title: Hamstring Muscle Strength Assessment and the Association with Injury Risk in Gaelic Football
Creators: name: McIntyre, M
Publisher: name: Liverpool John Moores University
Year: 2023

description: It is important to identify strategies to help minimise and reduce the risk of hamstring injury and subsequent re-injury in Gaelic football, particularly given the high incidence of hamstring injuries and the level of recurrent injuries within the sport. There are a number of predisposing risk factors of which hamstring strength, has been proposed as a modifiable risk factor, in which interventions are reported to reduce the incidence of injury and risk of re- injury. Therefore, this research investigated various modes of hamstring strength assessment and its association with hamstring strain injury.
Study 1 : Nordic maximal eccentric torque (NBEcc) of the hamstrings was tested for 67 players during pre-season and late in-season using the Nordic hamstring exercise (Nordbord systemTM). Maximal force, maximal torque in both the pre and in-season were analysed and univariate relative risk (RR) were used to determine future HSI. Eccentric hamstring strength levels over the season were not predictive of hamstring injury occurrence in Gaelic football players, although a minimum level of strength (120 Nm) is required.
Study 2 : A novel device, specific to the mechanism of injury in late swing/early stance was developed to evaluate isometric bilateral hamstring strength (IsoBI). 70 amateur Gaelic Footballers were assessed where a moderate to high reliability was reported. Isometric strength testing better identifies those with residual strength deficits following HSI in the previous season, with strength levels below 150Nm suggestive of previous HSI.
Study 3 : Subsequently a unilateral hamstring strength (IsoUNI) test was developed. A total of 35 non-elite (club) GF players were tested on two separate occasions to determine the test- retest reliability of the new IsoUNI assessment where a moderate to high reliability was reported.
Study 4 : A novel hamstring strength battery was undertaken to determine the relationship of NBECC, ISOBI, IsoUNI and also isokinetic (IKD) metrics in HSI. A total of 49 amateur Gaelic club Football players underwent NBECC, ISOBI, IsoUNI and IKD assessment at 600/s and 1800/s. Residual isometric and eccentric IKD torque weaknesses exist in previously injured players, with IKD ratios for opposite hamstring to hamstring, conventional and functional ratios all lower in players with previous HSI.
Study 5 : Fascicle length (Lf) and pennation angle (θp) were determined and their relationship to HSI assessed. In total, Lf and θp was determined in 49 amateur Gaelic club Football players and compared to the battery of strength testing from Study 3 where players were tested in pre-season. There was a trend towards lower but non-significant Biceps Femoris long head (BFlh) Lf in those with previous HSI. Lf was related to isometric strength and not NBECC. There were only 4 prospective HSI injuries identified during the shorter playing season (due to Covid).
Study 6 : 30 players with HSI were clinically assessed (0-7 days post injury) by an experienced clinician and underwent IsoUNI, IsoBI, and NBEcc tests to examine the diagnostic accuracy of these isometric tests for HSI classification. A high level of agreement and correlation between IsoUNI and clinical assessment was reported in the classification of HSI which can aid the diagnosis and classification of HSI.
Summary : NBECC strength is not predictive of previous HSI. ISOBI and ISOUNI tests, both with moderate to high reliability better identifies those with residual strength deficits following HSI. Lower hamstring isometric strength and IKD eccentric torque, bilateral hamstring deficits in peak torque, conventional and functional ratios exist in previously injured players. Isometric strength deficits which identify residual deficits had a strong relationship to Lf and have a tendency to be shorter in players with previous HSI. It is recommended that the ISOBI, ISOUNI and IKD ratios at 600/s be used to screen for previous hamstring injury, while the ISOBI, ISOUNI be utilised to aid in the diagnosis and classification of HSI following acute injury.