Isometric knee extension test: A practical, repeatable, and suitable tool for lower-limb screening among...

Area of Science:

• Gerontology
• Kinesiology
• Physical Therapy

Background:

• Sarcopenia, characterized by loss of muscle mass and function, is prevalent in institutionalized older adults.
• Effective screening tools are needed to identify individuals at risk for sarcopenia and related functional decline.

Purpose of the Study:

• To evaluate the intra- and inter-session repeatability of the isometric knee extension (IKE) test.
• To examine the relationship between IKE test performance and functional parameters and body composition factors associated with sarcopenia in institutionalized older adults.

Main Methods:

• Thirteen institutionalized older adults (mean age 87 years) underwent repeated maximal isometric knee extension tests.
• Functional assessments included Handgrip, 6-m Gait Speed, Time Up and Go (TUG), and Sit-to-stand tests.
• Body composition was assessed using appendicular lean mass adjusted by body mass index (ALM/BMI).
• Repeatability was analyzed using intraclass correlation coefficient (ICC) and standard error of measurement (SEM).

Main Results:

• The IKE test exhibited high to very high intra-session repeatability (CV ≤ 6.0%, ICC ≥ 0.989) and inter-session repeatability (ICC ≥ 0.959) for both legs.
• Significant positive correlations were observed between IKE test results and 6-m Gait Speed, ALM/BMI, and Handgrip strength.
• A significant negative association was found between dominant leg IKE/BM and TUG performance.

Conclusions:

• The isometric knee extension test is a reliable and repeatable measure for assessing lower-limb strength in institutionalized older adults.
• The IKE test shows significant associations with key functional and body composition indicators of sarcopenia.
• The IKE test is a practical and suitable screening tool for identifying sarcopenia risk in this population.