Muscle hardness measurement by using ultrasound elastography: a feasibility study

Area of Science:

• Biomechanics
• Musculoskeletal Imaging
• Exercise Physiology

Background:

• Vigorous exercise can lead to muscle hardening and delayed onset muscle soreness.
• Existing methods for measuring muscle hardness have limitations.
• Freehand ultrasound (US) elastography, initially applied in breast imaging, offers a potential new approach.

Purpose of the Study:

• To assess the feasibility of using US elastography to detect changes in muscle hardness.
• To investigate post-exercise alterations in elbow flexor muscles following eccentric contractions.

Main Methods:

• Six healthy males underwent eccentric exercise of elbow flexors.
• Ultrasound elastography with a stabilizer and reference gel pack was employed.
• Muscle hardness was quantified using strain ratios and compared with durometer measurements.

Main Results:

• US elastography revealed significant muscle hardening and subsequent recovery (P<0.01).
• Muscle hardness peaked on day 2 post-exercise and gradually decreased by day 4.
• Durometer measurements corroborated the US elastography findings; control arms showed no significant changes.

Conclusions:

• Ultrasound elastography is a feasible method for quantifying muscle hardness.
• The technique can generate a two-dimensional map illustrating muscle hardness variations.
• US elastography provides a reliable, non-invasive tool for assessing exercise-induced muscle changes.