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  • #16
    Is the voluntary control of breathing the same as normal involuntary breathing?

    http://motorimpairment.neura.edu.au/...ary-breathing/

    Most of the time, our breathing is controlled involuntarily so that we don’t need to consciously think about breathing in and out all the time (for reviews, see Feldman & Del Negro, 2006; Richter & Smith, 2014). However, there are many instances where we need to voluntarily control how fast and/or deep we breathe. For example, we need to control our breathing when we speak or sing, hold our breath, play musical instruments, for swimming, and for relaxation techniques. While voluntary and involuntary breathing uses the same muscles, and the typical respiratory variables of lung volume, airflow, and airway pressure can be accurately matched, we don’t know what happens to the involuntary neural control signals during voluntary breathing. It is possible that voluntary control signals from the cortex override and replace the involuntary signals that originate in the brainstem or both neural signals summate at the motoneurones to produce the desired level of breathing.
    Jo Bowyer
    Chartered Physiotherapist Registered Osteopath.
    "Out beyond ideas of wrongdoing and rightdoing,there is a field. I'll meet you there." Rumi

    Comment


    • #17
      Identifying the Functional Flexion-extension Axis of the Knee: An In-Vivo Kinematics Study

      http://journals.plos.org/plosone/art...l.pone.0128877

      Abstract

      Purpose

      This study aimed to calculate the flexion-extension axis (FEA) of the knee through in-vivo knee kinematics data, and then compare it with two major anatomical axes of the femoral condyles: the transepicondylar axis (TEA) defined by connecting the medial sulcus and lateral prominence, and the cylinder axis (CA) defined by connecting the centers of posterior condyles.

      Methods

      The knee kinematics data of 20 healthy subjects were acquired under weight-bearing condition using bi-planar x-ray imaging and 3D-2D registration techniques. By tracking the vertical coordinate change of all points on the surface of femur during knee flexion, the FEA was determined as the line connecting the points with the least vertical shift in the medial and lateral condyles respectively. Angular deviation and distance among the TEA, CA and FEA were measured.

      Results

      The TEA-FEA angular deviation was significantly larger than that of the CA-FEA in 3D and transverse plane (3.45° vs. 1.98°, p < 0.001; 2.72° vs. 1.19°, p = 0.002), but not in the coronal plane (1.61° vs. 0.83°, p = 0.076). The TEA-FEA distance was significantly greater than that of the CA-FEA in the medial side (6.7 mm vs. 1.9 mm, p < 0.001), but not in the lateral side (3.2 mm vs. 2.0 mm, p = 0.16).

      Conclusion

      The CA is closer to the FEA compared with the TEA; it can better serve as an anatomical surrogate for the functional knee axis.
      The functional knee axis comes up in my discussions with patients contemplating TKR. The London surgeons I work with don't do them unless the patient has "failed physiotherapy" as they put it. Most of my patients do well following TKR, they are fully aware that the implant is not going to be the same as the knee that they were born with and that it will take a while for the brain maps to reconfigure kinaesthetic processing as well as the persistent/complex pain issues. My key message is that replacement surgery is not a soft option although it is probably less of an ordeal than osteotomy.
      Jo Bowyer
      Chartered Physiotherapist Registered Osteopath.
      "Out beyond ideas of wrongdoing and rightdoing,there is a field. I'll meet you there." Rumi

      Comment


      • #18
        Humans Can Continuously Optimize Energetic Cost during Walking

        http://www.cell.com/current-biology/...822(15)00958-6

        Highlights
        •People readily adapt established gait patterns to minimize energy use
        •People converge on new energetic optima within minutes, even for small cost savings
        •Updated predictions about energetically optimal gaits allow re-convergence within seconds
        •Energetic cost is not just an outcome of movement, but also continuously shapes it
        Summary
        People prefer to move in ways that minimize their energetic cost [ 1–9 ]. For example, people tend to walk at a speed that minimizes energy use per unit distance [ 5–8 ] and, for that speed, they select a step frequency that makes walking less costly [ 3, 4, 6, 10–12 ]. Although aspects of this preference appear to be established over both evolutionary [ 9, 13–15 ] and developmental [ 16 ] timescales, it remains unclear whether people can also optimize energetic cost in real time. Here we show that during walking, people readily adapt established motor programs to minimize energy use. To accomplish this, we used robotic exoskeletons to shift people’s energetically optimal step frequency to frequencies higher and lower than normally preferred. In response, we found that subjects adapted their step frequency to converge on the new energetic optima within minutes and in response to relatively small savings in cost (<5%). When transiently perturbed from their new optimal gait, subjects relied on an updated prediction to rapidly re-converge within seconds. Our collective findings indicate that energetic cost is not just an outcome of movement, but also plays a central role in continuously shaping it.



