Limbs Of Healthy Subjects Research Articles

Balance improvements in healthy subjects are independent to postural strategies involved in the training

BackgroundAdequate postural strategies have a pivotal role in ensuring balance during the performance of daily or sport activities. These strategies are responsible for the management of center of mass kinematics and depend on the magnitude of perturbations and posture assumed by a subject. Research questionAre there differences in postural performance after a standardized balance training performed in sitting versus standing posture in healthy subjects? Does a standardized unilateral balance training with the dominant or non-dominant limb improve balance on trained and untrained limbs in healthy subjects? MethodsSeventy-five healthy subjects reporting a right-leg dominance were randomized into a Sitting, Standing, Dominant, Non-dominant or Control groups. In the Experiment 1, Sitting group performed a 3-week balance training in seated posture, whereas Standing group performed the same training in bipedal stance. In the Experiment 2, Dominant and Non-dominant groups underwent a 3-week standardized unilateral balance training on the dominant and non-dominant limbs, respectively. Control group underwent no intervention and was included in both experiments. Dynamic (Lower Quarter Y-Balance Test with the dominant and non-dominant limbs and trunk and lower limb 3D kinematics) and static (center of pressure kinematics in bipedal and bilateral single-limb stance) balance were assessed before and after the training, and at 4 weeks follow-up. ResultsA standardized balance training in sitting or standing posture improved balance without between-group differences, while a unilateral balance training with the dominant or non-dominant limb improved postural stability on the trained and untrained limbs. Trunk and lower limb joints range of motion increased independently to their involvement in the training. SignificanceThese results may allow clinicians to plan effective balance interventions even when a training in standing posture is not possible or in subjects with restricted limb weight-bearing.

Strategies for maintaining dynamic balance in persons with neurological disorders during overground walking.

Maintaining a stable gait requires a dynamic balance control, that can be altered in persons with Multiple Sclerosis (MS), Stroke (ST), and Parkinson's disease (PD). The understanding of the strategy for Center of Mass (CoM) positioning adopted by patients during walking is important to be able to program treatments aimed at improving gait control and preventing falls. Forty-four persons with a mild-to-moderate neurological disorder (20 with MS, 14 with ST, 10 with PD) underwent clinical examination and gait analysis. Ten Healthy Subjects (HS) walking at matched speed provided the normative data. Dynamic balance was assessed using the margin of stability (MoS). It was calculated as the distance between the extrapolated Center of Pressure and the extrapolated CoM at mid-stance. The MoS values for lower limbs were calculated in patients and compared with speed-matched values of HS. Persons with neurological disorder showed increased MoS in the medio-lateral direction with respect to HS. Within-group comparison analysis showed a symmetry between lower limbs in HS (Mean (95%CI) [mm], dominant vs non-dominant limb, 43.3 (31.9-54.6) vs 42.9 (28.8-56.9)) and PD (less affected vs more affected limb, 71.1 (59.8-82.5) vs 72.5 (58.5-86.6)), while a significant asymmetry was found in MS (54.4 (46.4-62.4) vs 81.1 (71.2-91.1)) and ST (52.1 (42.6-61.7) vs 74.7 (62.8-86.6)) participants. The history of falls was comparable among PD, MS, and ST groups, and the MoS in the frontal plane showed a strong correlation with these records. Objective assessment of MoS revealed pathology-specific strategies showing different impacts in MS, ST, and PD on the ability to control CoM information to manage the balance between limbs during gait. MoS evaluation will provide useful information to address a tailored rehabilitation program and to monitor disease progression.

Possible Assessment of Calf Venous Pump Efficiency by Computational Fluid Dynamics Approach.

Three-dimensional simulations of peripheral, deep venous flow during muscular exercise in limbs of healthy subjects and in those with venous dysfunction were carried out by a computational fluid-dynamics (CFD) approach using the STAR CCM + platform. The aim was to assess the effects of valvular incompetence on the venous calf pump efficiency. The model idealizes the lower limb circulation by a single artery, a capillary bed represented by a porous region and a single vein. The focus is on a segment of the circuit which mimics a typical deep vein at the level of the calf muscle, such as the right posterior tibial vein. Valves are idealized as ball valves, and periodic muscle contractions are given by imposing time-dependent boundary conditions to the calf segment wall. Flow measurements were performed in two cross-sections downstream and upstream of the calf pump. Model results demonstrate a reduced venous return for incompetent valves during calf exercise. Two different degrees of valvular incompetence are considered, by restricting the motion of one or both valves. Model results showed that only the proximal valve is critical, with a 30% reduction of venous return during calf exercise in case of valvular incompetence: the net flow volume ejected by the calf in central direction was 0.14 mL per working cycle, against 0.2 mL for simulated healthy limbs. This finding appeared to be consistent with a 25% reduction of the calf ejection fraction, experimentally observed in chronic venous disease limbs compared with healthy limbs.

