Author(s): PARODI, A., TORRES, C., ESCAJAL, B., MAGALLANES, C. , Institution: HIGHER INSTITUTE OF PHYSICAL EDUCATION, UNIVERSITY OF THE REPUBLIC, Country: URUGUAY, Abstract-ID: 342

INTRODUCTION:
Tensiomyography is a technique that allows a rapid, non-invasive assessment of the contractile mechanical characteristics of superficial muscles. However, few studies have analyzed the effect of overlying soft-tissue thickness (OSTT) on tensiomyographic assessment. The aim of this study was to examine the relationship between tensiomyographic parameters of the rectus femoris (RF) and OSTT assessed at the same measurement site.
METHODS:
In a sample of 109 healthy subjects (39 women; age = 37 ± 19 [minimum 18, maximum 82] years; body mass index = 25.4 ± 3.8 [minimum 19.5, maximum 36.4] kg·m⁻²) and using a TMG S2 system tensiomyograph (EMF-Furlan and Co., Ljubljana, Slovenia), the following RF variables were assessed in both lower limbs: contraction time (Tc), maximal radial displacement (Dm), delay time (Td), sustain time (Ts), and relaxation time (Tr). Measurements were performed at the site where the muscle belly reached its maximum thickness during voluntary contraction.
At the exact same location, OSTT (including skin, subcutaneous adipose tissue, and superficial fascia) was measured using a SonoSite Micromaxx ultrasound system (USA) in B-mode, with a frequency range of 6–13 MHz. Tensiomyographic parameters and OSTT were compared between lower limbs using the Wilcoxon signed-rank test to exclude laterality effects. Subsequently, correlations between tensiomyographic parameters and OSTT were analyzed using Spearman’s rho, with the right hemibody taken as reference.
RESULTS:
No significant differences were observed between limbs for any analyzed variables (p > 0.05), except for Td (p = 0.007, rrb = 0.31, difference = 2.3%), which was considered functionally negligible. A weak positive correlation was found between Tc and OSTT (rho = 0.288; p = 0.002), and a weak negative correlation between Dm and OSTT (rho = -0.321; p < 0.001). No other significant correlations were observed (p > 0.05).
CONCLUSION:
The observed correlations suggest that OSTT might exert a subtle mechanical damping effect, potentially delaying the detection of muscle deformation onset and attenuating the radial expansion signal. While this mechanism could help explain the associations found with Tc and Dm, the relatively low magnitude of the correlations indicates that OSTT accounts for only a limited portion of the total variance. Nevertheless, to further refine the interpretation of tensiomyographic data, it may be prudent to consider OSTT as a potential confounding factor, particularly when assessing populations with significant differences in subcutaneous fat thickness.