Given conflicting studies regarding the effect of land-based and water-based training on the jump performance of volleyball and basketball players, a randomized controlled trial is conducted. This study hypothesizes that combined land- and water-based core and lower strength training significantly increase jump performance of volleyball and basketball players in comparison to either land- and/or water-based training alone.

Numerous studies focused on the effect of sole land- or water-based exercise training to improve either core and/or lower extremities alone, which could result in improved jump performance. With the continuously increasing popularity of volleyball and basketball, where players get better and better, competition in these fields is also heightened. Hence, identifying other methods to improve game performance, such as improving muscle strength and jump performance can be explored to contribute to the existing literature and could benefit the volleyball and basketball players themselves, trainers/coaches, universities competing in sports competitions locally, nationally, and even internationally, and to physical therapists who are venturing to sports physical therapy.

The study then seeks to investigate whether combined land- and water-based exercises targeting the core and lower extremity muscle strength can enhance the jump performance of basketball and volleyball players. With this, a three-arm, single-blinded randomized controlled trial is being conducted among basketball and volleyball players. Participants are grouped into combined land- and water-based exercise, land-based exercise, and water-based exercise.

To proceed with the implementation, the researchers acquired ethical clearance from the MMSU Ethics and Review Board. Recruitment of participants happened within a University at Ilocos Norte, Philippines. Acquisition of informed consent was done before other screening procedures to identify the eligibility of participants to participate in the study. Eligible participants were randomized accordingly to either the three (3) aforementioned groups.

The exercises implemented in each group are based on existing literature regarding their effect on either the core or lower extremity strength, and combined to create a new and applicable exercise program, These exercise programs were also verified applicable by two licensed physical therapists who are also well-versed in strength training protocols. The participants are being trained accordingly one hour/day, three days/week for two consecutive weeks.

As to the pre-and post-test measurements of the primary and secondary outcomes, assessment is done by two independent licensed physical therapists who are blinded to the participants and interventions. Moreover, the assessors are well-versed in the assessment of the different outcome measurements (Plank core strength test, 1RM, 10-meter Sprint Test, Margaria-Kalaman Power Test) and in using the MyJump Lab Mobile App, duly purchased by the researchers, used for the assessment of countermovement jump and squat jump.

The SPSS version 22 will be used for data analysis by an independent statistician. Descriptive and comparative statistics will be used to analyze all data within- and between-groups, respectively. For the descriptive statistics, frequency, percentages, mean, and standard deviation will be utilized, while the two-way ANOVA and/or the paired T-test will be utilized for the comparative statistics.

Inclusion Criteria. Volleyball and basketball players, specifically who:

• are at least 18 years-old,
• are enrolled in an Ilocos-based university during the second semester of academic year 2023-2024,
• played in at least one (1) official university-wide game,
• are physically prepared for the training, which is identified using the Physical Activity Readiness Questionnare for Everyone (PAR-Q+), and
• have provided informed consent.

Exclusion Criteria: Volleyball and basketball players who:

• sustained injuries within 6 weeks before the start of the study,
• have uncontrolled angina, uncontrolled hypertension, uncontrolled dysrhythmias, recent history of congestive heart failure, and/or severe aortic valve disease,
• has condition/s that is/are contraindicated for pool therapy such as open wounds, skin infections, high fever, incontinence, fear of water, etc.,
• answered "Yes" to at least one question from the PAR-Q+; and
• declined to participate.

Based on the approved ethical considerations of the study by the ethics review board, the raw data will be kept with utmost confidentiality for at most five years. It can be viewed if required by the public, but with limitations, such as the provision of code names of participants to abide with data privacy.

Outcome assessors are blinded to the grouping of the participants and the interventions of the study.