42,000 tickets for one New York event. 15,000 gym affiliates. $0 spent on influencers. HYROX CGO Douglas Gremmen joins Kyriakos, CEO of Terra API , at the Connected Health Summit in Stanford to talk through what actually drove that — and what didn't work.

The US was their first market outside Germany and their hardest. Three years of losses. A single Lance Armstrong weekend changed the momentum — not because they paid him, but because he just turned up. The gym affiliate program started as inbounds with no structure; it's now the foundation of a bet to reach 100 million people. The CrossFit comparison gets a real answer, not a PR one.

But the most interesting parts are the early decisions: rejecting the $2 race t-shirt, the photo package that created the organic flywheel, and a simple principle — invest in the event experience and don't run paid marketing.

00:00 Welcome to Stanford

01:46 Running HYROX at a Conference & the "Bubble" Moment

03:48 The Sweaty Barrier to Participation Problem

05:44 Douglas's Backstory: Sports Marketing & How HYROX Was Born

08:59 From First Event in Hamburg to Leading Global Expansion

10:29 Early Growth: The Van, T-Shirts, Red Bull & the Photo Flywheel

12:36 Global Expansion: Japan, Brazil, India & Getting on the Calendar

14:56 Why the US Was the Hardest Market to Crack

17:28 Losing Money in America — Keeping Belief When the P&L Doesn't Work

19:09 The Lance Armstrong New York Bet: $1M & 30M Impressions

20:27 Influencers at HYROX: Always Organic, Never Paid

21:52 Scaling to 42,000 Tickets: 9 Days of Racing Bigger Than NYC Marathon

23:45 Building Operations: Christian Tutske's Eye for Detail

25:39 Why Athletes Keep Coming Back: Community & Identity

28:00 HYROX 365: From Events Company to 15,000-Gym Affiliate Business

30:54 Accelerating Gym Growth: Big Box Operators & Chicken-and-Egg Dynamics

34:27 HYROX as a Gym Retention Play: Coach Education & Member Stickiness

36:49 Fragmented Gym Tech & the Data Opportunity

38:23 HYROX vs. CrossFit: Honest Comparison & 1,500 Shared Affiliates

43:10 The Pickleball Analogy: Low Barrier + Social + Price = Rocket Ship

46:49 The Path to 100 Million People: Events, Gyms & Knowing Who Trains

49:50 HYROX x Puma: Building a Fashion Brand & the First Dedicated Shoe

54:14 Contrarian Take on the Future of Fitness: Back to Fundamentals

56:35 Physical Events vs. Social Media: Why Credibility Is Harder to Fake

59:11 Post-COVID Perfect Storm & Tickets Selling Out as the New Challenge

01:01:09 Where Will HYROX Be in 5 Years? Formula One, Olympics 2032 & 100M People

In the latest episode, Kyriakos Eleftheriou sat down with Roman Bugaev , CTO of Flo and Vlad Nedosekin Director of AI Platform, at the Terra API HQ in London, to discuss how they built the top health AI platform globally for women's health.

CHAPTERS

(0:00) Intro — Flo Health: From 20 People to 80 Million Users

(1:02) How Flo became the fastest-growing health company in the world

(1:48) Roman's early days: 20 employees, no revenue, product-market fit

(3:15) How did you know the product was a hit?

(3:25) The underserved women's health market — everyone was building Uber alternatives

(4:31) First ML: neural networks for cycle and symptom prediction

(5:31) Product evolution — from symptom tracking to AI-powered insights

(5:38) Building chatbots inspired by how doctors ask questions

(9:18) A/B testing at scale — Flo's custom experimentation platform

(11:43) Engineering structure: autonomous two-pizza teams

(13:51) Team mistakes — why separate mobile and backend teams failed

(15:29) Scaling from 4 servers to 600 services and petabytes of data

(17:53) "Whenever it's possible, we are NOT doing AI"

(23:15) Why temperature data is critical for ovulation prediction

(25:09) Why Flo is the most accurate period tracker — data diversity advantage

(28:04) Competition: "We don't really have real competitors"

(29:00) AI content creation — generating personalized medical articles

(31:01) Hallucinations vs. conflicting medical sources

(32:34) The three-person blind test: when AI disagrees with humans

(35:10) AI is more consistent than clinicians — but biased against women

(36:52) Fine-tuning open-source models on synthetic women's health data

(38:25) User profile: the foundation of Flo's personalization

(41:19) The digital avatar — your AI health twin that notices what you don't

(43:09) AI router: like a GP triage system for language models

(46:04) Router also controls tone of voice and remembers past conversations

(47:29) "Evaluation, evaluation, evaluation" — how Flo picks models

(48:40) Model stability: why proprietary model updates are dangerous for medical AI

(51:01) Anonymous mode: privacy that enables AI instead of blocking it

(53:49) On-device ML for the most sensitive health data

(56:03) Cloudflare outage — "when everyone is down, you're allowed to be down"

(56:58) Fine-tuning Llama 7B on Databricks — 10,000+ GPU hours per run

(58:07) Training vs. inference cost breakdown

(59:45) 100,000-token prompts: the hidden cost of medical AI

(1:01:05) Build vs. buy: "Build your competitive advantage, buy everything else"

(1:04:47) Value creation vs. value capture teams

(1:07:04) The future: AI that knows you better than you know yourself

(1:09:00) Time series models: the future of health prediction from wearables

(1:10:38) Q&A

In this episode, Kyriakos Eleftheriou, Terra API CEO sits down with Sacha Michaud, co-founder of Glovo, one of the biggest tech successes in the European tech ecosystem,and Yellow.VC, an early-stage fund

Sacha shares the journey of building the on-demand delivery service from its inception in Barcelona to its expansion across 25 countries and a $2.3 billion acquisition.

