Estimation of Ground Contact Time with Inertial Sensors from the Upper Arm and the Upper Back.

Ground contact time (GCT) is one of the most relevant factors when assessing running performance in sports practice. In recent years, inertial measurement units (IMUs) have been widely used to automatically evaluate GCT, since they can be used in field conditions and are friendly and easy to wear devices. In this paper we describe the results of a systematic search, using the Web of Science, to assess what reliable options are available to GCT estimation using inertial sensors. Our analysis reveals that estimation of GCT from the upper body (upper back and upper arm) has rarely been addressed. Proper estimation of GCT from these locations could permit an extension of the analysis of running performance to the public, where users, especially vocational runners, usually wear pockets that are ideal to hold sensing devices fitted with inertial sensors (or even using their own cell phones for that purpose). Therefore, in the second part of the paper, an experimental study is described. Six subjects, both amateur and semi-elite runners, were recruited for the experiments, and ran on a treadmill at different paces to estimate GCT from inertial sensors placed at the foot (for validation purposes), the upper arm, and upper back. Initial and final foot contact events were identified in these signals to estimate the GCT per step, and compared to times estimated from an optical MOCAP (Optitrack), used as the ground truth. We found an average error in GCT estimation of 0.01 s in absolute value using the foot and the upper back IMU, and of 0.05 s using the upper arm IMU. Limits of agreement (LoA, 1.96 times the standard deviation) were [-0.01 s, 0.04 s], [-0.04 s, 0.02 s], and [0.0 s, 0.1 s] using the sensors on the foot, the upper back, and the upper arm, respectively.

The association between physical activity and musculoskeletal disorders-a cross-sectional study of teachers.

Purpose: Combined with insufficient physical activity (PA) prolonged and improperly performed sedentary work can lead to musculoskeletal disorders (MSDs). The aim of this study was (I) to evaluate the self-reported level of PA and the prevalence of MSDs in male and female teachers, and (II) to investigate the association between PA and MSDs in teachers in Polish primary and secondary schools. Methods: The study included 254 teachers from primary and secondary schools from Upper Silesia, Poland, excluding physical education teachers. The level of PA was assessed using the Seven-Day Physical Activity Recall (SDPAR). A standardized Nordic Musculoskeletal Questionnaire (NMQ) was used to assess the prevalence of MSDs. Results: A similar percentage of female (80%) and male (90%) teachers met the WHO recommendations on moderate-intensity PA. The recommendations on performing vigorous-intensity PA were met by significantly (p = 0.002) less female than male teachers (50% and 75% respectively). Lower back disorders during the last 12 months and the last 7 days (57% and 45%, respectively) were the most commonly reported MSDs by teachers, followed by neck (53%, 40%), upper back (39%, 28%), and knee disorders (37%, 26%). The highest pain intensity was experienced by the teachers in the lower back and neck. Teachers with a greater number of MSDs were less likely to engage in vigorous-intensity PA and total PA than those with fewer painful areas of the body. Pain intensity in the neck, knees, upper- and lower back, and wrists/hands was negatively related to moderate and total PA. BMI negatively correlated with total PA, moderate-intensity PA vigorous-intensity PA, and high vigorous-intensity PA. Conclusions: The study revealed the association between PA and MSDs in studied teachers. The most of the studied teachers met the WHO recommendation, and women were less likely to perform vigorous and high-vigorous PA than men. The lower back and neck disorders were the most common among the teachers.

Using Raw Accelerometer Data to Predict High-Impact Mechanical Loading.

The purpose of this study was to develop peak ground reaction force (pGRF) and peak loading rate (pLR) prediction equations for high-impact activities in adult subjects with a broad range of body masses, from normal weight to severe obesity. A total of 78 participants (27 males; 82.4 ± 20.6 kg) completed a series of trials involving jumps of different types and heights on force plates while wearing accelerometers at the ankle, lower back, and hip. Regression equations were developed to predict pGRF and pLR from accelerometry data. Leave-one-out cross-validation was used to calculate prediction accuracy and Bland-Altman plots. Body mass was a predictor in all models, along with peak acceleration in the pGRF models and peak acceleration rate in the pLR models. The equations to predict pGRF had a coefficient of determination (R2) of at least 0.83, and a mean absolute percentage error (MAPE) below 14.5%, while the R2 for the pLR prediction equations was at least 0.87 and the highest MAPE was 24.7%. Jumping pGRF can be accurately predicted through accelerometry data, enabling the continuous assessment of mechanical loading in clinical settings. The pLR prediction equations yielded a lower accuracy when compared to the pGRF equations.

