Background
Within football, the physical part of performance is evident, and to evaluate player status and development both field- and laboratory tests have frequently been used. An important aspect of physical performance, that recently has been subject to investigations is the ability to change direction quickly. The current practice in Danish elite football is to evaluate this through timed sprint running including one or multiple changes of direction (CODt), i.e. the 505 or the arrowhead test (AH). A recent proposed advancement to this is to eliminate the linear sprint by calculating the change of direction deficit (CODd) in the 505 (505-CODd). The present project investigates this proposal in elite Danish female football players. Furthermore, a novel approach of using CODd in combination with AH (AH-CODd) is investigated in elite Danish male and female football players.
Methods
Three groups participated, with one group being further divided in three age-groups. The groups consisted of 21 top-level female players (“EK”; age: 19.6±4.9 years, height: 171.6±7.3 cm, bodyweight: 61.8±6.1 kg), 17 female national team football players (“LK”; age: 23.2±3.6 years, height: 171.1±4.5 cm, bodyweight: 64.1±4.2 kg) and 48 elite male football players (“EM”). The last group was further divided into three subgroups based on the teams age-category; under-17 (“EM17”; n=17, age: 15.5±0.5 years, height: 180.5±6.7 cm, bodyweight: 70.4±7.9 kg), Under-19 (“EM19”; n=14, age: 17.2±0.7 years, height: 181.0±7.9 cm, bodyweight: 68.8±7.76 kg) and senior (“EMS”; n=17, age: 23.5±4.17 years, height: 183.5±6.0 cm, bodyweight: 78.6±5.7 kg). All groups performed a 30 m sprint test, with EK also recording a 10 m split time. EK furthermore performed the 505 and 505-CODd. For the remaining groups AH was performed, with an additional time retracting the first and last 5 m being recorded and used for AH-CODd by subtracting 30 m sprint time. Relationships between linear sprint times, CODt and CODd within groups were investigated. Differences in 30 m sprint time were evaluated between all groups. Within EM differences in all variables between subgroups were evaluated.
Results
Across groups EMS was fastest in the 30 m sprint, followed EM19 and EM17 (who weren’t significantly different), LK and EK. For EK, 10 m sprint and 505 correlated (ρ = 0.67) on the non-preferred side, as did 505 and 505-CODd on either side (r = 0.49-0.60). For LK 30 m sprint was correlated with AH (r = 0.63-0.72). Furthermore, in LK AH and AH-CODd correlated (r = 0.64-0.69). For EM 30 m sprint and AH correlated (ρ = 0.68-0.74), and small to moderate correlations was found for AH and AH-CODd (ρ = 0.29-0.48). Additionally, EMS was faster than EM19 and EM17 in AH on either side. No differences were found between subgroups in AH-CODd. For more than 70% of the athletes, the evaluation of the ability to change direction was different depending on the use of either CODt or CODd.
Discussion
The premise for developing CODd was the relationship found between change of direction tests and sprint times, and the assumption that these should be independent. However, the origin of that assumption is earlier, studies that did not find the same relationship. This project, along with many other studies, does indeed present large correlations between CODt and linear sprint times, and it is therefore proposed that this relationship is further investigated, before concluding that CODt is invalid. Instead, a novel illustration of the test results from CODt relative to linear sprint is presented by comparing individual scores to those of the team. Furthermore, a method of applying this to programming of individual training is proposed.
Conclusion
The use of CODd is unlikely to be a better approach than the traditional CODt. However, tests should be minimized in both overall distance as well as number of changes of direction. A novel method of presenting and applying test results is presented in the project.