Symmetry and spatial distribution of muscle glucose uptake in the lower limbs during walking measured using FDG-PET.

PurposeThis study aimed to elucidate whether muscle activity (in terms of glucose uptake) between the legs can be considered symmetrical during walking. Furthermore, we aimed to determine whether the [18F]-fluorodeoxyglucose was distributed heterogeneously throughout each muscle, and if so, whether areas of high uptake would be clustered.MethodsTen healthy participants walked on a treadmill at self-selected comfortable walking speed for a total of 90 minutes, 60 minutes before and 30 minutes after intravenous injection of 50 MBq [18F]-fluorodeoxyglucose. Thereafter, a positron emission tomography/computed tomography scan of the lower limb was acquired. Three-dimensional muscle contours of 78 (= 39x2) muscles of the left and right lower limb were semi-automatically determined from magnetic resonance imaging scans. After non-rigid registration, those muscle contours were used to extract [18F]-fluorodeoxyglucose uptake from the positron emission tomography scans.ResultsLarge asymmetries were observed in the lower leg muscles (e.g. median absolute asymmetry index of 42% in the gastrocnemius medialis) and in the gluteus minimus (30% asymmetry) and gluteus medius (15% asymmetry), whereas the uptake in the thighs was relatively symmetrical between the limbs (<6% asymmetry). These were not related to limb-dominance nor to inter-limb differences in muscle volume. The [18F]-fluorodeoxyglucose distribution was not distributed normally; most voxels had a relatively low standardized uptake value, and a minority of voxels had a relatively high standardized uptake value. The voxels with higher [18F]-fluorodeoxyglucose uptake were distributed heterogeneously; they were clustered in virtually all muscles.ConclusionThe findings in this study challenge the common assumption of symmetry in muscle activity between the limbs in healthy subjects. The clustering of voxels with high uptake suggests that even in this prolonged repetitive task, different spatial regions of muscles contribute differently to walking than others.

A study investigating the effect of ice on three sensory outcome measures of the contralateral limb in healthy subjects

A study investigating the effect of ice on three sensory outcome measures of the contralateral limb in healthy subjects

82. Inter- and intraexaminer reliability of nerve conduction measurements in the upper limb of healthy subjects

To verify the test-retest, inter and intraexaminer variability of the Compound Muscle Action Potential (CMAP) and Sensory Nerve Action Potential (SNAP) within our neurophysiology laboratory; to identify the technical variables that can affect the reproducibility of signals in the follow-up studies. Distal CMAP of Median and Ulnar nerves and SNAP of radial nerve (I ° finger), median nerve (I° and IV° fingers), ulnar nerve (IV and V fingers) of the right hand were recorded by 9 operators (5 technicians of neurophysiology and 4 physicians) in healthy volunteers. Each test was repeated 3 times randomly within 4 months. The latency, amplitude, and intensity of stimulus were collected. The montages were photographed. Our data showed a discrete stability of CMAP parameters mainly for ulnar nerve. On the contrary the amplitudes of SNAPs were fairly variables. The results suggest that it is crucial to check the neurophysiological techniques commonly applied in laboratories were several operators work. More time must be dedicated to a common training, to get consistent results useful in repeated trials.

