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Background <p>Increased muscle stiffness and co-activation are common in knee osteoarthritis (KOA) and may contribute to balance impairments. To our knowledge, no study has examined whether these associations vary across specific movement phases in KOA. This study aimed to examine phase-specific associations among stiffness, co-activation, and balance in KOA and compare them with healthy controls.</p> Methods <p>Sixty-four older adults with KOA (69 ± 4&#xa0;years) and 25 controls participated. Quadriceps and hamstring stiffness were measured using shear-wave elastography, and co-activation was assessed via surface electromyography during squat-down (SD), stand-up (SU), and transition (SUSD). Balance was evaluated using the Y-Balance Test (YBT) and Balance Error Scoring System (BESS). Pearson correlations examined relationships between stiffness, co-activation, and balance in the KOA group.</p> Results <p>Compared with controls, KOA participants showed higher quadriceps stiffness, greater co-activation during SD and SU, and poorer dynamic balance (all p &lt; 0.001). In SD, co-activation was negatively correlated with balance (YBT r = −&#xa0;0.45 to −&#xa0;0.39; BESS r = 0.40) and stiffness (quadriceps r = -0.25; hamstrings r = −&#xa0;0.33; all p &lt; 0.05). In contrast, during SU and SUSD, co-activation was positively correlated with balance (YBT r = 0.61 to 0.67; BESS r = −&#xa0;0.37 to −&#xa0;0.35) and stiffness (quadriceps r = 0.56 to 0.58; hamstrings r = 0.71 to 0.73; all p &lt; 0.05).</p> Conclusion <p>Co-activation in KOA shows phase-specific associations with stiffness and balance. Rehabilitation should incorporate phase-specific neuromuscular strategies, particularly reducing maladaptive eccentric responses to improve balance and reduce fall risk.</p>

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Associations between muscle stiffness, muscle co-activation, and balance in older individuals with knee osteoarthritis: a cross-sectional study

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2025年12月7日

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  • Ping Liu,
  • Mohamad Shariff Bin A Hamid,
  • Yueyue Shi,
  • Xiaohan Fan,
  • Hengzhi Deng,
  • Eliza Hafiz,
  • Xuelin Zhang

摘要

Background

Increased muscle stiffness and co-activation are common in knee osteoarthritis (KOA) and may contribute to balance impairments. To our knowledge, no study has examined whether these associations vary across specific movement phases in KOA. This study aimed to examine phase-specific associations among stiffness, co-activation, and balance in KOA and compare them with healthy controls.

Methods

Sixty-four older adults with KOA (69 ± 4 years) and 25 controls participated. Quadriceps and hamstring stiffness were measured using shear-wave elastography, and co-activation was assessed via surface electromyography during squat-down (SD), stand-up (SU), and transition (SUSD). Balance was evaluated using the Y-Balance Test (YBT) and Balance Error Scoring System (BESS). Pearson correlations examined relationships between stiffness, co-activation, and balance in the KOA group.

Results

Compared with controls, KOA participants showed higher quadriceps stiffness, greater co-activation during SD and SU, and poorer dynamic balance (all p < 0.001). In SD, co-activation was negatively correlated with balance (YBT r = − 0.45 to − 0.39; BESS r = 0.40) and stiffness (quadriceps r = -0.25; hamstrings r = − 0.33; all p < 0.05). In contrast, during SU and SUSD, co-activation was positively correlated with balance (YBT r = 0.61 to 0.67; BESS r = − 0.37 to − 0.35) and stiffness (quadriceps r = 0.56 to 0.58; hamstrings r = 0.71 to 0.73; all p < 0.05).

Conclusion

Co-activation in KOA shows phase-specific associations with stiffness and balance. Rehabilitation should incorporate phase-specific neuromuscular strategies, particularly reducing maladaptive eccentric responses to improve balance and reduce fall risk.