Phase 2 Trial of Difelikefalin in Notalgia Paresthetica.

BACKGROUND: Notalgia paresthetica is a neuropathic disorder characterized by pruritus in a circumscribed region of the upper back. Difelikefalin, a selective kappa opioid receptor agonist, has shown efficacy in other chronic pruritic conditions and is being investigated for the treatment of notalgia paresthetica. METHODS: In this phase 2, double-blind, placebo-controlled trial, we randomly assigned, in a 1:1 ratio, patients with moderate-to-severe pruritus caused by notalgia paresthetica to receive 2 mg of oral difelikefalin or placebo twice daily for 8 weeks. The primary outcome was the change from baseline at week 8 in the weekly mean score on the daily Worst Itch Numeric Rating Scale (WI-NRS; scores range from 0 [no itch] to 10 [worst itch imaginable]). The secondary clinical outcomes were itch-related quality-of-life and itch-related sleep measures. RESULTS: A total of 126 patients were enrolled; 62 patients were assigned to receive difelikefalin, and 63 were assigned to receive placebo. One patient who had been assigned to receive difelikefalin withdrew consent before the first dose and is not included in the main analyses. The mean baseline WI-NRS score was 7.6 (indicating severe itch) in each group. The change from baseline in the weekly mean WI-NRS score at week 8 was -4.0 points in the difelikefalin group and -2.4 points in the placebo group (difference in change, -1.6 points; 95% confidence interval, -2.6 to -0.6; P = 0.001). The results for the secondary outcomes generally did not support those of the primary analysis. Headache, dizziness, constipation, and increased urine output occurred more frequently in the difelikefalin group than in the placebo group. CONCLUSIONS: Among patients with notalgia paresthetica, oral treatment with difelikefalin resulted in modestly greater reductions in itch intensity scores than placebo over a period of 8 weeks but was associated with adverse events. Larger and longer trials are needed to assess the efficacy and safety of difelikefalin treatment in this disorder. (Funded by Cara Therapeutics; KOMFORT ClinicalTrials.gov number, NCT04706975.).

The Effect of Key Anthropometric and Biomechanics Variables Affecting the Lower Back Forces of Healthcare Workers.

Wearable devices are becoming ubiquitous and can be used to better estimate postures and movements to reduce the risk of injuries. Thirty-three participants were recruited in this study to perform two daily repetitive patient transfer tasks while the full body movements were acquired using a set of magneto-inertial wearable devices. The use of wearable devices allowed for the estimation of the forces provoked on the lower back during the entire task performance. In postures where the forces exceeded the warning threshold found in the literature, healthcare workers were considered to have a greater risk of injury. Additionally, the maximum force exerted by each hand to avoid injury to the spinal column was also estimated. Knowing the key anthropometric variables associated with musculoskeletal disorders (MSDs) will enable engineers and researchers to design better assistive devices and injury prevention programs in diverse workplaces.

Musculoskeletal-Modeling-Based, Full-Body Load-Assessment Tool for Ergonomists (MATE): Method Development and Proof of Concept Case Studies.

A new ergonomic-risk-assessment tool was developed that combines musculoskeletal-model-based loading estimates with insights from fatigue failure theory to evaluate full-body musculoskeletal loading during dynamic tasks. Musculoskeletal-modeling output parameters, i.e., joint contact forces and muscle forces, were combined with tissue-specific injury thresholds that account for loading frequency to determine the injury risk for muscles, lower back, and hip cartilage. The potential of this new risk-assessment tool is demonstrated for defining ergonomic interventions in terms of lifting characteristics, back and shoulder exoskeleton assistance, box transferring, stoop lifting, and an overhead wiring task, respectively. The MATE identifies the risk of WMSDs in different anatomical regions during occupational tasks and allows for the evaluation of the impact of interventions that modify specific lifting characteristics, i.e., load weight versus task repetition. Furthermore, and in clear contrast to currently available ergonomic assessment scores, the effects of the exoskeleton assistance level on the risk of WMSDs of full-body musculoskeletal loading (in particular, the muscles, lower back, and hips) can be evaluated and shows small reductions in musculoskeletal loading but not in injury risk. Therefore, the MATE is a risk-assessment tool based on a full-body, musculoskeletal-modeling approach combined with insights from the fatigue failure theory that shows the proof of concept of a shoulder and back exoskeleton. Furthermore, it accounts for subject-specific characteristics (age and BMI), further enhancing individualized ergonomic-risk assessment.

