Bosco Jump Test Calculator

Understanding the Bosco Jump Test Protocol

The Bosco Ergo Jump System is a comprehensive series of jump tests developed by sports scientist Carmelo Bosco for assessing leg muscular mechanics and explosive power in athletes. This scientifically validated protocol measures different aspects of jumping ability through variations in jump technique, allowing coaches and athletes to identify specific strengths and weaknesses in lower body power production.

According to research by Robert J. Wood, PhD in Exercise Physiology from the University of Western Australia and founder of Topend Sports, the Bosco protocol provides one of the most comprehensive assessments of athletic jumping ability available, with applications across virtually all power-based sports from basketball to Olympic weightlifting.

The Six Bosco Jump Tests Explained

Each test in the Bosco protocol measures distinct neuromuscular qualities essential for athletic performance:

1. Squat Jump (SJ) - Pure Concentric Power

The athlete starts with knees flexed at 90 degrees, hands on hips, and jumps without any countermovement. This test isolates pure concentric muscle contraction and measures the ability to generate force rapidly from a static position. Sports scientist data indicates that elite basketball players typically achieve 45-55cm in the squat jump, while Olympic volleyball players range from 50-60cm.

2. Countermovement Jump (CMJ) - Elastic Energy Utilization

Similar to SJ, but the athlete starts standing and performs a quick downward movement before jumping. This test measures the stretch-shortening cycle (SSC) and elastic energy storage capacity. Research shows that CMJ height should always exceed SJ height by 10-15% in healthy athletes, as documented in over 200 peer-reviewed studies on the pre-stretch effect.

3. Abalakov Jump (ABK) - Total Jumping Ability

The traditional vertical jump test with arm swing allowed. This measures total body coordination and upper-lower body integration. Elite athletes typically show 10-15% improvement over CMJ when arm swing is incorporated, demonstrating proper kinetic chain sequencing.

4. Squat Jump Plus (SJ+) - Maximum Strength Assessment

A squat jump performed with additional load on the shoulders. When combined with unloaded SJ, this allows calculation of the Bosco Index, which identifies whether an athlete needs more maximum strength or power training. The optimal Bosco Index sits at 33%, meaning an athlete should jump at least one-third of their unloaded height when carrying their body weight as additional load.

5. Drop Jump (DJ) - Reactive Strength

Athletes drop from standardized heights (20cm, 40cm, 60cm, 80cm, 100cm) and immediately jump for maximum height. This measures reactive strength and the ability to rapidly utilize the stretch-shortening cycle under high eccentric loads. Elite sprinters and jumpers excel in this test.

6. Repetitive Jump (RJ) - Anaerobic Endurance

Continuous maximal jumps performed for 5-60 seconds. This test measures anaerobic power endurance and fatigue resistance. The average power generated can be calculated using the Bosco formula: W = (Ft × Ts × g²) / 4n(Ts - Ft), where elite athletes maintain 15-25 W/kg throughout a 60-second test.

Key Performance Indices from Bosco Testing

Elasticity Index - Measuring Elastic Energy Storage

The Elasticity Index quantifies how effectively an athlete uses elastic energy stored in muscles and tendons during the stretch-shortening cycle. It's calculated as: [(CMJ - SJ) / SJ] × 100

Research compiled by Robert Wood indicates typical values across athletic populations:

• 15% or higher: Excellent elastic capability - common in elite jumpers and sprinters
• 10-15%: Good SSC utilization - typical for most trained athletes
• 6-10%: Average elastic ability - recreational athletes
• Below 6%: Poor SSC function - indicates need for plyometric training

Bosco Index - Strength vs Power Balance

Named after Carmelo Bosco himself, this index determines whether maximum strength or power is the limiting factor in an athlete's performance. When an athlete performs a squat jump with a load equal to their body weight, the Bosco Index is calculated as: (SJ Loaded / SJ Unloaded) × 100

According to SimpliFaster research on hundreds of athlete profiles, the interpretation breaks down as:

• 36% or higher: Power/RFD is limiting factor - focus on explosive training
• 33-35%: Well balanced - maintain current programming
• Below 33%: Maximum strength is limiting - prioritize heavy strength work

Eccentric Utilization Ratio (EUR)

A simpler index calculated as CMJ / SJ, the EUR should typically range from 1.10 to 1.15 for trained athletes. Values below 1.05 suggest inefficient use of elastic energy, while exceptionally high values (above 1.20) may indicate poor maximal strength relative to elastic capabilities.

