Nano Dimension Increases Application Footprint

Tim and the DragonFly Pro 3D printer [Image: Fabbaloo]

Space, defense, smart homes: Nano Dimension is expanding the reach of 3D printed electronics.

Announcement after announcement seems to come out of the Israeli company as the 3D printing of electronics is gaining momentum. New installations, agreements, and achievements seem to come at full speed; in the last month and a half alone, the company has announced second and third DragonFly Pro purchases at TTM, a 3D printed IoT communication device, and, just today, a collaboration to develop hardware for the International Space Station.

Phew.

It’s a lot to keep up with, so I sat down recently with VP of Global Sales and Customer Care Tim Sheehan of Nano Dimension USA.

TTM, which now has its three systems, is a world leader for printed circuit boards (PCBs), Sheehan noted — and a strong strategic partner. Nano Dimension, TTM, and Germany-based Hansoldt are strategic partners “making great plans” to address Tier 1 research for the Department of Defense, Sheehan noted.

“We’re seeing an increased application footprint,” he noted mildly.

That also includes a new feature set, such as the recently-introduced ability to design capacitors.

“You can print a layer just for the capacitor. At the R&D level, you don’t have to buy a capacitor, you can design it. That saves on the need to buy it, to spend the time soldering. There’s increasing productivity, which reduces the cycle time of efforts. We’re giving the ability to test projects without all that other extraneous work involved,” Sheehan said.

The ability to 3D print electronics in-house is “expanding the minds of electrical engineers,” he added.


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3D printed electronics configurations possible [Images: Fabbaloo]

3D printing is famously able to expand the possible geometries for a given part. While often this means space-age structures that reek of generative design and a love of lattices, when it comes to PCB manufacture, that means much more.

We often talk about part consolidation, which comes in handy for reducing weight and welding in complex aerospace assemblies — but in this sense can also mean printed capacitors, mountings on the side instead of just the traditional top or bottom, and other interesting feature applications that are broadening possibilities for integrated electronics.

“It stretches their minds when we show them circuitry in three dimensions,” Sheehan said, holding up an indeed three-dimensional Molded Interconnect Device (MID).


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The 3D-MID [Images: Fabbaloo]

If you’re thinking only DoD and ISS for their parts, think again; for the MID, Sheehan pointed to use cases that are well outside the box. Or inside, if your McDonald’s still packages Happy Meals in boxes — such parts could be used to power kids’ toys in fast food meals, offering “safe, internal” powering.

The parts possible with Nano Dimension’s powerful DragonFly Pro system are indeed relatively mind-stretching. The company is always looking ahead, “beyond the bubble” of 3D printing, as it were, and toward production, toward real-world, realizable usage.

And there’s certainly much more to come from the busy company. Loosely, Sheehan would say on the record, there’s “a lot to look forward to in Q3 and Q4.” (Stay tuned around formnext.)

Via Nano Dimension

Novel interactions between the HTLV-1 antisense protein HBZ and the SWI/SNF chromatin remodeling family: Implications for viral life cycle [Virus-Cell Interactions]

The human T-cell leukemia virus type 1 (HTLV-1) regulatory proteins Tax and HBZ play indispensable roles in regulating viral and cellular gene expression. BRG1, the ATPase subunit of the SWI/SNF chromatin remodeling complex, has been demonstrated to be essential not only for Tax transactivation but also for viral replication. We sought to investigate the physical interaction between HBZ and BRG1 and to determine the effect of those interactions on Tax-mediated LTR activation. We reveal that HTLV-1 cell lines and ATL cells harbour high levels of BRG1. Using GST pulldown and co-immunoprecipitation assays we have demonstrated physical interactions between BRG1 and HBZ and characterised the protein domains involved. Moreover, we have identified PBAF-signature subunits BAF200 and BAF180 as novel interaction partners of HBZ suggesting that PBAF complex may be required for HTLV-1 transcriptional repression by HBZ. Additionally, we found that BRG1 expression translocates HBZ into distinct nuclear foci. We show that HBZ substantially represses HTLV-1 LTR activation by Tax/BRG1. Interestingly, we found that Tax stabilizes the expression of exogenous and endogenous BRG1 and HBZ reverses this effect. Finally, using Chromatin Immunoprecipitation-qPCR (ChIP-qPCR) assay we illustrate that HBZ facilitates the down-regulation of HTLV-1 transcription by deregulating the recruitment of SWI/SNF complexes to the promoter. Overall, we conclude that SWI/SNF complexes, in addition to other cellular transcription factors are involved in HBZ-mediated suppression of HTLV-1 viral gene expression.

