Abstract
ABSTRACT
Ultrasound-derived morphological measures of quadriceps cross-sectional area (CSA) and echo intensity (EI) are often used to assess lower-body muscle size and quality in older adults. Muscle CSA and EI of the quadriceps have been shown to be significantly correlated with physical performance outcomes, including gait speed and vertical jump power; however, their association with postural balance performance remains unclear. PURPOSE: The purpose of this study was to examine the relationships between unilateral postural balance performance and quadriceps muscle morphology (CSA and EI) in older men. METHODS: Fourteen healthy older men (mean ± SD: age = 69 ± 6 years; body mass = 86 ± 14 kg; height = 178 ± 6 cm) volunteered to participate in this study. Unilateral postural balance was assessed on the right leg using a commercially available balance testing system that quantified balance via the overall stability index (OSI), with lower values indicating less postural sway and better balance. Panoramic ultrasound imaging of the quadriceps, including the rectus femoris (RF) and vastus lateralis (VL), was performed on the right thigh to determine the CSA (cm2) and EI (AU) of each muscle. Images were obtained in the transverse plane at 50% of the distance between the greater trochanter and the lateral epicondyle of the femur while participants rested supine with the lower limbs relaxed. Two images were collected for each participant, and the mean CSA and EI values of the RF and VL were analyzed. Higher CSA values reflect greater muscle size, whereas lower EI values indicate reduced intramuscular fat and connective tissue content and thus, superior muscle quality. Pearson correlation coefficients (r) were used to examine the relationships between OSI and muscle morphology measures of the RF and VL. RESULTS: Mean ± SD values for CSA and EI were 5.93 ± 1.39 cm2 and 81.63 ± 7.18 AU for the RF and 20.60 ± 4.20 cm2 and 74.92 ± 5.27 AU for the VL, respectively. The mean ± SD for OSI was 1.46 ± 0.79. Correlation analysis indicated that OSI was significantly related to CSA (r = -0.539, P = 0.047) and EI (r = 0.589, P = 0.027) of the RF; however, OSI was not significantly related to CSA (r = 0.042, P = 0.886) and EI (r = 0.156, P = 0.593) of the VL. CONCLUSION: These findings demonstrate that unilateral postural balance performance is significantly related to muscle size and quality of the RF but not the VL in older men. The biarticular function of the RF and its role as a hip flexor may explain its greater relevance to postural stability compared with the monoarticular VL. Clinicians and practitioners may consider incorporating RF muscle morphology assessments into balance evaluation protocols, as these measures may serve as an additional screening tool for identifying individuals with impaired postural control. Given that balance impairments are a major contributor to falls during physical activity, RF muscle size and quality may also have meaningful implications for the assessment and prediction of falls risk in older adults.
Recommended Citation
Khartabil, Alexandra L. and Palmer, Ty B.
(2026)
"Relationships between Postural Balance Performance and Muscle Morphology of the Quadriceps in Healthy Older Men,"
International Journal of Exercise Science: Conference Proceedings: Vol. 2:
Iss.
18, Article 71.
Available at:
https://digitalcommons.wku.edu/ijesab/vol2/iss18/71