Arm Swing Contribution

Calculated as [(ABK - CMJ) / ABK] × 100, this measures upper-lower body coordination. Elite athletes demonstrate 10-15% contribution from arm swing, while poor coordination results in values below 5%, indicating technical deficiencies in kinetic chain sequencing.

Sport-Specific Applications of Bosco Testing

Basketball - Vertical Dominance

NBA players demonstrate elite Bosco test performances with average CMJ heights of 71-76cm (28-30 inches). Guards typically show higher elasticity indices (12-18%) due to reactive training emphasis, while centers generate more absolute power despite potentially lower relative elastic capabilities. Professional scouts use Bosco testing to identify explosive athletes with high draft potential.

Volleyball - Explosive Jumping Endurance

Olympic volleyball players, particularly middle blockers and outside hitters, commonly achieve 50-65cm in CMJ testing. The repetitive jump test proves especially valuable for volleyball, as matches demand sustained jumping ability over 2-3 hour competitions. Elite players maintain 85-90% of initial jump height throughout a 60-second RJ test.

Track & Field - Power-Speed Development

Sprinters and jumpers use Bosco testing to optimize their power-speed profile. Long jumpers typically show CMJ heights of 55-70cm with elasticity indices above 15%, while high jumpers may achieve 60-80cm with slightly lower elastic indices but superior absolute power. Drop jump performance from 40-60cm heights strongly correlates with sprint acceleration ability.

Soccer - Multi-Directional Power

Professional soccer players average 40-55cm in CMJ testing, with position-specific variations. Attackers and wingers demonstrate higher elastic indices (10-15%) reflecting their need for repeated explosive actions, while defensive players show more balanced strength-power profiles. The Bosco protocol helps identify players' physical readiness throughout the competitive season.

Rugby & American Football - Explosive Strength

Power athletes in collision sports typically show Bosco Index values below 33%, indicating that maximum strength development remains a priority. Running backs and defensive backs achieve CMJ heights of 50-65cm, while linemen focus more on absolute power production measured through loaded jump variations.

Olympic Weightlifting - Rate of Force Development

Elite weightlifters demonstrate exceptional jump performance despite their focus on maximal strength. Top performers achieve 50-70cm CMJ heights with very low Bosco Indices (below 30%), reflecting their enormous absolute strength. The drop jump test correlates strongly with clean and snatch performance.

How to Use This Bosco Jump Calculator

Follow these steps to analyze your jumping performance and identify training priorities:

Step 1: Measure Your Flight Time

Use a timing mat, force plate, or high-speed video (240fps minimum) to measure flight time accurately. The most accessible method for athletes is smartphone slow-motion video - count frames from takeoff to landing and divide by frame rate. For example, if 60 frames pass at 240fps, flight time = 60/240 = 0.250 seconds.

Step 2: Enter Basic Jump Data

Input your flight time from a single maximal jump. The calculator instantly converts this to jump height using the validated Bosco formula: height = 4.9 × (flight time / 2)². This physics-based calculation provides ±2% accuracy for trained athletes when proper measurement technique is employed.

Step 3: Add Advanced Protocol Data (Optional)

For comprehensive analysis, perform all three jump variations (SJ, CMJ, ABK) and input each flight time. If assessing strength-power balance, add your body weight and perform a loaded squat jump with weight equal to body mass. The calculator computes all relevant indices automatically.

Step 4: Toggle Units as Needed

Switch between metric (kg, cm) and imperial (lbs, inches) using the unit toggle. The calculator automatically converts all inputs and results, ensuring consistency across measurement systems.

Step 5: Interpret Your Results

Review the calculated indices and compare to sport-specific benchmarks. The calculator provides performance level classification, identifies training priorities, and suggests appropriate sports based on your jumping profile. Elite performers should retest every 4-6 weeks to track progress, while developing athletes benefit from monthly assessments.