IMPORTANCE

The pathogenic potential of HTLV-1 is linked to the indispensable multifaceted functions of the viral regulatory proteins Tax and HBZ, encoded by the sense and antisense viral transcripts, respectively. The interaction between Tax and SWI/SNF family of chromatin-remodeling complexes has been associated with HTLV-1 transcriptional activation. To date, the relationship between SWI/SNF chromatin remodeling family and HBZ, the only viral protein that is consistently expressed in infected cells and ATL cells, has not been elucidated. Here, we have characterized the biological significance of SWI/SNF family in regard to viral transcriptional repression by HBZ. This is important because it provides a better understanding of the function and role of HBZ in down-regulating viral transcription and hence its contribution to viral latency and persistence in vivo, a process that may ultimately lead to development of ATL.

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Inside ACEO’s Silicone 3D Printing Lab

L-R: Ty Larson, Sarah Burke, and Dr. Vera Seitz at Wacker’s R&D site in Ann Arbor, Michigan [Image: Fabbaloo]

A look inside ACEO’s US 3D printing operations proved illuminating.

In Ann Arbor, Michigan, about 20 companies share an incubator space. Since 2016, about 10,000 square feet of that space has been dedicated to Wacker Chemie’s R&D operations.

RAPID + TCT this year was located in Detroit, a relatively short drive from Ann Arbor. It was a pleasure to get into town a bit early on the first day of RAPID to accept an invitation from ACEO to go on-site at their lab. We’ve heard about ACEO’s silicone 3D printing abilities for some time now, and have seen their 3D printers at events, but there’s certainly something to be gained from going right into the lab where it happens.

The Ann Arbor 3D printing lab is relatively new still, and run by ACEO Print Lab Manager Sarah Burke, who welcomed another guest and me to the facility. She and Dr. Vera Seitz, a product design engineer based in ACEO’s main campus in Burghausen, Germany, together with Senior Manager of Business Development Ty Larson provided insights into operations and the company’s technology.

Outside the incubator space [Image: Fabbaloo]

Outside the incubator space [Image: Fabbaloo]

Silicone is a major area of interest in 3D printing. The material offers unique capabilities with applications ranging from medical to industrial. ACEO has been at the forefront of developing viable 3D printing capabilities for the viscous material. Earlier this year they even introduced electrically conductive silicone 3D printing.

ACEO built its own hardware, software, and materials to develop their offerings. The company does not sell 3D printers, but offers services as well as, in Ann Arbor, an Open Print Lab session offering.

“We have developed a systems solution to create the final part,” Seitz explained. “We think it’s the best way to handle it; we have all the parameters in hand, as well as the materials expertise and control over the process.”

Their technology looks a bit like extrusion-based (e.g., FFF/FDM) 3D printing, but is a material dosing, drop-on-demand process. Individual droplets of liquid silicone are placed and merge together; layer by layer, they are then UV-cured.

“We have seen that single droplets offer advantages,” Seitz said of the process. “Drop on demand is our silicone chemistry magic. Single droplets are dosed and have a window to flow and connect, then we cure every layer.”

This is why, Larson added, he calls it “chemical 3D printing.” The monomer crosslinking that occurs this way leads to great strength in the Z-axis, where many 3D printing results can lack.

At ACEO’s lab, the 3D printers are equipped with up to four nozzles, enabling the printing of up to three different silicones and a support material. (The machines we watched start and complete small builds were working with two nozzles.)

The lab works with silicones of various Shore hardnesses — “20-60 Shore A as standard, and aiming for the full silicone range,” Seitz said — and is capable of Pantone color grading. The materials are also biocompatible and food compatible.

“Parts come off the print bed pretty much functional, but we also go one step further and completely cure it at the end. This was a choice made by the company when launching,” Larson said.

That final curing step ensures that parts are indeed completely safe; for example, if a baby came into contact with a part and instinctively put it in her mouth, she wouldn’t be in danger from uncured or toxic chemicals.

Because of the consistent curing, post-processing is minimal. Any supports are easily removed, as they are water-soluble. Supports are generally necessary, as the highly viscous material can’t, for example, create overhangs. The specific material used for the supports is proprietary, but they could say that it is a water-soluble polymer that can be printed on all the same types of materials.


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[Silicone prints from ACEO / Images: Fabbaloo]

The multi-material capabilities are, Seitz said, “one of the most fascinating things about 3D printing” from an engineering point of view.

