Changes in forearm muscle stiffness in relation to grip strength

Grip strength plays a critical role in sports involving the upper extremities, prompting extensive research in this area. This study investigated the forearm muscles, which are considered to be closely associated with grip strength, with the aim of quantitatively evaluating how individual muscles are influenced by variations in grip strength by using shear wave speed measurements.

Grip strength was measured using a grip strength dynamometer, and muscle stiffness was evaluated using shear wave elastography to determine shear wave speed. Forearm muscle shear wave speed measurements were performed on nine adult men at two grip strength levels: 0 kg and 5 kg.

The flexor digitorum superficialis (0 kg: 2.61 ± 0.24 m/s; 5 kg: 5.46 ± 1.51 m/s; P = 0.001; d = 2.631), flexor carpi ulnaris (0 kg: 3.11 ± 0.40 m/s; 5 kg: 3.75 ± 0.29 m/s; P = 0.005; d = 1.824), and flexor digitorum profundus (0 kg: 2.30 ± 0.14 m/s; 5 kg: 6.50 ± 0.75 m/s; P = 0.000; d = 7.819) all showed significant increases in shear wave speed at 5 kg than at 0 kg. Quantitative analysis of the forearm muscles revealed that the flexor digitorum superficialis, flexor carpi ulnaris, and flexor digitorum profundus significantly contribute to grip strength.

These findings indicate that training these specific muscles could be beneficial not only for athletes but also for older adults engaged in upper limb sports and physical activities.