What you need to know about Wearable Technology

23 November 2019; Peter Tierney from the English FA in attendance during a GPA ‘Balance 2020’ Conference at Croke Park in Dublin. Photo by Matt Browne/Sportsfile *** NO REPRODUCTION FEE ***

  1. Be clear about your health and performance goal/s and then define how wearable technology might be able to help you.
  2. Make sure if you decide to utilise technology that it is accurate and reliable, and can actually tell you what you need it to. 
  3. Seek help or advice if you are unsure. Technology provides us with a lot of data, and it is important to highlight the signal (what’s important) from the noise! 

I’m a sports scientist and performance coach and I use technology as a tool in a variety of ways in my role and life. Technology can provide data that we can interpret to help answer questions to problems that we have, and help us better understand the stresses people and athletes are exposed to, and how they respond to these. My curious nature also has led me to buying and using various types of consumer wearables for my own personal use over the last number of years. However my curiosity also makes me question pretty much everything that I use.


This article will hopefully raise your awareness around wearable technology, what it can offer you with the context of your goals. As technology and software evolve extremely quickly – this article is predominantly focused on the application and use of more commonly used wearables (there are many, many wearables out there ), and how they can help change your behaviour and mindset when it comes to technology. It focuses less on the validity and reliability of specific measures or wearables, but there are some comparisons that may be useful to consider. Hopefully it makes you think about the data that you are using and collecting on yourself. 

Where the importance of overall health (mental & physical) has become even more apparent since the beginning of the pandemic, I have personally seen the adoption of wearable technology by friends, peers and athletes. I do feel as a practitioner we/ I have an obligation to try help people in this space, and try to provide some clarity. The last thing I would want is  or a wearable to create more stress than people are already under.  


A scientific review from Peake et al. (2018) identified that over 50% of the wearables they reviewed had not been independently validated (external testing for accuracy). Something to be mindful of when thinking about investing in some technology! 


The first thing I would say when thinking about purchasing any wearable or software is why? Do I really know why I am buying or using one? Am I just following a trend or a friend? Will a wearable device help me achieve my goals? 

A few potential reasons why you might think about investing in a wearable:

  • I want to try improve your health and would like something to help keep me accountable. 
  • I’m tired all the time and I think I if I improve my sleep it will help.
  • I’m interested in exploring some data around my health and wellbeing.
  • I want to get fitter. 
  • I train a lot but feel like I am not recovering properly and want to explore potential factors that might affect this. 

I would say the more specific the better. Of course we have overarching goals to be healthy and happy, but be SMART. For example: 

  • I want to run a half marathon in August year and want feedback from a wearable to help me achieve this in 2 hours. 
  • I would like something to keep me accountable to accumulating a certain activity level per day (e.g. 10,000 steps per day).


How can I achieve these goals? Do I need to alter my health behaviours? Do I definitely need the technology, or could I achieve these goals without it? Will the technology help (not control) my motivations and behaviours. Does the wearable fit the purpose you want it to? You would not buy a weighing scales to measure your height! Identify what you want your wearable to do before a wearable chooses you. Is the wearable accurate and reliable for what you want it for? 


Well it can provide you with objective data that if used correctly, can help you achieve your why! Insights into your activity levels, sleep and recovery can be hugely beneficial.   



Wearables and illness  

There is some really promising research coming out that some wearable technology could even help identify the onset of illness. A few examples include potential early identification of COVID-19 infection through respiratory rate changes using Whoop, identification of the onset of fever through increases in baseline temperature using Oura Ring, identification of COVID-19 through integration of self-reported symptoms and wearable data using DETECT and using a combination of changes in resting heart rate, heart rate variability, and respiration rate utilising data from Fitbit.

For clarity – I’m not saying these devices are perfect and will predict every possible illness there is, but the data is promising and more research is definitely needed. A definite positive is that if these wearables can detect changes outside of your normal health biomarkers, it may prompt you to get tested for an illness, not visit someone who is more vulnerable, or even prompt a lighter day of activity to prevent greater stress compounding.   

The midweek wine!

Data can be useful to remove your own bias from your health. An example that might resonate with some people. You might try justify a bottle of wine midweek, and convince yourself that it is not affecting your sleep. Even though you wake up tired and dehydrated, you will convince yourself that you slept well and feel fine, because you want keep drinking those glasses of wine mid-week. A wearable might provide a contrasting view, such as an increase in your resting heart rate or a poorer sleep on the nights that you drink alcohol. This is where your interpretation of data is important and how you interact with your data and your feel. It takes a strong-minded person to battle their own bias! 


Here is some data (of my own) that explores the affect that alcohol has on sleep:  

I’ve noticed an increase in resting heart rate with alcohol consumption, and this increase is much greater with a higher amount of alcohol (some more detail here). 

I see potential in this space with wearables that may offer a way to determine the volume and or type of alcohol that does not have a massive impact on sleep or overnight health markers, but still gives the enjoyment to relax with a glass of wine! 


This vs that – Walking!  

Here are some comparative data to highlight the differences that can exist in wearable consumer technology. I’ll try provide some examples below that demonstrate this. I certainly  don’t recommend that you compare your data to other people with different devices.