On the drive to Ann Arbor, Larson told the story of a complex stomach model that could be 3D printed with different materials to exactly replicate the feel of human organs within a single model. Surgeons and other medical professionals “learn with their hands,” he said, adding great value to created medical models that precisely replicate anatomy.

The focus at ACEO is, as with the broader 3D printing industry today, on production. Prototyping remains important, but end-use parts are a large part of the future.

The materials used in ACEO’s 3D printing operations are 100% silicone elastomers, “very similar in 3D printing to what is familiar in injection molding as the intrinsic material properties stay the same,” Seitz said. These familiar, proven materials enable that step toward providing functional parts.

That said, ACEO’s capabilities are not ready for full production scale 3D printing. Solutions are still best-fit, and at the moment that means small-volume and just-in-time supply, not runs of millions of parts.

“There will be a time after mass production where 3D printing will be important again, such as for spare parts,” Seitz said, indicating a major use case.

The materials are also sustainable, and produce just ash, no unwelcome byproducts, when burned or destroyed.

ACEO’s 3D printing operations also illustrate one of the more common operations methods we often see with dedicated activities from large organizations. The 3D printing team operates as a sort of well-supported startup with the resources from its large chemical parent. The many decades of expertise developed at Wacker provide a solid starting place for ACEO, including access to advanced silicone know-how. Operations are also quite small; perhaps with 20 people involved between Ann Arbor and Burghausen.

Going into the ACEO R&D lab was a great experience, especially as I had the pleasure of visiting with visual artist and Certified Clinical Anaplastologist Irene Healey, who is familiar from the practical side of working with silicones.

Watching the printers at work (unfortunately I was not able to take photos/video inside the lab), handling prints moments after completion, and getting hands-on with a variety of parts for different applications — even being challenged to break them, even when just one layer thick (Irene and I both failed to do so) — underscored something important. Silicone 3D printing is a very real solution available today, and ACEO’s expertise and early lead in the space make them one to watch (something their approximately 1300 global customers already know).

Via ACEO

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Fabrisonic To Space!

Fabrisonic is working toward a space-rated 3D printer [Source: Fabbaloo]

This week we found out Fabrisonic intends to develop a space-rated 3D printer.

The Ohio-based company offers a unique 3D printing process that is based on ultrasonic technology. They leverage the natural ability for metals to fuse together when vibrational energy is applied.

Their process involves applying ultrasonic waves to a stack of very thin sheets of metal. The vibrations cause these sheets to fuse together. It’s a unique 3D printing approach that uniquely allows different types of metals to be fused together, where normal methods would not permit such combinations. For example, you could produce an aluminum-titanium object.

But what is the outer space angle?

NASA has been investigating the possibility of a Space Station-based 3D printing service for some time. The advantages are obvious: they need only send up a stock of material, and then when parts are required, they can simply be printed on demand, rather than expensively shipping them up by cargo rocket.

We’ve seen several systems to solve this puzzle, as there are very different characteristics to the space environment. Most notably there is no noticeable gravity, thus most powder-based 3D printing processes are not applicable. Curiously, extrusion-based approaches do work in microgravity, as the extrusion bead naturally adheres to the build plate, regardless of orientation — or gravity. Welding-style metal 3D printing processes also work in microgravity.

Fabrisonic’s SonicLayer 1200 ultrasonic 3D printer [Source: Fabbaloo]

Fabrisonic’s SonicLayer 1200 ultrasonic 3D printer [Source: Fabbaloo]

But both of these processes have two issues that could compromise their ability to be used in the confined quarters of a space station. First, there is significant heat involved in the printing process. Heat is not a welcome phenomenon on a ship, as accidents could result in a catastrophic fire.

Secondly, the heat could generate air pollutants, be they chemical or microscopic particles. Again, this is certainly not welcome on a space station where everyone shares the air.

Of course, it would certainly be possible to engineer methods of bypassing these issues, but that makes them more complex and, of course, heavier — also an unwelcome characteristic for an environment where every gram is expensive.

Fabrisonic’s proposition is that their process neither emits pollutants, nor involves heat. Ultrasonic 3D printing is a cold process.

Inside Fabrisonic’s ultrasonic 3D printer, the SonicLayer 1200 [Source: Fabbaloo]

Inside Fabrisonic’s ultrasonic 3D printer, the SonicLayer 1200 [Source: Fabbaloo]

So far they have redesigned their device to be at a somewhat smaller scale, demonstrating that the technology can be made to fit within the necessary smaller volumes for space use. This is Phase 2, and Fabrisonic calls it the SonicLayer 1200.