        Intra-individual gait patterns across different time-scales as revealed by means of a supervised learning model using kernel-based discriminant regression

        http://journals.plos.org/plosone/art...l.pone.0179738

        Abstract

        Objective

        Traditionally, gait analysis has been centered on the idea of average behavior and normality. On one hand, clinical diagnoses and therapeutic interventions typically assume that average gait patterns remain constant over time. On the other hand, it is well known that all our movements are accompanied by a certain amount of variability, which does not allow us to make two identical steps. The purpose of this study was to examine changes in the intra-individual gait patterns across different time-scales (i.e., tens-of-mins, tens-of-hours).

        Methods

        Nine healthy subjects performed 15 gait trials at a self-selected speed on 6 sessions within one day (duration between two subsequent sessions from 10 to 90 mins). For each trial, time-continuous ground reaction forces and lower body joint angles were measured. A supervised learning model using a kernel-based discriminant regression was applied for classifying sessions within individual gait patterns.

        Results and discussion

        Discernable characteristics of intra-individual gait patterns could be distinguished between repeated sessions by classification rates of 67.8 ± 8.8% and 86.3 ± 7.9% for the six-session-classification of ground reaction forces and lower body joint angles, respectively. Furthermore, the one-on-one-classification showed that increasing classification rates go along with increasing time durations between two sessions and indicate that changes of gait patterns appear at different time-scales.

        Conclusion

        Discernable characteristics between repeated sessions indicate continuous intrinsic changes in intra-individual gait patterns and suggest a predominant role of deterministic processes in human motor control and learning. Natural changes of gait patterns without any externally induced injury or intervention may reflect continuous adaptations of the motor system over several time-scales. Accordingly, the modelling of walking by means of average gait patterns that are assumed to be near constant over time needs to be reconsidered in the context of these findings, especially towards more individualized and situational diagnoses and therapy.
        Update 16/06/2017
        Last edited by Jo Bowyer; 16-06-2017, 03:07 PM.
        Jo Bowyer
        Chartered Physiotherapist Registered Osteopath.
        "Out beyond ideas of wrongdoing and rightdoing,there is a field. I'll meet you there." Rumi

        Comment


        • #19
          Movement-based embodied contemplative practices: definitions and paradigms

          http://journal.frontiersin.org/artic...014.00205/full

          Over the past decades, cognitive neuroscience has witnessed a shift from predominantly disembodied and computational views of the mind, to more embodied and situated views of the mind. These postulate that mental functions cannot be fully understood without reference to the physical body and the environment in which they are experienced. Within the field of contemplative science, the directing of attention to bodily sensations has so far mainly been studied in the context of seated meditation and mindfulness practices. However, the cultivation of interoceptive, proprioceptive and kinesthetic awareness is also said to lie at the core of many movement-based contemplative practices such as Yoga, Qigong, and Tai Chi. In addition, it likely plays a key role in the efficacy of modern somatic therapeutic techniques such as the Feldenkrais Method and the Alexander Technique. In the current paper we examine how these practices are grounded in the concepts of embodiment, movement and contemplation, as we look at them primarily through the lens of an enactive approach to cognition. Throughout, we point to a series of challenges that arise when Western scientists study practices that are based on a non-dualistic view of mind and body.
          Jo Bowyer
          Chartered Physiotherapist Registered Osteopath.
          "Out beyond ideas of wrongdoing and rightdoing,there is a field. I'll meet you there." Rumi

