1,721,024 research outputs found
Lower-limb kinematics of single-leg squat performance in young adults
No full textPurpose: To determine the kinematic parameters that characterize good and poor single-leg squat (SLS) performance. Methods: A total of 22 healthy young adults free from musculoskeletal impairment were recruited for testing. For each SLS, both two-dimensional video and three-dimensional motion analysis data were collected. Pelvis, hip, and knee angles were calculated using a reliable and validated lower-limb (LL) biomechanical model. Two-dimensional video clips of SLSs were blindly assessed in random order by eight musculoskeletal physiotherapists using a 10-point ordinal scale. To facilitate between-group comparisons, SLS performances were stratified by tertiles corresponding to poor, intermediate, and good SLS performance. Results: Mean ratings of SLS performance assessed by physiotherapists were 8.3 (SD 0.5), 6.8 (SD 0.7), and 4.0 (SD 0.8) for good, intermediate, and poor squats, respectively. Three-dimensional analysis revealed that people whose SLS performance was assessed as poor exhibited increased hip adduction, reduced knee flexion, and increased medio-lateral displacement of the knee joint centre compared to those whose SLS performance was assessed as good (p=0.05). Conclusions: Overall, poor SLS performance is characterized by inadequate knee flexion and excessive frontal plane motion of the knee and hip. Future investigations of SLS performance should consider standardizing knee flexion angle to illuminate other influential kinematic parameters.No Full Tex
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
The influence of antiresorptive bone medication on the effect of bone-targeted exercise on indices of fracture risk in postmenopausal women with low bone mass
No full textFirst-line therapy for postmenopausal osteoporosis comprises antiresorptive medication such as bisphosphonates (BPs) and denosumab (Dmab; a human monoclonal antibody). Exercise is an effective non-pharmacological stimulus for bone, however, is traditionally dismissed as a singular therapy for osteoporosis. High-intensity resistance and impact training (HiRIT) applies the principles of osteogenic loading determined from animal trials. There is increasing evidence to support the feasibility and efficacy of HiRIT to safely improve bone health and indices of fall and fracture risk in postmenopausal women and middle-aged to older men. We hypothesised that the combination of exercise and bone medication may provide a more effective bone stimulus than either alone. To examine the influence of antiresorptive medication on the effects of bone-targeted exercise, we conducted a systematic review and meta-analysis of existing evidence, and a novel, randomised controlled exercise trial in postmenopausal women either on or off medication therapy.
The thesis comprises five manuscripts, presented as four publications and one manuscript in preparation for submission. The first two manuscripts present a two-part review series on the effect of exercise intensity on bone in postmenopausal women. Part one is a systematic review (Chapter 3) and part two, a meta-analysis (Chapter 4). The systematic review included 100 trials, which examined the effect of 120 exercise interventions on bone mass, bone structure or bone turnover markers (BTMs) in healthy postmenopausal women on or off bone medication. Classification of each exercise intervention into low, moderate and high intensity, using predefined classification criteria, revealed the majority (95%) of trials have applied low to moderateintensity loading. Effects of exercise on bone structure and BTMs has only been evaluated in a small proportion of trials and heterogeneity of trial design and outcome measures made it difficult to draw conclusions. The meta-analysis included 53 RCTs (63 interventions) which reported BMD results derived from dual-energy X-ray absorptiometry (DXA). Results showed a positive relationship between exercise intensity and bone response for lumbar spine (LS) and total hip (TH) BMD, whereas femoral neck (FN) results were less conclusive, possibly due to the small number of studies in the high-intensity category. Resistance training was the most effective exercise type, potentially in combination with weight-bearing impact activities. Furthermore, preliminary evidence suggests that exercise (any type, any intensity) significantly reduces the risk of osteoporotic fracture. There was a small benefit of adding exercise to medication therapy at the FN but not at the LS or TH. Results are limited to a small number of studies to the extent that the influence of exercise intensity on medication therapy could not be examined. The three subsequent manuscripts comprise the study protocol (Chapter 5), and the main outcomes (Chapter 6) and secondary outcomes (Chapter 7) of the Medication and Exercise for Osteoporosis (MEDEX-OP) trial. The MEDEX-OP trial was an eight-month, randomised controlled exercise trial of postmenopausal women with low bone mass (T-score ≤ -1.0), on or off stable doses of antiresorptive bone medications (BPs or Dmab) for at least 12 months at entry. Eligible participants were randomly assigned, stratified by medication intake, to twice-weekly, 40-min, supervised HiRIT or a low-intensity control exercise intervention (Buff Bones®, BB) matched for training frequency and duration. Outcomes included spine, hip, forearm and whole body BMD, bone structure at the proximal femur, body composition, anthropometrics, indices of functional performance and posture, number of falls and fractures, quality of life related to mental and physical health and pelvic floor health, osteoarthritis symptoms, physical activity enjoyment, and willingness to pay for supervised bone-targeted exercise classes. Exercise and medication compliance and safety of the intervention (adverse events and injuries) were also monitored. A total of 115 participants were randomised at baseline; BB n = 44, HiRIT n = 42, BB-med n = 14, HiRIT-med n = 15. We found that HiRIT plus medications improved proximal femur BMD more than HiRIT-only or BB on medications. HiRIT was superior to BB for LS and trochanteric BMD, back and leg extensor strength, functional mobility and stature. We observed positive relationships between the maximum weight lifted in the deadlift exercise and changes in LS BMD and back muscles strength, as well as between maximum squat weight and changes in leg muscle strength. Compliance and retention rates were high for all groups. HiRIT increased willingness to pay for bone-targeted exercise and physical activity enjoyment, whereas BB only increased the latter. Neither of the programs led to changes in quality of life related to physical and mental health, pelvic floor dysfunction and osteoarthritis, nor resting blood pressure and heart rate.
In summary, the current work confirms the benefits of HiRIT for musculoskeletal health and suggests that the combination of bone-targeted exercise with antiresorptive medication may be more beneficial for proximal femur BMD than either intervention alone. There is a positive relationship between exercise intensity and bone response at the spine and hip. The direct comparison of high to low-intensity exercise revealed superior effects of high-intensity exercise for spine, hip and forearm BMD, muscle strength and mobility and stature. We conclude that HiRIT is an efficacious, safe and appealing exercise program that is superior to other, bonetargeted exercise interventions applied at low to moderate intensity. The combination of HiRIT with first line antiresorptive medication therapy may be superior to HiRIT-alone for hip bone strength, however, a large-scale trial is needed to fully investigate this interaction.Thesis (PhD Doctorate)Doctor of Philosophy (PhD)School of Health Sci & Soc WrkGriffith HealthFull Tex
LIFTMOR-M: Lifting Intervention For Training Muscle and Osteoporosis Rehabilitation for Men
No full textDrug treatment has traditionally been considered the gold standard therapy for osteoporosis, due to limited efficacy of lifestyle interventions such as low to moderate intensity exercise and dietary interventions. Recently, however, the LIFTMOR (Lifting Intervention For Training Muscle and Osteoporosis Rehabilitation) trial demonstrated that a novel, high-intensity progressive resistance and impact training (HiRIT) program markedly improved bone and functional indices of falls and fracture in postmenopausal women with low to very low bone mass. While men also suffer from osteoporosis, prevalence is lower than in women, leading to fewer studies in men. To determine if the same exercise protocol would be effective for older men with low bone mass, the LIFTMOR-M (LIFTMOR for Men) trial was conceived. Another recent development in the field of osteoporosis was the bioDensity™ exercise machine, designed theoretically to load bone via isometric axial compression (IAC). Although the manufacturers claimed osteogenic efficacy, no high-quality evidence existed. By examining the effects of two novel exercise programs on musculoskeletal health and risk factors for falls in a poorly researched population, our findings will contribute evidence towards developing efficacious non-pharmacological osteoporosis therapy. The current Thesis reports the results of the eight-month LIFTMOR-M exercise intervention trial. That is, we compared the efficacy, compliance and safety of supervised HiRIT in comparison to supervised machine-based IAC exercise or control (usual activities) on indices of bone strength and risk factors related to falls and fracture susceptibility in middle-aged and older men with low areal bone mineral density (aBMD).
