Upper Limb Mass Research Articles

The impact of androgen deprivation therapy on bone microarchitecture in men with prostate cancer: A longitudinal observational study (The ANTELOPE Study)

IntroductionAndrogen Deprivation Therapy (ADT) for prostate cancer (PC) has substantial negative impacts on the musculoskeletal system and body composition. Many studies have focused on the effects of ADT on areal bone mineral density (aBMD), but aBMD does not capture key determinants of bone strength and fracture risk, for example volumetric bone density (vBMD), geometry, cortical thickness and porosity, trabecular parameters and rate of remodelling. More specialist imaging techniques such as high-resolution peripheral quantitative computed tomography (HR-pQCT) have become available to evaluate these parameters. Although it has previously been demonstrated that bone microarchitectural deterioration occurs in men undergoing ADT, the aim of the ANTELOPE study was to examine longitudinal changes in bone microstructure alongside a range of musculoskeletal parameters and frailty, comparing men with PC receiving ADT alone or ADT plus chemotherapy for metastatic disease, with a healthy age-matched population. MethodsWe used HR-pQCT to investigate effects of 12 months of ADT on vBMD and microstructural parameters, complemented by assessment of changes in aBMD, serum bone turnover markers, sex hormones, body composition, grip strength, physical and muscle function, frailty and fracture risk. We studied three groups: Group A − men with localised/locally advanced PC due to commence ADT; Group B − men with newly diagnosed hormone-sensitive, metastatic PC, starting ADT alongside docetaxel chemotherapy and steroids; Group C − healthy, age-matched men. The primary endpoint was change in vBMD (Group A vs Group C) at the distal radius. ResultsNinety-nine participants underwent baseline study assessments (Group A: n = 38, Group B: n = 30 and Group C: n = 31). Seventy-five participants completed all study assessments (Group A (29), Group B (18), Group C (28). At baseline, there were no significant differences between Groups A and C in any of the BMD or bone microstructure outcomes of interest. After 12 months of ADT treatment, there was a significantly greater decrease in vBMD (p < 0.001) in Group A (mean 12-month change = -13.7 mg HA/cm3, −4.1 %) compared to Group C (mean 12-month change = -1.3 mg HA/cm3, −0.4 %), demonstrating achievement of primary outcome. Similar effects were observed when comparing the change in vBMD between Group B (mean 12-month change = -13.5 mg HA/cm3, −4.3 %) and Group C. These changes were mirrored in aBMD. ADT resulted in microstructural deterioration, a reduction in estimated bone strength and an increase in bone turnover. There was evidence of increase in total fat mass and trunkal fat mass in ADT-treated patients, with marked loss in upper limb mass, along with BMI gain. Frailty increased and physical performance and strength deteriorated in both ADT groups, relative to the healthy control group. ConclusionThe study showed that ADT has profound effects on vBMD, aBMD, bone microstructure and strength and body composition, and important impacts on frailty and physical performance. Whilst DXA remains a valuable tool (changes in aBMD are of the same magnitude as those observed for vBMD), HR-pQCT should be considered for assessing the effects of anti-androgens and other newer PC therapies on bone, as well as potential mitigation by bone-targeted agents.

Adaptive Tracking Control of an Exoskeleton Robot With Uncertain Dynamics Based on Estimated Time-Delay Control

In this paper, we present a backstepping approach integrated with time-delay estimation to provide an accurate estimation of unknown dynamics and to compensate for external bounded disturbances. The control was implemented to perform passive rehabilitation movements with a 7-DOF exoskeleton robot named ETS-Motion Assistive Robotic-Exoskeleton for Superior Extremity. The unknown dynamics and external bounded disturbances can affect the robotic system in the form of input saturation, time-delay errors, friction forces, backlash, and different upper-limb's mass of each subject. The output of the time-delay estimator is coupled directly to the control input of the proposed adaptive tracking control through a feed-forward loop. In this case, the control system ensures a highly accurate tracking of the desired trajectory, while being robust to the uncertainties and unforeseen external forces, and flexible with variation of parameters. Due to the proposed strategy, the designed control approach does not require accurate knowledge of the dynamic parameters of the exoskeleton robot to achieve the desired performance. The stability of the exoskeleton robot and the convergence of its state errors are established and proved based on Lyapunov–Krasovskii functional theory. Experimental results and a comparative study are presented to validate the advantages of the proposed strategy.

A Simple Method for Assessing Upper-Limb Force-Velocity Profile in Bench Press.

To analyze the reliability and validity of a field computation method based on easy-to-measure data to assess the mean force ([Formula: see text]) and velocity ([Formula: see text]) produced during a ballistic bench-press movement and to verify that the force-velocity profile (F-v) obtained with multiple loaded trials is accurately described. Twelve participants performed ballistic bench presses against various lifted mass from 30% to 70% of their body mass. For each trial, [Formula: see text] and [Formula: see text] were determined from an accelerometer (sampling rate 500Hz; reference method) and a simple computation method based on upper-limb mass, barbell flight height, and push-off distance. These [Formula: see text] and [Formula: see text] data were used to establish the F-v relationship for each individual and method. A strong to almost perfect reliability was observed between the 2 trials (ICC > .90 for [Formula: see text] and .80 for [Formula: see text], CV% < 10%), whatever the considered method. The mechanical variables ([Formula: see text], [Formula: see text]) measured with the 2 methods and all the variables extrapolated from the F-v relationships were strongly correlated (r2 > .80, P < .001). The practical differences between the methods for the extrapolated mechanical parameters were all <5%, indicating very probably no differences. The findings suggest that the simple computation method used here provides valid and reliable information on force and velocity produced during ballistic bench press, in line with that observed in laboratory conditions. This simple method is thus a practical tool, requiring only 3 simple parameters (upper-limb mass, barbell flight height, and push-off distance).

Additional Weight Influences the Reaching Behavior of Low-Risk Preterm Infants

ABSTRACT The authors investigated the influence of additional weight in the reaching behavior of preterm infants. Nine low-risk preterm and 10 full-term infants age 5–7 months participated. A toy was presented in two procedures: (a) baseline and (b) additional weight (bracelet with weight of 20% of the infant's upper limb mass). The additional weight reduced the straightness index at 5 months, increased the mean velocity and decreased the movement units at all months, and increased unsuccessful grasps at 5 and 7 months in preterm infants. Preterm infants showed less movement units at all months and less unsuccessful grasps at 6 months compared with full-term infants. Weight disturbance seems to change the intrinsic dynamics involved in reaching movements of 5–7-month-old preterm infants.