There is a possible Phase 3. Evidently NASA is to make decisions about what to do in the next phase later this year. It is possible they may choose Fabrisonic as one of their partners to continue development of a safer space 3D printer.

If that happens, Fabrisonic would engage in design of a space-rated device, one that would need to meet a myriad of NASA requirements for effective and safe use on the Space Station. If this is successful, at some point in the future the new 3D printer design might actually be launched to the International Space Station for testing by astronauts.

Via Fabrisonic

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Characterization of novel splice variants of zinc finger antiviral protein (ZAP) [Cellular Response to Infection]

Given the unprecedented scale of the recent Ebola and Zika viral epidemics, it is crucial to understand the biology of host factors with broad antiviral action in order to develop novel therapeutic approaches. Here, we look into one such factor; zinc-finger antiviral protein (ZAP) inhibits a variety of RNA and DNA viruses. Alternative splicing results in two isoforms that differ at their C-termini; ZAPL (long), encodes a poly(ADP-ribose) polymerase (PARP)-like domain that is missing in ZAPS (short). Previously it has been shown that ZAPL is more antiviral than ZAPS while the latter is more induced by interferon (IFN). In this study, we discovered and confirmed the expression of two additional splice variants of human ZAP — ZAPXL (extra-long) and ZAPM (medium). We also found two haplotypes of human ZAP. Since ZAPL and ZAPS have differential activities, we hypothesize that all four ZAP isoforms have evolved to mediate distinct antiviral and/or cellular functions. By taking a gene knockout and reconstitution approach, we have characterized the antiviral, translational inhibition, and IFN activation activities of individual ZAP isoforms. Our work demonstrates that ZAPL and ZAPXL are more active against alphaviruses and hepatitis B virus (HBV) than ZAPS and ZAPM and elucidates the effects of splice variants on the action of a broad spectrum antiviral factor.

IMPORTANCE

ZAP is an IFN-induced host factor that can inhibit a wide range of viruses and there is great interest in fully characterizing its antiviral mechanism. This is the first study that defines the antiviral capacity of individual ZAP isoforms in the absence of endogenous ZAP expression and hence crosstalk with other isoforms. Our data demonstrate that ZAP is expressed as four different forms — ZAPS, ZAPM, ZAPL and ZAPXL. The longer ZAP isoforms better inhibit alphaviruses and HBV while all isofoms equally inhibit Ebola virus transcription and replication. In addition, there is no difference in the ability of ZAP isoforms to enhance the induction of type I IFN expression. Our results show that the full spectrum of ZAP activities can change depending on the virus target and the relative levels of basal expression and induction by IFN or infection.

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Effects of Acute High-Intensity Exercise With the Elevation Training Mask or Hypoxicator on Pulmonary Function, Metabolism, and Hormones

Ott, T, Joyce, MC, and Hillman, AR. Effects of acute high-intensity exercise with the elevation training mask or hypoxicator on pulmonary function, metabolism, and hormones. J Strength Cond Res XX(X): 000–000, 2019—The elevation training mask (ETM) 2.0 is an increasingly popular hands-free respiratory muscle training modality proposing to mimic altitude; however, the degree to which this occurs has been questioned. The purpose of this study was to investigate the efficacy of this modality in comparison with using a hypoxicator (HYP) during acute aerobic exercise. Eight regularly active subjects (age: 25 ± 8 years; height: 166 ± 12 cm; body mass 64 ± 10 kg; and V[Combining Dot Above]O2max: 46 ± 6 ml·kg−1·min−1) completed 3 trials, each including resting metabolic rate measurement, pulmonary function tests, and 13 sprint intervals at 90% V[Combining Dot Above]O2max using either the HYP, ETM, or control. There was no significant difference in metabolism or heart rate between conditions. Fraction of expired air in the first second was greater after exercise (p = 0.02), while oxygen saturation was lower during exercise with the HYP (p < 0.001). Human growth hormone increased with exercise, but no differences were found between conditions; however, a trend was observed for higher growth hormone after exercise in HYP vs. ETM (p = 0.08). Elevation training mask does not seem to change acute pulmonary function, metabolism, heart rate, or oxygen saturation, indicating it likely does not create a hypoxic environment or mimic altitude.
Address correspondence to Dr. Angela R. Hillman, hillman@ohio.edu.
Copyright © 2019 by the National Strength & Conditioning Association.

