Abstract
Background: This study evaluated the relationship between grip strength and forearm skeletal muscle architecture during maximal grip contractions. Grip strength is a gauge for many different health related attributes, yet research on muscle architecture has been primarily completed in lower limb studies. This study aims to develop a better understanding of how biomechanical architecture of muscle operates to produce force during maximal isometric contractions of the forearms.
Methods: Sixteen individuals participated in this investigation (12 males, 4 females, mean age: 20.6 ± 2.5 years, mean height: 177.8 ± 8.3cm, mean weight: 79.2 ± 17.6Kg). Participants tested grip strength by performing maximal voluntary isometric contractions (MVIC) using a Jamar Hand Dynamometer (Lafayette Instruments, Lafayette, IN, USA) in a narrow (position 2) and a wide (position 3) setting. Longitudinal and transverse ultrasound images were captured on participants’ right and left extensor carpi radialis longus (ECRL) muscle at rest and during MVIC. Muscle architecture was assessed by anatomical cross-sectional area (ACSA), muscle thickness (MT), and pennation angle (PA). All participants provided written informed consent before testing; the project was approved by the Marshall University Institutional Review Board (IRBnet#2113986).
Results: All data is presented as mean ± standard deviation. Grip strength was greater in the wide position (43.1 ± 9.8Kg) than the narrow position (42.1 ± 10.0Kg) but did not reach statistical significance (p=0.509). Anatomical Cross-Sectional Area increased with muscle contraction in both wide (32.9 ± 23.6cm2, p < 0.001) and narrow positions (26.9 ± 27.3cm2, p = 0.001). There was no significant difference in ACSA change between the narrow and wide grip during MVIC (6.0 ± 23.2 cm2, p = 0.317). Muscle thickness increased in the wide (0.81 ± 0.8cm, p < 0.001) and narrow (0.24 ± 0.6cm, p = 0.111) positions, but the increase in the narrow position did not reach statistical significance. There was a significant difference in MT change between the narrow and wide grip during MVIC (0.56 ± 0.59cm, p < 0.001). Pennation angle increased during muscle contraction in the narrow (3.1 ± 2.6°, p < 0.001) and the wide position (2.6 ± 2.5°, p < 0.001). There was no significant difference in PA change between the narrow and wide grip during MVIC (0.53 ± 3.4°, p = 0.540).
Conclusion: Results suggest that a greater muscle length in the wide grip position contributes to a less complainant tendon, lessening the change in muscular pennation angle as opposed to the narrow position. This may result in alterations in force production based on fiber architecture and arrangement.
Keywords: Muscle Architecture, MVIC, Extensor Carpi Radialis Longus, Pennation Angle, Anatomical Cross-Sectional Area, Muscle Thickness
Recommended Citation
Hutchison, J., Timmons, M., & Jones, B. (2025). Forearm Muscle Alterations During Maximal Voluntary Isometric Contraction. Appalachian Student Healthcare Research Review, 1(1). Retrieved from https://mds.marshall.edu/ashrr/vol1/iss1/1