Jumps

In the evaluation of the typical technical movements of sports, jumping is clearly one of the actions mainly performed by athletes. A good elevation is fundamental for basketball or volleyball players, and of course there are various forms jumping in athletic disciplines such as the high jump, long jump or triple jump. The analysis of the vertical component is frequently used in the study of jumping performance as it is a practical, efficient method that can be repeated over time and allows obtaining useful data applicable to training.

One of the main contributors to the research in this field was Prof. Bosco who, in the 1980s and 1990s, published a series of articles on the variables involved in the analysis of the vertical jump, suggesting a battery of tests to investigate different motor skills. Over the last few decades, jump analysis has thus developed significantly and has become one of the fundamental tools of evaluation and monitoring. In particular, this “field” method is the basis of:

• performance or predictive assessments of an athlete; many professional sports clubs and championships select athletes based on the skills demonstrated during physical testing protocols. In addition, monitoring changes in the performance of a vertical jump during a season provides information on a subject's state of health.
• injury risk assessments; according to Impellizzeri et al [1], bilateral strength asymmetry during the jump is a risk factor for musculoskeletal injuries. Henderson et al [2] observed on the other hand that athletes who generate more power (jumping higher) are at greater risk of musculoskeletal injuries.
• monitoring the athlete’s training and condition to define workloads – even on a daily or weekly basis;
• rehabilitation protocols, in the recovery phase and in identifying the best time for the return-to-play. Comparing pre-accident performance data is a precise system for assessing recovery status during a rehabilitation period. In addition, a precise assessment of landing and jumping mechanics will help establish the underlying potential for re-injury [3].

Depending on the type of jump analysed, in addition to the height, other variables play a very important role for biomechanical evaluation:

• flight time; it is the result of the application of strength by the subject and the main objective of the performance is to make it as long as possible.
• contact time; together with the flight time this parameter is fundamental to calculate the power used (the lower its value, the greater the power).
• The rate of strength development (RSD) is a measure of the explosive force that tells how quickly an athlete is able to apply strength;
• The reactive strength index (RSI) is a measure of the reactive jumping capability and determines how athletes respond to the stress imposed on their body by plyometric exercises;
• Eccentric and concentric phase durations;
• Management of the displacement of the whole body during the jump (precision);
• Correct motor patterns