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Janis Fiedler

@fiejanis.bsky.social
1.1K followers 490 following 117 posts

PostDoc @KIT | wearable technology and mHealth Behavior Change | Exercise Physiology | enthusiastic R amateur | Views are my own orcid.org/0000-0002-9291-2191

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Reposted by Janis Fiedler
Wearable Landscape @wearable-landscape.bsky.social · 26/02/2026
#LivingReview Update ✨ We’ve submitted our Living Review on #wearables #validation studies (2022–2024) to a special issue of the @jmpbjournal.bsky.social! Huge thanks to all co-authors — and special thanks to @fiejanis.bsky.social for the lead👏 🔄 Kick-off for the 2025 update already happened today
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Janis Fiedler @fiejanis.bsky.social · 16/12/2025
Träumchen :D Bei uns ist ein Lichtschalter so verkabelt, dass der Staubsauger angeht wenn man ihn drückt (da der Schalter die Steckdose darunter und nicht das Licht regelt).
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JMIR Publications @jmirpub.bsky.social · 15/12/2025
New in JMIR mhealth: A Refined #Mobile #Health Intervention (SMARTFAMILY2.0) to Promote #PhysicalActivity and Healthy Eating in a Family Setting: Randomized Controlled Trial
dlvr.it
A Refined #Mobile #Health Intervention (SMARTFAMILY2.0) to Promote #PhysicalActivity and Healthy Eating in a Family Setting: Randomized Controlled Trial
Background: Many #Mobile #Health (#mHealth) apps focus on promoting #PhysicalActivity (PA) and healthy eating (HE). However, there is limited empirical evidence regarding their effectiveness in initiating and sustaining behavior change, particularly among children and adolescents. Considering that behavior is influenced by social contexts, it is essential to take core settings like family dynamics into account when designing #mHealth apps. Objective: The purpose of this study was to further develop and refine the SMARTFAMILY (SF) #App targeting PA and HE in a collective family-based setting by enhancing design and usability, as well as by adding gamification aspects, #Health literacy, and just-in-time adaptive interventions to the first version of the #App. Methods: The SF2.0 #App, based on behavior change theories and techniques, was developed, implemented, and evaluated. The #App was used in a collective family setting, with family members using it individually and cooperatively. In a cluster-randomized controlled trial, the intervention group (IG) used the #App for 3 consecutive weeks, while the control group (CG) received no treatment. Primary outcomes included PA measured through self-reports and accelerometry, as well as self-reported fruit and vegetable intake (FVI) for HE. Secondary outcomes included intrinsic motivation, behavior-specific self-efficacy, and the Family #Health Climate. A follow-up assessment (T2) was conducted 4 weeks after the postmeasurement (T1) to assess intervention effects. Multilevel analyses were performed in R (R Foundation for Statistical Computing), considering the hierarchical structure of individuals (level 1) within families (level 2). Results: Overall, 55 families (28 CG, 105/209; 27 IG, 104/209 participants) were recruited for the study. In total, 3 families (3 CG, n=12) chose to drop out of the study due to personal reasons before T0. Overall, no evidence for meaningful and statistically significant increases in PA was observed in favor of the IG of our physically active sample. However, the #App elucidated positive effects in favor of the IG for FVI diary (T0-T1; P=.03), joint PA (T0-T1; P=.02 and T0-T2; P
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Janis Fiedler @fiejanis.bsky.social · 16/12/2025
🧪 Publication alert! Results of the SMARTFAMILY2.0 #mHealth study show: - no effect on physical activity in already active families - increase fruit & veggie intake, joint family activities, and shared meals. OA: doi.org/10.2196/65558 #DigitalHealth #FamilyHealth #BehaviorChange #RCT
This picture shows a family of four around a smartphone with a screenshot of the SMARTFAMILY App.
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Wearable Landscape @wearable-landscape.bsky.social · 01/12/2025
#Conference Time Last week our members Marco Giugiu, @fiejanis.bsky.social and @irinatimm.bsky.social presented our Wearable Landscape initiative at the International Symposium on Physical Behaviors 🏋️, Wearable Sensing ⌚️, and Health Analytics 🩺. Thanks to @tu-dortmund.de for hosting this event.
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Nicola Rennie @nrennie.bsky.social · 26/11/2025
One of the things that has been on my to do list for a very long time, is building a gallery of all of the charts I've made across #TidyTuesday, #30DayChartChallenge, #30DayMapChallenge, and other miscellaneous projects 📊 And it's finally here! Link: nrennie.rbind.io/viz-gallery/ #DataViz #RStats
nrennie.rbind.io
Data Visualisation Gallery
Gallery of data visualisations created by Nicola Rennie.
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Janis Fiedler @fiejanis.bsky.social · 27/11/2025
sounds like the review the autism paper would have deserved... bsky.app/profile/jack...
