Differences in non-weight-bearing and weight-bearing measures of lower leg muscle elasticity using shear wave...

Elasticity is a biomechanical property of muscle necessary for physical function and can be measured with shear wave elastography (SWE). SWE may be useful in diagnosing pathology, predicting injury, and monitoring rehabilitation. This would be beneficial for smaller muscles working synergistically to resist external loads during functional activities. Establishing clinical measures of elasticity in larger sample sizes is necessary prior to its use in assessing pathology and guiding intervention.

The study's primary aim was to investigate differences in elasticity for the tibialis anterior (TA), tibialis posterior (TP), peroneal longus (PL), and peroneal brevis (PB) muscles. It was hypothesized that there would be a statistically-significant difference in muscle elasticity both within and between non-weight-bearing (NWB) and weight-bearing (WB) positions.

Same-day, repeated-measures, cross-sectional design incorporating 109 healthy, recreationally active adults. Elasticity (kPa) was measured in NWB and 90 % WB.

There was a statistically-significant interaction between muscle (TA, TP, PL, PB) and position (NWB, WB). Utilizing pairwise simple effects with Bonferroni correction, there was a significant (p ≤ 0.001-0.007) difference within muscles for NWB measures. WB measures revealed a significant (p ≤ 0.001) difference within muscles, except the TA-PB (p = 1.000). A significant (p ≤ 0.001-0.018) difference was found between NWB and WB positions for the TA, TP, and PB but not the PL (p = 0.140).

The utility of SWE may help describe how the biomechanical property of elasticity differs between resting positions and functional states of muscle contraction. These findings may aid future clinical applications of SWE for injury prevention, rehabilitation, and physical performance.