Reliability of the Stryd Accelerometer on an Incline and Decline

Modern technology has evolved to include various health and fitness trackers to help the general population become more aware of their physical wellbeing. However, the reliability of these technologies is not well-established. PURPOSE: Determine the reliability of Stryd accelerometer during trail running. METHODS: Seventeen participants (25 ± 9 years; F = 7) completed a trail run. Each participant was fitted with one Stryd accelerometer (model 25; Stryd, Boulder, CO 80301) on the shoe of each foot, and both devices were started simultaneously. The participant then did a self-paced out and back run on a moderate difficulty hiking trail. The trail began at approximately 6000 feet elevation and climbed approximately 200 feet/mile. After ten minutes of running up the trail, the participant turned around and returned on the same trail. Upon finishing the run, the Stryd accelerometers were stopped simultaneously. Data collected by Stryd sensors includes distance, altitude, speed, power, form power, cadence, vertical oscillation, and leg stiffness. These Stryd data were exported to csv files. We divided the data into uphill and downhill phases of the run based on the peak elevation achieved and found the average and peak values for uphill and downhill phases of the run. We calculated the within-subjects coefficient of variation for each measure during downhill and uphill trail running. RESULTS: Of the mentioned variables, six were considered reliable-each with a CV less than 0.1-and three were considered unreliable-with a CV of over 0.1. The least reliable measures were form power (uphill: CV=0.124; downhill: CV=0.126) and power (uphill: CV=0.132; downhill: CV=0.135). The most reliable measures were cadence (uphill: CV=0.002; downhill: CV=0.005) and altitude (uphill: CV=0.004; downhill: 0.004). CONCLUSION: As the majority of the measures were statistically reliable, the Stryd accelerometer can be considered reliable. However, the power measures were the least reliable. This finding is important because Stryd advertises the ability to track training intensity based on power output. If this data is unreliable in outdoor locations Stryd may provide inaccurate training advice. Based on our findings tracking outdoor run intensity based on Stryd power may provide inconsistent results

Evaluation and Comparison of Wearable Technology Device Data Between Devices During Trail Running

An estimated 20 million people participate in trail running with this number expected grow at a rate of 15% annually. Wearable technology devices have become more relied upon to track running data such as distance, cadence, elevation gain, etc. The consistency between these devices is not well-established. PURPOSE: To determine the consistency of data across wearable technology devices. METHODS: Seventeen participants (F = 7) ran on the Thunderbird Gardens Lighting Switch trail in Cedar City, UT. The participants were each fitted with two Garmin Instincts, two Polar Vantage M2s, and two Stryd sensors. One device from each manufacturer was placed on the left side (wrist for watches and foot for Stryd), and the other devices were placed on the right. Each pair of devices was started simultaneously, and the participant then completed a self-paced out-and-back trail run of approximately 20 minutes. All devices were stopped simultaneously at the completion of the run. Data collected across all devices includes average pace, best pace, average cadence, distance, ascent, and descent. The average percent difference and coefficient of variation (CV) between similar and different devices was calculated. RESULTS: The pairs of devices from the same manufacturer were found to be most consistent with each other (Garmin to Garmin: 3.27%; Polar to Polar: 1.4%; Stryd to Stryd: 1.15%) while devices from different manufacturers were found to be very different (Garmin to Polar: 12.75%; Garmin to Stryd: 10.11%; Polar to Stryd: 17.75%). Between devices from the same manufacturer, ascent was found to be least reliable (Garmin: CoV=0.20; Polar: CoV=0.12; Stryd: CoV=0.26). CONCLUSION: Data collected by wearable technologies of the same manufacturer will be mostly consistent with each other. However, data collected by a technology from a different manufacturer may be inconsistent with data from another device. In addition, elevation data may vary more than other data between watches. This finding is important because trail runners tend to compare their trail runs with other runners and often find ascent data important to measure progress. The location of the trail in a canyon may have impeded accuracy. Based on our findings, it may not be accurate to compare trail runs completed by runners with a different wearable technology device manufacturer

