Abstract
Introduction
Hamstring strain injuries (HSI) are one of the most prevalent musculoskeletal injuries in footballers. Following a rise over the last 20 years HSI now make up 24% of all injuries [1]. HSI typically occur during maximal intensity running, during the late swing and early ground contact phase where the hamstring tendon is elongated and the muscle transitions from eccentric to concentric contraction [2]. Isometric testing is often used to measure hamstring strength and imbalances between legs, and to allow practitioners to identify athletes at risk of injury. As average knee joint angle during sprinting ground contact was 27.7 ± 5.6 degrees [3] the aim of this study was to compare testing at 0degrees to 30 degrees knee angles to determine if 30 degree is a more appropriate position for assessing strength.
Methods
42 professional and semi-professional male soccer players performed isometric hamstring strength testing at a 0 degree (straight leg, ISOProne) and 30 degree knee angles (ISO30) using the NordBord device (Vald Performance, Brisbane, QLD, Australia. Tests were performed in a randomised, counterbalanced order, 7 days apart,). Following a standardised warm up, 3, 5 second maximal isometric efforts, separated by 30 seconds recovery were performed. Per leg, peak and average force, and peak and average asymmetry was recorded. Statistical analysis was carried out using a paired t-test and a Pearson correlation coefficient (PCC). Statistical significance was set at p0.05 and correlations were categorised as <.1 negligible, .1-.39 weak, .4-.69 moderate and >.7 strong [4].
Results
Peak force production was 293 ± 56 N left, 311 ± 60N right in ISOProne, while ISO30 was 351 ±73N left, and 368 ±79N right, p<.001, PCC.54 left,.66 right, p<.001 for both. Average force production was 266 ± 51 N left, and 282 ± 58 N right in ISOProne, while ISO30 was 321 ± 68N left, and 338 ± 73N right, p<.001, PCC.524 left, .645 right, p<.001 for both. Tests in the ISOProne and ISO30 positions show a statistically significant difference with a bias of 55-58N in favour of the ISO30. However, the left-right imbalance was not statistically significant with peak ISOProne 5.6%, ISO30 4.2% p=.420, PCC .5, p<.001, and average ISOProne 5.4%, ISO30 4.5% p=.589, PCC .56, p<.001.
Conclusion
Both ISOProne and ISO30 display a moderate correlation with left and right peak, average, and imbalance with a statistically significant difference between angles, with players stronger in the 30 degree knee position. This is closer to the typical knee angle during ground contact when sprinting and given the prevalence of HSI practitioners should consider assessing strength and asymmetry with the ISO30 test.
1 Ekstrand et al. (2023)
2 Woods et al. (2004)
3 Miyashiro et al. (2019)
4 Schober et al. (2018)
Hamstring strain injuries (HSI) are one of the most prevalent musculoskeletal injuries in footballers. Following a rise over the last 20 years HSI now make up 24% of all injuries [1]. HSI typically occur during maximal intensity running, during the late swing and early ground contact phase where the hamstring tendon is elongated and the muscle transitions from eccentric to concentric contraction [2]. Isometric testing is often used to measure hamstring strength and imbalances between legs, and to allow practitioners to identify athletes at risk of injury. As average knee joint angle during sprinting ground contact was 27.7 ± 5.6 degrees [3] the aim of this study was to compare testing at 0degrees to 30 degrees knee angles to determine if 30 degree is a more appropriate position for assessing strength.
Methods
42 professional and semi-professional male soccer players performed isometric hamstring strength testing at a 0 degree (straight leg, ISOProne) and 30 degree knee angles (ISO30) using the NordBord device (Vald Performance, Brisbane, QLD, Australia. Tests were performed in a randomised, counterbalanced order, 7 days apart,). Following a standardised warm up, 3, 5 second maximal isometric efforts, separated by 30 seconds recovery were performed. Per leg, peak and average force, and peak and average asymmetry was recorded. Statistical analysis was carried out using a paired t-test and a Pearson correlation coefficient (PCC). Statistical significance was set at p0.05 and correlations were categorised as <.1 negligible, .1-.39 weak, .4-.69 moderate and >.7 strong [4].
Results
Peak force production was 293 ± 56 N left, 311 ± 60N right in ISOProne, while ISO30 was 351 ±73N left, and 368 ±79N right, p<.001, PCC.54 left,.66 right, p<.001 for both. Average force production was 266 ± 51 N left, and 282 ± 58 N right in ISOProne, while ISO30 was 321 ± 68N left, and 338 ± 73N right, p<.001, PCC.524 left, .645 right, p<.001 for both. Tests in the ISOProne and ISO30 positions show a statistically significant difference with a bias of 55-58N in favour of the ISO30. However, the left-right imbalance was not statistically significant with peak ISOProne 5.6%, ISO30 4.2% p=.420, PCC .5, p<.001, and average ISOProne 5.4%, ISO30 4.5% p=.589, PCC .56, p<.001.
Conclusion
Both ISOProne and ISO30 display a moderate correlation with left and right peak, average, and imbalance with a statistically significant difference between angles, with players stronger in the 30 degree knee position. This is closer to the typical knee angle during ground contact when sprinting and given the prevalence of HSI practitioners should consider assessing strength and asymmetry with the ISO30 test.
1 Ekstrand et al. (2023)
2 Woods et al. (2004)
3 Miyashiro et al. (2019)
4 Schober et al. (2018)
Original language | English |
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Publication status | Published - 4 Jul 2024 |
Event | 29th Annual Congress of the European College of Sport Science: Enhancing Health, Performance and Community Sport - Glasgow, United Kingdom Duration: 2 Jul 2024 → 5 Jul 2024 https://sport-science.org/index.php/congress/glasgow-2024 |
Conference
Conference | 29th Annual Congress of the European College of Sport Science |
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Country/Territory | United Kingdom |
City | Glasgow |
Period | 2/07/24 → 5/07/24 |
Internet address |