Passive exoskeletons alter low back load transfer mechanism.

Previous studies that tested passive back-support exoskeletons focused only on active low-back tissue. Therefore, this study examines the effect from a passive back-support exoskeleton by investigating changes in the load transfer mechanism between active and passive tissue in the low back. Twelve healthy male participants performed a full range of trunk flexion-extension movements under three conditions-FREE (no exoskeleton), the backX, or the CoreBot exoskeleton-while holding 0 kg, 4 kg, and 8 kg loads. Body kinematics and electromyography were recorded. Results showed that the average muscle activity of the lumbar erector spinae (LES) was significantly reduced while wearing the exoskeletons, with a 5.9%MVC reduction with the backX and a 3.3%MVC reduction with the CoreBot. Earlier occurrence of the flexion-relaxation phenomenon induced by the trunk extension moment of exoskeletons played an important role in reducing LES muscle activity because the LES returned to a relaxed state earlier (EMG-Off: a 3.1° reduction with the backX, and a 1.8° reduction with the CoreBot; EMG-On: a 2.3° reduction with the backX, and a 1.4° reduction with the CoreBot). In addition, the maximum lumbar flexion angle (a 2.2° reduction with the backX and a 1.5° reduction with the CoreBot) showed significant decreases compared to the FREE condition, indicating that exoskeleton use can prevent low-back passive tissue from being fully activated. These results suggested the overall effects of passive back-support exoskeletons in reducing loads on both active and passive tissue in the low back.

Correlation analysis of flow parameters in the olfactory cleft and olfactory function.

The olfaction is related to flow in the olfactory cleft. However, There is a lack of studies on the relationship between flow characteristics of the olfactory cleft and olfactory function. In this study, the anatomical structure of the olfactory cleft was reconstructed in three dimensions using the raw data obtained from the CT scans of sinuses of 32 enrolled volunteers. The Sniffin' Sticks test was used to examine the olfaction. We investigated the correlation between airflow parameters and olfactory function of the olfactory cleft in healthy adults by the computational fluid dynamics method. We found that three parameters, airflow, airflow velocity, and airflow ratio, were highly positively correlated with olfactory function. The mean pressure was not correlated with the olfactory function. Furthermore, there is the strongest correlation between air flow through the olfactory cleft and olfactory function. The correlation between the mean velocity in the anterior olfactory cleft region and olfaction was relatively poor, while the airflow velocity at the posterior olfactory cleft region was enhanced gradually. The correlation between the airflow ratio and olfaction was optimal in the initial position of superior turbinate. The flow parameters in the posterior olfactory cleft area were more stable.

Musculoskeletal Symptoms in Brazilian University Drummers and Percussionists: A Cross-Sectional Study.

BACKGROUND: In recent years, the number of university drummers and percussionists in Brazil has been increasing. Extensive instrumental practice and repetitive rehearsals are related to the presence of musculoskeletal symptoms among many of these percussion instrumentalists (e.g., repique, tambourine, agogô, rattle, surdo, and snare drums). Musculoskeletal injuries increase the costs of medical exams and treatment in percussionists. OBJECTIVE: The present study aimed to analyze the prevalence of musculoskeletal symptoms in Brazilian university drummers and percussionists. METHOD: An electronic survey addressing demographic features and musculoskeletal signs and symptoms was distributed via social media to university drummers and percussionists in Brazil from July to November 2021. The target sample included university drummers and percussionists over age 18 years, with no gender restrictions, more than 6 months of instrumental practice, and either enrolled in undergraduate studies for more than 1 year or completed undergraduate studies less than 1 year ago. The prevalence and severity of musculoskeletal signs and symptoms were analyzed by body region using the adapted Nordic Musculoskeletal Questionnaire. RESULTS: A total of 103 responses were collected from 2,640 emails sent (3.9% response rate with a 99% completion rate). Sixty participants were female (58.25%). A high frequency of pain and discomfort was reported among the students when participating in battery activities (85.58%). In the last 6 months, wrist/hand was the most involved region (50%), followed by the lower back (45.19%) and shoulders (39.42%). In the last 7 days, the three areas most affected areas when participants were active on the drums were the wrists/hands (75%), shoulders (51.92%), and upper back (33.65%). CONCLUSION: Most Brazilian university drummers and percussionists had experienced musculoskeletal pain. This pain may be related to repetitive movements, inadequate postures, or use of excessive force during performance and practice.