Motor Adaptation to Muscle Fatigue: Moderating Factors and Implications

Muscle fatigue reduces the force that a muscle can produce and causes sensations of weakness and discomfort. People can adapt to muscle fatigue by adopting new movement patterns and control strategies. These motor adaptations can affect performance and sometimes predispose people to injuries. However, the effects of fatigue are situation-dependent. This research examined how the effects of muscle fatigue are moderated by which muscles are fatigued, the fatigue state, and the sensation of pain. It was expected that these moderating factors would affect the motor adaptations that people use when fatigued, the rate of muscle fatigue, and the risk of error and injury. Since different joints make different contributions to the completion of movement tasks, fatigue that is localized in different muscle groups is expected to affect movement differently. Aim 1 compared changes in whole-body movement coordination following fatigue of proximal and distal muscle groups in the upper extremity. Subjects maintained task performance after both proximal and distal fatigue. Proximal fatigue led to widespread movement changes across several joints, but distal fatigue primarily caused changes at the distal joints. The observed changes after proximal fatigue may increase the risk of back pain and injury, while changes after distal fatigue may predispose people to errors in manipulation. Muscle fatigue is a complex, multifactorial process, and people may adapt to fatigue by changing the movement patterns of many joints. It is difficult to quantify the effects of muscle fatigue on multi-joint coordination. In Aim 2, I used principal components analyses to determine how multi-joint coordination changes during and after muscle fatigue. During fatigue, inter-joint x coordination decreased, and subjects utilized a stiffening strategy that may have reduced the complexity of movement. However, these changes began to reverse after cessation of a fatiguing task. The observed changes suggest that people learn novel coordinative patterns as they adapt to muscle fatigue. Adapting to muscle fatigue is a cognitively demanding process. In working environments, biological stimuli such as pain may compete for limited cognitive resources during movement tasks. Aim 3 used a goal equivalent manifold (GEM) approach to determine how experimental pain influences the ability to adapt to muscle fatigue. Ischemic muscle pain in the contralateral arm caused people to reduce movement control, but this did not lead to significantly faster fatigue rates. However, order of the painful, and non-painful experimental sessions had a significant effect on fatigue rate. Furthermore, people who exhibit catastrophic thinking used different movement strategies than those who did not exhibit catastrophic thinking. Together these results demonstrate that the fatigue state of the muscles and the presence of a noxious stimulus moderate the way that people adapt to muscle fatigue. People can adapt to muscle fatigue by modifying their movement patterns, but motor adaptation does not necessarily lead to optimal movement strategies. While motor adaptation did not affect the task outcome in these or previous fatigue studies, the lack of performance deficits is likely attributable to the selection of simple experimental tasks in highly controlled environments. The moderating factors examined here are likely to affect complex fatiguing situations encountered in real world environments where the observed reduction in movement coordination and control could negatively impact task execution and lead to inefficient movement and injury. The current results emphasize the need to better understand how fatigue affects movement in realistic working environments.PHDKinesiologyUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/138532/1/jccowle_1.pd

CD4−CD8− T cells control intracellular bacterial infections both in vitro and in vivo

Memory T cells, including the well-known CD4+ and CD8+ T cells, are central components of the acquired immune system and are the basis for successful vaccination. After infection, CD4+ and CD8+ T cells expand into effector cells, and then differentiate into long-lived memory cells. We show that a rare population of CD4−CD8−CD3+αβ+γδ−NK1.1− T cells has similar functions. These cells potently and specifically inhibit the growth of the intracellular bacteria Mycobacterium tuberculosis (M. tb.) or Francisella tularensis Live Vaccine Strain (LVS) in macrophages in vitro, promote survival of mice infected with these organisms in vivo, and adoptively transfer immunity to F. tularensis LVS. Furthermore, these cells expand in the spleens of mice infected with M. tb. or F. tularensis LVS, and then acquire a memory cell phenotype. Thus, CD4−CD8− T cells have a role in the control of intracellular infection and may contribute to successful vaccination

Continued Advancement of Supported Liquid Membranes for Carbon Dioxide Control in Extravehicular Activity Applications

The Development of a new, robust, portable life support system (PLSS) is currently a high NASA priority in order to support longer and safer extravehicular activity (EVA) missions that will be necessary as space travel extends to near-Earth asteroids and eventually Mars. One of the critical PLSS functions is maintaining the carbon dioxide (CO2) concentration in the suit at acceptable levels. The Metal Oxide (MetOx) canister has a finite CO2 adsorption capacity and therefore in order to extend mission times, the unit would have to be larger and heavier, which is undesirable; therefore new CO2 control technologies must be developed. While recent work has centered on the use of alternating sorbent beds that can be regenerated during the EVA, this strategy increases the system complexity and power consumption. A simpler approach is to use a membrane that vents CO2 to space but retains oxygen(O2). A membrane has many advantages over current technology: it is a continuous system with no theoretical capacity limit, it requires no consumables, and it requires no hardware for switching beds between absorption and regeneration. Conventional gas separation membranes do not have adequate selectivity for use in the PLSS, but the required performance could be obtained with a supported liquid membrane (SLM), which consists of a microporous film filled with a liquid that selectively reacts with CO2 over oxygen (O2). In a recently completed Phase II Small Business Innovative Research project, Reaction Systems developed a new reactive liquid that has effectively zero vapor pressure, making it an ideal candidate for use in an SLM. Results obtained with the SLM in a flat sheet configuration with representative pressures of CO2, O2, and water (H2O) have shown that the CO2 permeation rate and CO2/O2 selectivity requirements have been met. In addition, the SLM vents moisture to space very effectively. The SLM has also been prepared and tested in a hollow fiber form, which will be necessary to meet size requirements in the PLSS. In initial tests, the required CO2 permeance values have been obtained, while the current CO2/O2 selectivity values are somewhat lower than needed. However, the performance of the SLM is a strong function of the method used to impregnate the sorbent in the hollow fiber walls and rapid progress is being made in that area

Analysis of a Moon outpost for Mars enabling technologies through a Virtual Reality environment

