity and health.
  • Self reports are very good for determining what proportion of a population is active or inactive.
  • Self-reports are not accurate enough to quantify the optimal amount of physical activity to improve health.
child self reports
Child Self-Reports
  • Self-reports are commonly used with children due to the low cost and convenience.
  • There are several types of child physical activity self-reports:
    • Self-administered recall
    • Interviewer-administered recall
    • Diary
    • Proxy report (parent or teacher reports on activity)
  • The accuracy of the recall depends on a number of factors (age, detail, time, prompts).
child self reports1
Child Self-Reports
  • Should not be used in children younger than 9 yrs.
  • In children between 9 and 15 use caution with self-reports to improve reliability.
  • Adolescents older than 15 will provide results similar in reliability to adults.
  • Recalls of brief periods are always more accurate than recalling activity for an extended time period.
  • Direct observation is the most valid approach.
doubly labeled water
Doubly Labeled Water
  • Ingest a known amount of isotopes of 2H and 18O.
  • Isotopes distribute throughout body.
  • 1 to 3 weeks later energy for the time period can be calculated.
  • Labeled 18O leaves the body as water or as CO2.
  • Loss of CO2 is closely related to O2 consumption and can be used to estimate energy expenditure.
doubly labeled water1
Doubly Labeled Water
  • Gold standard for assessing energy expenditure.
  • Assesses all forms of energy expenditure.
  • Very high validity (less than 3% error).
  • Used in lab or field, and is very safe.
  • The main disadvantage is cost, each dose of 18O costs several hundred dollars.
  • Requires a mass spec.
  • Does not provide info on frequency, intensity and type of activity.
indirect calorimetry
Indirect Calorimetry
  • Measurement of O2 consumption during physical activity.
  • Previously needed to be conducted in a metabolic chamber.
  • Currently there are lightweight oxygen monitors that can allow O2 measurement in the field.
  • Newer O2 monitoring devices are becoming cheaper and more convenient, but it is still a time consuming and expensive process.
activity monitors
Activity Monitors
  • Activity and HR monitors have significant benefits over self-reports, by providing quantitative data on both physical activity and energy expenditure.
  • There are still limitations to these monitors.
  • Accelerometers and pedometers are the most common activity monitors.
  • There are mechanical and electronic models that vary in reliability.
  • The most commonly used activity monitors are accelerometers. Used for both children and adults.
  • Assess vertical movement of the trunk. Usually placed on the hip of the subject.
  • Electrical current proportional to the energy of acceleration.
  • Data reflects volume and intensity.
  • Does not work for all activities (cycling, skating, swimming etc.)
  • Small device that measures the number of steps taken during a given period of time.
  • Very popular and inexpensive (ipod).
  • Motivate people to be more active.
  • Limited to counting steps.
  • Does not provide information on upper body movement, and intensity.
global positioning systems
Global Positioning Systems
  • Use satellites to track the location, direction and speed of subjects.
  • GPS systems are getting cheaper and more readily available (smart phone).
  • Can be used in conjunction with a Heart Rate monitor or accelerometer to analyze intensity and activity patterns.
    • Sport watches
heart rate monitoring
Heart Rate Monitoring
  • HR is highly correlated to O2 consumption.
  • HR can be used to estimate intensity of activity and energy expenditure.
  • To estimate energy expenditure from HR you need to know the individual’s HR / O2 uptake curve.
  • Telemetry HR monitors are very accurate and HR data can be stored for up to 100 hours in some watches.
heart rate monitor limitations
Heart Rate Monitor Limitations
  • Individual variability in maximum HR.
  • Hard to distinguish between light and moderate activity. Other variables may  and  HR.
  • Limited storage capacity.
  • Problems with chest straps.
  • Difficult with children.
  • Electronic interference.
combined activity and hr monitors
Combined Activity and HR Monitors
  • Potential to overcome the limitations of both.
  • Could place activity monitors on different body parts and record HR to get a reasonably accurate measure for a wide range of activities.
  • Future R & D should provide instruments that can quantify the frequency, intensity and duration of different physical activities.
wearable technology
Wearable Technology
  • Watches
    • Garmin, Polar, Nike, Adidas (miCoach)
      • HR, speed, distance, elevation, calories etc.
  • Fitness Trackers - bands
    • FitBit , Nike Fuel band, Spree, Jawbone
      • Steps, calories, sleep, stairs, distance (Apps)
  • Glasses
    • Google Glass, Lumus
    • Head Monitoring Skull Cap - Reebok , Checklight
      • Wear with or without helmet during sports
      • Monitors impacts during activity
wearable technology1
Wearable Technology
  • Clothing - embedded with sensors
    • Smart socks, sensors in the heel and toe that send signals to an ankle bracelet, to measure the force of your foot strike and stride length while running.
    • Vibrado sleeve, accelerators fitted at the biceps, forearm, and hand track your arm’s movements and calculate the arc of your basketball shot.
    • OptimEye, a GPS tracking device you wear on the back of your jersey. It records your every movement.

