Resistance and Aerobic Training, Relationship With Birth Weight in Colombian Children

Type of study: Experimental study with individual analysis. Population object and sample: Adolescents from 12 to 17 years old of high school located in Bucaramanga's metropolitan area. The sample size was calculated to evaluate the difference between the maximum oxygen consumption (VO2max) between the control group and 20% of the intervention groups using an ANCOVA method, with a correlation of 0.5 between the initial and final evaluations. An error alpha of 0.05 and power of 0.8, obtaining a sample of 60 adolescents for each group.

Description of the physical intervention or program: This is a strength, power and endurance training program of moderate intensity combined with aerobic capacity training Moderate in the form of circuit. The trainings will be performed twice a week between 30-60 minutes of training, 1 hour including heating, stretching, explanations and cooling.

Baseline assessment: All adolescents will be provided with a CRF for past medical history and family history, a review of systems and physical examination. In addition, the following evaluation protocol is established: Health related physical fitness measurement (AFRS): Aerobic capacity, maximal strength, 6RM submaximal strength test, strength, power, muscular endurance and flexibility; Anthropometric measurements and body composition; Complete Blood Count (CBC), and Lipid Profile. Measurements with AFRS will be taken at baseline, after 3 months of the program and at the end (6 months).

Aerobic capacity: To measure the aerobic capacity, 20 Meter Shuttle Run Test will be applied. A site would be selected for the test, preferably a space of 25 meter or longer. It would need 4 cones, tape measure, compact disc (CD) with the test protocol and a CD player. The two ends of the 20-meter track should be clearly marked. For the execution, the adolescent will move from one line to another located 20 meters away and making the change of direction to the rhythm that is indicated by a sound signal that will progressively accelerate. The initial velocity of the signal would be 8.5 km/hr, and will increase by 0.5 km/hr/min (1 minute is equal to one shuttle). The test will end when the adolescent is not able to arrive for the second time in a row to the start line with the audio signal. Otherwise, the test will end when the teen stops because of fatigue. The participant would start running when the CD player emits the sound. The participant will touch the line at the end of the track with the feet, turn abruptly and run in the opposite direction. At first the speed will be low, but it will increase slowly and steadily every minute. The participant will stop when they no longer can keep the pace set. Or if they feel unable to complete the one-minute period. It is important to remember the last number announced by the CD player when the participant stops, because this will be the participant's score. This test would be performed only once. When the schoolchildren finish the test or cannot keep the pace, the last completed palier would be recorded.

Maximum isometric force: Hand dynamometry is an important test for assessing the physical performance and nutritional status of the participants and allows reference to the isometric muscular strength of the hand. The improve in muscle strengths are inversely associated with changes in total adiposity in childhood and adolescence. This test requires an adjustable dynamometer (TKK 5101 Grip D; Takey, Tokyo Japan) and a Right- and left-Hand Grip Rule. The Adolescent will tighten the dynamometer gradually and continuously for less than 2 seconds, performing the test twice (alternately with both hands) with the optimal grip adjustment according to the size of the hand (previously calculated with the hand grip rule). Allowing a short break between measurements for each measurement. The elbow should be in all its extension and the participant has to avoid the contact of the dynamometer with any part of the body. The Adolescent will take the dynamometer with one hand, try to apply the mayor strength possible. Would Squeeze gradually and continuously for less than 2 or 3 seconds. The examiner will show the correct form of execution. Adjust the grip measure according the size of the hand. The test will be done twice and the best result will be recorded. The maximum duration of the test will be 3-5 seconds, the size of the hand (right or left) should be measured to the maximum width. The accuracy of the measurement is 0.5 cm. During the test, the arm and hand holding the dynamometer do not touch the body. The instrument is held in line with the forearm. After a short break, a second attempt will be made.

Power: Vertical Jump Test is a test that measures the length reached in the vertical jump and with the Lewis's formula can calculate the power of the Adolescent. In addition, the participants can measure the force of the jump with a Platform Kinetics. To use it, the adolescent must stand at a side of a wall, and bring the hand closer to the wall, keeping their feet on the platform. They would have to jump vertically as high as possible with both legs. The platform kinetics would record the best of the three attempts. The participant must put the hands by the hips, to isolate the muscles of the legs. And three attempts are made to allow the coordination of arm movements. The vertical jump test is performed against a movement, where there is flexion of the knees before the jump. The necessary equipment to carry out this activity is the force plate (PASCO, USA, software, NMP technologies, London, UK).

