Physiological and biomechanical analysis of prolonged and repeated bouts of load carriage

Previous work has attempted to define the physiological determinants of load carriage over a single day of load carriage, primary aims of this thesis were to determine the physiological and biomechanical changes as a result of load carriage and to explore the causes of these changes during load carriage and to explore these changes over multiple days of activity. A secondary aim was to explore individual differences in performance and possible mechanisms for this. Chapter 4 observed acute changes in vertical ground reaction force, supported by effect sizes which suggests individual differences in performances (loading peak dCohens=1.66 and dGlass 4.49). These findings were supported by no change in first negative rate which suggests increased knee flexion is occurring to mitigate the effect of the load. Differences in anteroposterior ground reaction force variables suggest that changes in gait may affect movement economy. Energy expenditure was shown to be correlated to a number of strength variables, such as ankle plantarflexion (r=-0.47) and knee extensors(r=-0.46). Similar variables were studied as a result of 2 hours treadmill load carriage in chapter 5. An additional variable was the study of torque at specific joint angles in addition to peak torque. Drift was observed for V̇O2 (68.93%). The torque curves showed significant reduction for load carriage, around the optimum muscle lengths for force (Knee extension at 180°s-1: 95°-125°, knee flexion at 180°s-1: 95°-125°) with findings supported by the peak torque values, suggesting there is no shift in muscle function. These findings were supported by associations between knee extension neuromuscular function scores, ankle plantarflexion neuromuscular function scores and energy cost variables which suggest that reductions in neuromuscular function may account for the increased energy cost. Chapter 6 observed load carriage on repeated days. The chapter observed that energy cost did not recover to baseline 24 hours post day one (4.41%). Further increases in energy cost and V̇O2 were observed post day two for energy expenditure and V̇O2 which suggest that a cumulative increase in energy cost as a result of load carriage occurred. Knee extension at 60°s-1 and 0°s-1 was shown to not recover 24 hours post day one, these variables were shown to show increased reduction for post day two and day three. Similar findings were observed within the ankle plantarflexors but no significant changes were observed for knee flexion and ankle dorsiflexion. Variables were also studied in a field setting during a >12hour load carriage task by Greek Special Forces soldiers. This study observed increased Medial and lateral deviations of the centre of pressure which suggests ankle instability even during unloaded walking as a result of load carriage. Large reductions were observed in vertical jump height and power as a result of the task, however this did not correlate to any biomechanical findings

Including Generative Mechanisms in Project scheduling using Hybrid Simulation

Scheduling is central to the practice of project management and a topic of significant interest for the operations research and management science academic communities. However, a rigour-relevance gap has developed between the research and practice of scheduling that mirrors similar concerns current in management science. Closing this gap requires a more accommodative philosophy that can integrate both hard and soft factors in the construction of project schedules. This paper outlines one interpretation of how this can be achieved through the combination of discrete event simulation for schedule construction and system dynamics for variable resource productivity. An implementation was built in a readily available modelling environment and its scheduling capabilities tested. They compare well with published results for commercial project scheduling packages. The use of system dynamics in schedule construction allows for the inclusion of generative mechanisms, models that describe the process by which some observed phenomenon is produced. They are powerful tools for answering questions about why things happen the way they do, a type of question very relevant to practic

Project management frameworks and practitioner preferences for capturing lessons learned on projects

This study focuses on how practitioners view learning activities in projects and how these activities are influenced by the approach or emphasis espoused in different reference texts. The perceived importance of learning lessons in projects was surveyed in the literature, establishing the difficulties encountered, various methods for process improvement and the realities of current practice. The practices of individuals working within two major project management frameworks used in developed English-speaking economies were compared. A survey was constructed to address the question. Data from a pilot survey support the theory that the PMBoK and PRINCE2 are not perceived as synonymous and that differences will be more evident with a larger dataset. Inferences are drawn linking the pilot survey to the outcomes of previous studies and making recommendations for further research.</jats:p

