Reinforcing value of a behavior refers to the motivation to engage in the behavior. A reinforcing behavior will support more work to obtain the behavior. Individual differences in the reinforcing value of physical activity predict the usual physical activity in children. Another factor that may influence physical activity is liking of physical activity. Liking or hedonics refers to an affective rating associated with the behavior, and people are more likely to engage in physical activities that they like than ones that they do not like. Liking correlates with physical activity in youth. Although the independence of reinforcing value and liking of physical activity has not yet been tested, the motivation to gain access to a behavior and liking for that behavior are likely different constructs. PURPOSE: To determine whether liking and relative reinforcing value (RRV) of physical activity independently predict time youth spend in moderate-to-vigorous physical activity (MVPA). METHODS: Boys (n = 21) and girls (n = 15) age 8 to 12 years were measured for height, weight, aerobic fitness, liking and RRV of physical activity, and minutes in MVPA using accelerometers. RESULTS: Using multiple regression to control for individual differences in age, sex, BMI percentile, aerobic fitness, and time the accelerometer was worn, liking (P < 0.05) and RRV (P < 0.01) of physical activity independently predicted time in MVPA. When using median splits of the RRV and liking data to form subject groups, the group of children with both a high liking and RRV of physical activity participated in greater (P < 0.05) minutes per week of MVPA (1340 + 72 min) than groups with high RRV-low liking (1040 + 95 min), low RRV-high liking (978 + 89 min), or low RRV-low liking (1007 + 70 min) of physical activity. CONCLUSIONS: RRV and liking of MVPA are separate constructs as they independently predict MVPA of children. Those children who find physical activity the most reinforcing and also have a high liking of physical activity engage in 33% more MVPA than children who either find physical activity highly reinforcing or have a high liking of physical activity. Interventions that concurrently increase the reinforcing value and liking of physical activity may be the most effective for increasing youth participation in free-living MVPA. Supported by NIH Grant RO1 HD42766.
This study evaluated the effectiveness of an open-loop system that reinforces physical activity with TV watching to increase children's physical activity. Nonoverweight, sedentary boys and girls (8-12 y) were randomized to a group that received feedback of activity counts + reinforcement for physical activity by providing access to television (F+R, n = 20); or to feedback, no reinforcement (Feedback, n = 20) or no feedback, no reinforcement control (Control, n = 21) groups. Children wore an accelerometer with a count display for 4-months with a 1-year follow-up. F+R reduced TV by 68 min/day and TV time was lower than the Feedback (p < .005) and Control (p < .002) groups. TV time of F+R remained 31 min lower (p < .02) than baseline at 1-year. F+R had a 44% increase in physical activity, which was greater than the feedback (p < .04) and control (p < .01) groups. An open-loop system decreases TV viewing and increases physical activity of children for 4-months. TV of the F+R group remained lower at 12 months, suggesting a reduction in screen-time habits.
Easy access to reinforcing sedentary behaviors competes with increasing and maintaining youth physical activity. Short-term, 6 to 8 week, trials have shown that an open-loop feedback plus reinforcement paradigm where accumulated accelerometer activity counts are exchanged for access to sedentary reinforcers increases children's physical activity. PURPOSE: To evaluate the longer-term effectiveness of open-loop feedback plus reinforcement on children's physical activity and television (TV) time. METHODS: Normal weight boys and girls (8-12 years-old) were randomized to open-loop feedback of physical activity counts plus reinforcement intervention (open-loop, n = 21); feedback, no reinforcement (feedback, n = 20) or no feedback, no reinforcement control (control, n = 21) groups. Subjects wore a Biotrainer accelerometer with an activity count display for 16 wk. Accumulating physical activity counts gave subjects in the open-loop group access to TV time, controlled by a TV Allowance™ device, with 400 counts = 1 h of TV. The feedback group had feedback of activity counts, a goal of 400 counts/day, and free access to TV. The control group had no feedback for activity and free access to TV. RESULTS: The open-loop group (585+41 counts/day) participated in greater (p <0.05) total physical activity during the intervention than the feedback (425+37 counts/day) or control (499+34 counts/day) groups, but their activity peaked at 8 weeks (703+67 counts/day) and returned to feedback and control group levels by week 10. The feedback and control groups did not differ in physical activity. TV time of the open-loop group was reduced by 44% to an average of 87+11 min/day and this was lower (p < 0.005) than the feedback (200+24 min/day) or control (216+28 min/day) groups across the entire intervention. Total sedentary times (e.g., TV, computer, reading) were also lower (p < 0.05) in the open-loop group (134+18 min/day) than the feedback (229+23 min/day) or control (235+29 min/day) groups. CONCLUSION: Open-loop feedback produces a transient increase in physical activity of children that peaks at about 2 mo. The open-loop paradigm successfully reduced television time for 16 wk, which was not fully compensated for by participation in other measured sedentary activities. Supported by NIH grant R01 HD042766 to Dr. Roemmich
Parks may be ideal community resources for promoting youth physical activity. However, there are few data on the activity of children when they visit a park. PURPOSE: To determine the duration of use and intensity of activity when using various park elements and the psychosocial determinants of physical activity when children visit a park. METHODS: Non-obese younger (8-11y, n=21) and older (12-15y, n=26) boys and younger (n=33) and older (n=26) girls from the 1-mile neighborhood around an urban park in Buffalo, NY freely played or rested during a scheduled 1-h park visit with a friend. The starting location and overview of park elements were standardized. Targeted elements within the park were digitized into a GIS map. Behavioral maps were created by placing point location markers and coding the activity type using a tablet-PC observation tool designed to work within GIS. Markers were placed when a child changed location, activity type or intensity. Intensity (METs) was coded using a compendium of children's physical activities and categorized as light (<3 METs) and moderate, hard, and very hard (3 and 4.5 and 6 METs). RESULTS: When covarying for SES, race, zBMI and usual activity, boys engaged in less light (12.3 vs 17.0 min) and greater very hard activity (11.8 vs 4.6 min) and MVPA (46.7 vs 40.5 min) than girls (p<0.05). MVPA decreased with age. There was no difference in hard activity. Younger children (p<0.05) spent more time climbing on play structures, but less time in open spaces and played more active games and had less sedentary time than older youth. Boys (p<0.05) spent greater time in sport and at courts and were less sedentary than girls. Average METs across the 1-h session were predicted by the child believing that there are fun things to do at the park (beta:0.46, p<0.004), and the parent wanting their child to visit the park (beta:0.42, p<0.03) and parental concern that the child would hurt himself/herself at the park (beta:-0.42, p<0.005). CONCLUSIONS: Boys and girls engaged in MVPA for 78% and 68% of the time. Thus, children met the goal of 60 min/day with MVPA making-up most of the time. This occurred with enjoyable unstructured free play. Properly designed parks can be ideal resources for children to meet activity goals. Supported by a Robert Wood Johnson Foundation, Active Living Research grant to Dr. Roemmich.
