BackgroundParticipation in aerobic exercise generates increased cardiorespiratory fitness, which results in a protective factor for cardiovascular disease and all-cause mortality. High-intensity interval training might cause higher increases in cardiorespiratory fitness in comparison with moderate-intensity continuous training; nevertheless, current evidence is not conclusive. To our knowledge, this is the first study to test the effect of high-intensity interval training with total load duration of 7.5 min per session.MethodsA randomized controlled trial will be performed on two groups of healthy, sedentary male volunteers (n = 44). The study protocol will include 24 exercise sessions, three times a week, including aerobic training on a treadmill and strength training exercises. The intervention group will perform 15 bouts of 30 s, each at an intensity between 90 % and 95 % of maximal heart rate. The control group will complete 40 min of continuous exercise, ranging between 65 % and 75 % of maximal heart rate. The primary outcome measure to be evaluated will be maximal oxygen uptake (VO2max), and systolic and diastolic blood pressure will be evaluated as secondary outcome measures. Waist circumference, body mass index, and body composition will also be evaluated.DiscussionEpidemiological evidence shows the link between VO2max and its association with chronic conditions that trigger CVD. Therefore, finding ways to improve VO2max and reduce blood pressure it is of vital importance to public health.Trial registrationNCT02288403. Registered on 4 November 2014.

Introduction: Aerobic exercise generates increased cardiorespiratory fitness, which results in a protective factor for cardiovascular disease. High-intensity interval training (HIIT) might produce higher increases on cardiorespiratory fitness in comparison with moderate-intensity continuous training (MICT); however, current evidence is not conclusive.Objective: To compare the effects of a low-volume HIIT and a MICT on maximal oxygen consumption (VO2max), systolic blood pressure, and diastolic blood pressure during eight weeks in healthy men between 18 and 44 years of age.Materials and methods: We conducted a randomized controlled trial. Forty-four volunteers were randomized to HIIT (n=22) or MICT (n=22). Both groups performed 24 sessions on a treadmill. The HIIT group completed 15 bouts of 30 seconds (90-95%, maximal heart rate, HRmax), while the MICT group completed 40 minutes of continuous exercise (65-75% HRmax). Results: Intra-group analysis showed an increase in VO2max of 3.5 ml/kg/min [95% confidence interval (CI) 2.02 to 4.93; p=0.0001] in HIIT and 1.9 ml/kg/min (95% CI -0.98 to 4.82; p=0.18) in MICT. However, the difference between the two groups was not statistically significant (1.01 ml/kg/min. 95% CI -2.16 to 4.18, p=0.52). MICT generated a greater reduction in systolic blood pressure compared to HIIT (median 8 mm Hg; p<0.001). No statistically significant differences were found between the groups for DBP.Conclusions: Results indicated no significant change in VO2max with a low-volume HIIT protocol versus MICT after 24 sessions. In contrast, MICT provided a greater reduction in systolic blood pressure compared to HIIT. The study is registered as a clinical trial via clinicaltrials.gov with identifier number: NCT02288403.

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Este estudio se planteó como objetivos determinar los niveles y los estados de cambio frente a la actividad física en la comunidad universitaria del campus “Ciudadela de Robledo” de la Universidad de Antioquia, Medellín, Colombia. Participaron de manera voluntaria 92 estudiantes, 72 docentes y 45 emplea- dos; utilizando un muestreo aleatorio simple para cada grupo. Se empleó el Cuestionario Global de Actividad Física (GPAQ) para identificar los niveles de actividad física, y el Sample Physical Activity Questionnaire para los estados de cambio; las encuestas fueron recolectadas durante el segundo semestre del año 2012. Se manejó el programa estadístico SPSS versión 21 para el análisis de los datos, utilizando técnicas de distribución de frecuencias para realizar el análisis descriptivo; las variables cualitativas fueron analizadas de acuerdo al vínculo con la universidad y al sexo, utilizando la prueba de X2 para comparar las proporciones. Pudo identificarse que el 51,1% de los estudiantes, el 48,6% de los docentes y el 46,7% de los empleados presentan niveles altos de AF. La mayor proporción encontrada para los estados de cambio de acuerdo al vín- culo, la obtuvo el estado de mantenimiento, 47,2% para los docentes, 28,9% para los empleados y 26,1% para los estudiantes. Los resultados del presente estudio podrían servir como insumos para la creación de estrategias que per- mitan mejorar los programas deportivos y de AF del campus universitario, y busquen incrementar los niveles de AF de la población. 

Introduction: The understanding of socialization processes during youth and their relationship with healthy behaviors are crucial for university education. Objective: To explore the associations of the characteristics of the social network of friends with being physically active and with sedentary behavior in university students. Materials and methods: Cross-sectional study, based on a social network analysis, conducted in a sample of 475 university students. Measurements included sociodemographic, physical activity, sedentary behavior, and social network variables. The associations of social network traits with physical activity and sedentary behavior were explored by logistic regression models. Confidence intervals (95%) were estimated and a significance level of p<0.05 was considered. Results: In women, being part of at least a cluster of friends was significantly associated with being physically active (adjusted OR 2.3; 95%CI: 1.2-4.6), and having high popularity was significantly associated with a lower probability of being physically active (adjusted OR 0.3; 95%CI: 0.1-0.7). Also, an increment of ten percentage points of active friends was significantly associated with a higher probability of being physically active (adjusted OR: 9.3; 95%CI: 3.5-24.6). Regarding sedentary behavior, in women, an increase of ten percentage points in the number of sedentary friends was significantly associated with a higher probability of being sedentary (adjusted OR: 5.5; 95%CI 2.5-12.3). In men, none of the studied associations were statistically significant. Conclusion: Some social network features are relevant for female university students in relation to their physical activity levels and sedentary behaviors. Findings highlight the need to consider social network dynamics for designing initiatives aimed at physical activity promotion and sedentary behavior reduction.