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Cameron Patrick @cameronpat.bsky.social · 25/11/2025
this is one of my favourite observations about sample size calculations. (afaik first articulated by Miettinen in 1985)
"On the first, and pivotal, level the decision is a binary one—the
choice between zero and nonzero as the size. Validity considerations alone are often sufficient to imply that zero is the optimal size"

- O. S. Miettinen "Theoretical Epidemiology" (1985)
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Mario Sixtus @sixtus.net · 24/11/2025
"Schaut man rein auf die Korrektheit der Antworten, beinhaltet ChatGPT zu 51,5 Prozent, Copilot zu 45,4 Prozent, Gemini zu 50 Prozent und Perplexity zu 45,7 Prozent wesentliche Fehler oder Ungenauigkeiten." www.tagesschau.de/wirtschaft/d...
tagesschau.de
Warum Künstliche Intelligenz nicht als Suchmaschine taugt
Die Hälfte der Deutschen verwendet mittlerweile ChatGPT & Co. als Google-Ersatz. Gleichzeitig arbeiten auch die klassischen Suchmaschinen immer mehr mit KI. Warum das ein Problem ist. Von Till Bücker.
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Wearable Landscape @wearable-landscape.bsky.social · 20/10/2025
#MemberMonday Insights from last week’s Wearable Landscape meeting: a big thanks to our core members and supporting students for weekly developing the initiative — and (of course) having some fun along the way :) Let’s keep building our living network! 🌍💡 #Wearables #OpenScience #Collaboration
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Janis Fiedler @fiejanis.bsky.social · 07/10/2025
man könnte auch ein bisschen umschreiben und statt geht vieles, gehen viele schreiben...
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Stephan Winter @stephanwinter.bsky.social · 25/09/2025
Exciting new job in Landau 🤩 We’re searching for a Professor of Political Psychology (W2). Very much looking forward to your applications – if you have any questions, please reach out to me. jobs.rptu.de/jobposting/3...
jobs.rptu.de
W 2-Professur für Politische Psychologie (m/w/d)
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Janis Fiedler @fiejanis.bsky.social · 26/09/2025
Can someone help me to find the full text of this? doi.org/10.1080/1074... I checked all my available ressources plus messaged the authors and need it for a systematic review. @academic-chatter.bsky.social @healthpsychology.bsky.social #behSci #SportScience #AcademicSky 🧪
doi.org
Measurement properties of activity monitoring for a rehabilitation (AMoR) platform in post-stroke individuals in a simulated home environment
The aim of this study was to evaluate the measurement properties of activity monitoring for a rehabilitation (AMoR) platform for step counting, time spent in sedentary behavior, and postural change...
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Dr. Irina Timm @irinatimm.bsky.social · 02/08/2025
🎓I'm thrilled to share that I've successfully defended my doctoral dissertation on July 25, 25. I want to extend my heartfelt gratitude to my esteemed supervisors, Dr. Marco Giurgiu & Prof. Markus Reichert & Prof. Uli Ebner-Priemer, for their invaluable guidance and support 🙏 @mhealthlab.bsky.social
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Dr. Laura M. König @lauramkoenig.bsky.social · 03/07/2025
#OpenScience principles help students gain lots of useful skills that are an advantage on the job market in and beyond academia. Read our latest book chapter where we provide tips for educators to bolster employability through open science: doi.org/10.31219/osf...
Open science contributes to more rigorous and impactful science. However, little attention is often paid to the benefits that it provides to its users, such as project management and programming skills. Although not its primary objective, these skills may be considered additional benefits supporting the transition to open science practices. Drawing from international perspectives, this chapter will discuss skills that students develop explicitly or implicitly by engaging in open science and their benefits to careers within and outside of academia. It will also showcase examples of how engagement in open science is considered in (academic) hiring decisions, including ongoing debates and areas for (structural) improvement. Ultimately, this chapter will inform educators about the most important open science skills and provide insights into how to strategically build a resume to present open science-related skills convincingly to improve employability, including practical tips and resources.
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Janis Fiedler @fiejanis.bsky.social · 23/06/2025
Authors: M. Thron, S. Altmann, S. Härtel, F. Barsch, L. Schlenker, S. Krug, K. Bös, A. Woll Data were pooled from the representative KiGGS wave 2 and DEGS1 study from the Robert Koch Institute. 🔬 Access the data: osf.io/u8h9b/
osf.io
Reference standards for power at fixed and individual anaerobic lactate thresholds for cycle ergometry throughout the Lifespan (14-64 years) in Germany: Pooled results of the KiGGS wave 2 and DEGS1 St...