          Comment


          • #20
            Difference in Postural Control during Quiet Standing between Young Children and Adults: Assessment with Center of Mass Acceleration

            http://journals.plos.org/plosone/art...l.pone.0140235

            Abstract

            The development of upright postural control has often been investigated using time series of center of foot pressure (COP), which is proportional to the ankle joint torque (i.e., the motor output of a single joint). However, the center of body mass acceleration (COMacc), which can reflect joint motions throughout the body as well as multi-joint coordination, is useful for the assessment of the postural control strategy at the whole-body level. The purpose of the present study was to investigate children’s postural control during quiet standing by using the COMacc. Ten healthy children and 15 healthy young adults were instructed to stand upright quietly on a force platform with their eyes open or closed. The COMacc as well as the COP in the anterior–posterior direction was obtained from ground reaction force measurement. We found that both the COMacc and COP could clearly distinguish the difference between age groups and visual conditions. We also found that the sway frequency of COMacc in children was higher than that in adults, for which differences in biomechanical and/or neural factors between age groups may be responsible. Our results imply that the COMacc can be an alternative force platform measure for assessing developmental changes in upright postural control.
            Jo Bowyer
            Chartered Physiotherapist Registered Osteopath.
            "Out beyond ideas of wrongdoing and rightdoing,there is a field. I'll meet you there." Rumi

            Comment


            • #21
              Benefits of Regular Exercise on Inflammatory and Cardiovascular Risk Markers in Normal Weight, Overweight and Obese Adults

              http://journals.plos.org/plosone/art...l.pone.0140596

              Abstract

              Obesity is a worldwide epidemic that increases the risk of several well-known co-morbidities. There is a complicated relationship between adipokines and low-grade inflammation in obesity and cardiovascular disease (CVD). Physical activity practices have beneficial health effects on obesity and related disorders such as hypertension and dyslipidemia. We investigated the effects of 6 and 12 months of moderate physical training on the levels of adipokines and CVD markers in normal weight, overweight and obese volunteers. The 143 participants were followed up at baseline and after six and twelfth months of moderate regular exercise, 2 times a week, for 12 months. The volunteers were distributed into 3 groups: Normal Weight Group (NWG,), Overweight Group (OVG) and Obese Group (OBG). We evaluated blood pressure, resting heart rate, anthropometric parameters, body composition, fitness capacity (VO2max and isometric back strength), cardiovascular markers (CRP, total cholesterol, LDL-c, HDL-c, homocysteine) and adipokine levels (leptin, adiponectin, resistin, IL-6 and TNF-alpha). There were no significant changes in anthropometric parameters and body composition in any of the groups following 6 and 12 months of exercise training. Leptin, IL-6 levels and systolic blood pressure were significantly elevated in OBG before the training. Regular exercise decreased HDL-c, leptin, adiponectin and resistin levels and diastolic blood pressure in OVG. In OBG, exercise diminished HDL-c, homocysteine, leptin, resistin, IL-6, adiponectin. Moderate exercise had no effect on the body composition; however, exercise did promote beneficial effects on the low-grade inflammatory state and CVD clinical markers in overweight and obese individuals.
              Discussion

              In the present study, the moderate exercise program improved the low-grade inflammatory state and cardiovascular system, reducing leptin and resistin levels and diastolic blood pressure in OVG, and leptin, resistin, IL-6 and homocysteine levels in OBG; however, body composition and some cardiometabolic markers that are more related to diet habits remained unchanged or worsened (HDL-c and adiponectin). We suggest that the control of energy balance through diet and physical activity are crucial to improve these markers and decrease cardiovascular risk.

              The lack of diet control was a limitation in our study. We estimated energy expenditure to be around 200 to 400 kcal per activity, i.e. 400 to 800 kcal per week, which should contribute to loss of 1 kg in approximately 11–12 weeks. However, the lack of effect on body composition could be explained by: the easy replacement of food intake; and/or, in a long run, the adaptations to exercise decreased the energy expenditure during the exercise; and/or the low frequency of exercise.

              In the lipostatic theory of body-weight set point, the release of leptin from adipocytes is a negative feedback loop to suppress appetite and prevent weight gain. Leptin acts in the hypothalamic arcuate nucleus and tractus solitarii and is responsible for controlling glucose homeostasis, energy balance and SNS activation [3]. The peripheral function of leptin involves angiogenesis, hematopoiesis, bone density, wound healing, the immune system, energy metabolism regulation, and nutrient intestinal absorption [20].