Hemiplegia affects the biomechanics of reaching with the unaffected upper limb

Objective To analyze the bio-mechanics when hemiplegics reach with the unaffected upper limb. Methods Thirty post-stroke hemiplegics were selected into the patient group, while 23 healthy counterparts were chosen for the control group. Both groups completed a reaching test of their upper limbs which divided reaching into a moving stage and a holding stage. Surface electromyography (sEMG) data were recorded during the tests along with the degree of torso twist, the range of motion of the shoulder, movement velocity, smoothness of movement and angle divergence collected using a wearable micro-sensor motion capture system. Results For the stroke patients whose dominant upper limb was unaffected, the average root mean square (RMS) signal from the upper trapezius (34.3 μV) and the average torso twist (-1.4°) in the moving phase were significantly larger than among the control subjects (19.7 μV and -2.3°), but their average movement velocity was significantly slower. In the holding phase the average RMS signal from the upper trapezius (55.4 μV) was still significantly higher than in the control group, but their average pectoralis major signal and the integrated EMG ratio of the anterior segments of the deltoid and upper trapezius muscle pairs were significantly lower. For the stroke patients whose dominant upper limbs were affected, in the moving phase their average signal from the middle segments of the deltoid were significantly greater than those of the controls, but their movement velocity was significantly slower. For the control subjects, in the moving phase the average signal from the upper trapezius on their non-dominant side was significantly higher than that from the dominant upper limb. The integrated EMG ratio from the anterior segments of the deltoid and upper trapezius muscle pairs on that side was smaller throughout the whole reaching movement. Conclusion The bio-mechanical characteristics in reaching of the unaffected upper limbs of stroke patients are not the same as those of the corresponding upper limbs of healthy subjects. It is more reasonable to select the corresponding upper limbs of healthy subjects as controls when a bio-mechanical study of the affected upper limbs is conducted. Key words: Stroke; Reaching; Kinematics; Electromyography

P 57 The influence of sports expertise on the extent of physiological mirror-EMG-activity in the upper and lower extremity

Introduction During unimanual motor tasks, muscle activity may not be restricted to the contracting muscle, but has also been reported to occur involuntarily in the contralateral resting limb in healthy subjects, referred to as physiological mirror electromyographic (MEMG) activity ( Sehm et al., 2015 ). To date, however, it is unknown if the physiological form of MEMG can also be observed in lower extremities during the performance of unilateral isometric leg contractions. Furthermore it still remains elusive if and how MEMG is affected by long-term exercise training. Here we investigated the influence of sports expertise on the extent of MEMG in healthy young adults. We hypothesized that MEMG isn’t restricted to both upper extremities but is also reliably observable in both lower extremities and that the extent of MEMG is related to force requirements during motor tasks. In addition we expected that endurance athletes show more MEMG than non-athletes during strong unilateral contractions of hand and foot muscles. Methods Twenty-two healthy young adults participated in this study and were split into two equally sized experimental groups in accordance to their athletic background (Endurance Group (EG): n = 11, age: 23.0 (6.0) years; Control Group (CG): n = 11, age: 25.0 (7.0) years; median (IQR)). Subjects performed one isometric force generation task for the upper (UEX) and lower extremity (LEX) respectively on two separate days. The test procedure corresponds to a block design with varying force levels (20%, 50% & 80%) which were individually adjusted in accordance to the appropriate maximum voluntary contraction (MVC). EMG surface electrodes were applied bilaterally on a distal and proximal muscle. The bilateral set-up allowed us to measure EMG activity over the primary moving muscles as well as subliminal MEMG over the homologous muscles of the resting limb during behavioral tests. Repeated isometric contractions of left and right extremities were tested in a randomized order. Results The extent of MEMG significantly increased in distal and proximal muscles of LEX and UEX respectively as a function of force demands. Group comparison between athletes and controls revealed that athletes demonstrated a higher extent of MEMG specifically in the trained LEX but only during very strong contractions (80% MVC). There was no difference in the extent of MEMG in UEX between groups. Discussion Physiological MEMG is measurable in UEX as well as LEX during strong unilateral contractions and significantly increases as a function of force demands. Long-term sports participation induces modulations of interhemispheric connectivity which could in accordance to the concept of Motor Overflow lead to increased reversal of IHI to IHF connecting motor relevant brain regions during strong unilateral contractions ( Perez and Cohen, 2008 ) and may therefore be responsible for the higher extent of MEMG in endurance athletes compared to controls under high force demands specifically in trained limbs.