Hosted on the Open Science Framework
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Janis Fiedler @fiejanis.bsky.social · 23/06/2025
📊 New Publication! We analyzed 5000+ cycle ergometer tests (ages 14-64) to create reference standards of lactate thresholds for health studies and clinical practice. Full text: doi.org/10.1080/0264... #Exercise #SportsScience 🧪
Displayed are the centile curves at different percentiles for relative and absolute power at the individual lactate threshold.
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Janis Fiedler @fiejanis.bsky.social · 04/06/2025
I feel you. And getting up is just the follow-up. It never ceases to amaze me how fast the little ones progress. If I'd learn in a year what they learn in a day I'd be happy :D
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Wearable Landscape @wearable-landscape.bsky.social · 02/06/2025
#MemberMonday Recap The past seven weeks introduced each member of our Management Group. A huge thank you to Marco Giurgiu, @fiejanis.bsky.social, @irinatimm.bsky.social, Simon Woll, Til Becker, Doreen Wohlfahrt and @clendt.bsky.social for your contribution to Wearable Landscape! #academicsky 🧪
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Claas Lendt @clendt.bsky.social · 26/05/2025
Happy to be on board! Go check out @wearable-landscape.bsky.social if you haven’t already!
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Janis Fiedler @fiejanis.bsky.social · 26/05/2025
Manchmal ist es wirklich schwierig die Lehre zu füllen.
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Wearable Landscape @wearable-landscape.bsky.social · 19/05/2025
#MemberMonday Doreen Wohlfarth is a research assistant at @kit.edu . She is involved in various projects at the Sports Institute, with her current focus on the Wearable Landscape project. Here she supports our Living Review and other important publications. #SportScience #BehSci #AcademicSky 🧪
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Janis Fiedler @fiejanis.bsky.social · 16/05/2025
crtl a, delete, yes here is the workflow I used. Hope it helps :)
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Janis Fiedler @fiejanis.bsky.social · 16/05/2025
I need help. My day only has 1 meeting, and all emails are done. How does this research thing work again? 🧪 #AcademicSky
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Julia M. Rohrer @dingdingpeng.the100.ci · 11/05/2025
Thanks to everybody who chimed in! I arrived at the conclusion that (1) there's a lot of interesting stuff about interactions and (2) the figure I was looking for does not exist. So, I made it myself! Here's a simple illustration of how to control for confounding in interactions:>
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Wearable Landscape @wearable-landscape.bsky.social · 12/05/2025
#MemberMonday Til Becker is a student assistant researcher at the Karlsruhe Institute of Technology ( @kit.edu ) during his master's degree. He sees the Wearable Landscape as great opportunity to improve his own competences and the field of wearables. #SportScience #BehSci #AcademicSky 🧪
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Wearable Landscape @wearable-landscape.bsky.social · 07/05/2025
🌱 This project is 100% non-commercial & driven by passion. We believe science should be accessible, connected & efficient. If you're working on, or interested in, wearable validation—follow along & join us!
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Wearable Landscape @wearable-landscape.bsky.social · 07/05/2025
💡 There is even more: We’re building a collaborative space for the scientific community to... ...share validation protocols ...coordinate studies ...pool equipment ...analyze data together Let’s reduce redundancy & work smarter. #ResearchNetwork #OpenScience
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Wearable Landscape @wearable-landscape.bsky.social · 07/05/2025
🔍 What is Wearable Landscape? An open-science project aiming to foster collaboration in the field of #Wearables. We want to bring experts together, to ultimately advance the validation and application in wearables that track 24-hour physical behavior (sleep, sedentary time, activity) #OpenScience
wearable-landscape.info
Wearable Landscape - Wearable Landscape
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Janis Fiedler @fiejanis.bsky.social · 30/04/2025
If you want to improve your performance sure.
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Janis Fiedler @fiejanis.bsky.social · 29/04/2025
Did they control for owning a Rolex?
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Janis Fiedler @fiejanis.bsky.social · 29/04/2025
My first last-authorship publication is now online! We combined 2 nationwide data sets and found physical exercise and non-smoking to be the most important correlates of aerobic fitness in 14-64. Led by the great Maximiliane Thron #AcademicSky #SportScience #BehSci 🧪 dx.doi.org/10.1002/ejsc...
dx.doi.org
Correlates of Aerobic Performance in Adolescents and Adults
Cardiorespiratory fitness (CRF) is considered as a main indicator of cardiovascular health and is associated with a reduced risk of noncommunicable diseases. The objective is to explore the potential...
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Janis Fiedler @fiejanis.bsky.social · 22/04/2025
Exactly this :D, but you need documentation somewhere so you don't get lost. A nice feature would be an email path diagram to get through this mess. I have a feeling we are revolutionalizing emails here...
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Janis Fiedler @fiejanis.bsky.social · 22/04/2025
I feel you! Maybe we should start sending emails that self-delete once they are irrelevant...