              Although the circulating leptin levels are very high in obese subjects, leptin is unable to effectively prevent weight gain, defined as leptin resistance, ant this was observed in our study [2].

              Thereby, these studies support that several mediators of inflammation are related with hyperleptinemia and leptin resistance development in states of obesity induced by diet. The activation of inflammatory signaling initiates the development of leptin resistance and up regulates pro inflammatory cytokines such as IL-6 [20]
              Elevated levels of muscle sympathetic nerve activity are associated with obesity-induced subclinical organ damage to the heart, even in the absence of hypertension [42]. In accordance with other studies, moderate exercise reduced diastolic blood pressure [38, 43]. Physical activity may alter vascular compliance due to diminished hormone release such as resistin, leptin, and IL-6 that could reduce SNS activity and peripheral resistance [3].

              In conclusion, moderate exercise without calorie restriction had no effect on body composition; however, training demonstrated beneficial effects on the low-grade inflammatory state, decreasing leptin, resistin and IL-6 and cardiovascular clinical markers such as blood pressure and homocysteine, mainly in overweight and/or obese individuals.
              I have several long term patients who are obese. They understand and feel the benefits of regular exercise They say that their quality of life would suffer if they were to change their diet and eating patterns, I advise them as to what they should be eating in the same way that I do with teenagers and I accept the fact that anything they choose to eat in addition to foods required for maintenance and repair is their business, some of them will have a go at weight reduction in order to reduce loading of injured structures if I advise it.
              Jo Bowyer
              Chartered Physiotherapist Registered Osteopath.
              "Out beyond ideas of wrongdoing and rightdoing,there is a field. I'll meet you there." Rumi

              Comment


              • #22
                Neuromuscular Activation of the Vastus Intermedius Muscle during Isometric Hip Flexion

                http://journals.plos.org/plosone/art...l.pone.0141146

                Abstract

                Although activity of the rectus femoris (RF) differs from that of the other synergists in quadriceps femoris muscle group during physical activities in humans, it has been suggested that the activation pattern of the vastus intermedius (VI) is similar to that of the RF. The purpose of present study was to examine activation of the VI during isometric hip flexion. Ten healthy men performed isometric hip flexion contractions at 25%, 50%, 75%, and 100% of maximal voluntary contraction at hip joint angles of 90°, 110° and 130°. Surface electromyography (EMG) was used to record activity of the four quadriceps femoris muscles and EMG signals were root mean square processed and normalized to EMG amplitude during an isometric knee extension with maximal voluntary contraction. The normalized EMG was significantly higher for the VI than for the vastus medialis during hip flexion at 100% of maximal voluntary contraction at hip joint angles of 110° and 130° (P < 0.05). The onset of VI activation was 230–240 ms later than the onset of RF activation during hip flexion at each hip joint angle, which was significantly later than during knee extension at 100% of maximal voluntary contraction (P < 0.05). These results suggest that the VI is activated later than the RF during hip flexion. Activity of the VI during hip flexion might contribute to stabilize the knee joint as an antagonist and might help to smooth knee joint motion, such as in the transition from hip flexion to knee extension during walking, running and pedaling.
                Jo Bowyer
                Chartered Physiotherapist Registered Osteopath.
                "Out beyond ideas of wrongdoing and rightdoing,there is a field. I'll meet you there." Rumi

                Comment


                • #23
                  Motor Skill Learning Is Associated with Phase-Dependent Modifications in the Striatal cAMP/PKA/DARPP-32 Signaling Pathway in Rodents