Wall Adhesion and Constitutive Modelling of Strong Colloidal Gels

Wall adhesion effects during batch sedimentation of strongly flocculated colloidal gels are commonly assumed to be negligible. In this study in-situ measurements of colloidal gel rheology and solids volume fraction distribution suggest the contrary, where significant wall adhesion effects are observed in a 110mm diameter settling column. We develop and validate a mathematical model for the equilibrium stress state in the presence of wall adhesion under both viscoplastic and viscoelastic constitutive models. These formulations highlight fundamental issues regarding the constitutive modeling of colloidal gels, specifically the relative utility and validity of viscoplastic and viscoelastic rheological models under arbitrary tensorial loadings. The developed model is validated against experimental data, which points toward a novel method to estimate the shear and compressive yield strength of strongly flocculated colloidal gels from a series of equilibrium solids volume fraction profiles over various column widths.Comment: 37 pages, 12 figures, submitted to Journal of Rheolog

Characteristics of torque production of the lower limb are significantly altered after 2 hours of treadmill load carriage

Load carriage is seldom completed in isolation, meaning load bearers need to be physically capable of physical activity after the load carriage task. This study aims to examine changes in lower limb muscle strength, as measured by torque production across a range of joint angles as a result of prolonged load carriage. Thirty-four healthy participants underwent two hours of loaded or unloaded treadmill load carriage, with lower limb muscle function variables assessed pre and post activity. The loaded group had a mass of (Mean(range)) 76.45 (27.12)kg, stature: 178.56 (17.63)cm, age: 23(6)yrs, and comprised of 13 males and 3 females. While the unloaded group had a body mass of 73.69(24.19)kg, stature: 178.89(18.49)cm, age: 22(5)yrs and comprised of 14 males and 4 females. Significant reductions across a range of parameters were observed. Characterised by reductions at the optimum muscle length for torque output, with all aspects demonstrating large (knee extension at 180˚·s-1: 0.51 Standardised SD, knee extnsion at 60˚·s-1: 0.98 standardised SD) or extremely large individual differences (knee flexion at 180˚·s-1: 2.17 standardised SD). These findings suggest after the completion of the load carriage task participants are in a significantly reduced physical state, which may have implications for secondary tasks

Is the project management field suffering from methodological inertia? Looking for evidence in publications in a recently established journal

Project management (PM) researchers have traditionally used quantitative methods in their research due to the origins of this practice-based discipline in defence and engineering. Although qualitative methods are starting to be used in PM research, most of the qualitative research reported tends to use case studies. Recently, there has been a call for PM researchers to use more novel methods to increase the variety of methods used by the researcher in the field contributing to its further development (Drouin, Muller and Sankaran 2013; Cameron, Sankaran and Scales 2015). A review of papers presented at the International Research Network on Organizing by Projects (IRNOP) conference in Berlin in 2009 showed a surprising trend that papers presented at these conferences used more qualitative methods in comparison with articles published in key PM journals. This paper analyses articles published over the past six years in a comparatively new PM journal, since its inception, to explore whether the new journal has motivated PM researchers to overcome their methodological inertia and broaden the variety of research methods they use. A mixed methods prevalence study was undertaken on articles published in the International Journal of Managing Projects in Business (IJMPiB) from 2008 to 2014 (n=265). The findings point to methodological inertia in the majority of research but also an unusually high proportion of the use of mixed methods. Future research is needed to add finer granularity to the analysis

Convergent validity of ratings of perceived exertion during resistance exercise in healthy participants: A systematic review and meta-analysis

