The Relationships Between the Dynamic Strength Index and Performance Metrics in Professional Football Players

The Dynamic Strength Index (DSI) assesses an athlete’s ability to dynamically utilise their maximal strength capacity for guiding training decisions, sharing similar physical qualities with change of direction (COD) activities, such as the involvement of the slow stretch-shortening cycle in larger degrees of COD, due to the greater ground contact times involved. To date, there is only one known study directly investigating the relationship between DSI and COD. For this thesis, Chapter 2 comprises a literature review on the different methods used to calculate the DSI in the existing literature and the links between DSI and performance, while Chapter 3 reports on an empirical study investigating the possible relationships between DSI and its components with COD performance and other commonly measured performance metrics, like jump height and sprint performance. The primary findings from the literature review in Chapter 2 were that the DSI was most commonly used to assess lower body bilateral strength, using the countermovement jump (CMJ) and isometric mid-thigh pull (IMTP). These findings were used to inform the methodology used in Chapter 3, where a cross-sectional study was conducted on professional football players during their pre-season. The main findings from Chapter 3 were that the DSI was not significantly related to any of the jump height, COD and sprint performances, which makes it unsuitable as a diagnostic tool for these physical measures. CMJ height was related to both 10 m and 30 m sprint performances, as well as performance in the longer COD test, the Illinois Agility Test (IAT). Thus, CMJ height can be considered by coaches as a monitoring tool for the performance of professional football players. When assessing COD ability, there could be value in including both a shorter COD test like the mod505 and a longer COD test like the IAT as they are not interchangeable measures and thus offer a more comprehensive overview.

Author

• Tan, Jian Zhi Kenny

Identifier

hdl:10292/17978

OAI identifier oai:identifier

oai:openrepository.aut.ac.nz:10292/17978