                  http://journals.plos.org/plosone/art...l.pone.0140974

                  Abstract

                  Abundant evidence points to a key role of dopamine in motor skill learning, although the underlying cellular and molecular mechanisms are still poorly understood. Here, we used a skilled-reaching paradigm to first examine changes in the expression of the plasticity-related gene Arc to map activity in cortico-striatal circuitry during different phases of motor skill learning in young animals. In the early phase, Arc mRNA was significantly induced in the medial prefrontal cortex (mPFC), cingulate cortex, primary motor cortex, and striatum. In the late phase, expression of Arc did not change in most regions, except in the mPFC and dorsal striatum. In the second series of experiments, we studied the learning-induced changes in the phosphorylation state of dopamine and cAMP-regulated phosphoprotein, 32k Da (DARPP-32). Western blot analysis of the phosphorylation state of DARPP-32 and its downstream target cAMP response element-binding protein (CREB) in the striatum revealed that the early, but not late, phase of motor skill learning was associated with increased levels of phospho-Thr34-DARPP-32 and phospho-Ser133-CREB. Finally, we used the DARPP-32 knock-in mice with a point mutation in the Thr34 regulatory site (i.e., protein kinase A site) to test the significance of this pathway in motor skill learning. In accordance with our hypothesis, inhibition of DARPP-32 activity at the Thr34 regulatory site strongly attenuated the motor learning rate and skilled reaching performance of mice. These findings suggest that the cAMP/PKA/DARPP-32 signaling pathway is critically involved in the acquisition of novel motor skills, and also demonstrate a dynamic shift in the contribution of cortico-striatal circuitry during different phases of motor skill learning.
                  So, learning movement is inherently rewarding, whatever the end game.
                  Jo Bowyer
                  Chartered Physiotherapist Registered Osteopath.
                  "Out beyond ideas of wrongdoing and rightdoing,there is a field. I'll meet you there." Rumi

                  Comment


                  • #24
                    Can Doping be a Good Thing? Using Psychoactive Drugs to Facilitate Physical Activity Behaviour

                    http://link.springer.com/article/10..../fulltext.html

                    1 A Psychobiological Approach to Facilitate Physical Activity Behaviour

                    A physically active lifestyle has so many health benefits that the Academy of Royal Medical Colleges in the UK has recently defined exercise as the “miracle cure” [1]. Unfortunately, however, most people do not meet current guidelines for physical activity. Therefore, effective interventions to facilitate physical activity behaviour can have a great impact on public health worldwide [2].
                    At present, recommended interventions to reduce physical inactivity are based on (1) campaigns and informational approaches, (2) behavioural and social approaches, and (3) environmental and policy approaches [3]. Examples of such interventions include mass media campaigns, social support, and creation of places for physical activity. These interventions are necessary to promote physical activity, and should be widely implemented. However, despite all the efforts, maintenance of physical activity behaviour change is still a major issue [4], and we urgently need to develop and implement new interventions. As suggested by Bauman et al. [5], innovative interventions may come from a better understanding of how the brain regulates physical activity behaviour, i.e. a psychobiological approach. Physical activity is a very complex behaviour, and only a combination of different interventions that target behaviour at all levels is likely to succeed [6].
                    Psychoactive substances have been in use since humans first identified those that gave them a buzz as opposed to injuring or killing them.

                    I never got picked for random dope testing, but if I had I would always have been close to the mark on caffeine, which has been off the banned list for ages now as so many people were over the limit. It is an effective ergogenic aid provided that you don't overdo it and give yourself the jitters.

                    Movement gives access to the pharmacy within. Why not start there? Human and animal babies have much to teach us.

                    (Also posted in Psychosocial Papers)
                    Last edited by Jo Bowyer; 13-01-2016, 11:28 PM.
                    Jo Bowyer
                    Chartered Physiotherapist Registered Osteopath.
                    "Out beyond ideas of wrongdoing and rightdoing,there is a field. I'll meet you there." Rumi

                    Comment


                    • #25
                      Learning Upright Standing on a Multiaxial Balance Board