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Amrei Bahr @amreibahr.bsky.social · 22/04/2025
In der Promotion fand ich Schreiben oft quälend, hab mit jeder Formulierung gekämpft & gehadert. Das hat sich inzwischen zum Glück verändert — v.a. durch Schreibkollaborationen, die das Zutrauen in mein Schreiben gestärkt haben, & durch Routine. Was ich daraus gelernt hab: Heute in #ArbeitInDerWiss!
arbeitinderwissenschaft.substack.com
Weiter im Text: Vom Schreiben inner- und außerhalb der Wissenschaft
Der beste Text ist einer, der gut genug ist, um fertig zu sein.
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Janis Fiedler @fiejanis.bsky.social · 22/04/2025
The joy of post-holiday email dschungle. Do you start with the newest or the oldest ones? 🧪 #AcademicSky
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Wearable Landscape @wearable-landscape.bsky.social · 21/04/2025
New week, new #MemberMonday Dr. Janis Fiedler ( @fiejanis.bsky.social ) is a post-doctoral researcher @kit.edu . His main research interests include #mhealth interventions, and #ExercisePhysiology. He is dedicated to foster an open science culture for the validation of wearables.
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Janis Fiedler @fiejanis.bsky.social · 21/04/2025
Messaged a bit back and forth and resubmitted elsewhere. Did get an apology but that doesn't really help :D
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Janis Fiedler @fiejanis.bsky.social · 21/04/2025
Not normal no. I received one after 13 months though...
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Wearable Landscape @wearable-landscape.bsky.social · 14/04/2025
Welcome Marco to our first #MemberMonday introducing our team: Dr. Marco Giurgiu is a postdoc @kit.edu and focuses his research on the relationship between 24-h #PhysicalBehavior and #Health. He initated and leads our initiative with the vision of a global network to address challenges together.
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ISBNPA @isbnpa.bsky.social · 28/03/2025
Missed the #ISBNPA Systems Science SIG #Webinar "An introduction to systems approaches in public health – where are we up to and how are they being used?" Now’s your chance to catch up! 🎬 Watch the recording here: isbnpa.org/sig/march-24...
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Janis Fiedler @fiejanis.bsky.social · 27/03/2025
Nur volle Arbeit nicht 120%? Die Stelle geht weg wie warme Semmeln...
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Peter Tennant @pwgtennant.bsky.social · 26/03/2025
The problem with working on big high-risk projects is they don't always end in the glorious impactful work. If they're truly 'high risk', they often just end in failure. Or else requiring huge effort to save. I'm painfully learning this lesson after seeing a few of my 'flagship' projects crash. 🧵
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Janis Fiedler @fiejanis.bsky.social · 26/03/2025
Do you use wearables or plan to implement them in your research? Then check out the @wearemntn.bsky.social ! #digitalhealth 🧪 #Wearables #SportScience
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Wearable Landscape @wearable-landscape.bsky.social · 07/03/2025
🗺️Discover more details on our website and have a look at our #LivingReview.
wearable-landscape.info
Wearable Landscape - Wearable Landscape
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Dr. Christian Scharun @christianscharun.de · 23/03/2025
Wissenschaftliche Artikel hinter Paywalls und wir haben keinen Zugriff? Ein ziemlicher Skandal, denn schließlich haben wir für diese Forschung ja mit unseren Steuergeldern bezahlt! Bei MAITHINK X decken wir heute auf, wie milliardenschwere Verlage die Wissenschaft im Würgegriff haben! Schaut rein! 🧐
zdf.de
Steuerskandal: Wissenschaft hinter Paywalls
Wissenschaftliche Artikel hinter Paywalls und milliardenschwere Verlage profitieren. Bei MAITHINK X zeigt Mai Thi Nguyen-Kim, was man noch tun kann.
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Prof Andy Field @profandyfield.com · 21/03/2025
Author copy arrived yesterday. It really was a joy working with @ejwagenmakers.bsky.social and Johnny (is he on here?) on this @jaspstats.bsky.social version of the book.
A photo of the textbook 'Discovering statsitics using JASP' on a desk./ The cover has the name in large letters and a drawn image of a futuristic female statuistics professor wearing blue clothes with a circuit-board style print on.
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Janis Fiedler @fiejanis.bsky.social · 14/03/2025
But they sure take their time to not read it.
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Janis Fiedler @fiejanis.bsky.social · 14/03/2025
Recent experiences with peer review indicate that either I am really good at writing next to flawless papers OR mmh nah let's not go down that road... #academicsky
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Eiko Fried @eikofried.bsky.social · 12/03/2025
Are you doing EMA research and wonder how to go about it? In recent work we've adressed some open questions and challenges, here is a brief summary of papers and materials. 🧵 #PsychSciSky 🧪 #StatsSky
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