Purpose: This study was conducted to test the validity of the Pictorial Children's Effort Rating Table (PCERT) and OMNI walk/run scales. Methods: Children (26 boys age 11.2 yr ± 1.6 and 25 girls age 11.1 yr ± 1.4) performed a five-stage incremental exertion treadmill test. The undifferentiated perceived exertion from the PCERT and OMNI scales was assessed for construct validity using Pearson correlations with V̇O2 and heart rate as criteria and concurrent validity by correlating PCERT and OMNI scores. Results: Increases in PCERT and OMNI scale scores were correlated with increases in V̇O2 (r = 0.90 and 0.92) and heart rate (r = 0.89 and 0.92). No difference was found in slope of the PCERT and OMNI scores when regressed against heart rate or V̇O2 and the slopes were invariant across sexes. To test concurrent validity of the PCERT and OMNI scales, subject scores at each stage were converted to a percentage of the maximal scale. No effect of sex was noted on perceived exertion (P = 0.32), and the percentage of the maximal PCERT and OMNI scales was almost identical at each stage (P = 0.73). Conclusions: Validity of both the PCERT and OMNI scales was established for submaximal exercise. PCERT and OMNI scores are not interchangeable because they have different scales, but at a given exercise intensity youth assign similar percentages of the maximal scores.
The relationship between cardiovascular stress reactivity and carotid artery intima-media thickness (IMT) has been established in adults, but not yet studied in children. Cardiovascular reactivity to an ad lib speech was measured in 20 boys and 20 girls age 11.0 +/- 1.4 years. Measures included heart rate (HR), systolic (SBP) and diastolic (DBP) blood pressure reactivity, and mean common carotid artery IMT. Sequential regression analyses were used to establish the incremental increase in R(2) for the prediction of IMT due to cardiovascular reactivity independent of age, socioeconomic status, race, percentage body fat, and baseline BP or HR. SBP reactivity (beta=0.002, , p<.05), but not DBP reactivity (p=.12) or HR reactivity (p=.82), independently predicted carotid artery IMT. This study provides initial evidence that SBP reactivity is associated with IMT and perhaps the early pathogenesis of cardiovascular disease in childhood.
The antecedents of atherosclerosis and CVD occur during childhood. Reactivity to psychological stress may be pathogenic for CVD in that it is associated with the precursors of essential hypertension and left ventricular mass in children. Carotid artery intima-media thickness (IMT) is a valid index of diffuse subclinical atherosclerosis. The relationship between cardiovascular stress reactivity and carotid artery IMT has been established in adults, but not yet studied in children. PURPOSE: To determine whether a child's cardiovascular reactivity to an interpersonal stressor is associated with greater carotid artery IMT. METHODS: Cardiovascular reactivity to an interpersonal stress (ad lib speech) was measured in 20 boys and 20 girls age 11.0 + 1.4 years. Each child was tested on three days; a stress day, non-stress control day, and an IMT measurement day. The order of the stress and non-stress days was counterbalanced across subjects. Measures included heart rate (HR), systolic (SBP) and diastolic (DBP) blood pressure reactivity by an automated monitor, and mean common carotid artery IMT measured by ultrasound imaging. RESULTS: Univariate correlation showed that SBP reactivity was correlated (r=0.40, p<0.05) with carotid artery IMT. DBP and HR reactivity were not significantly (p>0.22) correlated with carotid artery IMT. Sequential regression analyses were used to establish the incremental increase in R2 (R2inc) for the prediction of IMT due to cardiovascular reactivity independent of age, SES, race, percentage body fat, and baseline BP or HR. SBP reactivity (beta = 0.002, R2inc = 0.10, p<0.05) independently predicted carotid artery IMT. DBP reactivity (p>0.12) and HR reactivity (p>0.82) were not predictive of carotid artery IMT. CONCLUSIONS: Youth's cardiovascular reactivity to laboratory-based psychological stressors predicts BP responses to daily stress and is stable over time. Thus, youth who have the greatest BP reactivity to laboratory stressors may be most at risk for developing CVD later in life. SBP reactivity to psychological stress is associated with IMT and perhaps the early pathogenesis of CVD in childhood. Supported by grant RO1 HD42766 to Dr. Roemmich.
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