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Background <p>The assessment of the hamstrings-to-quadriceps (H:Q) strength ratio using an isokinetic dynamometer is commonly performed throughout the football season and is frequently used as an indicator of potential lower-limb injury risk. However, these evaluations are typically conducted under non-fatiguing conditions, even though most football-related lower-limb muscle injuries occur when players are already experiencing significant neuromuscular fatigue.</p> Aims <p>The aims of the present study were to (a) compare H:Q strength ratios across repetitions during a fatigue-inducing protocol in professional female football players and (b) evaluate the Fatigue Index (FI) of the knee flexors and extensors in response to the same fatigue-inducing protocol.</p> Methods <p>Fifteen professional football players (21.8 ± 5.3&#xa0;years; 60.1 ± 8.7&#xa0;kg; 163.6 ± 7.6&#xa0;cm) performed a 30-repetition concentric isokinetic fatigue test protocol. Peak knee joint torques were computed for each repetition, and the conventional H:Q ratio (the ratio between the hamstrings and quadriceps concentric peak torque) was then calculated.</p> Results <p>The 30-repetition isokinetic fatigue test significantly reduced Peak Torque (PT) for both knee extensors (34%) and flexors (47%). This PT reduction began notably from the 7th and 8th repetitions, respectively (<i>P</i> ≤ 0.001). FI was significantly greater for the knee flexors (47%) compared with the extensors (34%) (<i>P</i> ≤ 0.001). Crucially, the H:Q ratio decreased significantly only after the 15th repetition, reaching its lowest value at the end of the test H:Q<sub>27–30</sub> (0.52 ± 0.10), <i>P</i> ≤ 0.001 vs. (H:Q<sub>3–6</sub> (0.64 ± 0.10).</p> Conclusions <p>These results show a reduction (<i>P</i> ≤ 0.001) on H:Q ratio after fatigue-induced condition, and a greater reduction in the knee flexors (47% vs 34%). This fatigue-induced neuromuscular state may increase the potential risk of lower-limb injury in female football players. Considering the hamstrings’ susceptibility to fatigue, conditioning programs for female athletes should emphasize fatigue resistance to enhance performance and reduce the likelihood of injury.</p>

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Hamstring-to-quadriceps fatigue ratio in female professional football players

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年2月11日

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  • Rúbia Anelise Trabach Godinho,
  • Anderson Rech,
  • Enzo Guerra,
  • Diego Busin,
  • Douglas Jean Preussler Turella,
  • Filipe Veeck,
  • Ronei Silveira Pinto

摘要

Background

The assessment of the hamstrings-to-quadriceps (H:Q) strength ratio using an isokinetic dynamometer is commonly performed throughout the football season and is frequently used as an indicator of potential lower-limb injury risk. However, these evaluations are typically conducted under non-fatiguing conditions, even though most football-related lower-limb muscle injuries occur when players are already experiencing significant neuromuscular fatigue.

Aims

The aims of the present study were to (a) compare H:Q strength ratios across repetitions during a fatigue-inducing protocol in professional female football players and (b) evaluate the Fatigue Index (FI) of the knee flexors and extensors in response to the same fatigue-inducing protocol.

Methods

Fifteen professional football players (21.8 ± 5.3 years; 60.1 ± 8.7 kg; 163.6 ± 7.6 cm) performed a 30-repetition concentric isokinetic fatigue test protocol. Peak knee joint torques were computed for each repetition, and the conventional H:Q ratio (the ratio between the hamstrings and quadriceps concentric peak torque) was then calculated.

Results

The 30-repetition isokinetic fatigue test significantly reduced Peak Torque (PT) for both knee extensors (34%) and flexors (47%). This PT reduction began notably from the 7th and 8th repetitions, respectively (P ≤ 0.001). FI was significantly greater for the knee flexors (47%) compared with the extensors (34%) (P ≤ 0.001). Crucially, the H:Q ratio decreased significantly only after the 15th repetition, reaching its lowest value at the end of the test H:Q27–30 (0.52 ± 0.10), P ≤ 0.001 vs. (H:Q3–6 (0.64 ± 0.10).

Conclusions

These results show a reduction (P ≤ 0.001) on H:Q ratio after fatigue-induced condition, and a greater reduction in the knee flexors (47% vs 34%). This fatigue-induced neuromuscular state may increase the potential risk of lower-limb injury in female football players. Considering the hamstrings’ susceptibility to fatigue, conditioning programs for female athletes should emphasize fatigue resistance to enhance performance and reduce the likelihood of injury.