The effect of neuromuscular training on fatigue resistance in female footballers

• Main Author: Reed, Georgina
• Other Authors: De Ste Croix, Mark ; Deighan, Martine ; Lloyd, Rhodri
• Published: University of Gloucestershire 2017
• Subjects: 796; RC1200 Sports Medicine
• Online Access: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.732790

ACL injury is predominant in female footballers largely due to a combination of kinetic and neuromuscular risk factors. The majority of ACL injuries in football occur during an unanticipated cutting manoeuvre, and the risk of this injury is heightened during the final 30 minutes of each half of match-play. Due to an increased injury incidence towards the end of match-play, it is possible that fatigue might serve as a risk factor for ACL injury. However, there currently exists limited research examining the effects of fatigue on a variety of kinetic and electromyographic variables in female footballers during an unanticipated cutting manoeuvre. Neuromuscular training programmes have been utilised in injury prevention studies and proven effective in reducing injury incidence by improving certain kinetic and neuromuscular ACL injury risk factors. The overall aim of this thesis is to examine the effectiveness of neuromuscular training on the fatigue resistance of ACL injury risk factors in female footballers. Study one of this thesis examined the reliability of a combination of kinetic and electromyographic measures in female footballers performing an unanticipated cutting manoeuvre. There were no significant differences in mean values and large to nearly perfect correlations (ICC = 0.49 - 0.96) for all kinetic variables. The majority of kinetic variables displayed a CV of less than 10%, with the exception of loading rates and time to peak force (CV% = 17.33 - 24.51). In comparison to previous research, electromyographic variables displayed a greater range of typical error (CV% = 17.6 - 129.2); however, the majority of electromyographic variables displayed a large, very large or nearly perfect correlation (ICC = 0.26 – 0.91) and no significant differences in the mean score. In line with previous research, standards of reliability, and anticipated changes in response to acute fatigue, all kinetic and electromyographic variables were deemed acceptable to use in subsequent studies. Kinetic variables showed better reliability than electromyographic variables, which was to be expected due to electromyographic measures being a physiological measure. Previous research has established that 16 - 18 year old female footballers are at highest risk of ACL injury, and it is most commonly caused during performance of an unanticipated cutting manoeuvre. It has also been established that the majority of injuries in female football are sustained in the last 30 minutes of each half when fatigue is present. Therefore, acute fatigue appears to be an influential risk factor for ACL injury. Study two of this thesis examined the effects of acute fatigue on the electromyographic and kinetic ACL injury risk factors in 16 - 18 year old female footballers, when performing an unanticipated cutting manoeuvre. A modified SAFT90 protocol was used to mimic football match-play. Data showed that during the unanticipated cutting manoeuvre following the SAFT90, participants produced greater GRF (vGRF; possibly, apGRF very likely), lower GCT (very likely), increased background hamstring activation (0 - 30 ms; very likely) and increased short-latency feedback activation of the hamstrings (31 - 60 ms; likely and possibly). Results suggested that following a simulated match-play protocol, female footballers experienced greater force absorption while utilising a safer muscle recruitment strategy. Therefore, injury prevention training should seek to improve a player’s aility to tolerate ground reaction forces when experiencing acute fatigue, with a large emphasis on enhancing neuromuscular control within the hamstrings muscle group.