Lower limb muscle activation and kinematics modifications of young healthy adults while pushing a variable resistance sled

Introduction: The XPO Trainer used in this research is a novel device which provides low rolling resistance at low speeds with an immediate and automatic proportional increase in resistance with increased speed. Purpose: To examine the impact of using the XPO Trainer on gait and neuromuscular activation at low and high speeds in young, seemingly healthy adults. Materials and Methods: This work consisted of 48 healthy adults (age: 25.07 ± 3.46 years, weight: 148.2 ± 25.96 lbs, height: 66.57 ± 4.14 inches). Each participant wore accelerometers/gyroscopes sensors around each wrist and ankle, chest, and low back and surface electromyography (EMG) electrodes on their dominant leg over the quadriceps (QUAD), hamstring (HAM), anterior tibialis (TA), and gastrocnemius (GA). To initiate the tasks, participants walked then ran 40 feet with and without the XPO Trainer sled. Subjects did a total of 3 trials per tasks (total of 12) with one minute of rest between tasks to reduce fatigue factor. The data from the EMG and Mobility Lab sensors were then processed and compared through the SPSS 24 system for a repeated-measures ANOVA. Results: EMG- The QUAD muscle exhibited a significantly higher muscle activation (p ≤ .05) between walk (45.39 ± 24.43) and walk push (74.40 ± 56.73) tasks. Gait Parameters- There was a significant modification (p ≤ .05) between the different gait variables and tasks, including cadence, gait speed, stride length and trunk velocity while pushing the sled. Conclusion/Clinical Relevance: With the XPO Trainer being a novel device, it is important to understand how it affects the activation and response for muscles during different activities before using it as a training tool. Understanding the effect this particular sled can provide on the different components of the (temporospatial) gait parameters and muscle activation is valuable for a clinically appropriate application to specific populations.Supported by Texas Woman's University Small Grant Program

Differences in Temporal Gait Parameters When Walking on Even Surface Walkway, Treadmill, and Pushing a Constant Resistant Sled

Motorized treadmills and weighted sleds are employed in clinical settings to improve lower extremity strength, power, and endurance. However, little is known about how the spatio-temporal parameters compare when walking on an even surface walkway, walking on a treadmill, or pushing a sled. This study aimed to examine the variations in spatial and temporal gait parameters when walking on an even surface walkway (EW), on a treadmill (TW), and while pushing a sled (SP). Forty healthy subjects participated in this pilot study. The mean age and BMI of all participants were 24.39 (± 2.86) years and 68.26 (± 13.92) kg/m^2, respectively. Spatio-temporal parameters were gathered using the Mobility Lab ADPM software and six sensors containing accelerometers and gyroscopes. Participants were directed to walk at a normal and comfortable speed for 7 m on an even surface walkway for two trials. Next, the subjects walked on the treadmill for two trials at a speed based on age. For males aged <30 and females 20-40 years of age, the speed was 1.3 m/s. While for males aged 30 or older, the speed was set to 1.4 m/s. Finally, participants were instructed to walk at their normal pace while pushing a 60 lb sled for 9.1 meters (m). Treadmill walking provoked a significant increase in temporal variables, whereas pushing a sled significantly reduced the temporal variables. Treadmill walking resulted in a decrease in double limb support time and an increase in single-limb support time compared with even surface walking. Although cadence was greater when walking on a treadmill versus an even surface walkway, the difference may be attributed to a fixed speed on the treadmill, which was determined by age. Treadmill gait training is recommended for subjects that could benefit from an increase single limb support time to improve dynamic balance such as Parkinson patients. On the other hand, for those participants that dynamic activities are challenging, such as concussion and vestibular patients, pushing the sled will slow down gait parameters allowing gait training with an added resistance benefit. Finally, it has been proposed that further investigation should focus on the differences in lower extremity muscle activation and recruitment patterns under various walking conditions

Anteroposterior and mediolateral postural adaptations during single and duals tasks in healthy young adults

Dual tasks are fundamental and standard for daily walking and balance movements. However, further research is required to determine the comprehensive postural profile during challenging dual cognitive tasks. To distinguish the influence of dual cognitive tasks on anterior-posterior (AP) and mediolateral (ML) jerk (direction of sway), velocity, and distance in young adults with normal balance systems. Nineteen subjects took part in this inquiry (2 males and 17 females), with a mean age of 23.9+\- 2.3 years. The participants were instrumented using a lumbar accelerometer and a dynamometer designed to capture sway. All subjects completed eight balance tests comprising four single and four dual-cognitive tasks involving counting backward by three, starting at the number 100 (dual-task). Postural modifications were prominent in the AP direction, with a faster jerk, velocity, and considerable distance than in the ML direction. The introduction to challenging balance situations, including dual tasks, provoke AP direction adaptations to preserve balance through variations in AP parameters, indicating the engagement of the sensory reweighting system

Anthropometric characteristics, quality of life and functional capacity in adults living with HIV in Puerto Rico

