The Effect of Core Stability Programs With Different Training Intensities Quantified Using Accelerometers Integrated in Smartphones: a Randomized Controlled Trial

Sixty recreational male athletes will be evaluated twice (pre-test 1 and pre-test 2) before a core stability (CS) training program. Testing sessions will consist in several tests to assess sitting and global dynamic postural control, trunk isometric endurance, neuromuscular function of the lower extremities, trunk response to sudden and unexpected load perturbations and pelvic oscillation during CS exercises evaluated with a smartphone accelerometer. Later, they will be randomly assigned to one of the three groups included in the study: two experimental groups (low and high intensity) and a control group. The intervention will have a training frequency of 2 days per week for 6 weeks. Each CS training session will consist in 4 sets of one variation of four of the most popular stabilization exercises used to challenge core muscles: frontal bridge, back bridge, lateral bridge and bird-dog. Exercise variations will be performed isometrically in increasing order of difficulty through the modifications of the following mechanical constraints: lever-arm, number of supports and/or the use of unstable surfaces. The CS training programs will differ in exercises intensity, mainly. Each participant of the low intensity group will perform those exercise variations in which they have obtained an oscillation ranged between 0.2 and 0.3 m/s2 in pre-test, while participants of the high intensity group will perform the exercise variations in which they have obtained an oscillation ranged between 0.4 and 0.5 m/s2. The exercise duration will be set at 30 s and 15 s for the low intensity and high intensity group, respectively. All participants of the training groups will be revaluated every two weeks during the training period. After the intervention period, all participants will perform a post-test to evaluate the effectiveness of both CS programs. Statistical analysis will consist in repeated-measures ANOVAs for detecting possible significant differences within and between-groups.