Explosive force: The long jump test allows to measure muscle strength. For the test is needed a non-slip surface, a tape measure, tape and cones. The teenager is going to stand behind the jump line, they must stand with their feet in an equal distance to the anchor of their shoulders, parallel to the ground. Subsequently they will bend the knees with the arms in front of the body and from that position they will balance the arms, they will push with force and jump as far as possible. they will land on both feet simultaneously and in an upright position. The examiner will show the correct form of execution; the test will be done twice and the best result will be recorded. The horizontal lines of measurement are drawn in the drop landing zone at 10 cm, from 1 m from the take-off line. A tape measure is going to be put perpendicular to these lines. The examiner would be remained by the tape measure and will record the distance jumped by the adolescent. The jumped distance will be measured from the takeoff line to the back of the heel nearest to that line. A new attempt is allowed if the teenager falls backwards or contacts the surface with another part of the body.

Strength of resistance: Using the same test and the high jump protocol, but the participants would have to jump repeatedly for 15 seconds. The test is implemented with a Platform that allows the evaluation of the time in flight, time of contact between jumps and the power in each jump. The resistance is calculated with the average of these variables for 15 seconds and a fatigue index.

6-RM submaximal strength test: The American Academy of Pediatrics recommends strength training in the adolescent with a load adjusted to the ability of the Adolescent and with 6 maximal repetitions (6RM), which means that loading in an exercise should allow adolescents achieve 6 concentric and eccentric movements with good technique. In the program use a range of loads (RM's) It is going to be lighter adjusted to the assessment of the beginning of the program, and after every 6 weeks of training, the protocol will implement the test of 6 RM in exercise in machines (chest press, folding, shoulder press, extension of the Leg) to adjust the load according to the progression of the strength of each adolescent.

Flexibility: The protocol can define flexibility as the ability of the individual to get his/her body placed in as many positions as possible, both statics and moving positions. This implies a great capacity of mobility of the different corporal segments with an ample freedom of corporal movements.

Weight: The adolescent would be placed in the center of the scale in a standard upright position, without the body being in contact with anything around him/her. The participant will remain in the described position on the previously calibrated weight balance and it would be determined the weight in Kilograms.

Size: Have the participant stand erect on the floor board of the stadiometer with his or her back to the vertical backboard of the stadiometer. The weight of the participant is evenly distributed on both feet. The heels of the feet are placed together with both heels touching the base of the vertical board. Place the feet pointed slightly outward at a 60-degree angle. The adolescent will remain standing, keeping the position of Anthropometric attention with the heels, glutes, back and occipital region in contact with the vertical plane of the tallimeter. The evaluator makes an in-depth inspiration at the time of the measurement to compensate for the shortening of the intervertebral discs.

Body mass index - BMI: The body mass index or the Quetelet index, has been defined as the ratio of weight to height squared (kilogram/m2). This index changes substantially with age, at birth, is as low as 13 kg/m2. The CDC proposes to use as cutoffs of the 85th and 95th percentile of its own data.

Development of the study: There would be three arms of the study (strength group, aerobic exercise group and control group) of adolescents of 12 to 17 years old. The person responsible for the analyzes will be blind about the interventions. The analysis will be by intention to treat. Once the inclusion/exclusion criteria are checked, the selected candidates will receive information about the study objectives and methodology, and finally the adolescent will sign the informed consent and the guardian or responsible of the child will sign the informed consent too. After the screening procedures and the initial evaluation of the inclusion and selection criteria, the patients will begin the initial evaluation period. A balanced randomization will be carried out using random numbers generated in software systematized form, guaranteeing the homogeneity of the number of subjects in each arm, with internal random assignment with a ratio of 1:1:1 to receive the study intervention. This study is designed with a primary efficacy endpoint at six months and at twelve months. Upon completion of 6 months of intervention, the strength and aerobic capacity groups would be integrated into a single group to evaluate the combined effect of the interventions versus the control group.

The study is divided into two phases carried out in several visits: Phase I is constituted by a visit -1 and 1, which includes the selection of the sample and the randomization. Phase II includes the execution of the study with three arms, one group will be assigned to strength training and the other to aerobic capacity training, taking into account the plan of sessions per week defined for SIMAC (three sessions). The control group will be monitored passively for the detection of adverse or secondary events. At the end of this phase, anthropometric, clinical and biochemical markers will be monitored in the two intervention groups and in the control group. In Phase III a combined program of strength and aerobic capacity will be implemented, which will last six months more than will be compared with the previously defined control group. Again, at the end of phase III, the outcomes related to possible changes in the anthropometric, clinical and biochemical markers in the two groups will be evaluated.