977 research outputs found

    Change in Bone Mineral Density among High Frequency Apheresis Blood Donors

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    Exposure to citrate anticoagulant during apheresis blood donation induces significant decreases in serum ionized calcium with subsequent perturbations to parathyroid hormone, vitamin D, and markers of bone remodeling. Cross-sectional studies of bone mineral density (BMD) among apheresis donors exhibit conflicting results. Resolving the potential impact of the highest apheresis donation frequency represents a significant knowledge gap in ensuring adequate protections for volunteer apheresis blood donors. ALTRUYST (NCT02655055) was a randomized, longitudinal, controlled clinical trial designed to determine if repeated exposure to citrate through apheresis donation reduces BMD. Male donors, 18-65 years of age with no more than five previous apheresis donations and no diseases of bone or mineral metabolism, agreed to make ≥20 apheresis donations in the subsequent one year period. Dual-energy x-ray absorptiometry was performed at baseline and again after one year of participation. Paired t-test was used to assess change in mean BMD. Donors in the apheresis arm (n=26) made a median of 20 donations (range 4–22 donations) during the one-year study period with a mean donation interval of 17.8 days. Controls (n=15) made zero apheresis donations and a median of two whole-blood donations (range 0-6). Mean lumbar spine BMD at the end of the study period did not differ significantly from that at the beginning among donors in the control arm (mean change=-0.002 g/cm2, 95% CI [-0.020, 0.016], p=0.78), nor did it change significantly among donors in the apheresis arm (mean change=0.007 g/cm2, CI [-0.005, 0.018], p=0.24). Change in mean BMD at the total hip was not statistically significant for control donors (mean change=0.002 g/cm2, CI [-0.006, 0.009], p=0.63) or apheresis donors (-0.004 g/cm2, CI [-0.10, 0.002], p=0.16). Tests for differences in proportions of donors with change in BMD exceeding the least significant change (LSC) at the lumbar spine (0.00743 ±0.02058g/cm2) between the apheresis and control arms in either a positive [apheresis 13 (50%), control 5 (33%), p=0.84] or negative direction [apheresis 8 (31%), control 6 (40%)] were statistically non-significant (p=0.87). Proportional increases [apheresis 6 (23%), control 6 (40%), p=0.25] and decreases [apheresis 11 (42%), control 3 (20%)] were not significantly different (p=0.15) at the total hip (LSC=0.00671±0.01859g/cm2)

    Efficacy of six months neuromuscular exercise on lumbar movement variability : a randomized controlled trial

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    Introduction: Lumbar movement variability during heavy, repetitive work may be a protective mechanism to diminish the progression of lumbar disorders and maintain neuromuscular functional integrity. The effect of neuromuscular exercise (NME) on the variability of lumbar movement is still to be determined. Methods: A randomised controlled trial was conducted on a population of nursing personnel with subacute LBP. Following randomization, the NME group participants completed an NME program of six months duration. The participants in the control group only attended the assessment sessions. The outcomes were assessed at: baseline; after six months intervention; 12 months. The primary outcome was lumbar movement variability based on angular displacement and velocity. Results: A positive treatment effect on lumbar movement variability was seen after six months of NME intervention. Angular displacement improved, and angular velocity remained constant. At the 12-month follow up, however, the effect faded in the NME group. Lumbar movement variability worsened in the control group over all time periods. Conclusion: NME may improve lumbar movement variability in the short term and may indicate improved neuromuscular functional integrity. The design of an optimal NME program to achieve long-term improvement in lumbar movement variability is a subject worthy of further research

    Strength, balance, and range of motion as modifiers of the effect of external load-bearing on functional movement behaviors in the military recruitment population

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    Clinical movement screens have become increasingly popular in strength and conditioning programs designed for the tactical athlete. Whereas conventionally administered movement screens are largely not sensitive to behaviors which impact soldier-relevant physical performance, recent evidence suggests that modified screens which incorporate external load-bearing strengthen the relationship between movement behaviors and performance outcomes. It remains unclear, however, which mechanisms may account for this improvement in association. Physical performance is considered a multidimensional construct influenced by several independent factors. Among the factors which influence military physical performance, movement screens may require high levels of strength, balance, and range of motion. This project used penalized interaction models to determine the role of strength, balance, and range of motion in modifying the effects of external load bearing on movement quality and movement. Additional confirmatory analyses examined differences in the abilities of FMS item scores to predict physical performance outcomes when those scores were obtained during control vs. external load-bearing conditions. Results suggest that the effect of load on movement complexity is modified by strength, balance, and range of motion whereas the effect on clinically rated movement quality is modified by only balance and range of motion. While the direction of the observed effects did not always coincide with our hypotheses, the present findings mirror those of previous research with respect to differential validity of weighted vs. control FMS item scores in predicting criterion performance measures