32. Quantitative EEG evaluation during robot-assisted foot movement

Passive and imagined limb movements induce changes in cerebral oscillatory activity. Central modulatory effects play a role in plastic changes, and are of uttermost importance in rehabilitation. This has extensively been studied for upper limb (UL), but less is known for lower limb (LL). The aim of this study is to investigate the topographical distribution of event-related desynchronization/synchronization (ERD/ERS) and task-related coherence during a robot-assisted and a motor imagery task of lower limb in healthy subjects. 32-channels electroencephalogram (EEG) was recorded in twenty-one healthy right handed subjects during a robot-assisted single-joint cyclic right ankle movement performed by the BTS ANYMOV robotic hospital bed. Data were acquired with a block protocol for passive and imagined movement at a frequency of 0.2 Hz. ERD/ERS and task related coherence were calculated in alpha1 (8–12 Hz), alpha2 (10.5–12.5 Hz) and beta (13–30 Hz) frequency ranges. During passive movement, alpha2 rhythm desynchronized over the contralateral sensori-motor area and ipsilateral prefrontal cortex, and beta over the bilateral SM. During motor imagery, a significant desynchronization was evident for alpha1 over contralateral SM, for alpha2 over bilateral SM, and for beta over central scalp areas. No statistically significant difference emerged from the two conditions. Task-related coherence decreased in alpha2 band between left central - right frontal and left central – left parietal areas; beta band coherence decreased between C3–C4 electrodes, and increased between C3–Cz. These data contribute to the understanding of oscillatory activity during lower limb robot-assisted motor performance, and point to the advantages of this analysis to evaluate cortical oscillations changes.

Quantitative EEG Evaluation During Robot-Assisted Foot Movement.

Passiveand imagined limbmovements induce changes in cerebral oscillatory activity. Central modulatory effects play a role in plastic changes, and are of uttermost importance in rehabilitation. This has extensively been studied for upper limb, but less is known for lower limb. The aim of this study is to investigate the topographical distribution of event-related desynchronization/synchronization(ERD/ERS) and task-relatedcoherence during a robot-assisted and a motor imagery task of lower limb in healthy subjects to inform rehabilitation paradigms. 32-channels electroencephalogram (EEG) was recorded in twenty-one healthy right footed and handed subjects during a robot-assisted single-joint cyclic right ankle movement performed by the BTS ANYMOV robotic hospital bed. Data were acquired with a block protocol for passive and imagined movement at a frequency of 0.2 Hz. ERD/ERS and task related coherence were calculated in alpha1 (8-10 Hz), alpha2 (10.5-12.5 Hz) and beta (13-30 Hz) frequency ranges. During passive movement, alpha2 rhythm desynchronized overC3 and ipsilateral frontal areas (F4, FC2, FC6); betaERD was detected over the bilateral motor areas (Cz, C3, C4). During motor imagery, a significant desynchronization was evident for alpha1 over contralateral sensorimotor cortex (C3), for alpha2 over bilateral motor areas (C3 and C4), and for beta over central scalp areas. Task-related coherence decreased during passive movement in alpha2 band between contralateral central area (C3, CP5, CP1, P3) and ipsilateral frontal area (F8, FC6, T8); beta band coherence decreased between C3-C4 electrodes, and increased between C3-Cz. These data contribute to the understanding of oscillatory activity and functional neuronal interactions during lower limb robot-assisted motor performance. The final output of this line of research is to inform the design and development of neurorehabilitation protocols.

Ankle Intrinsic Stiffness in Subcortical Poststroke Subjects

ABSTRACTThe authors' purpose was to evaluate bilateral ankle intrinsic stiffness in subcortical poststroke subjects. Ten subcortical poststroke subjects and 10 healthy controls participated in this study. The ankle passive stiffness at 3 different speeds and the electromyographic activity of the soleus, the gastrocnemius, and the tibialis anterior muscles of poststroke contralesional (CONTRA) and ipsilesional (IPSI) limbs and of one limb of healthy subjects were assessed. Ankle electromyographic activity was collected to ensure that reflexive or voluntary muscle activity was not being elicited during the passive movements. A significant interaction was observed between the effects of the limb (IPSI vs. CONTRA vs. control) and ankle position, F(4, 28) = 3.285, p = .025, and between the effects of the limb and the velocity of stretch, F(2, 14) = 4.209, p = .037. While increased intrinsic stiffness was observed in the CONTRA limb of poststroke subjects at ankle neutral position when the passive stretch was applied with a velocity of 1°/s (p = .021), the IPSI limb of poststroke subjects presented increased stiffness at 20º of plantar flexion when the stretch was applied with a velocity of 5°/s (p = .009) when compared to healthy group. Subcortical poststroke subjects present increased intrinsic stiffness in both the CONTRA and IPSI limbs in specific ankle amplitudes.

Muscle focal vibration in healthy subjects: evaluation of the effects on upper limb motor performance measured using a robotic device.

