Hey, I'm Christiaan.

I train four times a week. Strength training and airbike. And I trained with personal trainers for years, with pleasure and with results.

What I never found was an app that followed my program exactly.

What I looked for and did not find

I tried them. Trainerize, PT Distinction, and about ten others. There are good apps among them. I used them with a personal trainer, and on my own.

But none of them did what I was looking for: follow my program exactly, move with how a week actually goes, and do that without clicking through twelve screens.

When I put it to trainers, I heard the same thing back. There is a lot. There is little that does exactly what you want and works easily.

What I did next

I started asking instead of building.

• Interviewed 78 personal trainers about how they program and what they are missing
• Ran a survey in the Netherlands, the United Kingdom and Germany
• Went through the training science and spoke with researchers about periodization, volume landmarks and autoregulation

CoNudge came out of that. Not out of an idea, out of 78 conversations.

Why for trainers, not instead of

Supervision works. A meta-analysis across twelve studies, with 301 supervised and 276 unsupervised participants, finds a measurable effect of direct supervision on strength gains. Small, but consistent, and it sits exactly where the trainer sits: in execution and in load.

We are not building around that. We are building for it.

You set your method. CoNudge remembers every session and prepares the next block. You approve. After every block: automatic evaluation. You adjust.

Where it comes from

CoNudge is built by P2P Concepts, my company in Haarlem.

The name: Co plus Nudge. Together, a gentle push in the right direction.

Where it stands now

In August 2026 I am testing CoNudge with ten Dutch trainers and small studios. Three months free. I want to know where it breaks.

Whatever comes out of that, I publish. Also if it disappoints.