    CONNECTING THE PIECES: HOW LOW BACK PAIN ALTERS LOWER EXTREMITY BIOMECHANICS AND SHOCK ATTENUATION IN ACTIVE INDIVIDUALS

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    Low back pain in collegiate athletes has been reported at a rate of 37% from a wide array of sports including soccer, volleyball, football, swimming, and baseball. Whereas, in a military population the prevalence of low back pain is 70% higher than the general population. Compensatory movement strategies are often used as an attempt to reduce pain. Though compensatory movement strategies may effectively reduce pain, they are often associated with altered lower extremity loading patterns. Those who suffer from chronic low back pain tend to walk and run slower and with less trunk and pelvis coordination and variability. Individuals with low back pain also tend to run with more stiffness in their knees. Moving with less joint coordination and more stiffness are potential compensatory movement patterns acting as a guarding mechanism for pain. Overall the purpose of this project was to determine how chronic low back pain influences lower extremity biomechanics and shock attenuation in active individuals compared to healthy individuals and examine how the altered lower extremity biomechanics are related to clinical outcome measures. We hypothesized that individuals who present with chronic low back pain are more likely to exhibit higher vertical ground reaction forces and less knee flexion excursion during landing, compared to healthy individuals. We also hypothesized that individuals with chronic low back pain will have a reduced ability to attenuate shock during landing compared to the healthy individuals. This study was a case control design in which physically active individuals suffering from chronic low back pain were matched to healthy controls. All participants reported for one testing session to assess self-perceived knee function in the form of the Knee Osteoarthritis Outcomes Score (KOOS), lower extremity strength and mechanics during three landing tasks. Isometric strength was assessed using an isokinetic dynamometer during hip abduction, hip extension, and knee extension. The landing tasks included a drop vertical jump, a single leg hop, and a crossover hop. A three-dimensional motion analysis system with two in-ground force plates and four inertial measurement units were used to assess lower extremity mechanics during the landing tasks. Individuals with low back pain presented with reduced KOOS scores compared to healthy individuals in four of the five subscales, including Symptoms (p=0.007), Pain (p=0.002), Activities of Daily Living (p=0.021), and Quality of Life (p=0.003). Alternatively, while there were some strength, kinematic, and kinetic between limb asymmetries noted in the low back pain group, there were not between group differences with the healthy individuals. In the low back pain group, individuals presented with greater dominant limb knee extension strength (p=0.039) and greater dominant limb ankle plantarflexion at initial contact during the drop vertical jump, compared to the non-dominant limb (p=0.022). Individuals with low back pain also presented with greater non-dominant limb tibia impact during the single limb hop (p=0.008). While we did not identify any mechanical differences between individuals suffering from chronic low back pain and those who do not, we did identify that an active population suffering from low back pain does present with decreased self-perceived knee function compared to active individuals without low back pain. As these groups biomechanically perform similarly, they do not clinically perform the same, specifically, in terms of the KOOS. Such differences should not be overlooked when treating active populations with low back pain. If this population is presenting with altered self-perceived knee function at a young age, it is likely that it will continue to decline and negatively affect their function

