Publicação
Hamstrings active shear modulus pattern following a repeated sprint task in football players with and without previous hamstring strain injury
| Resumo: | Hamstring strain injuries are among the most common injuries in a variety of sports, in particular football. Fatigue has been suggested as a possible risk factor since hamstring strain injuries mostly occur at the end of each half of the match. Moreover, the load sharing pattern has been increasingly studied as a possible hamstring strain injury predictor, reporting that the control of synergistic muscles could be the explanation for the HSI incidence. However, there are very few studies on this topic, especially using Shear wave elastography. Therefore, the main objective of this thesis was to determine whether football players with and without hamstring strain history presented different load sharing patterns (namely in the active shear modulus). Nevertheless, it would also be necessary to validate the entire methodology. For this purpose, six studies were conducted: 1) The first study with healthy participants demonstrated that the pressure applied with the transducer affects shear modulus values (soft vs. hard pressure) and that no differences exist between an examiner with more vs. less experience. 2) The second study reported a decrease in the semimembranosus after a hip extension task until failure, and a decrease in the semitendinosus with an increase in the biceps femoris long head after a knee flexion task until failure. Moreover, only the knee flexion set-up allows the possibility of measuring both limbs. 3) The third study evidenced that stretching impacts the active shear modulus load sharing pattern (semimembranosus decrease and biceps femoris short head increase) whereas the warm-up protocol does not. 4) The fourth study suggested that one of the possibilities to induce neuromuscular fatigue in the knee flexors is using 10 sprints of 30 meters. 5) The fifth study reported that after 10 sets of 30 meters the active shear modulus of biceps femoris long head and biceps femoris long head to medial hamstring ratio increased, however, with no physiological significance; along with validating the entire protocol designed and its repeatability (moderate to good), only demonstrating low repeatability for the passive shear modulus. 6) The final study determined that there are no differences in the pattern of shear modulus between football players with and without previous hamstring strain injury, only reporting differences in the rate of torque development between 0-50 ms when comparing limbs with injury on biceps femoris long head against their contralateral limbs. |
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| Autores principais: | Pimenta, Ricardo Jorge Lemos |
| Assunto: | Hamstrings Fatigue Repeated Sprints Active Shear Modulus Load-Sharing Pattern Isquiotibiais Fadiga Sprints Repetidos Módulo de Cisalhamento Ativo Padrão de Compartilhamento de Carga |
| Ano: | 2023 |
| País: | Portugal |
| Tipo de documento: | tese de doutoramento |
| Tipo de acesso: | acesso restrito |
| Instituição associada: | Universidade de Lisboa |
| Idioma: | inglês |
| Origem: | Repositório da Universidade de Lisboa |
| Resumo: | Hamstring strain injuries are among the most common injuries in a variety of sports, in particular football. Fatigue has been suggested as a possible risk factor since hamstring strain injuries mostly occur at the end of each half of the match. Moreover, the load sharing pattern has been increasingly studied as a possible hamstring strain injury predictor, reporting that the control of synergistic muscles could be the explanation for the HSI incidence. However, there are very few studies on this topic, especially using Shear wave elastography. Therefore, the main objective of this thesis was to determine whether football players with and without hamstring strain history presented different load sharing patterns (namely in the active shear modulus). Nevertheless, it would also be necessary to validate the entire methodology. For this purpose, six studies were conducted: 1) The first study with healthy participants demonstrated that the pressure applied with the transducer affects shear modulus values (soft vs. hard pressure) and that no differences exist between an examiner with more vs. less experience. 2) The second study reported a decrease in the semimembranosus after a hip extension task until failure, and a decrease in the semitendinosus with an increase in the biceps femoris long head after a knee flexion task until failure. Moreover, only the knee flexion set-up allows the possibility of measuring both limbs. 3) The third study evidenced that stretching impacts the active shear modulus load sharing pattern (semimembranosus decrease and biceps femoris short head increase) whereas the warm-up protocol does not. 4) The fourth study suggested that one of the possibilities to induce neuromuscular fatigue in the knee flexors is using 10 sprints of 30 meters. 5) The fifth study reported that after 10 sets of 30 meters the active shear modulus of biceps femoris long head and biceps femoris long head to medial hamstring ratio increased, however, with no physiological significance; along with validating the entire protocol designed and its repeatability (moderate to good), only demonstrating low repeatability for the passive shear modulus. 6) The final study determined that there are no differences in the pattern of shear modulus between football players with and without previous hamstring strain injury, only reporting differences in the rate of torque development between 0-50 ms when comparing limbs with injury on biceps femoris long head against their contralateral limbs. |
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