He discusses the initial challenges of fundraising, competing against larger companies, and the importance of passion and culture in building a successful team. Michaud reflects on the early days of Glovo, where they experimented with a simple app that allowed users to order anything from the city, leading to unexpected viral growth despite initial losses. He emphasizes the significance of adapting to market needs and the evolution of Glovo's business model over the years, particularly during the COVID-19 pandemic, which accelerated the demand for grocery delivery.

Chapters

00:00 Introduction

02:29 The Birth of Glovo: From Idea to Launch

05:59 Viral Growth and Initial Operations

12:06 Realizing the Potential of Glovo

21:39 Expanding into New Markets

38:55 Navigating Competition and Strategic Decisions

50:39 The $2.3B Acquisition

55:00 Yellow, and investing in new startups

01:04:11 AI and Future Trends in Delivery

The first Iranian entrepreneur to build a company worth over $1B in Europe, Dan Vahdat, founder of Huma, is joining Kyriakos Eleftheriou, founder of Terra API

They discuss:

00:00 - Intro

02:10 - Communicating with @EmmanuelMacron and @kmitsotakis

08:55 - Why are Greece and Persia not empires today

13:40 - How the best people look like

18:30 - Short-term vs long-term thinking

24:27 - Dropping out of PhD

26:57 - The first months of Huma

32:00 - Early days

32:27 - 'I never had the ego of being turned down'

34:00 - First customers

37:21 - How to price expensive contracts

48:30 - Regulation as a moat

59:10 - Raising $300m from partners instead of VC

1:02:58 - AI

1:06:00 - Storytelling advice

1:09:55 - Running

1:14:32 - Cyrus, Darius, and Achaemenid inspirations

1:19:23 - The future

David Turner is the Group CTO of Virgin Active, a global health brand with more than 230 fitness clubs across 8 countries. He previously led NHS tech during Covid.

The host: Kyriakos

More about Virgin Active00:00 - Intro01:26 - UK Tech05:33 - F1 telemetry vs fitness data07:33 - Betting + health data09:30 - Getting into software engineering13:51 - Inside NHS tech: joining mid-Covid chaos14:00 - Leading the NHS Covid digital response, 24/720:56 - Building national-scale testing tech24:49 - The real data engine behind the Covid travel pass26:00 - Virgin Active after NHS30:40 - Inside Virgin clubs tech33:40 - 360° member view41:40 - Rewards45:19 - Why true gym innovation came from outsiders54:40 - Advice to young engineers: fail fast, fail often58:17 - The future of health: your constant digital twin

The founder of Nucleus, Kian Sadeghi, joined Kyriakos Eleftheriou, in the second health day in San Francisco, and shared his learnings in front of a 300-person audience before the Y Combinator AI event.

00:00 Intro

02:01 The Jake Paul vs. Mike Tyson fight sponsorship story.

05:01 "Fundraising is an art."

08:01 Competing with Mr. Beast and the importance of storytelling.

11:01 The evolution and impact of genetic testing.

14:01 Future of genetics and embryo selection.

17:01 AI in genetics.

20:01 Narrative in startup success.

23:01 Regulatory challenges

26:01 Personal journey and insights on building a company.

29:01 Genetic testing market

32:01 The role of computational biology in genetics.

35:01 The impact of whole genome sequencing on healthcare.

38:01 The future of genetic engineering and its societal implications.

41:01 The intersection of AI and genetics.

44:01 The importance of storytelling in the tech industry.

50:01 Future vision.

53:01 Q&A

After the Y Combinator AI event, Kyriakos Eleftheriou sat down with Mark Gainey co-founder of Strava, who shared his entrepreneurial journey, discussing the evolution of Strava from a startup to a $2.2 billion fitness platform.

Chapters

00:00 Intro

04:15 How technology changed

11:35 Should you be niche with AI

13:20 Building a Community

17:00 Dealing with big companies early on

20:53 User Feedback

23:00 Elimination process

25:10 Fundraising

28:43 AI

30:50 Adding more sports

36:18 The Future of Fitness

42:20 Storytelling

46:00 Q&A

How do you build a $3B company from Portugal?

In this episode, Marcelo Lebre (Co-founder of Remote), in a discussion with Kyriakos , shares how he went to building one of Europe’s top startups and why health, culture, and ruthless focus were key to scaling Remote globally.

We talk fitness, healthcare, European bureaucracy, and the mindset behind building a generational company.

Follow Marcelo → https://x.com/marcelo_lebre

Follow Kyriakos → https://x.com/kyriakosel

Chapters:

00:00 Intro

03:08 Training for Longevity

05:11 Nutrition and Wearables

08:14 What Doctors Miss

11:06 DIY Health and Data

14:10 Health Isn’t Just Avoiding Sickness

17:20 The Quote That Hit Hard

18:53 Building a Unicorn in Portugal

23:35 Why European Startups Die

27:12 Bureaucracy and Politics

32:03 What Governments Must Fix

35:50 Remote Still Feels Like a Startup

38:05 Europe’s Investment Problem

40:11 Remote Was Built Out of Frustration

44:03 Building a Global HR Platform

49:06 The Backbone of Global Hiring

52:04 No Ego No Politics

55:15 Not a Family A Team

57:52 How to Attract Top Talent

59:39 His 100-Year Vision