Survival and longevity rates in people living with HIV (HIV+) have increased with the availability and use of antiretroviral therapy (ART). However, despite the above HIV+ adults treated with ART have a higher risk of developing dyslipidemia and high waist circumference. In addition, they have lower cardiorespiratory fitness, loss of muscle mass, reduced balance, and reduced functional capacity, which affects their quality of life. To explore the impact of balance perception, treadmill time, grip strength, body mass index (BMI), and waist-to-height ratio (WHtR) on quality of life in Latino Hispanic people living with HIV. This study recruited twenty-five participants from a community-based center, La Perla de Gran Precio, in San Juan, Puerto Rico, with the medical diagnosis of HIV. Descriptive measures were obtained for all variables of interest, and correlation and regression analyses were used to assess the associations between functional capacity, quality of life, and anthropometric measures. Result: Men had greater left- and right-hand grip strength than women (86.9±18.8, 56.9±26.8 kg; p=0.003 and 87.6±15.1 vs. 61.4±26.6 kg; p =0.004). Two anthropometric variables showed a trend toward a moderate positive correlation with quality of life:  WHtR (r= -0.38, p =0.12) and BMI (r= -0.38, p = p-0.14). Although gender differences in upper body strength are expected, handgrip strength is within the gender-specific average range of the general population. The integration of anthropometric characteristics and upper body strength when prescribing exercise must be considered since these factors influence functional capacity and quality of life among HIV+ adults

Blockade and Counterflow Supercurrent in exciton-condensate Josephson junctions

We demonstrate that perfect conversion between charged supercurrents in superconductors and neutral supercurrents in electron-hole pair condensates is possible via a new Andreev-like scattering mechanism. As a result, when two superconducting circuits are coupled through a bilayer exciton condensate, the superflow in both layers is drastically modified. Depending on the phase biases the supercurrents can be completely blocked or exhibit perfect drag.Comment: 4 pages, 2 figure

Positive cross-correlations induced by ferromagnetic contacts

Due to the Fermionic nature of carriers, correlations between electric currents flowing through two different contacts attached to a conductor present a negative sign. Possibility for positive cross-correlations has been demonstrated in hybrid normal/superconductor structures under certain conditions. In this paper we show that positive cross-correlations can be induced, if not already present, in such structures by employing ferromagnetic leads with magnetizations aligned anti-parallel to each other. We consider three-terminal hybrid structures and calculate the mean-square correlations of current fluctuations as a function of the bias voltage at finite temperature.Comment: 6 pages, 5 figures; accepted version by PRB, figures replace

Do cash incentives increase the uptake of chlamydia testing in pharmacies?

BACKGROUND: Chlamydia screening uptake rates in Australian and overseas pharmacies vary widely (11% to 58%). AIM: To determine the effect on the uptake of chlamydia screening in community pharmacies when a cash reward is offered to young people and participating pharmacies. METHODS: The study was advertised in print and electronic media. People aged 16–30 years requested, or were offered, chlamydia testing kits by pharmacy staff (assistants and pharmacists). Participants who provided a urine sample and completed a questionnaire received AUD$10; pharmacies received AUD$10 per person recruited. Urine specimens were tested in pools using PCR, with reflex testing of individual samples when the pool tested positive. Positive cases were notified by sexual health nurses and offered treatment. RESULTS: Six urban community pharmacies took part in the study, each for 15 days. 979 testing kits were given out and 970 sample pots returned (99.1%); 66 (7%) did not contain urine. 74% (670/904) of the urine samples were determined to be from unique individuals, 65% of whom were male. 19 people (13 females and 6 males) tested positive; positivity rates were 5.2% (95% CI 2.8 to 8.8) for females and 1.4% for males. 11 (61%) of those testing positive were contacted and eight attended a local sexual health centre for treatment, three were treated elsewhere. Of the eight people treated at the sexual health centre, two females aged 15 and 20 years were diagnosed with pelvic inflammatory disease. Contact with the remaining eight positive individuals was not possible due to disconnected, incorrect or non-existent telephone numbers. CONCLUSION: The 68% specimen return rate found in this study significantly exceeds those reported elsewhere. Strategies to prevent repeat testing, non-urine specimens and incorrect contact numbers are needed to ensure good clinical care and optimum use of resources

Evaluating static postural control in subjects with controlled-diabetes mellitus II

Diabetes and neuropathy have been linked to postural instability. Aims: The purpose of this study is to determine how each system involved in balance is affected when challenged in a static standing posture. The goal was to identify postural instability by measuring balance through the amount of sway and weight bearing distribution in non-neuropathic controlled type II diabetics. Methods: Twelve participants (five males and seven females) with controlled type II diabetes mellitus and no history of peripheral neuropathy (Non-PN cDMII) formed the diabetic group, whereas eighteen participants (7 males and 11 females) without type II diabetes formed the control group. The exclusion criteria was applied via a series of screening tests (Berg Balance Scale, Five Times Sit To Stand Test, Functional Reach Test and Monofilament Test). Postural stability and weight distribution during quiet standing were measured using a Tekscan Matscan pressure mat, which measured the amount of sway and weight distribution. Static postural control was evaluated during eight sensory conditions that perturbed or stimulated the visual, proprioceptive, and vestibular systems. Results: Postural control was found to be significantly deficient when the vestibular system was stimulated, whereas the proprioceptive system was perturbed. After the data analysis, there was a significant difference in antero-posterior sway (P=0.05) with the following tasks: eyes open with head movements on an unstable surface, and eyes closed with head movements on a firm surface. Conclusions: The results revealed that the experimental group with type II diabetes had greater postural instability when compared to the control group during tasks with the vestibular system on an unstable surface. This demonstrates that, due to their deficits, individuals with non-PN cDMII are unable to maintain their balance when the vestibular and proprioceptive systems are challenged simultaneously