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Characterization of the Physical Fitness of Police Officers: A Systematic Review

Marins, EF, David, GB, and Del Vecchio, FB. Characterization of the physical fitness of police officers: a systematic review. J Strength Cond Res XX(X): 000–000, 2019—Physical fitness tests (e.g., aerobic power, muscular endurance, and flexibility tests) are commonly used to assess the ability of police officers to perform work-related tasks. The purpose of this study was to describe, from a systematic literature review, data related to police physical fitness. The research was conducted in 5 electronic databases to search for original studies that measured physical fitness (aerobic and anaerobic capacity, strength, endurance, power, flexibility, agility, and speed) of police officers, as well as the article references. Original studies assessing objective measures of physical fitness in police officers were included, with no date restriction. Fifty-nine articles were included in the review. The studies mostly measured cardiorespiratory fitness indirectly, strength, and muscular endurance, as well as other performance components (body composition, power, flexibility, speed, agility, and anaerobic profile), with police officers generally presenting values similar or above the average of the general population. It can be concluded that intervention studies are needed to promote and incorporate programs related to improvement or maintenance of physical fitness in police officers, which would result in health benefits and specifically improvement in performance of specific tasks of police work. This review provides summary information to assist in the selection of physical fitness tests for police populations. Still, these findings have practical applications for public security agencies and its personnel responsible for the development and implementation of physical programs in policemen population.
Address correspondence to Eduardo F. Marins, dudufrio@gmail.com.
Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal’s Web site (http://journals.lww.com/nsca-jscr).
Copyright © 2019 by the National Strength & Conditioning Association.

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What 3D Printer Does Supermaker Colin Furze Use?

Supermaker Colin Furze uses 3D printing [Source: YouTube]

UK-based supermaker Colin Furze uses 3D printing.

The YouTube star has been making astonishing projects for several years, placing videos of the making-of and using-of incredible objects online for viewers worldwide. His projects are ingenious, sometimes dangerous and always completely outrageous.

How outrageous do we mean? Take a look at him riding an actual, fully operational hoverbike he built from basic components:

Supermaker Colin Furze riding a home-built hoverbike [Source: YouTube]

Supermaker Colin Furze riding a home-built hoverbike [Source: YouTube]

Be sure to watch to the end, where you’ll see he’s equipped the hoverbike with rocket-powered weaponry. Yes, he really did. And launched at night.

Furze has produced other insane projects, including:

And many, many more ridiculous items.

He produces all of these contraptions in his modest workshop in Stamford, UK. He uses a variety of tools to build them, mostly conventional tooling you’d find in any basic workshop.

But does he use 3D printing? It turns out, yes, he does.

Take a look at this shot of a part for his Machine Gun Briefcase (yes, that’s a thing and it actually worked):

3D printed part from one of Colin Furze’s projects [Source: YouTube]

3D printed part from one of Colin Furze’s projects [Source: YouTube]

It turns out that Furze, like many popular social media stars, is supplied with equipment by generous manufacturers hoping to see their machines portrayed by the star. Furze is no exception here, having been supplied with various CNC equipment and supplies. But also he’s obtained a 3D printer.

3D printed part from one of Colin Furze’s projects [Source: YouTube]

3D printed part from one of Colin Furze’s projects [Source: YouTube]

Last year Furze announced:

“Colin furze has entered the 21st century!

I have used the 3D printer given to me by LulzBot on many inventions, what a fab piece of technology. Big thanks LulzBot.

It’s odd doing something else knowing that a part is being made.”

A TAZ 6 desktop 3D printer [Source: Colin Furze]

A TAZ 6 desktop 3D printer [Source: Colin Furze]

Furze uses the popular LulzBot TAZ 6, which might be due for an upgrade given the company’s recent updates. He’s been using the equipment for over a year, and evidently has quite a supply of filament:

Part of Colin Furze’s supply of 3D printer filament [Source: YouTube]

Part of Colin Furze’s supply of 3D printer filament [Source: YouTube]

While he doesn’t specifically mention the 3D printing equipment in his videos, you do see evidence of it from time to time, just as he shows other making gear in his workshop. To Furze, 3D printing is not magic; it’s just another tool in the workshop.

And that’s how it should be.

