Cutoffs of isokinetic strength ratio and hamstring strain prediction in professional soccer players

Abstract

Hamstring strain injuries frequently occur during professional soccer practice. Low hamstring strength represents an intrinsic modifiable risk factor but cutoffs of isokinetic knee strength ratios are controversial to predict hamstring strain in professional soccer players. We aimed to predict hamstring strain in accordance with cutoffs of isokinetic knee strength ratios. Bilateral, conventional, and functional isokinetic strength ratios were calculated in 194 professional soccer players at the beginning of 15 consecutive seasons. 36 soccer players presented a moderate hamstring strain and 158 were not injured. The different calculated isokinetic ratios were compared with the right and left limb of the uninjured population. Different usual cutoffs were tested: at 0.85 and 0.90 for the bilateral concentric and eccentric hamstring-to-hamstring ratio, at 0.60 and 0.47 for the conventional hamstring-to-quadriceps ratio and at 0.80 and 1 for the mixed hamstring-to-quadriceps ratio. The specific ratios for the studied population were also determined by the 10th percentile and then tested. Hamstring strain prediction was established in terms of odds ratios. No cutoff with bilateral, conventional, or functional isokinetic strength ratio was predictive of hamstring strain after univariate analysis. Specific cutoffs determined from the studied population were not more predictive. Very few injured soccer players presented values under the cutoffs at 0.47 for the conventional ratio and at 0.80 for the mixed ratio. Regardless of their values, cutoffs of isokinetic strength ratios were not predictive of hamstring injuries. The use of isokinetic cutoffs is not recommended to predict hamstring muscle strain in professional soccer players.

Isokinetic strength assessment offers limited predictive validity for detecting risk of future hamstring strain in sport: a systematic review and meta-analysis

“…Similarly, there was no significant relationship with any strength ratio tested, despite previous reports and isolated study findings 17 19. This is consistent with recently published results, including risk examined against specified strength ratio cut-offs, showing a lack of predictive validity for detecting risk of hamstring muscle injury 20. Strength ratio calculation may have a more practical role elsewhere.…”

Change in knee flexor torque after fatiguing exercise identifies previous hamstring injury in football players

“…This analysis also documented optimal cutoff values for each variable, providing a “score” from the muscle‐specific IET which contributed to the perfect discrimination of previous hamstring injury (Table ). While previous research has found that specific hamstring tests were not strongly predictive of hamstring injury, the results of the present study highlight the value of measuring changes in torque production in a fatigued state. Although the differences were small, changes in knee flexion torque may be marginally better identifiers than the H:Q ratio (see Table ).…”

Adductor Muscles Strength and Strength Asymmetry as Risk Factors for Groin Injuries among Professional Soccer Players: A Prospective Study

“…The sample consisted of 45 healthy, male, professional outfield soccer players (mean ± SD; age: 22.8 ± 3.5 years; height: 1.82 ± 0.06 m; mass: 78.0 ± 7.0 kg), recruited from 3 Croatian Major League teams. Only players (i.e., 45 out of 68 players) who were injury-free 6 weeks before the start of preseason, and who played at least 45 min in more than 20 professional matches in the respective season, were included to decrease the influence of training and match exposures [23,24]. Thirteen out of 45 players were members of their respective national teams or U21 national teams.…”