Horizontal and Multidirectional Single-Leg Hop Tests Predict Isokinetic Quadriceps and Hamstring Strengths After Anterior Cruciate Ligament Reconstruction
Abstract
Background:: After anterior cruciate ligament reconstruction (ACLR), isokinetic strength and single-leg hop tests (SLHT) are used to assess return to sport readiness. This study examined the relationships and predictive effects of isokinetic knee extension (Ex) and flexion (Flx) strength with 5 SLHTs at 6 to 8 months post-ACLR.
Hypothesis:: There would be significant correlation between knee Ex and Flx strengths on the operated side and 5 different SLHTs; SLHTs would significantly predict knee isokinetic Ex and Flx strength.
Study Design:: Cross-sectional study.
Level of Evidence:: Level 3.
Methods:: Fifty-one male participants underwent unilateral ACLR. Lysholm, International Knee Documentation Committee (IKDC), and Tegner scales were assessed preoperatively and 6 to 8 months postoperatively. At the same follow-up, isokinetic strength at 60°/s, 180°/s, and 240°/s and 5 SLHTs were tested on both limbs. Data were analyzed with paired t tests, Pearson correlations, Fisher’s exact test, and simple linear regression; limb symmetry index (LSI) cut-off was ≥85%.
Results:: Isokinetic strength and single-leg hop (SH), crossover hop, and medial side triple-hop (TH) distances did not differ significantly between limbs (P > 0.05), whereas TH and 90° medial rotation hop distances were significantly shorter on the operated side (P < 0.05). Participants’ Lysholm and IKDC scores improved significantly at 6 to 8 months post-ACLR (P < 0.001), but Tegner activity level did not change significantly (P > 0.05). High correlation was found between Ex strength at 60°/s and SH and TH distances on the operated side, and high-moderate correlations were found at 180°/s and 240°/s. Flx strengths showed a similar but slightly lower degree of correlation. Simple linear regression models revealed that especially SH and TH distances significantly predicted both Ex and Flx strengths (adjusted R2 0.26-0.52; P < 0.001). Among the LSI values, only a significant correlation was found between 60°/s Ex and TH LSI ratio (P = 0.01).
Conclusion:: The findings show that SH and TH tests were highly predictive of isokinetic knee strength after ACLR.
Clinical Relevance:: SLHTs after ACLR can be used as a practical and accessible complement to isokinetic measurements.
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BibTeX
@article{kırık2026horizontal,
title = {{Horizontal and Multidirectional Single-Leg Hop Tests Predict Isokinetic Quadriceps and Hamstring Strengths After Anterior Cruciate Ligament Reconstruction}},
author = {Ayşe Birsu Topcugil Kırık and Enes Akdemir and Emre Karaduman and Nizamettin Güzel and Ahmet Serhat Genç and Berna Anıl and Esra Korkmaz Salkılıç and Lokman Kehribar and Yılmaz Önder and Ali Kerim Yılmaz},
journal = {Sports Health},
year = {2026},
month = nov,
doi = {10.1177/19417381261486269},
url = {https://doi.org/10.1177/19417381261486269},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Horizontal and Multidirectional Single-Leg Hop Tests Predict Isokinetic Quadriceps and Hamstring Strengths After Anterior Cruciate Ligament Reconstruction
AU - Ayşe Birsu Topcugil Kırık
AU - Enes Akdemir
AU - Emre Karaduman
AU - Nizamettin Güzel
AU - Ahmet Serhat Genç
AU - Berna Anıl
AU - Esra Korkmaz Salkılıç
AU - Lokman Kehribar
AU - Yılmaz Önder
AU - Ali Kerim Yılmaz
PY - 2026
DA - 2026/11/04
JO - Sports Health
DO - 10.1177/19417381261486269
UR - https://doi.org/10.1177/19417381261486269
AB - Background:: After anterior cruciate ligament reconstruction (ACLR), isokinetic strength and single-leg hop tests (SLHT) are used to assess return to sport readiness. This study examined the relationships and predictive effects of isokinetic knee extension (Ex) and flexion (Flx) strength with 5 SLHTs at 6 to 8 months post-ACLR. Hypothesis:: There would be significant correlation between knee Ex and Flx strengths on the operated side and 5 different SLHTs; SLHTs would significantly predict knee isokinetic Ex and Flx strength. Study Design:: Cross-sectional study. Level of Evidence:: Level 3. Methods:: Fifty-one male participants underwent unilateral ACLR. Lysholm, International Knee Documentation Committee (IKDC), and Tegner scales were assessed preoperatively and 6 to 8 months postoperatively. At the same follow-up, isokinetic strength at 60°/s, 180°/s, and 240°/s and 5 SLHTs were tested on both limbs. Data were analyzed with paired t tests, Pearson correlations, Fisher’s exact test, and simple linear regression; limb symmetry index (LSI) cut-off was ≥85%. Results:: Isokinetic strength and single-leg hop (SH), crossover hop, and medial side triple-hop (TH) distances did not differ significantly between limbs (P > 0.05), whereas TH and 90° medial rotation hop distances were significantly shorter on the operated side (P < 0.05). Participants’ Lysholm and IKDC scores improved significantly at 6 to 8 months post-ACLR (P < 0.001), but Tegner activity level did not change significantly (P > 0.05). High correlation was found between Ex strength at 60°/s and SH and TH distances on the operated side, and high-moderate correlations were found at 180°/s and 240°/s. Flx strengths showed a similar but slightly lower degree of correlation. Simple linear regression models revealed that especially SH and TH distances significantly predicted both Ex and Flx strengths (adjusted R2 0.26-0.52; P < 0.001). Among the LSI values, only a significant correlation was found between 60°/s Ex and TH LSI ratio (P = 0.01). Conclusion:: The findings show that SH and TH tests were highly predictive of isokinetic knee strength after ACLR. Clinical Relevance:: SLHTs after ACLR can be used as a practical and accessible complement to isokinetic measurements.
SN - 1941-7381
SN - 1941-0921
ER -