Measurement of Physical Activity
EPHE 348
Why is measurement of PA
Important?
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To specify which aspects are important
To monitor changes
To evaluate interventions
To determine prevalence
To predict with accuracy
Aspects to Measure
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Frequency
Duration
Intensity
Type
Techniques
• Criterion (direct observation)
• Objective (accelerometer)
• Subjective (questionnaire)
Popular Activities
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Walking (65%)
Gardening (41%)
Home Exercise (24%)
Cycling/Swimming (18-19%)
• Strength training (11%)
• Exercise classes (7%)
Key Aspects of Measurement
• Reliability
• Validity
Advantages of Self-Report
• Easy to use
• Inexpensive
• Easy to score
• Can administer quickly
Limitations of Self-Report
• Social desirability
• Memory
• Immediacy/recency
• Familiarity of terminology
Objective Measures
• Heart rate monitors
• Pedometers
• Accelerometers
Example of Accelerometry
PP003_1_Baseline 3/18/07 12:00:00 AM
6000
Hard
Moderate
5000
ACTIVITY
4000
3000
2000
Light
1000
0
TIME
Objective vs. Self-Report
• 83 study systematic review of adolescents and
children (Adamo et al., 2008). Correlations of .56 to .89 between measures and 72% of
studies showed over-estimation with self-report.
• 187 study systematic review of adults (Prince et al.
2008). Correlations of -.71 to .96 between measures (M
= .37). No discernable differences in terms of over or
under-estimation, but estimation was poorest for
vigorous activity.
Issues with self-report
• Response values provided can bias the
measure.
Courneya, K.S., Jones, L.W., Rhodes,
R.E. & Blanchard, C.M. (2004). Effects of
different combinations of intensity
categories on self-reported exercise.
Research Quarterly for Exercise and Sport,
75, 429-433.
Table 4. Percentage of respondents selecting each continuous-closed verbal response by response format and regular exercise
status.
Continuous-Closed Verbal
Response Format (r)
n
never
rarely
occasionally
often
always
Continuous-Open (.77)
<15
15+
77
23
10 (13.0%)
25 (32.5%)
30 (40.0%)
3 (13.0%)
10 (13.0%)
18 (78.3%)
2 (2.6%)
2 (8.7%)
Dichotomous-Yes/No(.70)
<15
15+
71
29
8 (11.3%)
27 (38.0%)
1 ( 3.4%)
30 (42.3%)
1 ( 3.4%)
6 ( 8.5%)
21 (72.4%)
6 (20.7%)
CCN-Low Frequency
<15
15+
(.85)
86
14
7 (8.1%)
30 (34.9%)
32 (37.2%)
1 ( 7.1%)
16 (18.6%)
6 (42.9%)
1 ( 1.2%)
7 (50.0%)
CCN-Medium Frequency (.75)
<15
80
15+
20
9 (11.3%)
30 (37.5%)
1 ( 5.0%)
35 (43.8%)
4 (20.0%)
6 (7.5%)
11 (55.0%)
4 (20.0%)
CCN-High Frequency (.68)
<15
55
15+
45
2 (3.6%)
23 (41.8%)
27 (49.1%)
16 (35.6%)
3 ( 5.5%)
26 (57.8%)
3 (6.7%)
Overall
500
36 (7.2%)
135 (27.0%) 179 (35.8%)
123 (24.6%) 25
(5.0%)
____________________________________________________________________________________________________________
Issues with self-report
• Intensity categories provided can influence accuracy
Courneya, K.S., Jones, L.W., Rhodes,
R.E., & Blanchard, C.M. (2003). Effect of
response scales on self-reported exercise
frequency. American Journal of Health
Behavior, 27, 613-622.
Self-Reported Exercise
Table 1. Means and standard deviations of mild, moderate, strenuous, and total exercise minutes per week by experimental condition.
Mild Minutes
(n=228)
Moderate Minutes
(n=250)
Strenuous Minutes
(n=175)
Total Minutes
(n=432)
Experimental Condition
Mild1 (n=95)
193 (289)b
193 (289)
Moderate1 (n=79)
204 (250)a
Strenuous (n=87)
204 (250)b
198 (240)
198 (240)b
Mild and Moderate1 (n=83) 126 (145)
129 (130)b
Moderate and Strenuous
(n=38)
153 (171)ab
177 (194)
330 (292)ab
80 ( 75)b
156 (206)
414 (322)a
Mild, Moderate, and
Strenuous (n=50)
1
179 (180)
256 (225)b
Participants were asked to report exercise of at least that intensity. Means within a column that have different superscripts are
significantly different from each other (p<.05).
1