An application of the flexible multibody approach used to estimate human skeleton loading

Skeletal loading can be estimated using several approaches. The most common approach is based on utilizing mechanical principles and ground reaction forces as predictors for skeletal loading. This method can be considered as a relatively simple approach since it cannot account for muscle forces. Flexible multibody approach allows for estimating skeletal loading and strains within the bones; once bone flexibility, muscle forces, ground reaction forces and the natural motion of a subject have been accounted for. This paper presents a summary that describes how deformable bodies can be introduced to the standard multibody formulation and explains the benefits and drawbacks. As an example of application, models used to assess tibial strains among two subjects are presented. The results of the multibody simulations are compared to in vivo studies, showing acceptable correlation and method performance.

The limitations of front-end loading in undergraduate university programs

This paper shows how Mead’s theory of emergence can prove explanatory in how the theory-practice gap is co-created and sustained in front-end loading university programs. Taking teacher education as an exemplar, we argue that the trainee teacher encounters different and oft-times conflicting environmental, social and cultural conditions in the two “fields of interaction” of the training program, namely, on-campus work and in-school experience. The argument draws on interview and focus group data collected via a study of first-year graduate teachers of an Australian teacher education program. We conclude that role taking and self-regulated behaviour within the two environmental fields of interaction in front-end loading programs inhibit the trainee professional from exercising the power of agency to implement theory learned at university in practice in the workplace. Further, we propose that Mead’s theory of emergence proves effective in explaining a major limitation of front-end-loaded university programs.

The limitations of front-end loading in undergraduate university programs

This paper shows how Mead’s theory of emergence can prove explanatory in how the theory-practice gap is co-created and sustained in front-end loading university programs. Taking teacher education as an exemplar, we argue that the trainee teacher encounters different and oft-times conflicting environmental, social and cultural conditions in the two “fields of interaction” of the training program, namely, on-campus work and in-school experience. The argument draws on interview and focus group data collected via a study of first-year graduate teachers of an Australian teacher education program. We conclude that role taking and self-regulated behaviour within the two environmental fields of interaction in front-end loading programs inhibit the trainee professional from exercising the power of agency to implement theory learned at university in practice in the workplace. Further, we propose that Mead’s theory of emergence proves effective in explaining a major limitation of front-end-loaded university programs.

Anodal-tDCS applied during unilateral strength training increases strength and corticospinal excitability in the untrained homologous muscle

Evidence suggests that the cross-transfer of strength following unilateral training may be modulated by increased corticospinal excitability of the ipsilateral primary motor cortex, due to cross-activation. Anodal-tDCS (a-tDCS) has been shown to acutely increase corticospinal excitability and motor performance, which may enhance this process. Therefore, we sought to examine changes in neural activation and strength of the untrained limb following the application of a-tDCS during a single unilateral strength training session. Ten participants underwent three conditions in a randomized, double-blinded crossover design: (1) strength training + a-tDCS, (2) strength training + sham-tDCS and (3) a-tDCS alone. a-tDCS was applied for 20 min at 2 mA over the right motor cortex. Unilateral strength training of the right wrist involved 4 × 6 wrist extensions at 70 % of maximum. Outcome measures included maximal voluntary strength, corticospinal excitability, short-interval intracortical inhibition, and cross-activation. We observed a significant increase in strength of the untrained wrist (5.27 %), a decrease in short-interval intracortical inhibition (−13.49 %), and an increase in cross-activation (15.71 %) when strength training was performed with a-tDCS, but not following strength training with sham-tDCS, or tDCS alone. Corticospinal excitability of the untrained wrist increased significantly following both strength training with a-tDCS (17.29 %), and a-tDCS alone (15.15 %), but not following strength training with sham-tDCS. These findings suggest that a single session of a-tDCS combined with unilateral strength training of the right limb increases maximal strength and cross-activation to the contralateral untrained limb.

Unilateral bicep curl hemodynamics: low-pressure continuous vs high-pressure intermittent blood flow restriction

 Light-load exercise training with blood flow restriction (BFR) increases muscle strength and size. However, the hemodynamics of BFR exercise appear elevated compared with non-BFR exercise. This questions the suitability of BFR in special/clinical populations. Nevertheless, hemodynamics of standard prescription protocols for BFR and traditional heavy-load exercise have not been compared. We investigated the hemodynamics of two common BFR exercise methods and two traditional resistance exercises. Twelve young males completed four unilateral elbow flexion exercise trials in a balanced, randomized crossover design: (a) heavy load [HL; 80% one-repetition maximum (1-RM)]; (b) light load (LL; 20% 1-RM); and two other light-load trials with BFR applied (c) continuously at 80% resting systolic blood pressure (BFR-C) or (d) intermittently at 130% resting systolic blood pressure (BFR-I). Hemodynamics were measured at baseline, during exercise, and for 60-min post-exercise. Exercising heart rate, blood pressure, cardiac output, and rate–pressure product were significantly greater for HL and BFR-I compared with LL. The magnitude of hemodynamic stress for BFR-C was between that of HL and LL. These data show reduced hemodynamics for continuous low-pressure BFR exercise compared with intermittent high-pressure BFR in young healthy populations. BFR remains a potentially viable method to improve muscle mass and strength in special/clinical populations.

Multibody approach to musculoskeletal and joint loading

Joint and muscular loads are the major internal loads in the human body. Knowing or being able to estimate those loads is of importance in multiple instances, such as in designing implants, predicting surgical outcomes, in estimating occupational loading, and in designing interventions. Unfortunately, the direct measurement of the body's internal forces is difficult, rather invasive, and requires surgical operations. Therefore, the need is growing for computational tools for muscular, bone and joint loading estimation. This article will present a review of the computational methods that can be utilized for musculoskeletal and joint system loading estimation. © 2014 CIMNE, Barcelona, Spain.