Via YouTube and Colin Furze

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Rescue of infectious recombinant Hazara nairovirus from cDNA reveals the nucleocapsid protein DQVD caspase cleavage motif performs an essential role other than cleavage. [Cellular Response to Infection]

The Nairoviridae family of the Bunyavirales order comprises tick-borne tri-segmented negative strand RNA viruses, with several members associated with serious or fatal disease in humans and animals. A notable member is Crimean-Congo hemorrhagic fever virus (CCHFV), which is the most widely-distributed tick-borne pathogen, and associated with devastating human disease with case/fatality rates averaging 30%. Hazara virus (HAZV) is closely-related to CCHFV, sharing the same serogroup and many structural, biochemical and cellular properties. To improve understanding of HAZV and nairovirus multiplication cycles, we developed for the first time a rescue system permitting efficient recovery of infectious HAZV from cDNA. This system now allows reverse genetics analysis of nairoviruses without the need for high biosafety containment, as is required for CCHFV. We used this system to test the importance of a DQVD caspase cleavage site exposed on the apex of the HAZV nucleocapsid protein arm domain that is cleaved during HAZV infection, and for which the equivalent DEVD sequence was recently shown to be important for CCHFV growth in tick but not mammalian cells. Infectious HAZV bearing an un-cleavable DQVE sequence was rescued and exhibited equivalent growth parameters to wild-type in both mammalian and tick cells, showing this site was dispensable for virus multiplication. In contrast, substitution of the DQVD motif with the similarly un-cleavable AQVA sequence could not be rescued despite repeated efforts. Together, this work highlights the importance of this caspase cleavage site in the HAZV lifecycle, but reveals the DQVD sequence performs a critical role aside from caspase cleavage.

IMPORTANCE

Hazara virus is classified within the Nairoviridae family along with Crimean-Congo hemorrhagic fever virus (CCHFV), which is one of the most lethal human pathogens in existence, requiring the highest biosafety level (BSL) containment (BSL-4). In contrast, HAZV is not associated with human disease and thus can be studied using less-restrictive BSL-2 protocols. Here, we report a system able to rescue Hazara virus (HAZV) from cDNAs, thus permitting reverse genetic interrogation of the HAZV replication cycle. We used this system to examine the role of a caspase cleavage site, DQVD, within the HAZV nucleocapsid protein that is also conserved in CCHFV. By engineering mutant viruses, we showed caspase cleavage at this site was not required for productive infection, and furthermore that this sequence performs a critical role in the virus lifecycle aside from caspase cleavage. This system will accelerate nairovirus research due to its efficiency and utility under amenable BSL-2 protocols.

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Reliability and Validity of the 6-Minute Step Test for Clinical Assessment of Cardiorespiratory Fitness in People at Risk of Cardiovascular Disease

Giacomantonio, N, Morrison, P, Rasmussen, R, and MacKay-Lyons, MJ. Reliability and validity of the 6-minute step test for clinical assessment of cardiorespiratory fitness in people at risk of cardiovascular disease. J Strength Cond Res XX(X): 000–000, 2018—The purpose of this study was to determine the test-retest reliability and validity of the 6-minute step test (6MST) as a potential assessment of cardiorespiratory fitness (CRF) of people at risk of cardiovascular disease (CVD). A prospective, cross-sectional, correlational study design was used. A single cohort of 30 adults with 2 or more risk factors for CVD was recruited. Exercise tests were scheduled on 2 days, separated by 1 week. Validity was determined by comparing 6MST results with those obtained in a symptom-limited treadmill test and the 6-minute walk test (6MWT). Main outcome variables were peak heart rate (HRpeak) and peak oxygen consumption (V[Combining Dot Above]O2peak) measured during the 6MST, treadmill test, and 6MWT. Test-retest reliability of HRpeak and V[Combining Dot Above]O2peak during the 6MST was very strong (intraclass correlation coefficient [ICC], 0.92; 95% confidence interval [CI], 0.83–0.97 and ICC, 0.93; 95% CI, 0.84–0.97, respectively). Correlations were also very strong between 6MST and treadmill test HRpeak (r = 0.81) and between 6MST and treadmill test V[Combining Dot Above]O2peak (r = 0.88). Correlations were moderate between 6MST HRpeak and 6MWT steady-state HR (r = 0.57) and strong between 6MST V[Combining Dot Above]O2peak and 6MWT steady-state V[Combining Dot Above]O2 (r = 0.70). The 6MST seems to be a reliable, valid option for assessing CRF of people at risk of CVD in a broad range of clinical settings. Providing practical, accessible tests will help facilitate the goal of establishing CRF as a clinical vital sign. The next step in the development of the 6MST should be to identify the most appropriate 6MST predictor variables to estimate V[Combining Dot Above]O2max.
Address correspondence to, m.mackay-lyons@dal.ca.
Copyright © 2019 by the National Strength & Conditioning Association.

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