Table 2 Integration of theoretical concepts and measurement procedures

Built and Natural Physical Environment

Walkability (connectivity, density, mixed-use), Perceived Attributes

• Geographical Information Systems (ArcGIS 10): 0.5 mile road network buffer for each geocoded address; walkability index based on street connectivity, residential density, and land use mix [80, 81]

• Walkscore [82]

• Neighborhood Environment Walkability Scale [83]

PA Settings and Resources: Number, Attributes, Homogeneity

• Convenient PA facilities questionnaire [84]

• Home exercise equipment questionnaire [84]

• Settings where PA was done (adapted scale) [85]

Population Attributes

Population Number and Density

• Census data

Population Individual Attributes

• Background characteristics questionnaire

Population Homogeneity

• Degree of similarity on selected characteristics between each participant and other participants by each recruitment cohort [86]

Interaction Mode

Use of Interaction Modes for Walking and Physical Activity

• Self-reported use of different communication modes (online, phone, in-person) to organize walking and PA*

• WalkLink+ group only: objective monitoring of frequency and types of activities conducted (e.g., posting walks, contributing to discussions) on online WalkLink site

Access and Use of Interaction Modes in General

• Self-reported ownership and use of cell phones to receive email*

• Self-reported use of Facebook, Twitter, and MySpace*

Social Network Centrality

In-Person Connections

• Self-reported number of different companions for walking and PA*

• Self-reported number of friends/family members participating in this program*

Online Connections

• WalkLink+ Group only: objective monitoring of number of “friends” on online WalkLink site

Social Network Relational Attributes

Physical Proximity

• Self-reported geographical proximity to existing walking and PA companions*

Network Relationship Roles

• Self-reported types of relationships (e.g., friend, family member) with existing walking and PA companions*

Social Network Functions: Behavioral

Resources, Assistance, Companionship, Encouragement, Praise

• Social support for walking and PA scales [87]

• Participant actions to prompt walking and PA scale*

Modeling/Norms

• Modeling and social norms for walking and PA scale*

Behavioral Monitoring and Refinement

• Goal setting and planning for walking scales (adapted) [74]

Social Network Functions: Perceived

Physiological Exertion

• Borg rating of perceived exertion immediately after each walk [88]

Emotional States/Enjoyment

• Rating of overall feeling/emotions immediately after each walk [14]

• Walking enjoyment (adapted scale) [89]

Perceived Benefits and Costs

• Proximal outcome expectations (adapted scale)* [14, 74]

Physical Activity

Sedentary Behavior, and Light, Moderate, and Vigorous PA

• Actigraph GT3X triaxial accelerometer, worn for 7 days, data stored as 1-min averages [90, 91]

Walking Activity

• Pedometer (Yamax SW-200), stopwatch, and weekly walking logs reporting walking steps and speed [92, 93]

• National Health Interview Survey (2 items) [94]

PA in Different Life Domains, Sedentary Behavior

• International PA Questionnaire, long version [95]

PA Modes (different types of PA)

• Aerobics Center Longitudinal PA Questionnaire [96]

Health Outcomes

Aerobic Fitness

• Submaximal treadmill test: submaximal heart rate (measured by Polar heart rate monitor) during test [97]

• Submaximal treadmill test: estimated VO₂max [97]

Vitals

• Pulse: calibrated hospital-grade Welch Allyn device [98]

• Blood pressure: calibrated hospital-grade Welch Allyn device [98]

Body Composition

• Body mass index: Physician’s balance beam scale (model Detecto 439) and calibrated Seca 242 digital stadiometer [97]

• Waist circumference: Gulick II tape measure [97]

Sleep Quantity and Quality

• Pittsburgh Sleep Quality Index [99]

• Exposure to ambient noise during sleep scale*

Intervention Fidelity

Participation[100]

• Return rate for weekly walking logs

• Attendance rate at program-organized walks for WalkLink+ group

• Activities on online social networking site for WalkLink+ group

Intervention Receipt and Satisfaction[100]

• Program evaluation survey: qualitative and quantitative assessment*

Change in Theoretical Mediators

• Degree to which theoretical mediators (listed above) changed in hypothesized direction for each of the intervention groups

Intervention Delivery and Quality Control

• Program records, weekly meetings, staff training, walking feedback double-checked each week and 10% of feedback reviewed by PI, double-verification of manually entered data, participants recontacted for missing data, multiple sources of contact information obtained for each participant