This study aimed to investigate the relationship between the muscle shear modulus of the biceps brachii, urinary titin N-terminal fragment (UTF), and other damage markers after eccentric exercise. Seventeen healthy males performed five sets of ten eccentric exercises with dumbbells weighing 50% of the maximum voluntary contraction (MVC) at the elbow joint. Muscle shear modulus with range of interest set to only biceps brachii muscle measured by ultrasound shear wave elastography, UTF, MVC, range of motion (ROM), and soreness (SOR) were recorded before, immediately after, and 1, 24, 48, 72, 96, and 168 h after eccentric exercise. Each marker changed in a time course pattern, as found in previous studies. The peak shear modulus showed a moderate negative correlation with peak MVC (r = –0.531, P < 0.05) and a strong positive correlation with peak UTF (r = 0.707, P < 0.01). Our study results revealed a significant relationship between muscle strength, shear modulus measured by ultrasound SWE, and titin measured by UTF, as a non-invasive damage marker after eccentric exercise to track changes in EIMD.

• This study was investigated based on the hypothesis that the shear modulus measured by ultrasound shear wave elastography of biceps brachii muscle and urinary titin N-terminal fragment (UTF) after eccentric exercise that occurs during eccentric exercises are involved in damage markers similar to those used in previous studies.

• The results revealed that shear modulus showed a significant relationship between muscle strength and titin content.

• The relationship between shear modulus as an index of stiffness and titin measured by UTF will be useful for observing changes in skeletal muscle condition that result from high-intensity training and games/practices in the field of sports competition.