Recognizing the intensity of strength training exercises with wearable sensors

In this paper we propose a system based on a network of wearable accelerometers and an off-the-shelf smartphone to recognize the intensity of stationary activities, such as strength training exercises. The system uses a hierarchical algorithm, consisting of two layers of Support Vector Machines (SVMs), to first recognize the type of exercise being performed, followed by recognition of exercise intensity. The first layer uses a single SVM to recognize the type of the performed exercise. Based on the recognized type a corresponding intensity prediction SVM is selected on the second layer, specializing in intensity prediction for the recognized type of exercise. We evaluate the system for a set of upper-body exercises using different weight loads. Additionally, we compare the most important features for exercise and intensity recognition tasks and investigate how different sliding window combinations, sensor configurations and number of training subjects impact the algorithm performance. We perform all of the experiments for two different types of features to evaluate the feasibility of implementation on resource constrained hardware. The results show the algorithm is able to recognize exercise types with approximately 85% accuracy and 6% intensity prediction error. Furthermore, due to similar performance using different types of features, the algorithm offers potential for implementation on resource constrained hardware.     

Investigating prismatic adaptation effects in handgrip strength and in plantar pressure in healthy subjects

BackgroundPrismatic Adaptation (PA) is a visuomotor procedure inducing a shift of the visual field that has been shown to modulate activation of a number of brain areas, in posterior (i.e. parietal cortex) and anterior regions (i.e. frontal cortex). This neuromodulation could be useful to study neural mechanisms associated with either postural measures such as the distribution of plantar pressure or to the generation of muscle strength. Indeed, plantar pressure distribution is associated to activation of high-level cognitive mechanisms taking place within the posterior regions of the brain dorsal stream, especially of the right hemisphere. Conversely, hand force mostly rely on sensorimotor mechanisms, fulfilled by anterior regions of the brain and involving both hemispheres.Research questionSince PA effects have been reported to affect both sensorimotor and higher level cognitive processes, is it possible to hypothesize a modulation of both hands strenght and plantar pressure after PA?MethodsForty-six healthy subjects (male = 23; mean age = 25 ± 3 years) were randomly divided into two groups: a leftward prismatic adaptation group (l-PA) and a rightward prismatic adaptation group (r-PA). Hand strength and plantar pressure were assessed, immediately before and after PA, using the handgrip task and baropodometric measurement, respectively.ResultsBoth l-PA and r-PA induced a significant decrease of strength in the hand contralateral to the lenses deviation side. Only r-PA was associated with an increase of the forefoot plantar pressure in both feet. Modulation of interhemispheric inhibitory processes at sensorimotor and higher cognitive level may account for the present results.SignificancePA exerts effects on body posture and hand strength relying on different mechanisms. The PA effects on hand strength are probably related to the modulation of interhemispheric inhibition of sensorimotor processes, involving both hemispheres. The PA effects on body posture are probably related to modulation of body representation, involving mainly the right hemisphere.     

Validity and reliability assessment of 3-D camera-based capture barbell velocity tracking device

Velocity-based training (VBT) requires the monitoring of lift velocity plus the prescribed resistance weight. A validated and reliable device is needed to capture the velocity and power of several exercises.ObjectivesThe study objectives were to examine the validity and reliability of the Elite Form Training System® (EFTS) for measures of peak velocity (PV), average velocity (AV), peak power (PP), and average power (AP).DesignValidity of the EFTS was assessed by comparing measurements simultaneously obtained via the Qualisys Track Manager software (C-motion, version 3.90.21, Gothenburg, Sweden) utilizing 6 motion capture cameras (Oqus 400, 240 Hz, Gothenburg, Sweden).MethodsSix participants performed 6 resistance exercises in 2 sessions: power clean, dead lift, bench press, back squat, front squat, and jump squat.ResultsSimple Pearson correlations indicated the validity of the device (0.982, 0.971, 0.973, and 0.982 for PV, AV, PP, and AP respectively) and ranged from 0.868 to 0.998 for the 6 exercises. The test-retest reliability of the EFTS was shown by lack of significant change in the Pearson correlation (<0.3% for each variable) between the 2 sessions. The multiple count error rate was 2.0% and the missed count error rate was 2.1%.ConclusionsThe validity and reliability of the EFTS were classified as excellent across all variables and exercises with only one exercise showing a slight influence by the velocity of the movement.     

Seldinger technique in repair of the parotid duct

Injuries to the parotid ducts are difficult to locate, assess, and repair, and traditionally, solid metal dilators and soft plastic tubes have had only limited success. We describe the Seldinger technique with a central venous catheter, which makes repair easier.     

Strength reduction and the effects of treatment of long bones with diaphyseal defects involving 50% of the cortex

Currently, three criteria are accepted as indications for prophylactic internal fixation of metastatic disease in long bone, including lesions (a) destroying 50% or more of the cortex; (b) 2.5 cm or greater in diameter; or (c) with pain unrelieved by radiation therapy. Using an oblong defect configuration in which one half of the cross-sectional area was destroyed, canine femora were torsion-tested at high speed to determine (a) the actual strength reduction incurred by a lesion destroying 50% of the cortical circumference, and (b) the effects and benefits of internal fixation using polymethylmethacrylate and/or a six-hole compression plate on such a defect. The femurs with a 50% circumferential cortical defect demonstrated only 12.7 +/- 3.8% of intact strength. Defects treated with a combination of plating (all screws bicortical) and polymethylmethacrylate (torque to failure 4.39 +/- 0.90 times greater than the defect alone or TE/TD = 4.39 +/- 0.90) were statistically stronger than defects treated with polymethylmethacrylate alone (TE/TD = 2.48 +/- 0.66; p less than 0.025) or by plating alone (TE/TD = 2.61 +/- 0.91; p less than 0.025), but torque-to-failure was only increased to approximately 56% of an intact bone. Plated intact bones (TE/TD = 5.33 +/- 0.41) were significantly weaker than intact bones (TE/TD = 8.50 +/- 2.52; p less than 0.001). Our results substantiate the need for using polymethylmethacrylate and internal fixation in combination when prophylactically fixing pathologic lesions of this proportion.     

黑米素的药理作用研究

对黑米素进行了强壮，耐缺氧及镇痛作用研究，结果表明：昆明种小鼠灌服给药０．５ｇ／ｋｇ，体重明显增加（α＜０．０１），提示有一定的强壮作用。腹腔注射４００ｍｇ／ｋｇ显著提高小鼠常压缺氧耐受性（α＜０．０１），并拮抗Ｉｓｏｐ所致的心肌缺氧。采用热板法及担体法则定［３，４］，对照及化学因素引起的疼痛有显著的抑制作用（α＜０．０１），且在提高痛阈的同时，不产生耐受性和成瘾性。