                      http://journals.plos.org/plosone/art...l.pone.0142423

                      Abstract

                      Upright stance on a balance board is a skill requiring complex rearrangement of the postural control. Despite the large use of these boards in training the standing posture, a comprehensive analysis of the learning process underlying the control of these devices is lacking. In this paper learning to maintain a stable stance on a multiaxial oscillating board was studied by analyzing performance changes over short and long periods. Healthy participants were asked to keep the board orientation as horizontal as possible for 20 sec, performing two sessions of 8 trials separated by 15-min pause. Memory consolidation was tested one week later. Amplitude and variability of the oscillations around horizontal plane and area and sway path of the board displacement decreased rapidly over the first session. The performance was stable during the second session, and retained after 1 week. A similar behavior was observed in the anterior-posterior and medial-lateral directions for amplitude and variability parameters, with less stable balance in the anterior-posterior direction. Approximate entropy and mean power frequency, assessing temporal dynamics and frequency content of oscillations, changed only in the anterior-posterior direction during the retention test. Overall, the ability to stand on a balance board is rapidly acquired, and retained for long time. The asymmetric stability between anterior-posterior and medial-lateral directions replicates a structure observed in other standing stances, suggesting a possible transfer from previous postural experiences. Conversely, changes in the temporal dynamics and the frequency content could be associated with new postural strategies developed later during memory consolidation.
                      It is rare that I see a new patient that doesn't (in my opinion) require balance training. My approach is to get them to use their home/work/travel environment for 15 second bursts of "mindful" balance training as that appears to be the length of time that most people can maintain focus. The same goes for advice that I give during sessions. If I notice that their attention may have wandered, I come back to it later on during the same session.

                      I don't use balance boards, but probably would if I could get a print out for the notes.
                      Jo Bowyer
                      Chartered Physiotherapist Registered Osteopath.
                      "Out beyond ideas of wrongdoing and rightdoing,there is a field. I'll meet you there." Rumi

                      Comment


                      • #26
                        A quantitative framework for whole-body coordination reveals specific deficits in freely walking ataxic mice

                        http://elifesciences.org/content/4/e07892

                        The coordination of movement across the body is a fundamental, yet poorly understood aspect of motor control. Mutant mice with cerebellar circuit defects exhibit characteristic impairments in locomotor coordination; however, the fundamental features of this gait ataxia have not been effectively isolated. Here we describe a novel system (LocoMouse) for analyzing limb, head, and tail kinematics of freely walking mice. Analysis of visibly ataxic Purkinje cell degeneration (pcd) mice reveals that while differences in the forward motion of individual paws are fully accounted for by changes in walking speed and body size, more complex 3D trajectories and, especially, inter-limb and whole-body coordination are specifically impaired. Moreover, the coordination deficits in pcd are consistent with a failure to predict and compensate for the consequences of movement across the body. These results isolate specific impairments in whole-body coordination in mice and provide a quantitative framework for understanding cerebellar contributions to coordinated locomotion.
                        Perhaps another argument for using meaningful functional activity to retrain coordination, rather than giving feedback on specific targeted exercise

                        My Italics
                        Jo Bowyer
                        Chartered Physiotherapist Registered Osteopath.
                        "Out beyond ideas of wrongdoing and rightdoing,there is a field. I'll meet you there." Rumi

                        Comment


                        • #27
                          Cortical Components of Reaction-Time during Perceptual Decisions in Humans

                          http://journals.plos.org/plosone/art...l.pone.0143339

                          Abstract

                          The mechanisms of perceptual decision-making are frequently studied through measurements of reaction time (RT). Classical sequential-sampling models (SSMs) of decision-making posit RT as the sum of non-overlapping sensory, evidence accumulation, and motor delays. In contrast, recent empirical evidence hints at a continuous-flow paradigm in which multiple motor plans evolve concurrently with the accumulation of sensory evidence. Here we employ a trial-to-trial reliability-based component analysis of encephalographic data acquired during a random-dot motion task to directly image continuous flow in the human brain. We identify three topographically distinct neural sources whose dynamics exhibit contemporaneous ramping to time-of-response, with the rate and duration of ramping discriminating fast and slow responses. Only one of these sources, a parietal component, exhibits dependence on strength-of-evidence. The remaining two components possess topographies consistent with origins in the motor system, and their covariation with RT overlaps in time with the evidence accumulation process. After fitting the behavioral data to a popular SSM, we find that the model decision variable is more closely matched to the combined activity of the three components than to their individual activity. Our results emphasize the role of motor variability in shaping RT distributions on perceptual decision tasks, suggesting that physiologically plausible computational accounts of perceptual decision-making must model the concurrent nature of evidence accumulation and motor planning.
                          Jo Bowyer
                          Chartered Physiotherapist Registered Osteopath.
                          "Out beyond ideas of wrongdoing and rightdoing,there is a field. I'll meet you there." Rumi

