Angle-Specific Torque Profile Analysis in the Wrist Joint

Overview

The wrist joint performs various tasks at multiple angles during daily activities, both in flexion and extension positions. Among the parameters that facilitate these tasks, strength-particularly in relation to coordination and motor control-plays a key role. Therefore, identifying potential strength deficits is important for maintaining the continuity of daily functional tasks. In the literature, a wide range of methods exist for evaluating strength, from manual tests to advanced technological devices (references). One such method, isokinetic dynamometry, is considered among the most reliable due to its ability to provide objective and standardized measurements across different types of muscle contractions (isometric, isotonic, and isokinetic). Isokinetic dynamometers yield various data including peak torque, average torque, total work, fatigue index, and torque slope. Researchers frequently interpret findings based on peak or average torque values generated during isokinetic contractions. These torque measures provide an overall representation of strength during a given movement. In wrist movements, rather than a single muscle, muscle groups are responsible for executing motion. However, when only peak or average torque at a single joint angle is assessed, the presence or absence of weakness in the movement can be detected, but it offers limited information. If weakness exists, identifying the specific joint angle at which it occurs can provide more direct insights into which muscles may be impaired. Furthermore, angle-specific profiling allows for characterization of muscle behavior throughout the movement, offering valuable information about potential kinematic disruptions. Having normative data on these profiles enables the detection of deviations from typical patterns across the full range of motion, which can be beneficial for both diagnosis and treatment planning. However, to derive such benefits, it is critical that the data be obtained using reliable methods. Reliability refers to the degree to which an instrument or technique yields consistent results across repeated measurements, and is a prerequisite for usability. Statistical Parametric Mapping (SPM) is an increasingly popular method that enables angle-specific torque analysis, providing clinically and scientifically meaningful information on muscle strength. Angle-specific mapping is considered the "gold standard" because it presents torque values across the entire joint range, eliminating the need for interpolation between angles. For example, during daily activities, the wrist joint commonly operates within a range from 40° extension to 38° flexion. Therefore, measuring strength at only one joint angle may not be sufficient to reflect the potential limitations experienced in everyday tasks. Despite its advantages, no reliability study involving SPM analysis has been found for the wrist joint. Furthermore, there is currently no study providing normative data for SPM-based analysis in the wrist. The aim of this study is to examine the reliability of angle-specific torque profile analysis during wrist flexion and extension movements and to provide normative data for healthy young adults.