    Adaptation of the Skeletal System during Long-duration Spaceflight

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    This review will highlight evidence from crew members flown on space missions greater than 90 days to suggest that the adaptations of the skeletal system to mechanical unloading may predispose crew members to an accelerated onset of osteoporosis after return to Earth. By definition, osteoporosis is a skeletal disorder - characterized by low bone mineral density and structural deterioration - that reduces the ability of bones to resist fracture under the loading of normal daily activities. Involutional or agerelated osteoporosis is readily recognized as a syndrome afflicting the elderly population because of the insipid and asymptomatic nature of bone loss that does not typically manifest as fractures until after age approximately 60. It is not the thesis of this review to suggest that spaceflight-induced bone loss is similar to bone loss induced by metabolic bone disease; rather this review draws parallels between the rapid and earlier loss in females that occurs with menopause and the rapid bone loss in middle-aged crew members that occurs with spaceflight unloading and how the cumulative effects of spaceflight and ageing could be detrimental, particularly if skeletal effects are totally or partially irreversible. In brief, this report will provide detailed evidence that long-duration crew members, exposed to the weightlessness of space for the typical long-duration (4-6 months) mission on Mir or the International Space Station -- 1. Display bone resorption that is aggressive, that targets normally weight-bearing skeletal sites, that is uncoupled to bone formation and that results in areal BMD deficits that can range between 6-20% of preflight BMD; 2. Display compartment-specific declines in volumetric BMD in the proximal femur (a skeletal site of clinical interest) that significantly reduces its compressive and bending strength and which may account for the loss in hip bone strength (i.e., force to failure); 3. Recover BMD over a post-flight time period that exceeds spaceflight exposure but for which the restoration of whole bone strength remains an open issue and may involve structural alteration; and 4. Display risk factors for bone loss -- such as the negative calcium balance and down-regulated calcium-regulating hormones in response to bone atrophy -- that can be compounded by the constraints of conducting mission operations (inability to provide essential nutrients and vitamins). The full characterization of the skeletal response to mechanical unloading in space is not complete. In particular, countermeasures used to date have been inadequate and it is not yet known whether more appropriate countermeasures can prevent the changes in bone that have been found in previous flights, knowledge gaps related to the effects of prolonged (greater than or equal to 6 months) space exposure and to partial gravity environments are substantial, and longitudinal measurements on crew members after spaceflight are required to assess the full impact on skeletal recovery

    Low Back Pain in Student Nurses: Literature Review and Prospective Cohort Study

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    There is consensus that registered nurses worldwide have a high prevalence of work-related musculoskeletal disorders, particularly of the back. Patient handling activities such as lifting present the highest risk of injury, activities that begin in nursing school. A literature review identified 21 studies of back pain in nursing students, indicating a wide range of prevalence rates. A prospective cohort study of nursing students in a United States baccalaureate program followed 119 students who completed the Nordic Musculoskeletal Questionnaire upon beginning the 16 month upper division major and then a year later. There was no statistically significant change in low back pain prevalence over time. While nursing students have intermittent and brief exposure to patient handling activities, nursing schools must nevertheless protect them before they enter the high risk profession of nursing by teaching evidence-based safe patient handling techniques, empowering students to refuse unsafe manual lifts, and ensuring that the clinical settings with which they affiliate have adequate mechanical equipment available

    Gender Differences in Low Back Pain and Self-Reported Muscle Strengthening Activity Among U.S. Adults

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    Objectives: We sought to examine the gender differences between low back pain (LBP) and muscle strengthening activity (MSA) in U.S. adults (≥20 years of age). Background: Low back pain is a well-known medical condition that has been shown to impact quality of life and professional productivity. It also adds to the financial burden of our healthcare system by augmenting medical treatment costs. Muscle strengthening activity is a recognized method to prevent and treat LBP. Studies analyzing the relationship between MSA and LBP by gender have produced mixed results. Methods: The sample (n=12,721) included participants in the 1999-2004 National Health and Nutrition Examination Survey (NHANES). Three categories of reported MSA participation were created: no MSA (referent group), some MSA (≥1 to/wk), and meeting the 2008 Department of Health and Human Services (DHHS) recommendation (\u3e2 d/wk). The dependent variable was LBP. Results: Gender stratified analysis revealed significantly lower odds ratio of reporting LBP for women (OR 0.82; 95% CI 0.70-0.96, P=0.03) and men (OR 0.86; 95% CI 0.70-0.96, P=0.01) reporting volumes of MSA meeting the DHHS recommendation. Following adjustment for smoking, the odds ratio remained significant in women (P=0.03) but not in men (P=0.21). Conclusions: Men and women reporting volumes of MSA meeting the current DHHS recommendation were found to have lower odds of reporting LBP when compared to those reporting no MSA prior to adjustment for smoking. After adjustment for smoking, the association between MSA and LBP continued to be significant in females but in males. These findings suggest that smoking may be an important mediating factor that should be considered in LBP research

