Ultrastretchable, Ultralow Hysteresis, High-Toughness Hydrogel Strain Sensor for Pressure Recognition with Deep Learning.

Hydrogel, as a promising material for a wide range of applications, has demonstrated considerable potential for use in flexible wearable devices and engineering technologies. However, simultaneously realizing the ultrastretchability, low hysteresis, and high toughness of hydrogels is still a great challenge. Here, we present a dual physically cross-linked polyacrylamide (PAM)/sodium hyaluronate (HA)/montmorillonite (MMT) hydrogel. The introduction of HA increases the degree of chain entanglement, and the addition of MMT acts as a stress dissipation center and cross-linking agent, resulting in a hydrogel with high toughness and low hysteretic properties. This hydrogel synthesized by a simple strategy exhibited ultrahigh stretchability (3165%), high breaking stress (228 kPa), high toughness (4.149 MJ/m3), and ultralow hysteresis (≈2% at 100% of strain). The fabricated hydrogel flexible strain sensors possessed fast response and recovery times (62.5:75 ms), a wide strain detection range (2000%), a strain detection limit of 1%, and excellent cycling stability over 500 cycles. Furthermore, the hydrogel flexible strain sensor can be used for human motion monitoring, gesture recognition, and pressure recognition assisted by deep learning algorithms, showing enormous promise for applications.

Prevalence and risk factors of self-reported wrist and hand symptoms and clinically confirmed carpal tunnel syndrome among office workers in China: a cross-sectional study.

BACKGROUND: Carpal tunnel syndrome (CTS) is a common cause of pain, numbness and tingling in the wrist and hand region and is associated with repetitive wrist and hand use in office workers. However, scarce knowledge exists about the epidemiology of clinically confirmed CTS among Chinese office workers. This study aimed to investigate the prevalence of wrist/hand symptoms and CTS in office workers in China and to identify associated risk factors. METHODS: A cross-sectional survey was carried out in a metropolitan city in China involving 969 respondents (aged 17-49 years) from 30 workplaces. A questionnaire was distributed to each participant to collect their demographic, work-related physical and psychosocial factors, and wrist and hand symptoms. The wrist and hand pain/numbness symptoms were marked on a body chart and the nature and intensity of symptoms, nocturnal symptoms, as well as aggravating activities were also recorded. Clinically confirmed CTS cases were screened based on the history, Phalen's test, Tinel Sign and skin sensation testing among symptomatic respondents. Logistic regression was employed to estimate the odds ratio (OR) and 95% confidence interval (95% CI) for the occurrence of self-reported wrist and hand symptoms and clinically confirmed CTS. RESULTS: The clinically confirmed CTS prevalence was 9.6%. The prevalence of wrist and hand symptoms were 22 and 15%, respectively. Frequently working in pain was associated with higher odds of CTS. Multivariate modelling adjusted for age and gender showed that prolonged computer use time and working without breaks were associated with presence of wrist/hand symptoms (adjusted ORs: 1.11 (95% CI 1.02-1.22) and 1.88 (95% CI 1.12-3.14)). Educational level was inversely associated with CTS and smoking was associated with wrist/hand complaints (adjusted OR: 2.20 (95% CI 1.19-4.07)). CONCLUSIONS: The prevalence of work-related clinically confirmed CTS symptoms among young office workers in China is high. Frequently working in pain is closely associated with clinically confirmed CTS. Intense computer use and no breaks at work are associated with wrist and hand symptoms.

The Efficacy of Dynamic Contract-Relax Stretching on Delayed-Onset Muscle Soreness Among Healthy Individuals: A Randomized Clinical Trial.

OBJECTIVE: To evaluate the efficacy of dynamic contract-relax stretching on delayed-onset muscle soreness (DOMS) in the calf muscle of healthy individuals. DESIGN: Randomized clinical trial. SETTING: Research laboratory. PARTICIPANTS: Three groups of 16 healthy participants (n = 48) were recruited by convenience sampling. INTERVENTIONS: Three sets of resisted bilateral heel-raising exercises until exhaustion were conducted to initiate DOMS. Participants were randomly allocated into control group without any interventions, dynamic contract-relax stretching (DS), or static stretching (SS) groups. Dynamic contract-relax stretching and SS groups performed DS and SS, respectively, on the dominant leg twice a day for 5 consecutive days (before time points of outcome measurements at 24, 48, 72, 96, and 120 hours postexercise, respectively). MAIN OUTCOME MEASURES: Muscle soreness, lower leg girth, pressure pain threshold (PPT), range of motion (ROM), and muscle strength were measured before exercise, immediately after, and at 24, 48, 72, 96, and 120 hours postexercise. RESULTS: There was a significant effect of time in all outcome measures including muscle soreness, lower leg girth, PPT, ROM, and muscle strength; however, there were no significant group differences or group by time interactions. CONCLUSIONS: The effect of DS on relieving DOMS in the calf muscle is insignificant in this study. Further evidence is needed to prove the efficacy of DS on DOMS. CLINICAL RELEVANCE: Stretching is commonly recommended before and after exercise; however, this study showed no significant impact of DS or SS in treating DOMS.