Muscle vibration is a technique that applies a low-amplitude/high-frequency vibratory stimulus to a specific muscle using a mechanical device. The aim of this study was to evaluate, using robot-based outcomes, the effects of focal muscle vibration, at different frequencies, on the motor performance of the upper limb in healthy subjects. Forty-eight volunteer healthy subjects (age: 31 ± 8 years) were enrolled. Subjects were assigned to three different groups: the first group, in which subjects underwent muscle vibration treatment with a frequency of 100 Hz; the second group of subjects underwent the same treatment protocol, but using a frequency of vibration of 200 Hz; finally, the control group did not undergo any treatment. The robot-based evaluation session consisted of visually guided reaching task, performed in the sagittal plane. Our results showed that the vibration treatment improved upper limb motor performance of healthy subjects from the baseline (T0) to 10 days after the end of the treatment (T2), but only the group treated with a frequency of 200 Hz reached statistical significance. Specifically, in this group we found an increase of the number of repetitions (T0: 51.4 ± 22.7; T2: 66.3 ± 11.8), and the smoothness of the movement, as showed by a decrease of the Normalized Jerk (T0: 10.5 ± 2.8; T2: 7.7 ± 0.5). The results of our study support the use of focal muscle vibration protocols in healthy subjects, to improve motor performance.

Comparative Analysis of Lower Limb Alignments in Healthy Subjects and Subjects with Back Pain

The objective of the present study was to comparatively analyze the clinical status of the lower limbs in healthy subjects and subjects with back pain. Forty three (43) male and female subjects with average age of 36.91± 3.97 were selected as the statistical sample of the study. This population was recognized intelligently by utilizing the Nordic Musculoskeletal Questionnaire (NMQ). Furthermore, the NMQ was used to designate 43 male and female subjects with average age of 37.88 ± 4.12 and similar anthropometric characteristics with the statistical population as the research control sample. In the next phase, tibial torsion and femoral torsion angles were measured using a goniometer. Foot typicality was designated using a foot arch index while intercondylar and intermalleolar distances were measured using a clinical caliper. The results depict that the size of the foot arch is steeper in people with back pains compared to those with flat foot arch (p<0.05). It also indicates that there is no significant correlation between the tibia, femur torsion, knee condition of the healthy subjects and subjects with back pain. Therefore, it is deduced that steep foot arch can be a key component in the generation of back pains.

Thermographic patterns of the upper and lower limbs: baseline data.

Objectives. To collect normative baseline data and identify any significant differences between hand and foot thermographic distribution patterns in a healthy adult population. Design. A single-centre, randomized, prospective study. Methods. Thermographic data was acquired using a FLIR camera for the data acquisition of both plantar and dorsal aspects of the feet, volar aspects of the hands, and anterior aspects of the lower limbs under controlled climate conditions. Results. There is general symmetry in skin temperature between the same regions in contralateral limbs, in terms of both magnitude and pattern. There was also minimal intersubject temperature variation with a consistent temperature pattern in toes and fingers. The thumb is the warmest digit with the temperature falling gradually between the 2nd and the 5th fingers. The big toe and the 5th toe are the warmest digits with the 2nd to the 4th toes being cooler. Conclusion. Measurement of skin temperature of the limbs using a thermal camera is feasible and reproducible. Temperature patterns in fingers and toes are consistent with similar temperatures in contralateral limbs in healthy subjects. This study provides the basis for further research to assess the clinical usefulness of thermography in the diagnosis of vascular insufficiency.

Impedance plethysmography as a tool for assessing exertion-related blood flow changes in the lower limbs in healthy subjects

Impedance plethysmography, also known as the impedance test, the blood flow test, or impedance phlebography, is a non-invasive test that measures blood flow in the vessels of the peripheral vascular system by monitoring changes in electrical resistance (impedance) to detect deep thrombosis (blood clots or thrombophlebitis).The aim of our study was to use this technique for assessing changes in blood flow in the lower limbs in healthy subjects wearing protective footwear while walking.The test was performed on a group of 30 professional firefighters (age 30.7±4.5, BMI 25.1±3). Blood flow was monitored in the peripheral vascular system of the lower limbs during walking on a treadmill. The testing protocol consisted of the following three phases: warm-up, exercise, and rest.In order to identify differences between the three phases of the study, analysis of variance (ANOVA) with repeated measures was conducted. The statistically significant parameters of blood flow in the lower limbs were the impedance ratio (IR) (p<0.001), slope ratio (SR) (p<0.001), crest width (CW) (p<0.001), and alternative blood flow (ABF) (p<0.001). All of them showed an upward trend.The study confirmed the validity of impedance plethysmography as a non-invasive technique for measuring blood flow changes in the lower limbs in healthy subjects, especially under non-steady-state conditions, such as walking. This technique provides valuable quantitative data.Therefore, impedance plethysmography may be considered a reliable research method enabling evaluation of local blood flow in healthy subjects under different conditions.

