The role of muscle tendon unit elasticity in real life activities.

The interaction of a muscle and associated tendon during dynamic activities such as locomotion is critical for both force production and economical movement. It is generally assumed that, under sub-maximal conditions, muscle activation patterns are optimised to achieve maximum efficiency of work. Here, I explore the interaction between the contractile component (CC) and the elastic tendinous tissue to understand the relationship between a muscle's power output and efficiency. In this thesis, I examine the interaction of the CE and the elastic tendinous tissue and its effect on power output and efficiency of muscle using both experimental and modelling techniques. In the first chapter, a model of muscle energetics is developed and validated against dynamic muscle contractions of different muscle types. I then used this model to explore how optimal muscle power and efficiency varies with different activation conditions, clastic properties and length change trajectories. The third and forth chapter presents experiments which explore ultrasound measurement techniques for determining the length changes and mechanical properties of the human gastrocnemius medial is (GM) muscle fibres and Achilles tendon (AT) respectively. I then used similar techniques to explore musclc-tcndon unit (MTU) interaction during gait under different gait conditions. Specifically, I explore how GM power output and efficiency vary with different speeds and inclination and explore how variation in tendinous compliance might influence muscle efficiency. The results suggest that muscles remain highly efficient due to compliant tendons allowing muscle fibres to act at highly powerful and efficient velocities. However variation in power output and particularly muscle function affects the efficiency of muscle. Finally, I determined that the optimal value of tendon stiffness for maximum GM efficiency during walking and running is close to that determined experimentally

Further validation of the New Zealand test of adult reading (NZART) as a measure of premorbid IQ in a New Zealand sample

Premorbid IQ estimates are used to determine decline in cognitive functioning following trauma or illness. This study aimed to: 1) further validate the New Zealand Adult Reading Test (NZART) in a New Zealand population and compare its performance to the UK developed National Adult Reading Test, and 2) develop regression formulae for the NZART to estimate Wechsler Adult Intelligence Scale-IV (WAIS–IV) IQ scores. The 67 participants (53 females; 16 Māori), aged 16 to 90 years old (mean age = 46.07, SD 23.21) completed the WASI-IV, the NART and the NZART. The NZART predicted Verbal Comprehension Index (VCI) scores slightly better than the NART (r =.63 vs. r = .62) and explained 33% of the variance in FSIQ scores. Reasons for developing regression formulae for the NZART are discussed, regression formulas for the NZART based on the WAIS–IV are included and suggestions of alternate ways of determining premorbid IQ are made

Partnering together to grow our future workforce - poster presentation

Quality clinical experience for students is built on a strong partnership between the academic organisation and their clinical practice partners. This strong partnership needs to be apparent in the RN – student partnership, nurse educator/ clinical tutor connection as well as at senior manager levels. Wintec and Waikato District Health Board have been working collaboratively to enhance their relationship, taking a partnership approach to workforce development. Our focus has been on learning together as a nursing community. A shared educator/clinical tutor development day was successful in strengthening connections. Tools to foster communication including newsletters and shared email addresses have been implemented. Significant activity to improve support and links for preceptors has occurred. A whakatau or formal welcome to the DHB for all students before placement begins has been another new initiative. Committing to partner with the learning of 200 fresh faced students has been powerful for all who attended. This presentation explores the strategies implemented to strengthen the academic/clinical partnershi

Estimating Premorbid IQ in New Zealand

The experience of brain injury changes the world for the person experiencing it and their family. It is important for health providers to know as accurately as possible how severe the brain damage is to be able to deliver the appropriate level of treatment and rehabilitation. Tests are available to measure current cognitive functioning which can be expressed as an intelligence quotient (IQ). One such test is the Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV). Other tests are able to estimate premorbid IQ, for example the National Adult Reading Test (NART), the Test of Premorbid Functioning (TOPF) and the New Zealand Adult Reading Test (NZART). The discrepancy between the current IQ and the estimated premorbid IQ scores provides an estimate of the decrease in cognitive function as a result of brain injury. Most of these IQ tests have not been developed or normed for the New Zealand population and their suitability for this population is therefore not known. This study aimed to evaluate the ability of the tests of premorbid IQ to estimate the current WAIS-IV IQ in a New Zealand sample. This sample consisted of 86 New Zealand born, neurologically healthy, men and women (mean age of 46 years), who were administered the WAIS-IV, NART, TOPF and NZART. The results showed that the tests of premorbid IQ significantly over estimated lower IQ scores and significantly under estimated higher IQ scores. New regression formulae for the NART, TOPF and NZART were developed based on the WAIS-IV FSIQ and were found to be only marginally better at predicting current IQ. These new regression formulae also over-and under-estimated current IQ in the lower and upper ranges. The NZART, a New Zealand developed test, showed slightly better performance than the overseas tests. It was concluded that the tests of premorbid functioning are not very accurate in in their prediction of WAIS-IV current IQ for people in New Zealand and alternative methods of estimating premorbid IQ are suggested

