Background: The core has two functions, both critical to soccer performance. The first is to provide proximal stability, allowing efficient mobility at the distal parts. This function requires a submaximal contraction of core muscles for as long as the movement takes. It was reported that core endurance is the construct most closely representing this function. The second function is generating and transferring forces from one extremity to another. This function operates via the kinetic chain theory, which implies that various body parts are connected through myofascial kinetic chains, and that a defect in one part of the chain can lead to faulty mechanics and balance, potentially causing injuries in other parts of that chain.

Aim: To investigate the efficacy of core stability training on core endurance, lower limb kinetic chain function, and lower limb dynamic balance in professional, healthy young adult soccer players.

Methods: This is a randomized, controlled trial with a parallel, two-arm, pre- and post-design. After screening for eligibility and obtaining participants' consents, at least 28 male and female soccer players will be randomly assigned to intervention and control groups and tested before and after eight weeks of core training intervention. The outcome measures include the Sport-specific Endurance Plank test, the Closed Kinetic Chain Lower Extremity Stability test, and the modified Star Excursion Balance test.

Data Analysis: The Shapiro-Wilk test, Q-Q plots, and Box plots will be used to evaluate the normality of the data. Lavan's test will check the homogeneity of variances. Based on the normality results, parametric or non-parametric tests will be implemented to compare within and between groups. A P-value of <0.05 will be used to reflect the significance of the results. An intention-to-treat (ITT) analysis will be employed to address potential missing data.

Keywords: core stability, endurance, kinetic chain, athletes, soccer.

Inclusion Criteria:

• Healthy, young adult soccer players of both genders between 18 and 35 years.
• Normal Body mass index (BMI) according to the World Health Organization (WHO) guidelines (18.5-24.9).
• Normal waist circumference (<88 cm for women and < 102 cm for men).

Exclusion Criteria:

• As reported by participants, they will be excluded if they have a history of:

  • Chronic diseases (e.g., cardiovascular diseases, diabetes mellitus, hypertension).
  • Peripheral vascular diseases (e.g., deep venous thrombosis).
  • Systemic diseases (e.g., rheumatoid arthritis, lupus erythematosus)
  • Limbs or trunk trauma, injuries, fractures, or surgeries that required medical attention in the past six months.
  • Concussion.
  • Neurological deficits or symptoms (e.g., numbness, referred to pain to the lower limbs, burning sensation).
  • The use of any medications that might affect the testing procedure and training.
  • Physical pain (e.g., back pain, limb pain).
  • Red flags (e.g., sudden loss of weight, night sweats, or fever).
  • Pregnancy and post-partum (1 year)

• Upon inspection and palpation by the primary researcher, participants will be excluded if they have:

  • Biomechanical abnormalities or deformities in the upper or lower limbs.
  • Swelling/ edema
  • Leg length discrepancy.

To ensure the confidentiality of our participants' information.