Activation timing of soleus and tibialis anterior muscles during sit-to-stand and stand-to-sit in post-stroke vs. healthy subjects

Introduction. Sit-to-stand (SitTS) and stand-to-sit (StandTS) are very important functional tasks that become compromised in stroke patients. As in other voluntary movements, they require an adequate postural control (PC) involving the generation of anticipatory postural adjustments (APAs). In order to give clues for more efficient and directed rehabilitation programs, a deeper knowledge about APAs during challenging and daily life movements is essential.Purpose. To analyze the activation timing of tibialis anterior (TA) and soleus (SOL) muscles during SitTS and StandTS in healthy subjects and in post-stroke patients.Methods. Two groups participated in this study: one composed of ten healthy subjects and the other by ten subjects with a history of stroke and increased H-reflex. Electromyographic activity (EMGa) of SOL and TA was analyzed during SitTS and StandTS in the ipsilateral (IPSI) and the contralateral (CONTRA) limb to the side lesion in stroke subjects, and in one limb in healthy subjects. A force plate was used to identify the movement onset.Results. In both sequences, in the stroke group SOL activation timing occurred prior to movement onset, contrary to the pattern observed in the healthy subjects. Statistically significant differences were found in SOL activation timings between each lower limb of the stroke and healthy groups, but no significant differences were found between the IPSI and the CONTRA limb. The TA activation timing seems to be delayed in the CONTRA limb when compared to the healthy subjects and showed a better organization of TA timing activation in StandTS when compared to SitTS.Conclusion. Compared to healthy subjects, APAs seem to be altered in both limbs of the post-stroke subjects, with the SOL activation timing being anticipated in both SitTS and StandTS.

Soleus activity in post-stroke subjects: Movement sequence from standing to sitting

Introduction. The beginning of the movement sequence from standing to sitting requires the modulation of plantar flexors activity, including the soleus muscle (SOL), to allow the forward translation of the tibia in relation to the foot, preserving its antigravity function.Purpose. To analyze the SOL activity during the initial phase of standing to sitting in stroke subjects.Methods. Two groups of ten subjects each participated in this study, one composed of healthy subjects and the other with subjects with a history of stroke. Electromyographic activity (EMGa) of SOL was analyzed in the ipsilateral (IPSI) and contralateral (CONTRA) limb to side lesion in stroke subjects, and in one limb in healthy subjects during the initial phase of standing to sitting. A force plate was used to identify the movement sequence phase.Results. The mean values of SOL EMGa were higher in healthy subjects than the ones obtained in the IPSI and CONTRA limb in stroke subjects. Significant differences were only observed between the IPSI and healthy limb (p = 0.035).Conclusion. When compared to the healthy subjects, stroke subjects showed a decreased SOL EMGa in the IPSI limb, which suggests that therapeutic decisions must consider the need to promote a better postural control also in the IPSI limb.

Automated photoplethysmography-based determination of ankle-brachial index: a validation study against Doppler sonography

Determination of ankle-brachial-index (ABI) by manual Doppler is well established to screen for lower extremity arterial disease (LEAD) and to predict cardiovascular risk. A new generation of digital-controlled devices promises automated ABI determination. The aim of this study was to determine comparability of automated photoplethysmography (PPG)-derived ABI calculation with the Doppler-ABI algorithm commonly used in cohort studies. Automated PPG-based ABI measurements [Vascular Explorer (VE) and Vicorder (VI)] were recorded from 112 limbs of healthy subjects and 22 limbs of patients with confirmed LEAD. Validity was evaluated on the basis of receiver-operating characteristic (ROC) analysis of clinical status and concordance with Doppler-ABI. Differences between cuff inflation [inf]- and deflation [def]-based method were studied in VE. PPG-based ABI values were higher compared to Doppler-ABI (VI +0.06, VEinf +0.15, VEdef +0.09, p < 0.001, respectively). The difference was pronounced in pathological (<0.9), borderline (0.9-0.99) and low normal (1.0-1.09) ABI, but less in ABI ≥1.1. However, ROC analysis revealed excellent diagnostic value for LEAD (sensitivity/specificity) and comparable area under the curve at method-adapted ABI thresholds for all methods: Doppler (95/90 %, 0.95), VI (75/96 %, 0.91), VEinf (85/89 %, 0.93) and VEdef (80/98 %, 0.94). Digital-controlled PPG-based ABI determination is a useful diagnostic application for LEAD. However, the systematic higher ABI in PPG-based measurement compared to Doppler and remarkable differences between the deflationary and inflationary method are critical for the interpretation of borderline and low normal ABI values where precise reading is essential to detect mild LEAD and subclinical disease and to predict cardiovascular risk.

