Methods of Assessing Physical Activity

There are a number of different methods used to asses how well groups and individuals adhere to the physical activity and sedentary behaviour guidelines. To determine which method is the most suitable you must look at whether it is an individual or group you want to analyse as for groups some of the more expensive and time consuming methods may be ruled out. Practicality must also be taken into account this means how easy the method is to use and ability to  interpret the data provided. And finally how reliable is the data from a particular method used.

Recall Surveys/ Diaries

The individual looks back and recalls physical activity levels from one to several days back.
Are considered subjective, as an individual may over or under report their level of physical activity and sedentary behaviour. They may do this to fit in with social expectations this is known as the social desirability bias.
It is also considered to be qualitative when using words and descriptions but it may include a numbered scale of level of exertion which would be considered quantitative.

Advantages:

  • Cheap and easy to use with large groups
  • Low impact on participants
  • Enables the assessment of both domains and dimensions of physical activity
  • Recall surveys are less likely to be reactive as the activity has already been completed

Disadvantages:

  • Participants can over report levels of physical activity
  • Participants may have difficulty recalling information

Suitability:

  • Usually used for large groups.
  • Recall surveys are not suitable for children under 10 and elderly due to troubles with comprehension and recall of information.

Diaries/Logs

Diaries are usually done immediately after the activity is performed or at the end of the day.
Are considered subjective, hence an individual may over or under report their level of physical activity and sedentary behaviour. They may do this to fit in with social expectations this is known as the social desirability bias.
It is also considered to be qualitative when using words and descriptions but it may include a numbered scale of level of exertion which would be considered quantitative.

Advantages:

  • Inexpensive
  • Allows for data collection with references to the context in which the activity was performed.
  • Data is also collected in regards to the dimensions of physical activity.

Disadvantages:

  • Continuous logging of activity can be tedious and lead to mistakes.
  • Tend to be quite reactive as individuals constantly monitor their own activity.

Suitability:

  • Not suitable for young children (below age of 10) and not suitable for elderly.
  • Also tend not to be suitable for large groups as survey’s work better due to standard questions that enable comparison between individuals.

Pedometry

  • Designed to count number of steps.
  • Recommended daily number of steps is 10,000.
  • Can be used to estimate distance walked/ran.
  • Can be used to calculate energy expenditure.
  • Is objective and records quantitative data.

Advantages:

  • Simple and cheap to use.
  • No impact on participants
  • Can act as a motivational tool to encourage physical activity.

Disadvantages:

  • There is some inaccuracy in calculating distance travelled due to differences in stride length.
  • The device itself may accidentally overestimate or underestimate step count.
  • Doesn’t provide any indication of intensity
  • Is likely to be reactive.

Suitability :

  • Suitable for large groups

Accelerometry

  • Assesses the acceleration of the body in certain directions, for example can determine if an individual is jumping.
  • Provides detail in regards to frequency, duration and intensity of physical activity allowing for a more comprehensive view of an individuals activity levels.
  • Detects movement patterns
  • Objective measure and is also quantitative.

Advantages:

  • Can record and relay data in real time, hence no delay and immediate changes to physical activity levels can be made.
  • Low impact on participants
  • Useful to measure activity levels in children as they are a more accurate measure then both surveys or diaries.

Disadvantages:

  • Expensive
  • Requires computer software to run, this can be difficult to use and results can be hard to interpret.

Suitability:

  • Not suitable for large groups.

Direct Observation

  • Involves watching individuals behave in a particular environment such as homes, workplaces, parks or school yards.
  • Provides a comprehensive view of the level of physical activity, providing details of frequency, intensity, type and duration of physical activity.
  • Objective measure and can be either qualitative or quantitative.

There are two types of Direct Observation:
SOPLAY: System for observing play and leisure activity in youth. It is usually used to assess physical activity levels within large groups. It can be used to determine the number of people engaging in physical activity in a particular area and the type of activity being performed.
SOFIT: System for Observing Fitness Instruction Time. It is intended to measure activity levels of school students during physical activity lessons. The context of their physical activity is categorised as management, knowledge, fitness, skill drills, game play and free play in regards to physical activity. The teachers behaviour is also monitored in whether they promote, instruct and observe the performance of physical activity amount their class.

Advantages:

  • Allows for a range of data to be gathered.
  • Particularly useful for measuring physical activity amongst children.
  • Enables for both assessment of physical domains and dimensions.

Disadvantages:

  • Time consuming as to gather complex data multiple periods of observation will have to occur.
  • Likely to be reactive.
  • It is difficult to compare between different observers hence a standardised measure will need to be used and this may require training.

Glossary

Reactivity: To what extent does the tool used influence or change the individuals level of physical activity when compared to their normal levels.
Domains of Physical activity: These are the areas of an individuals life that physical activity can be engaged in and includes leisure time, work/school time and engaging in active transport.
Dimensions of Physical activity: There are four key dimensions of physical activity these include the frequency, intensity, tim(duration) and type of physical activity being undertaken.
Subjective: The data is collected and assessed by the individual themselves.
Objective: The data is collected and assessed by someone other than the participant themselves.
Qualitative: Involves data that is mainly word based and describes the level of physical activity and is not considered solid based evidence.
Quantitative: Involves data that is predominately number based that provides a numerical value to the level of physical activity.