A Dynamic Submaximal Fatigue Protocol Alters Wrist Biomechanical Properties and Proprioception

Abstract

Fatigue is a temporary condition that arises as a result of intense and/or prolonged use of muscles and can affect skilled human performance. Therefore, the quantitative analysis of these effects is a topic of crucial interest in both ergonomics and clinical settings. This study introduced a novel protocol, based on robotic techniques, to quantitatively assess the effects of fatigue on the human wrist joint. A wrist manipulandum was used for two concurrent purposes: (1) implementing the fatigue task and (2) assessing the functional changes both before and at four time points after the end of the fatigue task. Fourteen participants completed the experimental protocol, which included the fatigue task and assessment sessions over 2 days. Specifically, the assessments performed are related to the following indicators: (1) isometric forces, (2) biomechanical properties of the wrist, (3) position sense, and (4) stretch reflexes of the muscles involved. The proposed fatigue task was a short-term, submaximal and dynamic wrist flexion/extension task designed with a torque opposing wrist flexion. A novel task termination criterion was employed and based on a percentage decrease in the mean frequency of muscles measured using surface electromyography. The muscle fatigue analysis demonstrated a change in mean frequency for both the wrist flexors and extensors, however, only the isometric flexion force decreased 4 min after the end of the task. At the same time point, wrist position sense was significantly improved and stiffness was the lowest. Viscosity presented different behaviors depending on the direction evaluated. At the end of the experiment (about 12 min after the end of the fatigue task), wrist position sense recovered to pre-fatigue values, while biomechanical properties did not return to their pre-fatigue values. Due to the wide variety of fatigue tasks proposed in the literature, it has been difficult to define a complete framework that presents the dynamic of fatigue-related changes in different components associated with wrist function. This work enables us to discuss the possible causes and the mutual relationship of the changes detected after the same task.

Prioritized adjustments in posture stabilization and adaptive reaching during neuromuscular fatigue of lower-limb muscles

“…Conversely, the Fatigue group also exhibited increased activation of the anterior deltoid (AD) muscle, alongside more frequent adjustments in hand movement trajectory – as evidenced by higher hand path variability (HPV) values ( Figure 3 ) – suggesting a greater reliance on visual input for correcting movement trajectories. This may be an attempt to offset the unreliable proprioceptive feedback from fatigued muscles (14, 88, 92). Additionally, the elevated AD muscle activity during the anticipatory phase suggests that participants pre-activated this muscle to enhance its response to force field disturbances, thereby increasing the muscle’s “apparent stiffness”, which has been broadly defined as the change in force per unit change in joint angle (93, 94).…”

“…Exercise-induced neuromuscular fatigue (NMF) is characterized by a temporary reduction in the ability of a muscle to produce force and/or power, (1)(2)(3). This phenomenon affects various dimensions of human motor function, including the planning of motor activities (4-7), coordination (8)(9)(10)(11), balance (12), sensorimotor integration (13,14), limb proprioception (15,16) and muscle activation patterns (17). Furthermore, NMF adversely affects gait characteristics (18)(19)(20)(21) and posture stabilization (22)(23)(24).…”

How does a motor or cognitive dual-task affect our sense of upper limb proprioception?

“…The influence of DTi on sensory processes has also been studied with postural sway and stability [ 24 ], visual attention [ 25 ] and conscious proprioception [ 19 , 22 ]. However, there is limited evidence regarding these effects involving the upper limbs [ 26 , 27 ]. Upper limb multitasking has become central to today’s complex work environment [ 28 ], whether that includes manual labour or working from a computer.…”

Kinematics but not kinetics alterations to single-leg drop jump movements following a subject-tailored fatiguing protocol suggest an increased risk of ACL injury

“…The state of fatigue often results in performance degradation, observed during the execution of several motor tasks including balance ( 4 ), walking ( 5 – 8 ), reaching movements ( 9 ), dynamic loading during running ( 10 , 11 ), and shock absorption during landing ( 12 , 13 ). Furthermore, recent results suggests that neuromuscular fatigue also affects basic mechanisms of human motor control, causing transient alterations to movement planning ( 14 ), sensorimotor integration ( 15 , 16 ), joint position sense ( 17 ) and postural control ( 18 – 20 ). Whether these alterations in force generation and control mechanisms lead to inappropriate motor commands ( 21 ) that increase the risk of musculoskeletal injury is still unclear.…”