A new device to measure isometric strength in upper limbs: comparison between dominant and non-dominant limbs*

Accurate assessment of the performance of the human muscular system has been the object of scientists and practitioners of physical medicine and rehabilitation for many years.1-3 Evaluation of muscle strength is a common practice carried out by professionals and researchers. Few medical professionals have accurate measuring instruments, and almost in its entirety, the muscle strength tests are carried out manually by physicians, physiotherapists, physical educators, among others. The concern about the lack of quantitative data based on tests carried out by hand strength resulted in the development of instrumental forms of muscle testing, such as Jamar®, Kratos® and computerized isokinetic dynamometer Biodex®. These instruments have earned wide acceptance in clinical research of muscular strength evaluation.4 Rabin and Post5 performed a comparison between the evaluation by manual methods and the instrumental evaluation of the flexor moment and external rotator of the shoulder before and after surgery. It was found that applying the manual method time was rated higher, however, this increase was not evident when using the instrumental evaluation. Hsu et al6 indicated that increased muscle strength improves the functionality of the patient and suggested that the methods of muscle strength measurement should be accurate and reliable. Therefore, it is important equipments that assist in the accurate assessment of muscle strength and an experimental analysis of engineering possibilities. This analysis refers to applications where measurement provided by an instrument is designed to be used as a post-measurement for the determination of some parameters, models and / or validation.7 Measurement devices extend the possibilities of physical examination, particularly in the case of complex musculoskeletal problems during rehabilitation of patients with muscular weakness or restricted range of motion.8 The grip strength refers to any process that seeks to measure the forces, thus, the dynamometer is a type of equipment that measures the behaviour of the load and strain deformation of structures.9 The use of dynamometers to measure muscle strength has increased in recent decades and various types of instruments have been improved and made available for researchers.10 In a review conducted by Jaric11 on strength tests most studies involving muscle strength evaluation are performed using the lower limbs, suggesting new studies involving the upper limbs. There is little information available regarding the functional connections of the shoulder and wrist and the factors involved in its strength.12 Given the necessity of obtaining quantitative data in Biomechanics, it is necessary the design and development of equipments to measure the forces that interact with the locomotor system. Thus, the aim of this study was to evaluate a new device from our laboratory capable of measuring the strength generated by the muscles of the upper limbs and to compare the muscle strength of shoulder between dominant and non-dominant upper limbs in healthy subjects.

Thoracolumbar multisegmental motor responses in the upper and lower limbs in healthy subjects

Experimental design. This descriptive study presents muscular responses from both the upper and the lower extremities during T11-12 segmental stimulation. Neuro Lab of the Texas Woman's University (School of Physical Therapy, TX, USA). A total of 13 healthy subjects were electrically stimulated using surface electrodes. In trial 1, signals were recorded from the flexor hallucis brevis, soleus, vastus medialis and gluteus medius in the lower right extremity. In trial 2, responses were recorded from the abductor digiti minimi, abductor pollicis brevis (APB), flexor carpi radialis and biceps brachii in the right upper extremity. In trial 3, stimulation was carried out and signals were recorded for both the upper and the lower extremities simultaneously, using different muscle combinations. Five traces per muscle were averaged for each step of the testing. Amplitude and deflection latency were the measured parameters and were compared using descriptive statistics. Results showed signal amplitudes ranging from 85 to 821 μV in the upper extremity and from 582 to 3927 μV in the lower extremity, with the largest signal recorded in the soleus muscle and the APB. Response latency varies between 5.5 and 14 ms in the upper limbs and between 7.7 and 27 ms in the lower limbs and was comparable in bilateral recording. These muscular responses seem to be elicited from electrical stimulation of motor nuclei in lower limb muscles or from pathways to those nuclei in upper limb muscles, and could be useful in testing patients with spinal disorders.