Effect of a Multicomponent Intervention in Children and Adolescents

Study design

This quasi-experimental pilot study is part of a research study called "ACTION FOR HEALTH (Adolescents and Children in a Training InterventiON FOR HEALTH)", developed with youth of both gender (7-15 year-olds). It is a multicomponent intervention program to promote PA classes and nutrition education, and based on the behavior change Ecological Model. This information is hypothesis of the study.

ACTION FOR HEALTH study was approved by the Ethics Committee of the Center of Health Sciences of Federal University of Paraíba- Brazil (UFPB). The parents of the participants signed out a consent term.

Study sample The project was announced in public and private schools of João Pessoa (Brazil), as well as through print (newspapers) and electronic (social network) media. 59 youth volunteered, and 43 children and adolescents (7-13 year-olds) met the eligibility criteria. 8 of them did not complete all the study protocol.

So, 35 comprised the sample and did all the evaluation protocol. Participants were divided in two groups: the intervention group (INT, n = 17, 7 boys) who attended at least 75% of PA classes and met more than 50% of food goals; and the control one (CONT, n = 18, 6 boys), with a minimum or less than 49% attendance in PA classes, and were not involved in the nutrition education program.

Methodologies study and preparation of the intervention The program was developed by 4 teachers, 7 graduate students, 1 nutritionist, 2 graduate Nutrition students, and 1 cardiologist, and participated in weekly meetings where methodologies and intervention sessions were prepared and tested. During this test period, activities that would promote greater adherence of students were listed. Additionally, participants randomly used a heart rate monitor (Polar Team2 Pro, Polar, Finland) and an accelerometer (Actigraph, GT3X model), in order to record activities that promoted more significant increases in heart rate and in moderate and vigorous PA intensities.

Physical exercise intervention The exercise sessions took 90 minutes, in order to assure at least 60 minutes of physical exercise, during 12 weeks. The sessions were always taught by the same staff, and were composed of: 10 minutes of warm-up; 30 minutes of circuit training; 15-minute of pre-sports and recreational games;and 5 minutes resting activities.

Warm-up included aerobic/anaerobic and recreational activities. The circuit, divided into 6 stations, included activities that prioritized conditional and/or coordinative physical capacities, accordingly with the purpose of the proposed session for the day, so that participants could maintain a high intensity throughout the circuit.

In the first month, the duration of each circuit station was 30 seconds, which was increased to 45 seconds and 60 seconds, in the second and third month, respectively. The transition time between each station was kept in 30 seconds throughout the intervention. Finally, low-heart rate activities were carried out, with games to music and stretching.

The intensity of the training sessions was defined in a heart rate (HR) average over 65% of maximum heart rate of each participant.

Nutritional education intervention The dietary intervention, designed by the nutritionist staff, consisted of two actions. The first was trough monthly events throughout the intervention, one in the beginning of each month, with participation of participants' parents. The second action consisted on the achievement of 3 dietary goals (an easy, an average and hard goal) to which children and adolescents should meet during the months of intervention. These goals were added during the intervention, so that the beginning of the 1st month of intervention participants had three goals to meet, and at the beginning of the 3rd month, 9 goals. They also received a worksheet to record if they met the minimum (1 star), average (2 stars) and maximum (3 stars) of the daily goal.

Parental support Simultaneously, exercise sessions were offered to parents in order to encourage family participation in the intervention performed with children and adolescents. The activities were carried out by a volunteer PA teacher in the center of sports of UFPB.

Study variables Sexual maturation Each participant self-assessed their own stage of secondary sexual characteristics: breast development stage in women and pubic hair in males (TANNER, 1962). The correlation between self-assessment of sexual maturity state and evaluation performed by the parent was 78% for female and 90% male. This variable was used as confounder in the statistical procedures.

Anthropometric measure Height, determined by a stadiometer "Holtain", followed the standard procedure of Lohman (1988). Two measurements were performed, recorded in meters to the nearest millimeter, and was considered the arithmetic mean of the two measurements. Body composition was measured after 4-hour-fasting and low water intake, and then, a bioimpedance scale was used (Inbody 720, Biospace Co., Ltd.) to determine body weight and fat mass.

