Bester MJ1, Dawood M2, Nkwenika T3, Mostert K1
1University of Pretoria, Physiotherapy, Pretoria, South Africa, 2Sefako Makgatho Health Sciences University, Physiotherapy, Pretoria, South Africa, 3South African Medical Research Council, Statistics, Pretoria, South Africa
Background: Research in South African adult professional football demonstrated that our injury incidence landscape differs to that of European professional football. The eccentric hamstring strength and functional ankle stability (FAI) status of elite male youth footballers in South Africa is not yet known.
Purpose: This study aims to determine the eccentric hamstring strength and prevalence of FAI, and how they may correlate to injury incidence over one season in a South Africa youth football academy.
Methods: Sixty-three male youth footballers aged 14-19 selected for the 2017 squad of an elite South African academy were included. Players with existing lower limb injuries or unable to submit written parental consent were excluded. A set of preseason tests were conducted. A demographic questionnaire was administrered. Thereafter, the Nordic hamstring curl test was performed to assess combined mean eccentric hamstring strength of both lower limbs using the TAKEI Back Strength Dynamometer (in Newtons). A Perspex goniometer was used to measure the resultant knee joint angle through which the NHC test was conducted (in ᵒ). The Star Excursion Balance Test was used to detect the presence of FAI objectively. The Cumberland Ankle Instability Tool was used to assess the subjective/'self-reported' presence of FAI. Injuries sustained in the 2017 season were recorded using the FIFA F-MARC 'Injury Report Form'. Statistical analysis was completed in partnership with the South African Medical Research Council using STATA 14, with p-values 0.05 considered significant.
Results: All participants present with at least one of the components of FAI: 74.58% displayed subjective/'self-reported' FAI, while 92.94% (left leg) and 96.47% (right leg) objectively present with FAI. The mean values for combined lower limb eccentric hamstring strength and the resultant mean knee joint angle is 328.51N and 21ᵒ respectively. The overall injury incidence was 32.4 injuries per 1 000 exposure-hours. Injury incidence during training was 28.4 injuries per 1 000 exposure-hours and during matches 39.6 per 1 000 exposure-hours. In terms of age group, the under15's recorded the weakest eccentric hamstring strengths and best objective/physical FAI results. The under17's recorded the strongest eccentric hamstring strengths and 'self-reported' FAI results. For player positions the Midfielders recorded the strongest eccentric hamstring strengths, with Goalkeepers recording the best objective/physical FAI results. Defenders had the weakest eccentric hamstring strengths and the worst objective/physical FAI results.
Conclusion(s): All participants present with at least one of the components of FAI. No correlations between eccentric hamstring strength, FAI and injury incidence were detected in this population. When performing preseason testing on youth footballers, assessments should be analysed in terms of both age group and player position to effectively identify at-risk players.
Implications: This study is an opportunity to develop a preseason assessment protocol that is objective, reliable and economically viable for youth footballing communities in Africa without access to sports science testing facilities or financial support.
Keywords: youth football, injury incidence, eccentric hamstring strength
Funding acknowledgements: The study was self-funded by the first author.
Purpose: This study aims to determine the eccentric hamstring strength and prevalence of FAI, and how they may correlate to injury incidence over one season in a South Africa youth football academy.
Methods: Sixty-three male youth footballers aged 14-19 selected for the 2017 squad of an elite South African academy were included. Players with existing lower limb injuries or unable to submit written parental consent were excluded. A set of preseason tests were conducted. A demographic questionnaire was administrered. Thereafter, the Nordic hamstring curl test was performed to assess combined mean eccentric hamstring strength of both lower limbs using the TAKEI Back Strength Dynamometer (in Newtons). A Perspex goniometer was used to measure the resultant knee joint angle through which the NHC test was conducted (in ᵒ). The Star Excursion Balance Test was used to detect the presence of FAI objectively. The Cumberland Ankle Instability Tool was used to assess the subjective/'self-reported' presence of FAI. Injuries sustained in the 2017 season were recorded using the FIFA F-MARC 'Injury Report Form'. Statistical analysis was completed in partnership with the South African Medical Research Council using STATA 14, with p-values 0.05 considered significant.
Results: All participants present with at least one of the components of FAI: 74.58% displayed subjective/'self-reported' FAI, while 92.94% (left leg) and 96.47% (right leg) objectively present with FAI. The mean values for combined lower limb eccentric hamstring strength and the resultant mean knee joint angle is 328.51N and 21ᵒ respectively. The overall injury incidence was 32.4 injuries per 1 000 exposure-hours. Injury incidence during training was 28.4 injuries per 1 000 exposure-hours and during matches 39.6 per 1 000 exposure-hours. In terms of age group, the under15's recorded the weakest eccentric hamstring strengths and best objective/physical FAI results. The under17's recorded the strongest eccentric hamstring strengths and 'self-reported' FAI results. For player positions the Midfielders recorded the strongest eccentric hamstring strengths, with Goalkeepers recording the best objective/physical FAI results. Defenders had the weakest eccentric hamstring strengths and the worst objective/physical FAI results.
Conclusion(s): All participants present with at least one of the components of FAI. No correlations between eccentric hamstring strength, FAI and injury incidence were detected in this population. When performing preseason testing on youth footballers, assessments should be analysed in terms of both age group and player position to effectively identify at-risk players.
Implications: This study is an opportunity to develop a preseason assessment protocol that is objective, reliable and economically viable for youth footballing communities in Africa without access to sports science testing facilities or financial support.
Keywords: youth football, injury incidence, eccentric hamstring strength
Funding acknowledgements: The study was self-funded by the first author.
Topic: Sport & sports injuries; Outcome measurement
Ethics approval required: Yes
Institution: University of Pretoria
Ethics committee: Faculty of Health Sciences Research Ethics Committee
Ethics number: 453/2016
All authors, affiliations and abstracts have been published as submitted.