Quantification of Training

Physiological adaptation to training may be quantified through a number of diagnostic tests.

  • Constant power
  • VO2max
  • Lactate threshold
  • Criterion performance
  • Resting and submax HR

To date there is no formal training theory that quantitatively and accurately prescribes the pattern, duration and intensity of exercise to elicit a specific physiological adaptation.

  • Without accurate quantification of a training dose, the results from training studies to date remain qualitative and argumentative.
  • In order to effectively utilize our knowledge of the health effects of being physically active, you need to understand the health behaviours of the entire population.
  • Descriptive epidemiology attempts to determine the distribution of health behaviours in the total population and in specific groups within the population.
  • Descriptive epidemiology tries to identify the physical activity level of different groups.
  • The demographic characteristics of these groups include; age, gender, ethnicity, socioeconomic status and location of residence.
  • The value of these studies is dependent on the quality of the measures used.
  • Since most of these studies use self-reported data, there is a range of error in all of the statistics reported by these studies.

Good descriptive epidemiology data can provide valuable insight:

  • Estimates the extent to which physical activity is integrated into people’s lives.
  • Estimates how physical activity is distributed throughout the population.
  • Identify less active groups, and provide the information required for intervention strategies for these groups.
  • What are the physical activity trends, and do these trends vary with different groups.
adult activity levels
Adult Activity Levels
  • In the past 25 years there has been a considerable amount of self-reported data collected on leisure time physical activity of adults.
  • This large volume of self-reported data provides a good estimate of the proportions of active and inactive people in the population.
  • This data also allows for estimatesof activity levels in different population groups.
world data lancet july 2012
World DataLancet, July 2012
  • Available data obtained with standardised self-report instruments now provide estimates of physical activity for 122 countries, or two-thirds of the 194 WHO Member States (90% of world population).
world data
World Data
  • Worldwide, 33% of adults do not achieve 30 min of moderate-intensity physical activity on at least 5 days a week.
  • The frequency of inactivity varies greatly between WHO regions, ranging from 17·0% in southeast Asia to about 43% in the Americas and the eastern Mediterranean.
  • 31.4% of adults report vigorous-intensity physical activity on 3 or more days per week.
world data1
World Data
  • A systematic review showed that adults' leisure-time physical activity, including sports participation, has increased in the past 20-30 years in high-income countries.
  • A comprehensive analysis of US data showed that daily energy expenditure in work-related physical activity has decreased.
  • Trend: less activity at work, more activity in leisure time.
world data2
World Data
  • 80% of 13 to 15-year-olds are doing less than 60 min of physical activity per day.
    • moderate to vigorous intensity
international studies
International Studies
  • International studies significantly increase the sample size for data collection.
  • When you compare data from these studies the results are relatively consistent.
  • 25% to 35% of adults in Canada, US, England and Australia can be characterized as sedentary (no physical activity in leisure time).
  • Only 10% to 15% of adults in these countries engage in regular vigorous exercise.
adult activity levels1
Adult Activity Levels
  • This high proportion of sedentary adults is a serious public health concern.
  • Moderate intensity physical activity has some significant health benefits, but is harder to quantify compared to vigorous or sedentary activity.
  • Moderate intensity activity is harder to report because it can be accumulated during the day and is harder to remember compared to vigorous activity.
demographic variations in adult activity levels
Demographic Variations in Adult Activity Levels
  • Men are more active than women.
  • Physical activity decreases with age.
  • Activity increases with increasing levels of education and income.
  • Physical inactivity is more common in countries of high income than in those of low income.

According to statistics, young, educated males are the most likely to be active.

  • There are difficulties in analyzing vigorous activity data from epidemiological studies.
  • Vigorous activity clearly declines with age, but some of this decline is due to the fact that moderate activity for young individuals may be vigorous activity for older individuals.
  • If a relative intensity classification is used, then older individuals do the same, if not more, vigorous activity compared to the younger adults.

A problem with using age-adjusted, relative-intensity, classifications is that lower levels of fitness will increase relative intensity.