Background: The validity of ratings of perceived exertion (RPE) during aerobic training is well established; however, it’s validity during resistance exercise is less clear. This meta-analysis used the known relationships between RPE and exercise intensity (EI), heart rate (HR), blood lactate (BLa), blood pressure (BP) and electromyography (EMG) to determine the convergent validity of RPE as a measure of resistance exercise intensity and physiological exertion, during different forms of resistance exercise. Additionally, this study aims to assess the effect of several moderator variables on the strength of the validity coefficients, so that clearer guidance can be given on the use of RPE during resistance exercise. Methods: An online search of 4 databases and websites (PubMed, Web of science, SPORT Discus and Research Gate) was conducted up to 28 February 2020. Additionally, the reference lists of the included articles were inspected manually for further unidentified studies. The inclusion criteria were; healthy participants of any age, a rating scale used to measure RPE, resistance exercise of any type, one cohort receiving no other intervention, and must present data from one of the following outcome measures: EI, HR, BP, EMG or BLa. Weighted mean effect sizes (r) were calculated using a random-effects model. Heterogeneity was assessed using the Tau2 and I2 statistics. Moderator analysis was conducted using random-effects meta-regression. Results: One-hundred and eighteen studies were included in the qualitative synthesis, with 75 studies (99 unique cohorts) included in the meta-analysis. The overall weighted mean validity coefficient was large (0.88; 95% CI 0.84 to 0.91) and between studies heterogeneity was very large (Tau2 = 0.526, I2 = 96.1%). Studies using greater workload ranges, isometric muscle actions, and those that manipulated workload or repetition time, showed the highest validity coefficients. Conversely, sex, age, training status, RPE scale used, and outcome measure did not have an effect. Conclusions: RPE provides a valid measure of exercise intensity and physiological exertion during resistance exercise, with effect sizes comparable or greater than those shown during aerobic exercise. Therefore, RPE may provide an easily accessible means of prescribing and monitoring resistance exercise training. Registration: The systematic review protocol was registered on the PROSPERO database (CRD42018102640)

Evidence-Based Nonpharmacological Practices to Address Behavioral and Psychological Symptoms of Dementia

Background and Objectives: To draw from systematic and other literature reviews to identify, describe, and critique nonpharmacological practices to address behavioral and psychological symptoms of dementia (BPSDs) and provide evidence-based recommendations for dementia care especially useful for potential adopters. Research Design and Methods: A search of systematic and other literature reviews published from January 2010 through January 2017. Nonpharmacological practices were summarized to describe the overall conceptual basis related to effectiveness, the practice itself, and the size and main conclusions of the evidence base. Each practice was also critically reviewed to determine acceptability, harmful effects, elements of effectiveness, and level of investment required, based on time needed for training/implementation, specialized care provider requirements, and equipment/capital requirements. Results: Nonpharmacological practices to address BPSDs include sensory practices (aromatherapy, massage, multi-sensory stimulation, bright light therapy), psychosocial practices (validation therapy, reminiscence therapy, music therapy, pet therapy, meaningful activities), and structured care protocols (bathing, mouth care). Most practices are acceptable, have no harmful effects, and require minimal to moderate investment. Discussion and Implications: Nonpharmacological practices are person-centered, and their selection can be informed by considering the cause and meaning of the individual's behavioral and psychological symptoms. Family caregivers and paid care providers can implement evidence-based practices in home or residential care settings, although some practices require the development of more specific protocols if they are to become widely used in an efficacious manner

A 4-week resistance training intervention improves stability, strength and neuromuscular activity in the lower limb: a case study of a cerebral palsy adult

Spastic diplegia, a form of cerebral palsy, is a neurological disorder that results in some degree of spasticity. It is often associated with impairment of both normal and selective movement of the lower limbs, and some degree of muscular weakness. Resistance training is an established exercise intervention with numerous neurological benefits. Evidence suggests that resistance training can positively improve stability in young populations with cerebral palsy. However, little research exists in adult populations, who are at greater risk of inactivity due to ageing and an increase in sedentarism. A single-subject (aged 35-years old, 150.5 centimetres, 81 kilograms) case-study was therefore carried out to investigate the effectiveness of a 4-week resistance training intervention on stability, neuromuscular activity and force output in a male adult with cerebral palsy. The variables measured were total centre of pressure displacement, peak torque in both the quadriceps and hamstrings and Surface Electromyography (sEMG) activity in the Rectus Femoris (RF), Vastus Lateralis (VL), Biceps Femoris (BF) and Semitendinosus (ST). The results demonstrated that a 4-week resistance training intervention reduced total centre of pressure displacement (-51.34%) whilst concomitantly increased sEMG output (RF left +80% right +22%, VL left +160% right +26%, BF left +203% right +44%, ST left +40% right +90%) and peak torque values (right leg extension -7%, right leg flexion +29%, left leg extension +11%, left leg flexion +42%). In conclusion, this case study demonstrates that a 4-week resistance training intervention improves the stability of the participant, possibly through neurological adaptations and improvements to lower limb strength