A Pilot Study on the Inter-Operator Reproducibility of a Wireless Sensors-Based System for Quantifying Gait Asymmetries in Horses.

Repeatability and reproducibility of any measuring system must be evaluated to assess possible limitations for its use. The objective of this study was to establish the repeatability and the inter-operator reproducibility of a sensors-based system (EQUISYM®) for quantifying gait asymmetries in horses.. Seven wireless IMUs were placed on the head, the withers, the pelvis, and the 4 cannon bones on three horses, by four different operators, four times on each horse, which led to a total of 48 repetitions randomly assigned. Data were collected along three consecutive days and analysed to calculate total variance, standard deviation and the variance attributable to the operator on multiple asymmetry variables. Maximal percentage of variance due to the operator (calculated out of the total variance) was 5.3% and was related to the sensor placed on the head. The results suggest a good reproducibility of IMU-based gait analysis systems for different operators repositioning the system and repeating the same measurements at a succession of time intervals. Future studies will be useful to confirm that inter-operator reproducibility remains valid in larger groups and on horses with different degrees of locomotor asymmetry.

A New Surface Technique for Phrenic Nerve Conduction Study.

Objective: To report a new patient friendly and convenient technique for phrenic nerve conduction with alternative sites of stimulation and recording. Methods: Phrenic nerve conduction was performed in forty volunteers and ten patients of peripheral neuropathy. Active recording electrode was placed in tenth intercostal space 2.5 cm away from para-spinal muscles (mid-scapular line), reference electrode in eighth intercostal space just medial to subcostal margin with ground between stimulating and recording electrode. Stimulation was done at the level of crico-thyroid space near or under the posterior margin of sternocleidomastoid muscle. This new method was compared with existing ones. Analysis: Data was analysed using SPSS 23 version. Correlation between height, weight, body mass index, age, and chest expansion was done using bi-variate correlation. Mean latency and amplitude of the study method were compared with other methods using MANNOVA test. Results: Total of forty subjects were studied. Thirty-seven were male subjects. Mean age was 28.03 ± 9.63 years, height 168.0 ± 9.60 cm and chest expansion 3.53 ± 0.64 cm. Right sided phrenic nerve mean latency was 5.99 ± 0.629 ms and amplitude 1.088 ± 0.178 mV. Left sided phrenic nerve conductions showed mean latency of 6.02 ± 1.82 ms, amplitude of 1.092 ± 0.2912 mV. These standard deviations were smaller than what were observed with other methods suggesting increased consistency of our results. There was no correlation between phrenic nerve conduction with age, height, gender or chest expansion. Conclusion: This study method gave a better as well as consistent morphology, higher amplitude and required lower amount of current strength. It was superior to previously reported methods in consistency of normative data.

Necrotizing Infundibular Crystalline Folliculitis-A Case Report of a Rare Entity and Review of the Literature.

ABSTRACT: Necrotizing infundibular crystalline folliculitis (NICF) is a rare distinct entity that was introduced in 1999. It typically presents with numerous eruptive waxy papules on the forehead and/or the upper back in adults in their fifth to seventh decade of life. The pathogenesis is unknown to date, but yeast and bacterial infection of the follicular ostia seems to contribute to the development. More recently, NICF has occasionally been observed as a side effect of targeted antitumoral therapy. Histopathologically, NICF is characterized by dilated follicular ostia filled with pale filamentous and birefringent material enclosed by parakeratotic columns of the epidermis and accompanied by a mild superficial inflammatory infiltrate of the dermis. This case report is about a 58-year-old male patient presenting with multiple eruptive keratotic papules on his forehead. Histopathology revealed all classic features of NICF. The case represents a classic example of NICF and is compared with previously published cases that are comprehensively summarized in this article.

Espina selar, una causa posible de pubertad precoz central / Sellar spine, a possible cause of central precocious puberty

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