Most overuse tendinopathies are thought to be associated with repeated microstrain below the failure threshold, analogous to the fatigue failure that affects materials placed under repetitive loading. Investigating the progression of fatigue damage within tendons is therefore of critical importance. There are obvious challenges associated with the sourcing of human tendon samples for in vitro a...

Human muscle fatigue is considered to be one of the main reasons for Musculoskeletal Disorder (MSD). Recent models have been introduced to define muscle fatigue for static postures. However, the main drawbacks of these models are that the dynamic effect of the human and the external load are not taken into account. In this paper, each human joint is assumed to be controlled by two muscle groups...

One aspect of motor fatigue is the exercise-induced reduction of neural activity to voluntarily drive the muscle or muscle group. Functional magnetic resonance imaging provides access to investigate the neural activation on the whole brain level and studies observed changes of activation intensity after exercise-induced motor fatigue in the sensorimotor cortex. However, in human, little evidenc...

Human dentin is susceptible to failure under repetitive cyclic-fatigue loading. This investigation seeks to address the paucity of data that reliably quantify this phenomenon. Specifically, the effect of alternating vs. mean stresses, characterized by the stress- or load-ratio R (ratio of minimum-to-maximum stress), was investigated for three R values (-1, 0.1, and 0.5). Dentin was observed to ...

The effects of fatigue on the ground reaction force (GRF) and the vibrations of the human lower extremity soft tissues are studied in this paper. A recently developed multiple degreesof-freedom mass-spring-damper model of the human body during running is used for this purpose. The model is able to take the muscle activity into account by using a nonlinear controller that tunes the mechanical pr...

The tensile fatigue properties of the collagen fibre meshwork in normal human articular cartilage were measured by subjecting isolated specimens of post-mortem femoral head cartilage to cyclic tensile stress. The results of the study showed (1) that the collagen fibre meshwork is fatigue prone and (2) that its fatigue strength decreases rapidly with age. Extrapolation of the data to physiologic...

The influence of tubule orientation on the transition from fatigue to fatigue crack growth in human dentin was examined. Compact tension (CT) and rectangular beam specimens were prepared from the coronal dentin of molars with three unique tubule orientations (i.e., 0 degrees , 45 degrees and 90 degrees). The CT specimens (N=25) were used to characterize fatigue crack initiation and steady-state...

BACKGROUND Muscle fatigue has high relevance in human performance yet little research has evaluated how it should be assessed. OBJECTIVE To perform a pilot study to identify suitable methods of generating and assessing fatigue of the trunk flexor and extensor muscles. METHODS Sixteen university rugby players (mean (SEM) age 21.9 (0.2) years) were recruited and subjected to four protocols (A...

The study of human fatigue stretches back centuries and remains a significant part of medical and social discourse. In the exercise sciences fatigue is routinely related to the ability to produce muscle force or to the recovery from force decrements. However, the study of fatigue has by virtue of the experimental paradigm excluded the subjective sense a person attributes to an event or experien...