                          Comment


                          • #28
                            Does the frequency and intensity of physical activity in adolescence have an impact on bone? The Tromsø Study, Fit Futures

                            http://www.biomedcentral.com/2052-18...ource=Teradata

                            Abstract
                            Background
                            Optimization of the genetic potential for bone accrual in early life may prevent future fractures. Possible modification factors include lifestyle factors such as nutrition and physical activity. Measured levels of bone mineral density (BMD) and bone mass content (BMC) are indicators of bone strength, and are correlated with fracture risk. This study explored the impact of self-reported physical activity frequencies and intensity on BMD and BMC in Norwegian adolescents.

                            Methods
                            In 2010–2011 school students in two North-Norwegian municipalities were invited to a health survey, the Fit Future study. 508 girls and 530 boys aged 15–18 years attended. BMD and BMC were measured by dual X-ray absorptiometry. Physical activity and other lifestyle-factors were reported by questionnaires and clinical interviews. Statistical analyses were performed sex stratified, using ANOVA for comparison of means and linear regression models adjusting for factors known to affect bone.

                            Results
                            Approximately 2/3 of girls and boys reported themselves as physically active outside school hours. Active participants had a significantly higher BMD and BMC at all sites (p < 0.001), except for BMC total body in girls, compared to inactive participants. In multiple linear regression analyses, increased physical activity measured as days a week, categorized into seldom, moderate and highly, was positively associated with BMD (g/cm 2 ) at all sites in girls. Girls reporting themselves as highly active had BMD levels 0.093 g/cm 2 , 0.090 g/cm 2 and 0.046 g/cm 2 higher (p < 0.001) than their more seldom active peers at femoral neck, total hip and total body respectively. Corresponding values for boys were 0.125 g/cm 2 , 0.133 g/cm 2 and 0.66 g/cm 2 . BMC measures showed similar trends at femoral neck and total hip.

                            Conclusions
                            Increased level of physical activity is associated with higher BMD and BMC levels in adolescents. For both sexes high activity frequency seems to be essential, whilst boys reporting quite hard intensity has an additional impact. The differential effects of physical activity on bone strength in adolescence have clinical implications, especially in preventive strategies.
                            Keywords: Population-based study; Physical activity; Adolescents; Bone mineral density; DXA
                            Jo Bowyer
                            Chartered Physiotherapist Registered Osteopath.
                            "Out beyond ideas of wrongdoing and rightdoing,there is a field. I'll meet you there." Rumi

                            Comment


                            • #29
                              Center of Pressure Displacement of Standing Posture during Rapid Movements Is Reorganised Due to Experimental Lower Extremity Muscle Pain

                              http://journals.plos.org/plosone/art...l.pone.0144933

                              Abstract

                              Background

                              Postural control during rapid movements may be impaired due to musculoskeletal pain. The purpose of this study was to investigate the effect of experimental knee-related muscle pain on the center of pressure (CoP) displacement in a reaction time task condition.

                              Methods

                              Nine healthy males performed two reaction time tasks (dominant side shoulder flexion and bilateral heel lift) before, during, and after experimental pain induced in the dominant side vastus medialis or the tibialis anterior muscles by hypertonic saline injections. The CoP displacement was extracted from the ipsilateral and contralateral side by two force plates and the net CoP displacement was calculated.

                              Results

                              Compared with non-painful sessions, tibialis anterior muscle pain during the peak and peak-to-peak displacement for the CoP during anticipatory postural adjustments (APAs) of the shoulder task reduced the peak-to-peak displacement of the net CoP in the medial-lateral direction (P<0.05). Tibialis anterior and vastus medialis muscle pain during shoulder flexion task reduced the anterior-posterior peak-to-peak displacement in the ipsilateral side (P<0.05).

