RESUMO
BACKGROUND: Metabolic carts measure the carbon dioxide (CO2) produced and oxygen consumed by an individual when breathing to assess metabolic fuel usage (carbohydrates versus fats). However, these systems are expensive, time-consuming, and only available in health care laboratory settings. A small handheld device capable of determining metabolic fuel usage via CO2 from exhaled air has been developed. OBJECTIVE: The aim of this study is to evaluate the validity of a novel handheld device (Lumen) for measuring metabolic fuel utilization in healthy young adults. METHODS: Metabolic fuel usage was assessed in healthy participants (n=33; mean age 23.1 years, SD 3.9 years) via respiratory exchange ratio (RER) values obtained from a metabolic cart as well as % CO2 from the Lumen device. Measurements were performed at rest in two conditions: fasting, and after consuming 150 grams of glucose, in order to determine changes in metabolic fuel usage. Reduced major axis regression and simple linear regression were performed to test for agreement between RER and Lumen % CO2. RESULTS: Both RER and Lumen % CO2 significantly increased after glucose intake (P<.001 for both) compared with fasting conditions, by 0.089 and 0.28, respectively. Regression analyses revealed an agreement between the two measurements (F1,63=18.54; P<.001). CONCLUSIONS: This study shows the validity of Lumen for detecting changes in metabolic fuel utilization in a comparable manner with a laboratory standard metabolic cart, providing the ability for real-time metabolic information for users under any circumstances.
RESUMO
Purpose: Given the unequal distribution of physical activity (PA) opportunities across middle schools, alternative options for promoting it should be explored. Faith-based schools are positioned to offer religious-themed PA interventions, yet few have been reported. We replicated previous research by investigating the effects of the Physical Activity for Lent (PAL) program on change in step count (ΔPA) and its associations with religiosity, enjoyment, and motivation (four subscales). Method: Over the 6-week Lenten season, three Catholic middle schools' students (n = 128) participated in a randomly allocated controlled crossover trial of a pedometer-based virtual journey that followed Jesus's life path. We used the Reliable Change Index (RCI), general linear mixed models, and logistic regression to identify changes (pre- to post-Lent) in the independent variables, and their association with ΔPA overall and of being in the highest ΔPA tertile. Results: Between 11.6% (religiosity) and 34.7% (external regulation) of participants' scores changed. School (School 3 > Schools 1 and 2 by ~2,400 steps/day, p < .001) and grade (6th grade > 7th and 8th grades by ~2,500 steps/day, p < .001) - but not religiosity, enjoyment, or motivation - were significant predictors of ΔPA. As RCI for intrinsic motivation and identified regulation increased, students were more (OR = 2.49) and less (OR = 0.74) likely, respectively, to be in the high ΔPA tertile. Conclusion: Desirable ΔPA was situational (i.e., school, grade) and highest ΔPA tertile was associated with autonomous motivation. Faith-based PA interventions may need to include additional components to realize even greater gains.
