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Low pre-season hamstring-to-quadriceps strength ratio identified in players who further sustained in-season hamstring strain injuries

a retrospective study from a Brazilian Serie A team


  • Filipe Veeck Universidade Federal do Rio Grande do Sul
  • Cassio V. Ruas
  • Matheus Daros Pinto
  • Rafael Grazioli
  • Gustavo Pacheco Cardoso
  • Thiago Albuquerque
  • Lucas Schipper
  • Henrique Valente
  • Victor Henrique da Silva Santos
  • Márcio Dornelles
  • Paulo Rabaldo
  • Clarice S. Rocha
  • Bruno Manfredi Baroni
  • Eduardo Lusa Cadore
  • Ronei Silveira Pinto



Isokinetic, muscle strength balance, peak torque, hamstring strain injury, football


A common pre-season injury prevention assessment conducted by professional football clubs is the hamstring-to-quadriceps (H:Q) strength ratio calculated by peak torque (PT). However, it is debatable whether players that present low pre-season H:Q ratios are more susceptible to further sustaining in-season hamstrings strain injuries (HSI). Based upon retrospective data from a Brazilian Serie A football squad, a particular season came to our attention as ten out of 17 (~59%) elite male football players sustained HSI. Therefore, we examined the pre-season H:Q ratios of these players. H:Q conventional (CR) and functional (FR) ratios, and the respective knee extensor/flexor PT from the limbs of players further sustaining in-season HSI (injured players, IP) were compared to the proportional number of dominant/non-dominant limbs from uninjured players (UP) of the squad. FR and CR were ~18-22% lower (P<0.01), whereas quadriceps concentric PT was ~25% greater for IP than UP (P=0.002). Low scores of FR and CR were correlated (p<0.01) with high levels of quadriceps concentric PT (r=-0.66 to -0.77). In conclusion, players who sustained in-season HSI had lower pre-season FR and CR compared to UP, which appears to be associated with higher levels of quadriceps concentric torque than hamstrings concentric or eccentric torque.


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