Purpose: Increasing age, high quadriceps strength, and low hamstring muscle strength are associated with hamstring strain injury in soccer. The authors investigated the age-related variation in maximal hamstring and quadriceps strength in male elite soccer players from under-13 (U-13) to the senior level. Methods: A total of 125 elite soccer players were included from a Danish professional soccer club and associated youth academy (first tier; U-13, n = 19; U-14, n = 16; U-15, n = 19; U-17, n = 24; U-19, n = 17; and senior, n = 30). Maximal voluntary isometric force was assessed for the hamstrings at 15° knee joint angle and for the quadriceps at 60° knee joint angle (0° = full extension) using an external-fixated handheld dynamometer. Hamstring-to-quadriceps strength (H:Q) ratio and hamstring and quadriceps maximal voluntary isometric force levels were compared across age groups (U-13 to senior). Results: Senior players showed 18% to 26% lower H:Q ratio compared with all younger age groups (P ≤ .026). Specific H:Q ratios (mean [95% confidence interval]) were as follows: senior, 0.45 (0.42–0.48); U-19, 0.61 (0.55–0.66); U-17, 0.56 (0.51–0.60); U-15, 0.59 (0.54–0.64); U-14, 0.54 (0.50–0.59); and U-13, 0.57 (0.51–0.62). Hamstring strength increased from U-13 to U-19 with a significant drop from U-19 to the senior level (P = .048), whereas quadriceps strength increased gradually from U-13 to senior level. Conclusion: Elite senior soccer players demonstrate lower H:Q ratio compared with youth players, which is driven by lower hamstring strength at the senior level compared with the U-19 level combined with a higher quadriceps strength. This discrepancy in hamstring and quadriceps strength capacity may place senior-level players at increased risk of hamstring muscle strain injuries.
Background: Hamstring strain injuries (HSI) occur particularly in the later stages of a football match, suggesting that fatigue may play an important role. Moreover, sprint is the principal mechanism to sustain an HSI since it demands the hamstrings muscle group. It has been reported that a higher contribution of BFlh in the load sharing pattern could possibly explain the greater injury rate in BFlh.
Objective: To compare the effects of a (i) repeated sprint protocol on the sprint performance, hamstrings shear modulus pattern and mechanical parameters between players with and without previous HSI; and (ii) between limbs with HSI and their healthy contralateral limbs on the hamstrings shear modulus pattern and mechanical parameters.
Methods: One hundred and five professional and semiprofessional football field players were invited to participate in this study during the pre-season 2021/2022 (June-July), resulting in a sample size of 210 limbs with 46 sustaining HSI in the previous 2 years.
Results: No differences were seen between injured and non-injured players regarding their sprint performance, hamstrings shear modulus pattern and mechanical parameters, except for the early rate of torque development (0-50ms) with BFlh injured limbs displaying higher rates than their contralateral (injured: 0.48±21 N/ms; contralateral 0.40±0.18 N/ms; p=0.005; η2p=0.469).
Conclusion: The present study provides evidence for no differences regarding sprint performance, hamstrings load sharing pattern and mechanical parameters between players with previous HSI in the last 2 years and non-injured players, although an increase in early rate of torque development was seen in BFlh-injured limbs compared to their healthy counterpart. Therefore, the results can possibly suggest that the duration between injury and screening could recover the differences between injured-control and injured-contralateral groups.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.