    The effects of continuous, intermittent and mode of exercise on mechanical bone remodelling

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    Bone health is known to deteriorate with age, which can increase the risk of osteoporotic fractures and subsequently all-cause mortality. Current life expectancies are higher than ever before and with our ageing population, osteoporosis and low bone density levels are an ever growing problem that command a lot of medical attention and resources. Women are at a greater risk than men due to increased rates of bone loss that occur in the early years following the menopause. Mechanical loading in the form of exercise is known to reduce the rates of postmenopausal bone loss although an optimal exercise programme is yet to be established. Furthermore, investigations conducted with animals have found intermittent mechanical loading to provide a greater stimulus for bone adaptation than continuous mechanical loading, this has not been investigated in human populations to date. The aim of this thesis was to establish a sufficient exercise mode for stimulating bone adaptation in postmenopausal women and investigate the effects of continuous and intermittent exercise on postmenopausal bone loss. This was attempted with a 12 month randomised controlled trial with postmenopausal women.The first study gave a systematic review of the current literature that investigated continuous or intermittent exercise. The review found that as the studies were not designed to specifically analyse continuous or intermittent exercise, there were numerous problems regarding the control of previous exercise programmes with regards to defined exercise and rest intervals. This was due to the design of the included studies, as many of them were not specifically designed to analyse the different effects of continuous and intermittent exercise on bone mineral density (BMD). In addition, BMD outcomes were not reported in a standardized manner, which complicated the comparisons drawn. From this investigation, it was evident that well-controlled exercise interventions (using a single exercise), are required for the comparison of the effect of continuous and intermittent exercise on BMD in human populations.The second study investigated the feasibility of developing a non-motorised treadmill exercise intervention that included both continuous and intermittent exercise groups. Non-motorised treadmill (NMT) locomotion allows for the instantaneous quantification of ground reaction forces (GRF) and is well suited to both continuous exercise and intermittent exercise with the potential for the use of a range of intermittent running based protocols. In order to establish the osteogenic potential of this mode of exercise, it was necessary to quantify the mechanical loading parameters. This study found that loading parameters showed large reductions during NMT locomotion when compared to overground or motorised treadmill locomotion (24 to 29 %), which could potentially compromise the level of bone adaptation if this mode of exercise was used for intervention purposes.The third study investigated the loading parameters of more traditional high impact exercises in a population of postmenopausal women. All exercises were performed under both continuous and intermittent conditions to assess for consistency during the two conditions. This project showed that countermovement jumps (CMJ) and box drops (BD) produced the highest loading parameters when compared to heel drops (HD) and stamping (STP) (d = 0.83 – 2.38), along with no statistical differences between continuous and intermittent conditions (continuous: 10.7 ± 4.8 g for CMJ, 9.6 ± 4.1 g for BD; intermittent 10.0 ± 5.0 g for CMJ, 9.5 ± 4.0 g for BD). CMJ, BD and HD exercises all appeared to generate a sufficient level of peak acceleration and acceleration gradient for osteogenic adaptation however. For consistency purposes and the fact that no equipment was required, CMJs were selected as the most appropriate home-based exercise for use in a 12 month intervention to reduce postmenopausal bone loss.The fourth study investigated the effects of continuous and intermittent exercise on BMD in early postmenopausal women over the course of a 12 month randomised control trial. Unfortunately the study was underpowered and in addition, the findings showed no statistically significant differences in the bone response between groups. Only the control group experienced a statistically significant loss in both lumbar spine (-2.7% [95%CI: -3.9 to -1.4]) and femoral neck (-3.0% [95%CI: -5.1 to -0.8]) BMD, which exceeded the 95% least significant change at the lumbar spine and femoral neck in 57% of control group participants. There appeared to be no beneficial effect of continuous or intermittent exercise on BMD, hip structural analysis (HSA) parameters or muscular force characteristics when compared to a control group however. In conclusion, this thesis has identified that future research should further investigate the effects of continuous and intermittent exercise on BMD with appropriately controlled randomised control trials, with greater participant numbers. Whilst CMJ and BD provide adequate loading parameters, this does not translate into BMD adaptations. Continuous and intermittent CMJ exercises had no effect on reducing postmenopausal BMD loss at the lumbar spine and the femoral neck, although further investigation is required in an adequately powered study
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