The Thesis comprises four publications, presented as one published manuscript, one manuscript accepted for publication and two manuscripts under review. The published manuscript (Chapter 3) is the protocol paper outlining the study design, recruitment, exercise interventions, control activities, and primary and secondary outcomes of LIFTMOR-M. The trial was a three-arm, eight-month, semi-randomised controlled exercise intervention trial. Community-dwelling, middle-aged and older men (≥ 45 years) with low aBMD at the lumbar spine (LS), total hip and/or femoral neck (FN) (T-score ≤ - 1.0) were recruited. Eligible participants were randomly assigned to eight months of twice-weekly, supervised HiRIT (five sets of five repetitions, ≥ 80-85% of one repetition maximum) or machine-based IAC exercise (five-second isometric contraction, rating of perceived exertion ≥ 16) stratified on presence or absence of osteoporosis medications. The self-selected, non-randomised control group, who received no intervention, were instructed to maintain customary dietary and physical activity patterns. Participants underwent testing at baseline and eight months. Outcomes included: whole body and regional bone, muscle and fat; anthropometry; indices of functional performance; thoracic kyphosis; and vertebral fracture assessment. Compliance and adverse events (falls, fractures, and injuries) were monitored. In the second manuscript (Chapter 4), we reported the primary outcome (FN aBMD) and secondary outcomes of regional aBMD, calcaneal ultrasound parameters, anthropometrics, body composition, physical performance, compliance, and adverse events. We found that HiRIT improved LS aBMD, trochanteric aBMD, broadband ultrasound attenuation and stiffness index of the calcaneus, lean mass, and five physical performance measures compared to loss or minimal change for control. IAC improved lean mass and one physical performance measure compared with control. HiRIT effects were superior to IAC for LS aBMD, stiffness index of the calcaneus and five-times sit-to-stand performance. Compliance and retention were high, and there were few adverse events. In the subsequent manuscript (Chapter 5), secondary outcomes of bone strength indices at the proximal femur, tibia and radius are presented. We found that HiRIT provided a positive stimulus to cortical bone at the medial FN compared with IAC and control, and both HiRIT and IAC preserved bone strength at the distal tibia and distal radius in comparison to control. The final manuscript (Chapter 6) presents clinical measures of thoracic kyphosis with inclinometry, Cobb angle of kyphosis and vertebral fracture assessment for a sub-group of LIFTMOR-M exercise intervention participants. We observed that both HiRIT and IAC improved clinical measures of thoracic kyphosis, and HiRIT improved Cobb angle of kyphosis, at eight months. HiRIT had no incident fractures nor progression of prevalent vertebral fractures over the course of the trial. By contrast, IAC experienced five incident vertebral wedge fractures and one wedge fracture progressed.
In summary, the current Thesis reports the positive effects of twice-weekly, supervised HiRIT on bone, muscle, kyphosis, incident vertebral fracture, and functional indices of falls and fracture risk in older men with osteopenia and osteoporosis. Furthermore, strong compliance and retention suggests HiRIT training was appealing and well tolerated, with no incident fractures or major adverse events across the intervention period. IAC may improve lean mass and posture to a lesser extent but does not improve or preserve bone at clinically relevant sites, nor prevent incident vertebral fracture. Based on these findings, we conclude that HiRIT is a safe, efficacious and appealing exercise program, superior to IAC, for the management and rehabilitation of osteopenia and osteoporosis in middle-aged and older men.Thesis (PhD Doctorate)Doctor of Philosophy (PhD)School Allied Health SciencesGriffith HealthFull Tex
A comparison of the bone response to impact loading and resistance training in young adult women: The OPTIMA-Ex trial
No full textMany factors are linked to developing osteoporosis; however, the inadequate accumulation of peak bone mass prior to skeletal maturity is considered an important factor. As peak bone mass is often achieved by the end of the third decade, young adulthood provides an important and possibly final opportunity for its augmentation. Physical activity has been proposed as one of the most effective strategies to improve bone mass, however, the bone response to physical activity is highly dependent on the nature of the loads imposed. The most osteogenic loads are those that induce high magnitude bone strains at high loading rates. As most mechanical forces acting on the skeleton are generated through either gravitational-derived loads or muscle-derived loads, debate exists as to the predominant source of the adaptive stimulus. Despite this, few direct comparisons of the effect of gravitationally-derived (impact) loading and muscle-derived (resistance training) loading on bone have been undertaken, with none examined under true high-intensity training conditions. Consequently, the primary goal of the current work was to compare the bone response to two known osteogenic loading methods, impact loading exercise versus resistance training exercise in young women with below average bone mass.
