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Limitations of sleep tracking using a wearable

Comparison with a chest strap HR-monitor

July 16, 2019
Limitations of heart rate analyses during sleep, why you should reconsider tracking your sleep.

Sleep monitoring is a popular feature of many smartwatches and wearables. Devices like Fitbit, Withings, Apple Watch and Biostrap analyse biometrics during your sleep. These wearables are worn on the wrist and use optical sensors to capture your heart rate. I wondered how the optical sensors would compare to a high resolution chest strap HR-monitor.

Optical vs chest strap heart rate monitors

Measuring beats per minute using different sensors

July 15, 2019
Understanding the differences in common HR monitors used in wearables, smartwatches and fitness trackers

With modern wearables, smartwatches and fitness bands, it has become easy and common to measure your heart rate. There are however fundamental differences in sensor types. Some sensors capture the electrical signal from your heart while others use light to analyse the blood flowing through your vessels. If you're interested in measuring heart rate, it's good to understand these differences.

The best bike computer app: Cyclemeter

Get advanced ride data with a flexible setup

Apr. 30, 2019
Collect advanced bike ride data using your smartphone connected to external Bluetooth sensors and a steer mounted display.

This month I have intensified my training to become fit for this year's Fietselfstedentocht, a 235KM bicycle ride through Friesland. Over the years I have tested different kinds of bike computer setups: from dedicated (and expensive) Garmin Edge bike computers to no data at all. Eventually I came up with a flexible setup to gather advanced ride data using my smartphone, let me explain how this works.

Is the Apple Watch the modern tool watch?

Testing the Apple Watch's usefulness in real life

Nov. 2, 2018
I tested the Apple Watch during my work in Frankfurt this week where I had to go inside an internet data centre.

This week I went to Frankfurt for business. I had to perform maintenance to servers in a data centre. This seemed like a great opportunity to test the Apple Watch's usefulness in real life (other than health and fitness). I wondered, is the Apple Watch the modern tool watch?

Swimming and cycling with Apple Watch

Different activities in the workout app in watchOS

Sep. 27, 2018
This month I tested the newest watchOS while swimming and cycling.

This month Apple launched a new Apple Watch series and released an update to watchOS. The focus of the smartwatch is more and more gearing towards health and fitness. This made me curious, how well does Apple Watch work for different activities?

Listen to your body

Why I stopped using health and fitness sensors

May 17, 2018
Using health data gathered by sensors and wearables I learned to listen to my body. Now I have stopped using bluetooth sensors all together.

A good customer of mine was once a physiotherapist, he told me about people asking him to "feel their muscles" to tell them how they where doing. "Crazy!" he told me: "I can never feel better than the people themselves, if they only would listen to their body". This caused me to question the health and fitness sensors I use.

Something the smartwatch will never have: patina

Wear and tear by the hands of time

Jan. 21, 2018
Patina is often neglected when comparing smartwatches with regular watches.

A good friend of mine had an issue with his Apple Watch, the digital crown lost a rubber ring causing the watch to lose its water resistance. Apple made no problem of it and offered to replace his "device". While it solved his problem, it felt painful to my watch lover's ears. It made me realise the one thing a smartwatch will never have: patina.

Collecting health data with Biostrap

Wearing a clinical-grade photoplethysmography (PPG) sensor for a month

Nov. 15, 2017
Wearing a clinical-grade PPG sensor for a month to collect advanced biometrics from my wrist.

Most wearables (smartwatches, fitness trackers, etc.) use very basic sensors to capture heart rate. Their signal is binary: just counting beats. Biostrap is different, instead of just checking pulses, it captures a high-fidelity PPG waveform. These waveforms are the same kind that doctors use, making me wonder what I could learn from them!

Smartwatches vs Mechanical watches

Why I still wear mechanical and why smartwatches have potential

Apr. 30, 2017
Why I still wear a mechanical watch and why smartwatches have potential.

Technology has come a long way since the first computer. Smartwatches today are very much an achievement of miniaturisation of technology. I recently used an Apple Watch Series 2 to find out if technology has come far enough to replace my mechanical watch, today I share you my findings.

Programming on Apple Watch

Serious about crazy experiments

Feb. 16, 2017
Programming with VIM over SSH on Apple Watch using a bluetooth keyboard

Over the past years I have been no stranger to crazy experiments, but this time I really wanted to push it into the extreme: programming on an Apple Watch. Would it be possible to actually write code on such a tiny device? Why even bother? This post is about the case for crazy experiments, and why you should try too!

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Apple Watch has an optical heart rate sensor, cleary visible in the middle of the underside
Apple Watch has an optical heart rate sensor, cleary visible in the middle of the underside
Time can only tell how future generations will look back to the Apple Watch
Time can only tell how future generations will look back to the Apple Watch
Unboxing Biostrap: it comes well packed in a nice box.
Unboxing Biostrap: it comes well packed in a nice box.
The combined speed and cadence sensor mounted on my bike
The combined speed and cadence sensor mounted on my bike
Happy engineer with Apple Watch inside the data centre!
Happy engineer with Apple Watch inside the data centre!
The Pebble Smartwach is no longer supported by software an will not develop patina
The Pebble Smartwach is no longer supported by software an will not develop patina
a Zerdax (from the 1960's, worth about €100), a Citizen (1970's ~ €80) and a Seiko (2008, €130)
a Zerdax (from the 1960's, worth about €100), a Citizen (1970's ~ €80) and a Seiko (2008, €130)
Omata One (omata.com) minimal analogue bike computer
Omata One (omata.com) minimal analogue bike computer
Heart rate monitor in hospital uses electrode pads to capture the heart's electric activity
Heart rate monitor in hospital uses electrode pads to capture the heart's electric activity
The world on your wrist - using Apple Maps in downtown Frankfurt
The world on your wrist - using Apple Maps in downtown Frankfurt
The plated gold is worn through, but the watch still shines in sunlight
The plated gold is worn through, but the watch still shines in sunlight
The Apple Watch Series 2
The Apple Watch Series 2
Comparing the quality of sleep during two different nights. Being awake more often reduces quality of sleep.
Comparing the quality of sleep during two different nights. Being awake more often reduces quality of sleep.
Feeling adventurous mounting a €1659 iPhone on my steer with a rubber strap
Feeling adventurous mounting a €1659 iPhone on my steer with a rubber strap
Data Centre in Frankfurt
Data Centre in Frankfurt
Apple Watch summary screen after swimming
Apple Watch summary screen after swimming
Feeling mobile: this blog post was created using an iPhone, a keyboard and some coffee! No PC!
Feeling mobile: this blog post was created using an iPhone, a keyboard and some coffee! No PC!
My mechanical watch in action
My mechanical watch in action

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