                              Conclusions

                              The central nervous system in healthy individuals was sufficiently robust in maintaining the APA characteristics during pain, although the displacement of net and ipsilateral CoP in the medial-lateral and anterior-posterior directions during unilateral fast shoulder movement was altered.
                              Jo Bowyer
                              Chartered Physiotherapist Registered Osteopath.
                              "Out beyond ideas of wrongdoing and rightdoing,there is a field. I'll meet you there." Rumi

                              Comment


                              • #30
                                Reactive Balance Control in Response to Perturbation in Unilateral Stance: Interaction Effects of Direction, Displacement and Velocity on Compensatory Neuromuscular and Kinematic Responses

                                http://journals.plos.org/plosone/art...l.pone.0144529

                                Abstract

                                Unexpected sudden perturbations challenge postural equilibrium and require reactive compensation. This study aimed to assess interaction effects of the direction, displacement and velocity of perturbations on electromyographic (EMG) activity, centre of pressure (COP) displacement and joint kinematics to detect neuromuscular characteristics (phasic and segmental) and kinematic strategies of compensatory reactions in an unilateral balance paradigm. In 20 subjects, COP displacement and velocity, ankle, knee and hip joint excursions and EMG during short (SLR), medium (MLR) and long latency response (LLR) of four shank and five thigh muscles were analysed during random surface translations varying in direction (anterior-posterior (sagittal plane), medial-lateral (frontal plane)), displacement (2 vs. 3cm) and velocity (0.11 vs. 0.18m/s) of perturbation when balancing on one leg on a movable platform. Phases: SLR and MLR were scaled to increased velocity (P<0.05); LLR was scaled to increased displacement (P<0.05). Segments: phasic interrelationships were accompanied by segmental distinctions: distal muscles were used for fast compensation in SLR (P<0.05) and proximal muscles to stabilise in LLR (P<0.05). Kinematics: ankle joints compensated for both increasing displacement and velocity in all directions (P<0.05), whereas knee joint deflections were particularly sensitive to increasing displacement in the sagittal (P<0.05) and hip joint deflections to increasing velocity in the frontal plane (P<0.05). COP measures increased with increasing perturbation velocity and displacement (P<0.05). Interaction effects indicate that compensatory responses are based on complex processes, including different postural strategies characterised by phasic and segmental specifications, precisely adjusted to the type of balance disturbance. To regain balance after surface translation, muscles of the distal segment govern the quick regain of equilibrium; the muscles of the proximal limb serve as delayed stabilisers after a balance disturbance. Further, a kinematic distinction regarding the compensation for balance disturbance indicated different plane- and segment-specific sensitivities with respect to the determinants displacement and velocity.


                                Assessing Somatosensory Utilization during Unipedal Postural Control

                                http://journal.frontiersin.org/artic...017.00021/full

                                Multisensory—visual, vestibular and somatosensory information is integrated for appropriate postural control. The primary goal of this study was to assess somatosensory utilization during a functional motor task of unipedal postural control, in normal healthy adults. Assessing individual bias in the utilization of individual sensory contributions during postural control may help customization of rehabilitation protocols. In this study, a test paradigm of unipedal stance control in supine orientation with and without vision was assessed. Postural control in this test paradigm was hypothesized to utilize predominantly contributions of somatosensory information from the feet and ankle joint, with minimal vestibular input. Fourteen healthy subjects “stood” supine on their dominant leg while strapped to a backpack frame that was freely moving on air-bearings, to remove available otolith tilt cues with respect to gravity that influences postural control when standing upright. The backpack was attached through a cable to a pneumatic cylinder that provided a gravity-like load. Subjects performed three trials each with Eyes-open (EO) and Eyes-closed (EC) while loaded with 60% body weight. There was no difference in unipedal stance time (UST) across the two conditions with EC condition challenging the postural control system greater than the EO condition. Stabilogram-diffusion analysis (SDA) indicated that the critical mean square displacement was significantly different between the two conditions. Vestibular cues, both in terms of magnitude and the duration for which relevant information was available for postural control in this test paradigm, were minimized. These results support our hypothesis that maintaining unipedal stance in supine orientation without vision, minimizes vestibular contribution and thus predominantly utilizes somatosensory information for postural control.
                                Update 21/04/2015
                                Last edited by Jo Bowyer; 21-04-2017, 05:01 PM.
                                Jo Bowyer
                                Chartered Physiotherapist Registered Osteopath.
                                "Out beyond ideas of wrongdoing and rightdoing,there is a field. I'll meet you there." Rumi

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