The goal of this randomized controlled trial is to evaluate the effect of a 4-week core strengthening program on flat serve velocity and arc of shoulder rotation in amateur young adult tennis players .

Participants will serve the tennis ball four times during the initial and final flat tennis serve assessments. Furthermore, participants will be divided into two groups and given different strengthening programs.

Researchers will compare Group A (shoulder strengthening group) and Group B (core strengthening group) to see if there is any difference between the core and shoulder training programs on the flat serve velocity.

Design:

This study was designed as a double-blinded, randomized controlled trial to investigate the effect of a 4-week core strengthening program on the flat serve velocity and arc of shoulder rotation in amateur young adult tennis players.

Sample Size:

The sample size was estimated using data from websites that provide information on the Lebanese population, the International Tennis Federation (ITF, 2020), and the Lebanese Tennis Federation (LTF). It is estimated that the age range is 18-25 years. accounts for around 13.84% of the 2,000 tennis players in Lebanon, which equates to 276 players. Of these 276, 64 players (23.19%) were professionals (LTF, 2021), 53 players (25%) were estimated as beginners and the remaining 159 were assumed amateur players. By estimation, 39 players (25%) of the 159 players were excluded as per the exclusion criteria. The population size for the study was determined to be a total of 120 players. Using a scientific sample size calculator software (Qualtrics 2021), the confidence level was set to 90%, and the margin of error was set to 10%. The ideal sample size for this study was calculated and determined to be around 44 ± 10% amateur tennis players. According to this calculation, around 50 amateur tennis players will be recruited for this study.

Participants :

The amateur tennis players will be recruited from multiple tennis academies and online platforms in Beirut, Lebanon through an electronic enrollment form. After collecting all the questionnaires, those that meet the inclusion criteria will be selected, and the participants will be contacted later by email, phone calls, or WhatsApp messages with additional information about the length of the study, the training program, and the number of times per week they expect to be seen.

Players will sign an informed consent sheet provided by the Beirut Arab University (BAU) Institutional Review Board (IRB).

Evaluation:

The initial and final assessments will be performed will be completed in an indoor tennis court to limit the air factor interfering and impacting the serve's velocity after receiving consent from one of the academies and, if necessary, paying rent to use it for 1-2 hours. Following approval, the specific shoulder and core training programs will take place in the BAU gym or at the BAU Physical Therapy Outpatient Clinic under the supervision of the therapists.

Materials

Radar Gun :

Radar will be used to measure the serve speed; it will calculate the time elapsed between the ball's emission and the reception of its reflected echo and the distance traveled by the ball between two points (the ball launch point and a second point) (Tubez et al., 2018). The radar that's held by the assessor will be positioned at least 6 ft behind the player and at a height approximate to the center of the racket head at the point of ball contact.

Resistance Bands Therapy resistance bands will be used for the shoulder and core training resistance exercises (Treiber et al., 1998). For the core exercises, the bands will be placed above the knees, ankles, or around the feet while the participants are performing the exercises in various positions. Additionally, the band will be used for shoulder flexion, abduction, IR, and ER exercises while wrapped around different surfaces.

Statistical Analysis The normal distribution of the data will be checked using the Shapiro-Wilk test. Paired t-tests will be used to compare mean differences between pre-and post-test assessment data for the separate experimental and control groups. One-way ANOVA test will used to compare the pre- and post-assessment means between the groups. The relationship between the independent variables (height, BMI, experience, dominant hand) and dependent variables (pre and post-serve velocity) will be described using Pearson's product-moment correlation coefficients (r). The level of significance for all statistical tests will be set at p < 0.05. All statistical analysis will be conducted through the statistical package for social studies (SPSS).

Inclusion Criteria:

(1)Tennis playing experience between 1 to 3 yrs.(2)Trains 2-3 times per week for a minimum of 1-2 hours per day.(3)Trained in flat serve.(4) Right and Left-handed Players.(5) Females and males.(6) Young adults age ranging from 18-25 years.

Exclusion Criteria:

(1)Players who underwent specific shoulder or core strength training in the past year.(2)Players who had a history of UE injury (dislocation, rupture, fracture, surgery ) that prevents them from playing .(3) back or knee pain for at least the past year .(4) Players with Cardiovascular diseases or metabolic disorders. (ex: DM)

In this study, double-blinding will be optimized to ensure that the participants are unaware of the study's aim and exact details; in addition, the pre- and post-radar gun assessments will be performed by someone other than the researchers, preferably a tennis coach. Furthermore, shoulder and core training will be performed in the BAU gym under the direction and supervision of coaches and physical therapists; the training program will be given and performed with the coaches before implementing them with the participants.