(2015) demonstrated that the wrist extensor muscles of the forearm contribute more to joint rotational stiffness (JRS) than the wrist flexors during external wrist perturbations. This work serves as an important step to future research into workplace health and preventing injuries of the distal upper-limb. These findings demonstrate that sustained isometric extension/flexion contractions similarly impair tracking accuracy of the hand. However, error rapidly recovered, with no differences in error from baseline after 1-min post-fatigue. While there were no differences in tracking error between flexion/extension sessions, tracking error significantly increased immediately post-fatigue (Baseline: 1.40 ± 0.54°, Post-fatigue: 2.02 ± 0.51°, P < 0.05). Performance fatigability was assessed using various metrics to account for errors in position-tracking, error tendencies, and movement smoothness. Participants then performed 7 tracking trials from immediately post-fatigue to 10 min after. Participants then exerted either maximal wrist extension or flexion force (performed on separate days) against a force transducer until they were unable to maintain 25% of their pre-fatigue maximal voluntary contraction (MVC). Five baseline tracking trials were performed prior to the fatiguing task. A blue, circular target moved about the trajectory and participants tracked the target with a yellow circle (corresponding to the handle's position). While gripping the handle of a three-degrees-of-freedom wrist manipulandum, 12 male participants tracked a 2:3 Lissajous curve (☓2° wrist flexion/extension ☑8° radial/ulnar deviation). Thus, the purpose of this study was to examine how sustained isometric contractions of the wrist extensors/flexors influence hand-tracking accuracy. However, minimal fatigue research has been conducted at the wrist. 4Faculty of Health Sciences, Ontario Tech University, Oshawa, ON, Canadaĭue to their stabilizing role, the wrist extensor muscles demonstrate an earlier onset of performance fatigability and may impair movement accuracy more than the wrist flexors.3Robotics, Brain and Cognitive Sciences, Istituto Italiano di Tecnologia, Genoa, Italy.2Faculty of Applied Health Sciences, Brock University, St.
Published by John Wiley & Sons Ltd.Davis A. Despite relatively few studies meeting the inclusion criteria, this review provides practitioners with insight into which isometric training variables (eg, joint angle, intensity, intent) to manipulate to achieve desired morphological and neuromuscular adaptations.Įccentric fascicle force mechanical loading muscle stiffness strength tendon. Additionally, long muscle length training results in greater transference to dynamic performance. High-intensity (≥70%) contractions are required for improving tendon structure and function. Substantial improvements in muscular hypertrophy and maximal force production were reported regardless of training intensity. Isometric training at longer muscle lengths (0.86%-1.69%/week, ES = 0.03-0.09/week) produced greater muscular hypertrophy when compared to equal volumes of shorter muscle length training (0.08%-0.83%/week, ES = -0.003 to 0.07/week). Twenty-six research outputs were reviewed. These studies were evaluated further for methodological quality. English, full-text, peer-reviewed journal articles and unpublished doctoral dissertations investigating medium- to long-term (≥3 weeks) adaptations to isometric training in humans were identified. Exploration of the relevant subject matter was performed through MEDLINE, PubMed, SPORTDiscus, and CINAHL databases. The objective of this systematic review, therefore, was to detail the medium- to long-term adaptations of different types of isometric training on morphological, neurological, and performance variables. Understanding the adaptive response to specific loading parameters would be of benefit to practitioners.
However, little consensus exists regarding training guidelines for a variety of desired outcomes. Isometric training is used in the rehabilitation and physical preparation of athletes, special populations, and the general public.