  • This relative intensity problem also arises when you compare males to females, due to the lower cardiovascular capacity in females.
physical activity participation by youth
Physical Activity Participation by Youth
  • There is less epidemiological data on youth compared to adults.
  • Research studies show that more than half of Canadian youth are not active enough for optimal growth and development.
  • Canadian girls are less active than boys with only 38% of girls and 48% of boys considered active enough.
physical activity participation by youth1
Physical Activity Participation by Youth
  • There is less epidemiological data on youth compared to adults.
  • Children become less physically active as they age.

Total Daily Energy Expenditure (kcal/kg) (Several Countries)

Age 6 8 10 12 14 16 18

Boys 82 74 75 58 50 44 44

Girls 76 70 58 53 45 42 42


Physical Activity Participation by Youth

  • Boys are more active than girls at all ages.
  • A review of HR data found that boys spend 23% more time being active than girls.
  • Overall physical activity levels drop steeply from ages 13 to 16 in both boys and girls.
intensity differences
Intensity Differences
  • Girls spend more time doing light-intensity activity.
  • Light intensity activity increases from age 13 to 21.
  • Boys and girls report a similar amount of moderate activity, which declines with age.
  • Boys spend much more time doing vigorous activity at age 13 compared to girls.
  • By age 21 both boys and girls do a similar amount of vigorous activity (low level).
  • It is not clear if these trends are due to biology or social influences.
active healthy kids canada
Active Healthy Kids Canada
  • Established in 1994, a national organization with a passionate voice for the development of active healthy children and youth in Canada.
  • Focused on making physical activity a major priority in the everyday lives of Canadian families.
active healthy kids canada1
Active Healthy Kids Canada
  • The 2012 report found that 46% of Canadian children and youth are getting less than 3 hours of active play (unstructured physical activity) each week.
  • Kids are spending 63% of their free time after school and on weekends being sedentary.
  • 92% of Canadian kids said, if given the choice, they would choose to play with friends over watching TV
active healthy kids canada2
Active Healthy Kids Canada
  • The proportion of Canadian kids who play outside after school dropped 14% over the last decade.
  • At lunch and after school, kids are getting only 24 minutes of moderate- to vigorous- intensity physical activity out of a possible 4 hours.
physical activity levels
Physical Activity Levels
  • Only 7% of children and youth are meeting Canada’s guidelines of 60 minutes of physical activity a day
  • It is encouraging to note that 44% of Canadian kids are getting 60 minutes of physical activity on 3 days
organized sport physical activity participation
Organized Sport & Physical Activity Participation
  • 75% of kids aged 5-19 participate in organized physical activities or sport.
  • Kids from higher-income families have a 25% higher participation rate than those from lower-income families.
organized sport physical activity participation1
Organized Sport & Physical Activity Participation
  • Children and youth aged 5 to 17 average 7 hours and 23 minutes of physical activity per week. This is down from 8 hours and 37 minutes per week in 2005.
screen based sedentary behaviour
Screen-Based Sedentary Behaviour
  • Children and youth get an average of 7 hours and 48 minutes of screen time per day.
  • Only 19% of kids aged 10-16 report meeting the Canadian Sedentary Behaviour Guidelines, which recommend no more than 2 hours of recreational screen time per day
active healthy kids canada3
Active Healthy Kids Canada
  • The 2013 report found that 84% of 3- to 4-year-olds meet the Physical Activity Guidelines (180 min/day).
  • 5% of 5- to 17-year-olds meet the CPA Guidelines for Children and Youth of at least 60 minutes of daily moderate- to vigorous-intensity physical activity.
  • 40% of 5- to 17-year-olds in Canada accumulate at least 60 minutes of MVPA at least 3 days per week.
  • Kids are spending 63% of their free time after school and on weekends being sedentary.
reasons for decline in physical activity in youth
Reasons for Decline in Physical Activity in Youth
  • Increase in sedentary activities: smart phones, internet, video games, TV, and socializing.
  • The majority of Canadian children and youth need to make permanent changes to their routine physical activity patterns.
  • Changes can include increased active transportation, engagement in a new sport or activity club, and regular outdoor active play.
  • Children and youth should be encouraged to add bits of physical activity throughout their day: before school, during school, after school, in the evenings and on the weekend.
  • If your child has no free time, consider reducing the number of scheduled activities.
  • Encourage children to spend time outdoors, every day, instead of in front of a TV or video games.
  • Parents should implement household rules on screen time and provide alternative opportunities for active play, sport and physical activity participation.