Working with SAM (Student Allocation Management) ANEC presentation

Managing student practicum requirements is always a challenge for tertiary institutions and service providers. Getting it right so that students have a well-supported learning experience but numbers don’t overwhelm the practice partners requires skilled negotiation at all levels. In 2013, Wintec had 2370 placements to arrange amongst 139 clinical providers for 795 nursing students and the equivalent of 2 full time equivalent staff members to make it happen. The placements were geographically spread across the greater Waikato region from Coromandel to Taumarunui and were with a mix of Waikato DHB and private providers. Students were allocated placements by staff with little choice. There were acres of spreadsheets, students were often disgruntled, allocations needed to be at DHB 8 weeks before needed, it was time consuming. Automating the clinical placement process had been on discussed previously after much discussion the Student Allocator module (SAM) developed by Scientia was chosen by Wintec to integrate with plans for software and timetabling management. Since late 2013 bachelor of nursing students at Wintec have selected their clinical placements using student allocator, out talk will cover the process to implement the project and the strengthening relationships between Wintec and Waikato DHB to continue management and development of SAM to support student learning experience in clinical placement

Energy turnover in mammalian skeletal muscle in contractions mimicking locomotion: effects of stimulus pattern on work, impulse and energetic cost and efficiency

Active muscle performs various mechanical functions during locomotion: work output during shortening, work absorption when resisting (but not preventing) lengthening, and impulse (force–time integral) whenever there is active force. The energetic costs of these functions are important components in the energy budget during locomotion. We investigated how the pattern of stimulation and movement affects the mechanics and energetics of muscle fibre bundles isolated from wild rabbits (Oryctolagus cuniculus). The fibres were from muscles consisting of mainly fast-twitch, type 2 fibres. Fibre length was held constant (isometric) or a sinusoidal pattern of movement was imposed at a frequency similar to the stride frequency of running wild rabbits. Duty cycle (stimulation duration×movement frequency) and phase (timing of stimulation relative to movement) were varied. Work and impulse were measured as well as energy produced as heat. The sum of net work (work output−work input) and heat was taken as a measure of energetic cost. Maximum work output was produced with a long duty cycle and stimulation starting slightly before shortening, and was produced quite efficiently. However, efficiency was even higher with other stimulation patterns that produced less work. The highest impulse (considerably higher than isometric impulse) was produced when stimulation started while the muscle fibres were being lengthened. High impulse was produced very economically because of the low cost of producing force during lengthening. Thus, locomotion demanding high work, high impulse or economical work output or impulse requires a distinct pattern of stimulation and movement

The influences of added mass on muscle activation and contractile mechanics during submaximal and maximal countermovement jumping in humans

This is the final version. Available from the Company of Biologists via the DOI in this recordMuscle contractile mechanics induced by the changing demands of human movement have the potential to influence our movement strategies. This study examined fascicle length changes of the triceps surae during jumping with added mass or increasing jump height to determine whether the chosen movement strategies were associated with relevant changes in muscle contractile properties. Sixteen participants jumped at sub-maximal and maximal intensities while total net work was matched via two distinct paradigms: (1) adding mass to the participant or (2) increasing jump height. Electromyography (EMG) and ultrasound analyses were performed to examine muscle activation, fascicle length and fascicle velocity changes of the triceps surae during jumping. Integrated EMG was significantly higher in the added mass paradigm with no difference in mean or maximal EMG, indicating that the muscle was activated for a significantly longer period of time but not activated to a greater intensity. Fascicle shortening velocity was slower with added mass compared than with increasing jump height; therefore, intrinsic force–velocity properties probably enabled increased force production. Improved fascicle contractile mechanics paired with a longer activation period probably produced a consistently larger fascicle force, enabling a greater impulse about the ankle joint. This may explain why previous research found that participants used an ankle-centred strategy for work production in the added mass paradigm and not in the jump height paradigm. The varied architecture of muscles within the lower limb may influence which muscles we choose to employ for work production under different task constraints.Australian Postgraduate Awar

Achilles tendon (3D): Do the mechanical properties of tendon change in response to exercise?

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this recor

The effect of cadence on the muscle-tendon mechanics of the gastrocnemius muscle during walking

This is the author accepted manuscript. The final version is available from Wiley via the DOI in this recordHumans naturally select a cadence that minimizes metabolic cost at a constant walking velocity. The aim of this study was to examine the effects of cadence on the medial gastrocnemius (MG) muscle and tendon interaction, and examine how this might influence lower limb energetics. We hypothesized that cadences higher than preferred would increase MG fascicle shortening velocity because of the reduced stride time. Furthermore, we hypothesized that cadences lower than preferred would require greater MG fascicle shortening to achieve increased muscle work requirements. We measured lower limb kinematics and kinetics, surface electromyography of the triceps surae and MG fascicle length, via ultrasonography, during walking at a constant velocity at the participants' preferred cadence and offsets of ±10%, ±20%, and ±30%. There was a significant increase in MG fascicle shortening with decreased cadence. However, there was no increase in the MG fascicle shortening velocity at cadences higher than preferred. Cumulative MG muscle activation per minute was significantly increased at higher cadences. We conclude that low cadence walking requires more MG shortening work, while MG muscle and tendon function changes little for each stride at higher cadences, driving up cumulative activation costs due to the increase in steps per minute.Scott Brennan is supported by an Australian Postgraduate Scholarship. Dominic Farris is supported by the Australian Sports Commission