This study protocol investigates whether adding core stability training to a plyometric training program enhances vertical jump performance in elite high jump athletes over a six-week period. It is hypothesized that combined core stability and plyometric training will result in greater improvements in vertical jump distance compared to plyometric training alone.

Elite high jump athletes are allocated into two groups based on their existing training squads: a combined intervention group (COMBO) receiving both core stability and plyometric training, and a plyometric-only group (PLYO). Both groups follow a structured six-week training program, with vertical jump distance measured before and after the intervention period to assess changes in performance.

From a clinical and applied sports science perspective, the findings of this protocol may help determine whether incorporating core stability exercises into existing plyometric programs provides additional benefit for improving explosive lower-limb performance, thereby informing evidence-based training prescription for high jump athletes.

This study is a six-week, non-randomized, two-arm comparative intervention designed to evaluate the effects of combined core stability and plyometric training versus plyometric training alone on vertical jump performance in elite high jump athletes.

A total of eligible elite high jump athletes are allocated into two groups based on their existing training squads to minimize disruption to routine coaching structures. This non-randomized allocation reflects real-world training environments. The intervention group (COMBO) receives a combined program of core stability and plyometric training, while the comparison group (PLYO) performs plyometric training alone.

Plyometric Training Protocol (Both Groups - COMBO and PLYO)

The plyometric program is designed to enhance explosive power, speed, and agility using structured progressive exercises. Equipment includes variable-sized Swiss balls, 45 cm plyometric boxes for box jumps, a 30 cm depth jump box, sports cones for agility drills, and a synthetic long jump surface.

Each training session begins with a 5-10 minute active warm-up involving light jogging, dynamic stretching, and mobility exercises, and ends with a 10-minute cool-down phase. Participants continue their regular resistance training twice weekly on non-consecutive days targeting upper body, lower body, and trunk muscle groups.

Plyometric exercises are organized according to progression principles based on intensity, coordination, balance demands, limb involvement, and impact level. Training progresses from low-impact bilateral linear jumps to higher-intensity multidirectional and single-leg landing drills, with gradual increases in complexity to improve neuromuscular control and landing mechanics.

Core Stability Training Protocol (COMBO Group Only)

The core stability program follows a structured progression from basic stabilization to dynamic control based on established core training principles.

Week 1 includes supine pelvic tilts, lunge-position pelvic control exercises, and bilateral pelvic bridges. Week 2 progresses to unilateral pelvic bridges and quadruped bracing exercises without Swiss ball support. Weeks 3 and 4 focus on static core stability tasks, including contralateral single-leg holds and quadruped exercises using a Swiss ball. During Weeks 5 and 6, dynamic core exercises such as upper body roll-outs are introduced once adequate control is achieved.

Core stability exercises are performed for 12-15 minutes per session, with 8-10 repetitions per set and 2-3 sets per session, three times per week for six weeks.

Training Delivery and Supervision

Both interventions are demonstrated prior to commencement by two qualified physical therapists and two athletic coaches. Training is conducted at separate training sites according to group allocation. The structure of each program remains consistent throughout the intervention period.

Outcome Measurement

The primary outcome is vertical jump distance measured in centimeters using a standardized protocol. Participants perform a standing reach test followed by a maximal vertical jump. Jump height is calculated as the difference between standing reach and maximal jump reach. Each participant performs three trials, and the highest value is used for analysis. Assessments are conducted before and after the six-week intervention by an independent blinded assessor.

Inclusion Criteria

• Elite voluntary high jump athletes (male and/or female)
• Age range between 19-24 years
• Minimum of 3 years of structured high jump training experience
• Currently participating in regular training (at least 3 sessions per week)
• Medically fit to participate in plyometric and core stability training
• Enrolled in this study

Exclusion Criteria

• History of lower limb musculoskeletal trauma within the past three months
• Chronic asthma
• Ongoing physiotherapy for musculoskeletal pain
• Neurological conditions
• History of severe anxiety and depression

Individual participant data will not be shared with other researchers. Institutional policies and the approved ethics protocol do not permit external sharing of raw participant data. Additionally, participants provided informed consent only for the use of their data in aggregated, de-identified form for publication purposes. Only summary statistics and final outcome measures will be reported in the manuscript.