The Moon is now being considered as the starting point for human exploration of the Solar System beyond low-Earth orbit. Many national space agencies are actively advocating to build up a lunar surface habitat capability starting from 2030 or earlier: according to ESA Technology Roadmaps for Exploration this should be the result of a broad international cooperation. Taking into account an incremental approach to reduce risks and costs of space missions, a lunar outpost can be considered as a test bed towards Mars, allowing to validate enabling technologies, such as water processing, waste management, power generation and storage, automation, robotics and human factors. Our natural satellite is rich in resources that could be used to pursue such a goal through a necessary assessment of ISRU techniques. The aim of this research is the analysis of a Moon outpost dedicated to the validation of enabling technologies for human space exploration. The main building blocks of the outpost are identified and feasible evolutionary scenarios are depicted, to highlight the incremental steps to build up the outpost. Main aspects that are dealt with include outpost location and architecture, as well as ISRU facilities, which in a far term future can help reduce the mass at launch, by producing hydrogen and oxygen for consumables, ECLSS, and propellant for Earth-Moon sorties and Mars journeys. A test outpost is implemented in a Virtual Reality (VR) environment as a first proof-of-concepts, where the elements are computer-based mock-ups. The VR facility has a first-person interactive perspective, allowing for specific in-depth analyses of ergonomics and operations. The feedbacks of these analyses are crucial to highlight requirements that might otherwise be overlooked, while their general outputs are fundamental to write down procedures. Moreover, the mimic of astronauts’ EVAs is useful for pre-flight training, but can also represent an additional tool for failures troubleshooting during the flight controllers’ nominal operations. Additionally, illumination maps have been obtained to study the light conditions, which are essential parameters to assess the base elements location. This unique simulation environment may offer the largest suite of benefits during the design and development phase, as it allows to design future systems to optimize operations, thus maximizing the mission’s scientific return, and to enhance the astronauts training, by saving time and cost. The paper describes how a virtual environment could help to design a Moon outpost for an incremental architecture strategy towards Mars missions

Transgenic amplification of glucocorticoid action in adipose tissue causes high blood pressure in mice

Obesity is closely associated with the metabolic syndrome, a combination of disorders including insulin resistance, diabetes, dyslipidemia, and hypertension. A role for local glucocorticoid reamplification in obesity and the metabolic syndrome has been suggested. The enzyme 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) regenerates active cortisol from inactive 11-keto forms, and aP2-HSD1 mice with relative transgenic overexpression of this enzyme in fat cells develop visceral obesity with insulin resistance and dyslipidemia. Here we report that aP2-HSD1 mice also have high arterial blood pressure (BP). The mice have increased sensitivity to dietary salt and increased plasma levels of angiotensinogen, angiotensin II, and aldosterone. This hypertension is abolished by selective angiotensin II receptor AT-1 antagonist at a low dose that does not affect BP in non-Tg littermates. These findings suggest that activation of the circulating renin-angiotensin system (RAS) develops in aP2-HSD1 mice. The long-term hypertension is further reflected by an appreciable hypertrophy and hyperplasia of the distal tubule epithelium of the nephron, resembling salt-sensitive or angiotensin II–mediated hypertension. Taken together, our findings suggest that overexpression of 11β-HSD1 in fat is sufficient to cause salt-sensitive hypertension mediated by an activated RAS. The potential role of adipose 11β-HSD1 in mediating critical features of the metabolic syndrome extends beyond obesity and metabolic complications to include the most central cardiovascular feature of this disorder

Assessing the Reliability of Stryd 27 for Variable Speed Running

Wearable technology is beneficial when it comes to tracking and optimizing performance. The Stryd 27 is a wearable footpod marketed as being more responsive in measuring power during running than the previous version (Stryd 25). However, the reliability of this newer device to return consistent values has not been determined. PURPOSE: This study aimed to observe whether Stryd 27 gives reliable metrics during variable speed running. METHODS: Sixteen participants (N = 16; 50% female; height = 174.1 ± 8.1 cm; mass = 73.0 ± 12.4 kg) were recruited, each equipped with two Stryd 27 footpods (updated to the same software version) affixed to the shoelaces of their running shoes. The researchers recorded data using the Stryd app on a mobile device that was connected to the Stryd 27 via Bluetooth. Recording on both devices were started and stopped at the same time. Each participant completed two, 10-minute runs on an indoor track. The initial run was used to establish a baseline. Following a 5-minute rest period, participants proceeded with the second run, during which they alternated between faster and slower intervals. The pace for these intervals was set to be 20% faster and 20% slower than what each participant’s average pace was during the first run. Reliability of power, cadence, form power, ground contact time (GCT), vertical oscillation (VO), leg spring stiffness (LSS), and stride length during the interval run was determined using coefficient of variation (CV) and intraclass correlation coefficient (ICC), with CV0.70 (p \u3c 0.05) being considered evidence of reliability. RESULTS: Reliability data are shown in Table 1. The following measures were found to be reliable: power, cadence, form power, GCC, and VO. The measures of LSS and stride length were not found to be reliable. CONCLUSION: Runners using the new Stryd 27 can have confidence that most measures return reliable values (power, cadence, form power, GCT, and VO). Unfortunately, two measures were observed to not meet the threshold for reliability (LSS and stride length). Athletes interested in these measures should be cautious when interpreting their data