The Effect of Eight-week Specific Core Training on Core Stability, Balances and Jumps in Young Rhythmic Gymnasts
Condition: ATHLETIC PERFORMANCE
Study type: Interventional

Summary: 
      The aim of the study is to evaluate the effect of an eight-week specific Core Stability
      Training (CST) on young rhythmic gymnasts. The literature suggests CST may help improve sport
      performance, however, more studies implementing functional CST and accurate methodology are
      needed to validate this statement. Little is known about Core Stability (CS) and Rhythmic
      Gymnastics (RG). The study intends to find out whether CST contributes to the Rhythmic
      gymnasts core stability, balances and jumps execution enhancement, very important RG
      performance determinants. It is hypothesized the rhythmic gymnasts will increase their CS,
      balances and jumps performance once the specific CST is conducted.
    

Detailed description: 
      Gymnasts were recruited from the Gymnastics Club "Gimnàstica Muntanyenc". All participants
      were rhythmic gymnasts who had at least two-year experience competing in RG at regional
      federated and school competition level and trained three times per week. Individuals who
      didn't meet these criteria or were injured at the moment were excluded. The participants were
      invited to take part in the study voluntarily, and along with their parents were informed
      verbally and in writing as to the characteristics of the program. Parents or legal guardians
      signed informed consent forms, and a document that explained the objectives and planned
      activities of the provided program. The study was approved by the FPCEE Blanquerna Research
      Ethics Committee. All protocols applied in this research (including the management of the
      personal data of the participants) complied with the requirements specified in the
      Declaration of Helsinki of 1975 and its subsequent revisions.

      The specific CST program is aimed for Rhythmic gymnasts between 8 and 15 years of age who
      train in the competitive group and their goal is to improve their RG level. All the study
      participants were asked to sign an informed consent document that was drafted in keeping with
      all applicable research ethics protocols, including a guarantee of the confidentiality of
      personal data and an assurance that participants can choose to abandon the study at any time.

      Control group (CG), experimental group (EG) and pre-test, post-test methodology was selected.
      EG performed the specific CST while CG carried out the traditional RG training.

      The CST intervention had been carried out over the course of one academic year (2018-19). The
      first 3 months allowed investigators to recruit the participants and design the CST adapted
      to the Rhythmic gymnasts and pursuing the highest specificity for the CS exercises. This
      design took into account prior experiences of a CS physiotherapist expert and a RG national
      coach. The load of the sessions was controlled according to a Rate of Perceived Exertion
      (RPE) scale, a valid method of quantifying exercise training during a wide variety of types
      of exercise. A training protocol trial will be applied where the subjects will be asked to
      point out which is their perceived exercise intensity, thirty minutes after the training
      ends. The repetitions will be adjusted to the 7-8 RPE scale values (very hard) allowing the
      correct execution of the exercises to the participants and yet permitting adaptations
      produced by the training. The conclusions drawn from this initial experience formed the
      scientific basis for the definitive version of the CST.

      During the fourth month a pre-test was carried out including an anthropometric study of the
      gymnasts, three CS tests, seven balance tests and six jump tests. The participants warmed up
      before each test except for the anthropometric study and the order of the subjects and the
      order of the applied tests were randomly determined using a true random number generator to
      avoid order effects. A group blinded specialized physiotherapist conducted the anthropometric
      study and the CS tests, and a group blinded RG expert led the rest of the tests.

      CS tests: Two pressure biofeedback unit (PBU) tests were applied to evaluate the lumbopelvic
      motor control (LPMC) and the pelvic tilt tests were conducted to evaluate CS endurance.

      Balance tests: One leg stand test (OLST) was performed on a force platform to evaluate the
      gymnasts' balance. Right and left and open and closed eyes conditions were used to perform
      the four Romberg variants balance tests. Three specific Rhythmic balances were chosen to
      execute over the force platform and were also evaluated by three RG judge experts.

      Jump Tests: Counter movement jump (CMJ) and single leg countermovement jump (SLCMJ) were
      performed on a force platform to assess the gymnasts' jump. Three specific RG jumps outside
      the force platform were evaluated by three RG judge experts.

      Anthropometric study: A complete anthropometric study was carried out by a professional
      physiotherapist and will allow the investigators to verify the results are not affected by
      group initial differences.

      From February to April the eight-week CST sessions were offered in the gymnasts' regular
      training space suitable for the intervention exercises and guaranteeing the safety of the
      participants. The investigators provided all the extra equipment required for the study. The
      EG participants performed the CST 3 times per week at the same time of their scheduled
      training. The duration of the specific training was approximately 30 minutes for 8 weeks with
      a total of 24 sessions. EG gymnasts were observed while performing the exercises to ensure
      the training was performed correctly.

      Thirty minutes after every CST session all gymnasts (EG and CG) were asked to pick the score
      of the RPE scale that best described their sensation. This score, multiplied by the minutes
      of the session (RPE session), helped us modulate the training periodization plan. The average
      RPE session values were calculated to ensure no load training differences existed among
      groups.

      This CST program involves exercises that challenge the balance, postural control and
      explosive strength of the gymnasts, executed with specific RG elements and postures.

      The specific CST training contains three blocks; a circuit, plyometric exercises and CS
      exercises. Three different balances and leaps very common in RG (novice to intermediate
      competitive level) were selected to convert the core and the explosive strength exercises
      into a very specific and functional training. The balances selected were the passé balance,
      the side balance with help and the arabesque, the three leaps were the scissors, the stag
      from assemble and the split leap. The mentioned RG elements were selected due to their lower
      limb position planes variety and different techniques since it is advised that a range of
      exercises should be performed to challenge the core musculature in all three planes and
      ranges of movement to develop total CS. Moreover, all exercises were executed equitably for
      the right and left side. Unstable superficies as the Bossu, unstable discs and soft balls
      were included to perform core and balance exercises. The gymnasts performed 3 exercises of
      the circuit on an unstable surface. It is reported, when standing on an unstable support, the
      stabilizing muscles make anticipatory adjustments subsequently minimizing postural
      destabilization. The protocol training and the exercises were conducted by Club Muntanyenc
      professional RG coaches.

      A post-test was performed after the eight-week specific CST following the same procedure as
      the pre-test.

      The Statistical Analysis will be performed using an Excel spreadsheet and then exported to
      the computer program SPSS statistics 22.0, to then perform the various statistical tests.
      Initially, a normality test will be performed to check the distribution of the data and to
      decide whether parametric or non-parametric tests are applied. The G-POWER program will be
      used to calculate the statistical power of the sample with a value of p <0.05 and an
      estimated effect size of 0.5.
    

Intervention name(s): Core stability training
Intervention type(s): Other
Intervention description(s): Functional Rhythmic Core Stability exercises performed by the experimental group. 30 minutes insert included in the Gymnasts regular training.
Allocation: Randomized
Intervention model: Parallel Assignment
Intervention model description: Pre-test, intervention and post-test. The Experimental Group performs an eight-week Core Stability Training 3 days a week and the Control Group performs the traditional Rhythmic Gymnastics Training during that period of time.
Masking: Single (Outcomes Assessor)
Primary purpose: Other
Keywords: Core Stability; Core Stability Training; Rhythmic Gymnastics; Plyometric Training; Balance; Rhythmic Gymnastics Jumps