Metabolic variables Blood samples from the participants were collected after a nocturnal 12 hour-fasting, by laboratory specialists, through peripheral puncture in the cubital vein. The analysis of CT, HDL-C, triglyceride, and glucose was carried out by spectrophotometry (Cobas Integra 400 Plus) with Roche® kits. The LDL-C fraction was indirectly calculated using the Friedewald formula (1972). The aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels were determined by enzyme kinetic assay for spectrophotometrically obtained after centrifugation 10 minutes / 3500 rpm. Insulin was determined by Luminex-100 IS (Integrated System: Luminex Corporation, Austin, TX, USA), using the Linco Human Gut Hormone panel kit (Linco Research Inc., MO, USA). The insulin resistance was determined by HOMA-IR.

Physical activity and sedentary behavior PA was measured by accelerometer (Actigraph, GT3X model, Florida). The participants used an accelerometer for 10 consecutive days, and they also received instructions for the correct use of the device. At the time of explanation and visual demonstration of the proper use of the device, participants received a list of instructions, along with a diary of activities in which they were required to record wear and non-wear time of the instrument, and also habitual physical activities.

Data reduction was performed by Actlife software, version 6.11.7. For the validation data, at least 4 days of recording at least 8 hours per day (480 minutes / day) were considered 40. Of these 4 days, 2 days corresponded to the intervention and 2 without intervention (1 weekend day). The time of non-use was estimated based on periods of more than 20 consecutive minutes of zero. For data download, 15 seconds epochs were performed, based on recommendations to similar populations. The useful and non-time has been determined according to Troiano (2007). The cutoff points for determining the time spent on different intensities of PA followed the standards proposed by Evenson et al (2008). To determine time spent for physical activity /week in each of the intensities was necessary to perform a calculation to generate weighted averages in minutes / day, of PA intensities. Time spent in moderate-to-vigorous physical activity corresponded to the sum of moderate physical activity (AFM) and vigorous physical activity (AFV) values.

Health related Physical Fitness Health related Physical Fitness components were evaluated from different tests of Fitnessgram battery test (1999) and ALPHA battery test, which those protocols were performed internationally for similar populations. Thus, cardiorespiratory fitness (CRF) was measured using the test-run Suttle 20 m. The test was complete when the participant failed to reach the final lines simultaneously with the audio signals on two consecutive occasions, or when it ended the test due to fatigue.

Muscle strength of upper limbs was measured by handgrip dynamometer with adjustable pinch (TKK 5101 Grip D; Takey, Tokyo Japan), which was conducted twice on each hand and recorded the maximum score achieved in kilograms. For analysis, it was calculated a mean value between the measurements of each hand. Muscle strength of the lower limbs was assessed by Jumping test with feet together. The participant leaped forward as much as possible, on a stable, non-slip surface. The test was performed twice and the best score was recorded in centimeters. Abdominal strength and endurance were measured by repetitions of abdominal test, when the participant had to perform a maximum possible number of sit-ups, up to a maximum of 75 for one minute.

Trunk strength and flexibility were assessed by trunk extension test. There were performed two attempts and validated the best one. Flexibility of the lower limbs was assessed by sit-and-reach test, and were performed two attempts for each leg and used the average value between the two attempts for each leg. Body composition was measured by body mass index (BMI), calculated using the formula (weight / height) 2. Motor fitness was evaluated by Koordinations Test für Kinder Tests - KTK battery of tests, which is recommended for evaluation of motor components such as balance, coordination, speed and agility, in children.

Food consumption Food consumption was carried out by a 24-hour recall. Participants, along with their parents informed food consumption during the past two weekdays and one weekend day before evaluation. Data from the three days were tabulated in the software "Virtual Nutri", to calculate the total energy consumption values for each of the three days. For analytical procedures, it calculated the average caloric intake among the three measurements.