This comparison is from a walk where I wore a commonly available wrist-worn smart watch and a heart-rate chest strap. The wrist device is reporting burning twice the calories compared to what the chest strap is showing. (The dip in heart rate near the start of the walk is when I bumped into a friend and stopped to chat!) 






This vs that – Circuit at home!  

Here I’ve cropped the heart rate trace from a bodyweight circuit session at home, again for both chest strap and wrist-based device. You can see some pretty large differences even from the heart rate trace. The max heart rate from the chest strap reported 189bpm, whilst the wrist based device reported a max heart rate of 135bpm. Calories burned 384kcal from the chest strap, and 141kcal from the wrist based device!










This vs that – Resting Heart Rate response to alcohol! 

Here is a comparison of resting heart rate data from a finger-based device (blue) and a wrist based device (red) for 30 days.

Here the finger device is showing the average resting heart rate over night. The wrist based  device is calculates “the number of times your heart beats per minute when you’re still and well-rested”, and “measuring your heart rate when it detects sleep, and by measuring it throughout the day while you are awake but inactive (no steps detected)”. In my opinion this is slightly flawed, as it includes data from during the day when there can be many more contributors to your heart rate. 



My interpretation of this is that the finger device is certainly more sensitive at detecting true changes in my RHR as it is measuring this overnight, consistently. The 3 large spikes in the finger data (blue) below are from nights of alcohol. This is expected – however there is minimal change from the wrist based device (red). 

This article is certainly not one to oppose certain companies or technology, but is aimed at ensuring you question the data that you get from wearable technology, and ensure that it is used in your life in the right way. I personally own a few different pieces of technology and various apps housed on my phone! I use a Polar H10 chest strap for workouts, and wear an Oura Ring overnight. I use different things in various ways to help my health and wellness goals, and to appease my curious nature!

If you are considering a wearable device, the following profiles might help you to make an informed decision on which one would suit your goals and lifestyle best: 

A few notes for context & to be clear:

  • There is a lot (almost anything) you can do with your phone and a good chest strap. This would be my starting place for most people.
  • In the same way that Daniel always talks about the Relationship with Food, this is the same with wearables and technology. Develop a good relationship with wearables, software & technology, and how you use them.
  • If you are interested in tracking heart rate during any training, my advice is to invest in a good chest strap, such as the Polar H10 (https://www.polar.com/en/products/accessories/H10_heart_rate_sensor).
  • If you are completely against a chest strap for whatever reason, I would suggest a sensor that is place around the upper forearm / bicep, such as the Polar Verity Sense (https://www.polar.com/en/products/accessories/polar-verity-sense)
  • Most devices that track sleep are hugely limited from a sleep stage detection point of view. Some are good for total sleep time, and sleep efficiency. Be cautious how you interpret this as there are some real nuances needed to do this well – seek advice and help if you need it.
  • I am not here to dismiss any particular brand or device, and I have no affiliation to any particular company.
Concluding points:  
  • Intention. Define a clear why so that wearables and trackers can be hugely valuable for helping you keep accountability to fitness and health goals. They can also help promote positive behaviours such as maintaining activity throughout the day, and sticking to a consistent sleep schedule. 
  • Be mindful. Companies are also integrating mindfulness features to their apps as they realise the benefits of meditation and mindfulness. I’ve personally found these really good – and am currently using Headspace, and doing some breathwork biofeedback with HRV4Training.
  • Believe yourself first. Don’t allow trackers to fully determine how you feel and tell you how you slept – only you can know this. Use them to help inform the decisions you make around good sleep behaviours, daily activity levels and calorie balance. However, sometimes they can offer objective data that remove your own bias towards your health.
  • Consistency. It is probably best to stick with the same tracker, and not compare data between devices. Use data consistently so you can identify relative changes from your own norms (i.e. if your resting heart rate changes substantially outside of your normal  ranges).
  • You vs you! Data is highly individualised – it’s sometimes hard to compare to others.  Don’t get down on yourself if “my friend has a better sleep score than I do“. However I would encourage you to share your experiences and “data” with friends and colleagues as it can lead to positive behaviours and mindset towards health and  performance.


Miller, D.J., Capodilupo, J.V., Lastella, M., Sargent, C., Roach, G.D., Lee, V.H., Capodilupo, E.R. (2020). Analyzing changes in respiratory rate to predict the risk of COVID-19 infection. PLoS  One.,10;15(12):e0243693.

Natarajan, A., Su, H.W., Heneghan, C., (2020). Assessment of physiological signs associated with  COVID-19 measured using wearable devices. NPJ Digit Med., 30;3(1):156.  

Peake, J.M., Kerr, G., Sullivan, J.P., A, (2018). Critical Review of Consumer Wearables, Mobile Applications, and Equipment for Providing Biofeedback, Monitoring Stress, and Sleep in Physically Active Populations. Front Physiol, 28;9:743. 

Smarr, B.L., Aschbacher, K., Fisher, S.M., Chowdhary, A., Dilchert, S., Puldon, K., Rao, A., Hecht, F.M., Mason, A.E. (2020). Feasibility of continuous fever monitoring using wearable devices. Sci  Rep., 14; 10(1):21640. 

Quer, G., Radin, J.M., Gadaleta, M. et al. (2021). Wearable sensor data and self-reported  symptoms for COVID-19 detection. Nat Med 27, p73–77.