The thesis comprises six manuscripts, presented as three published papers, two under review and one submitted. The first paper (Chapter 3) details the protocol for the Osteoporosis Prevention Through Impact and Muscle-loading Approaches to Exercise (OPTIMA-Ex) trial. Therein, the methods of the three-arm randomised controlled trial, comparing the bone responses of 10-month, twice-weekly, either supervised high-intensity impact training, high-intensity resistance training, or unsupervised home-based low intensity exercise (active control) in young adult women with lower than average bone mass have been described. The two subsequent papers describe the outcomes of methodological studies related to the measurement of forces associated with the exercise interventions, specifically the impact training intervention. The first study (Chapter 4), determined the validity and reliability of a Gym-aware linear positional transducer to track the progression of the novel punching exercise of the impact training arm of the OPTIMA-Ex trial. The second (Chapter 5) quantified the intensity of mechanical loading associated with the lower limb exercises of the impact training exercise program. We found that vertical ground reaction forces generated were greater than four times body weight for all seven training stages and increased over time, suggesting that the impact intervention arm of the OPTIMA-Ex trial achieved its goal of being both high-intensity and progressive in nature.
The fourth manuscript (Chapter 6) comprises the overall findings of the between-group comparisons of the OPTIMA-Ex trial. We found that high-intensity resistance training may provide a broader osteogenic loading stimulus than high-intensity impact training for young adult women with lower than average bone mass, although findings were site-specific. More specifically, high-intensity resistance training had a greater osteogenic effect for cortical bone than impact training, while impact training provided a greater stimulus for trabecular bone. Furthermore, resistance training evoked greater improvements in both body composition and physical performance measures. Manuscript five (Chapter 7), presents a comparison of upper and lower limb responses to high-intensity impact training and high-intensity resistance training on indices of bone strength. Only those who completed the intervention arms of the OPTIMA-Ex trial were included in this analysis. Similar site-specific responses were observed from these analyses, irrespective of upper or lower extremity. Resistance training elicited greater effects at the proximal femur and along the shaft of long bones, while the effects of impact training were greater in the distal segments of long bones nearest to the points of impact.
The final manuscript (Chapter 8) describes a mixed-methods study to explore participant experiences during the OPTIMA-Ex trial, determine enjoyment and acceptability of each exercise mode, and identify barriers and facilitators to bone-targeted exercise in young adult women. Overall, the program was well received, with all groups demonstrating an improvement in the ‘mental health’ domain of the quality of life measure, however, the two supervised exercise groups reported greater levels of physical activity enjoyment. Qualitative analysis revealed the impact and resistance training groups had ‘richer’ exercise experiences than controls, through perceived improvements in emotional and mental well-being along with the an overall sense of achievement through progression and skill acquisition. Furthermore, clear group differences were observed in terms of willingness to recommend their training mode to a friend and intention to continue the program after the trial period, with resistance training participants appearing most positive for both outcomes.
Overall, the current work demonstrates site-specific effects of high-intensity impact training and high-intensity resistance training in young adult women with lower than average bone mass. Within the limits of the modest sample size, we conclude that both impact training and resistance training have important beneficial effects on bone in the participant demographic and are safe, enjoyable and well received. High-intensity resistance training, however, may have a slightly broader effect on bone outcomes than impact training, as well as on body composition, strength and acceptability in young adult women.Thesis (PhD Doctorate)Doctor of Philosophy (PhD)School Allied Health SciencesGriffith HealthFull Tex
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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