Table 1.
Description of study measures
| Measure | Measurement instrument | Instrument description | Reliability and validity |
|---|---|---|---|
| Physical activity (PA) | Godin-Shephard Leisure-Time Physical Activity Questionnaire43 | Requires entry of number of weekly sessions of strenuous (~ 9 METs; eg, running), moderate (~ 5 METs; eg, fast walking), and light (~ 3 METs; eg, easy walking) physical exertion for “more than 15 minutes.” Incorporates METs, or the energy costs associated with specific physical activity intensities (1 MET accelerometer and peak volume of approximates the use of 3.5 ml of O2/kg/minute).44 | Test-retest reliability (2 weeks) was 0.74.45 Construct validity was indicated through strong correlations with both oxygen uptake measurements.46,47 |
| Healthy eating measured by fruit and vegetable intake (FV) | Self-report survey of FV48 | Foods and beverages consumed “in a typical day over the past week” are based on examples and serving sizes of fruits (eg, apple, banana, peach [1 small or 118 mL or 4 ounces canned]; raisins, dates [0.59 mL or 2 ounces]; 100% fruit juice [118 mL or 4 ounces]) and vegetables (eg, broccoli, carrots, tomatoes, green beans [118 mL or 4 ounces]; raw spinach [236 mL or 8 ounces]) that correspond to both the US Department of Agriculture’s current MyPlate and former Food Guide Pyramid.49 Increases in FV were strongly associated with both weight loss and weight-loss maintenance,50 and an increase in FV was a stronger predictor of weight loss than reduction in fat intake.51 Previous research indicates that FV alone is a strong predictor of overall energy consumption and healthfulness of the diet.52,53 | Test-retest reliability (3 weeks) was 0.77–0.83 for women.33 Validated against comprehensive food frequency questionnaires,54 in which pilot research indicated strong correlations (r-values = 0.70–0.85) with the full-length Block Food Frequency Questionnaire.54,55 |
| Self-regulation for exercise (SR-exercise) and self-regulation for controlled eating (SR-eating) | Adaptation of a previously validated scale56,57 | The 10 items for SR-exercise (eg, “I say positive things to myself about being physically active”) and SR-eating (eg, “I make formal agreements with myself regarding my eating”) assess the degree that barriers to those behaviors are addressed through the use of self-regulatory skills. Responses range from 1 (never) to 5 (often), and are summed. A higher score indicates a greater use of self-regulation. | Cronbach α-values for internal consistency were 0.75,56 0.83, and 0.80 for the present versions and sample, respectively. Test-retest reliability (2 weeks) was 0.77.56 |
| Self-efficacy for exercise (SE-exercise) | Exercise Self-Efficacy Scale58 | After beginning with the stem, “I am confident I can participate in regular exercise when ...,” each of the scale’s 5 items end with a possible barrier to overcome (eg, “I am tired,” “I have more enjoyable things to do”). Responses range from 1 (not at all confident) to 7 (very confident), and are summed. A higher score indicates greater self-efficacy | Cronbach α-values for internal consistency were 0.76–0.82. Test-retest reliability (2 weeks) was 0.90.59 Cronbach α-value for internal consistency for the present sample was 0.80. |
| Overall negative mood (Mood) | Profile of Mood States Short Form scale of Total Mood Disturbance60 | The 30 items (5 items per factor) assess feelings during the past week on depression (eg, “sad”), tension/anxiety (eg, “tense”), vigor (eg, “energetic”), fatigue (eg, “weary”), anger (eg, “angry”), and confusion (eg, “forgetful”). Responses range from 0 (not at all) to 4 (extremely) and are summed after reversing the scores of the vigor factor. A lower score indicates better mood. | Cronbach α-values for internal consistency were 0.84–0.95 across factors,60 and 0.79–0.89 for the present sample. Test-retest reliability (3 weeks) averaged 0.69.60 |
| Self-efficacy for controlling eating (SE-eating) | Weight Efficacy Lifestyle Scale61 | The 20 items (4 per factor) assess feelings of ability to control eating when the following situations are present: negative emotions (eg, “I can resist eating when I am anxious [nervous]”), food availability (eg, “I can resist eating even when I am at a party”), physical discomfort (eg, “I can resist eating when I am uncomfortable”), positive activities (eg, “I can resist eating when I am watching TV”), and social pressure (eg, “I can resist eating even when I have to say ‘no’ to others”). Responses range from 0 (not confident) to 9 (very confident), and are summed. A higher score indicates greater self-efficacy. | Cronbach α-values for internal consistency were 0.70–0.90 across its factors,61 and 0.74–0.81 for the present sample. |
MET = metabolic equivalent; TV = television.