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Peer-reviewedCC BYJournal of Sport and Health Science

Deficits in quadriceps voluntary activation following anterior cruciate ligament reconstruction do not improve over time despite increases in quadriceps strength: A systematic review with meta-regression analyses of temporal trends

  • Shane C. Scott1
  • Daniel Kadlec2
  • Dana Hince3
  • Kieren G. Hill2
  • Ebonie Rio4
  • Ann-Maree Vallence5
  • George H. White3
  • Myles C. Murphy3
5 affiliations
  1. 1Centre for Injury Prevention and Pain, Institute for Health Research, The University of Notre Dame Australia, Fremantle, WA 6160, Australia; Nutrition and Health Innovation Research Institute, Edith Cowan University, Joondalup, WA, 6027, Australia; Corresponding author.
  2. 2Centre for Injury Prevention and Pain, Institute for Health Research, The University of Notre Dame Australia, Fremantle, WA 6160, Australia; Nutrition and Health Innovation Research Institute, Edith Cowan University, Joondalup, WA, 6027, Australia
  3. 3Centre for Injury Prevention and Pain, Institute for Health Research, The University of Notre Dame Australia, Fremantle, WA 6160, Australia
  4. 4La Trobe Sport and Exercise Medicine Research Centre, La Trobe University, Bundoora, VIC 3086, Australia; The Victorian Institute of Sport, Albert Park, VIC 3206, Australia
  5. 5School of Psychology, College of Health and Education, Murdoch University, WA 6150, Australia; Centre for Healthy Ageing, Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, WA 6150, Australia
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Abstract

Background: Quadriceps weakness is common following anterior cruciate ligament reconstruction (ACLR). Voluntary activation (VA) deficits may contribute to persistent weakness, but their recovery trajectory remains unclear. This systematic review examined temporal changes in quadriceps strength and VA following ACLR. Methods: Six databases and 2 clinical trial registries were searched to March 2025. Studies reporting quadriceps strength and VA following ACLR were included. Random-effects meta-analyses and meta-regression examined temporal trends. Risk of bias was assessed using JBI tools and certainty of evidence using GRADE. Results: Fifty studies (1772 participants; 91 effect sizes) were included. Three-level meta-regression demonstrated that VA showed no significant improvement over time (0.03% per month, 95% confidence interval (95%CI): −0.25% to 0.29%; mean = 86.8%, 95%CI: 83.9%–89.8%, p = 0.876). Quadriceps strength improved nonlinearly ( Q = 31.53, p < 0.001), reaching 2.63 Nm/kg (95%CI: 2.00–3.27) by 69 months. Participant age ( p = 0.60), sex ( p = 0.50), assessment position ( p = 0.44), graft type ( p = 0.32) or primary vs . secondary reconstruction ( p = 0.56) did not moderate VA. Studies that measured VA with the central activation ratio overestimated VA compared to the interpolated twitch technique by 6.5% (95%CI: 2.4%–10.6%, p = 0.002). Evidence certainty was rated as very low. Conclusion: Following typical rehabilitation, quadriceps strength improved over time, whereas VA showed no detectable recovery. Strength recovery may therefore occur despite ongoing impairments in neural activation, suggesting strength symmetry alone may overestimate neuromuscular recovery. Given the very low certainty of evidence, these findings should be interpreted cautiously.

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Cite

BibTeXRIS
BibTeX
@article{scott2026deficits,
  title = {{Deficits in quadriceps voluntary activation following anterior cruciate ligament reconstruction do not improve over time despite increases in quadriceps strength: A systematic review with meta-regression analyses of temporal trends}},
  author = {Shane C. Scott and Daniel Kadlec and Dana Hince and Kieren G. Hill and Ebonie Rio and Ann-Maree Vallence and George H. White and Myles C. Murphy},
  journal = {Journal of Sport and Health Science},
  year = {2026},
  month = oct,
  doi = {10.1016/j.jshs.2026.101160},
  url = {https://doi.org/10.1016/j.jshs.2026.101160},
  note = {CC BY},
}
RIS
TY  - JOUR
TI  - Deficits in quadriceps voluntary activation following anterior cruciate ligament reconstruction do not improve over time despite increases in quadriceps strength: A systematic review with meta-regression analyses of temporal trends
AU  - Shane C. Scott
AU  - Daniel Kadlec
AU  - Dana Hince
AU  - Kieren G. Hill
AU  - Ebonie Rio
AU  - Ann-Maree Vallence
AU  - George H. White
AU  - Myles C. Murphy
PY  - 2026
DA  - 2026/10/31
JO  - Journal of Sport and Health Science
DO  - 10.1016/j.jshs.2026.101160
UR  - https://doi.org/10.1016/j.jshs.2026.101160
AB  - Background: Quadriceps weakness is common following anterior cruciate ligament reconstruction (ACLR). Voluntary activation (VA) deficits may contribute to persistent weakness, but their recovery trajectory remains unclear. This systematic review examined temporal changes in quadriceps strength and VA following ACLR. Methods: Six databases and 2 clinical trial registries were searched to March 2025. Studies reporting quadriceps strength and VA following ACLR were included. Random-effects meta-analyses and meta-regression examined temporal trends. Risk of bias was assessed using JBI tools and certainty of evidence using GRADE. Results: Fifty studies (1772 participants; 91 effect sizes) were included. Three-level meta-regression demonstrated that VA showed no significant improvement over time (0.03% per month, 95% confidence interval (95%CI): −0.25% to 0.29%; mean = 86.8%, 95%CI: 83.9%–89.8%, p = 0.876). Quadriceps strength improved nonlinearly ( Q = 31.53, p < 0.001), reaching 2.63 Nm/kg (95%CI: 2.00–3.27) by 69 months. Participant age ( p = 0.60), sex ( p = 0.50), assessment position ( p = 0.44), graft type ( p = 0.32) or primary vs . secondary reconstruction ( p = 0.56) did not moderate VA. Studies that measured VA with the central activation ratio overestimated VA compared to the interpolated twitch technique by 6.5% (95%CI: 2.4%–10.6%, p = 0.002). Evidence certainty was rated as very low. Conclusion: Following typical rehabilitation, quadriceps strength improved over time, whereas VA showed no detectable recovery. Strength recovery may therefore occur despite ongoing impairments in neural activation, suggesting strength symmetry alone may overestimate neuromuscular recovery. Given the very low certainty of evidence, these findings should be interpreted cautiously.
SN  - 2095-2546
ER  -