Withings is the company which basically pioneered the “smart scale” bringing the first Wifi connected scale to market as their debut product in 2009. However a lot has changed in the health monitoring market since 2009, and the smart scale market is certainly rather crowded now. Withings have just released a new flag ship scale, the Withings Body Cardio WiFi Scale. So can Withings teach an old dog new tricks?
Withings Body Cardio WiFi Scale Review
Even before I finished medical school I have used a Withings Smart scale. Apart from one mishap when Withings updated their software, I have weight measurements going back to 2012, so when I was poking around the Withings app doing to Withings Go review, and noticed an unreleased scale buried in the app, I immediately wanted to know more… and here we have it the Withings Body Cardio WiFi Scale, replacing the previous Withings Smart Body Analyser. With new Body Cardio we have a thoroughly redesigned scale inside and out. But we have lost a few features along the way.
There are a LOT of competitors on the market for Smart Scales now, so merely being able to measure your weight and body fat percentage isnt quite going to cut it. As a result Withings have followed a line from the Garmin Index Scale by including water, and muscle composition as well as bone mass. Not to be out done however, with the Body Cardio Withings have heart rate monitoring, a nicety, but also a new metric Pulse Wave Velocity, which we will look at in a bit.
(Withings will also offer to sell you a standard Body scale, omitting the cardio features and saving you £40 currently)
Withings continue with trend of copying the Apple box design, with eye seeringly white boxes. Perhaps it’s not a coincidence that currently the only place where you can buy the Withings Body Cardio is through brick and mortar Apple Stores.
Unboxing the Withings Body Cardio WiFi Scale, there really is nothing there. Just the scales and a quick start leaflet.
One of the reasons there is nothing else in the box is that Withings have completely done away with the feet on the Withings Body Cardio.
Now we have two thin rubber strips, on a large bottom plate.
The plates are separated down their length by a piece of foam, which also helps to keep the detritus associated with living on a floor from getting into the scales too easily.
The removal of feet does make the Withings Body Cardio much thinner than the older Withings Smart Body Analyser.
Plus the slab like nature of the Withings Body Cardio base means that the device is happy to live on a hard bathroom floor, as much as it is to live on a carpeted bedroom floor.
On one thin end, is housed the scale’sUSB port, along side the power button to enable to you pair your device.
- Rechargeable battery!! (Woo, no more changing the batteries every 6 months-ish)
- Withings states 12 months potential battery life.
- Bluetooth 2.0 Compatibility
- Height: 1.8 cm
- Length: 32.7 cm
- Width: 32.7 cm
- Weight: 2.6 kg
- (There is something a bit odd about weighing the weight of a pair of scales)
- Fat mass
- Muscle mass
- Bone mass
- Heart Rate
- Pulse Velocity
But wait – what has happened to Room Temperature Monitoring and CO2 monitoring from the Withings Smart Body Scale? Apparently Withings didnt consider people had found any real world value to these metrics. Personally I quite liked seeing what happened with regard to CO2 as I slept over night, but as most people will probably have had their scales positioned in the bathroom, I can see it not being a widely used feature. Still a slight shame from my perspective.
Using the Device
It’s a pair scales! Stand on it! But in all seriousness, that isnt going to get you very far. The first time you power up the scales, and stand on the Withings Body Cardio you are asked to pair your scales to the Withings Health Mate app
Pairing the Withings Body Cardio
From within the Withings app, you need to select your particular scales
Before following the on screen instructions to connect to the unit via bluetooth
This allows you to push your Wifi details directly to the scales, allowing the Withings Body Cardio to download the latest update and send you on your way
Once the firmware upgrade is complete, you set your target weight, and you are ready to jump on!
(To any Zwifters who think I’m weight doping, I’m fully clothed in this picture, save socks!!!)
You can configure the Withings Body Cardio to hold up to 8 profiles. The unit will identify you from your previous readings if users have very different weights.
Here my name has been auto selected and shown in the top LEFT of the screen
If the users have similar weights then you select between them by shifting your weight from one side to another.
After your weight has been recorded, the Withings Body Cardio displays a graph of your last 7 weigh-ins. Assuming you are not weighing multiple times (I tend to weigh pre and post rides/runs to ensure I’m hydrating properly), this is likely to show you your weeks weight trend.
As mentioned the unit can record the following metrics: Weight, fat mass, bone mass, muscles mass, water content and pulse.
Whilst all the data is recorded, you can select from the Health Mate app, which data, including trend, weather and previous steps (which can be recorded from any Withings Activity monitor, like the Go, or from the Health Mate app itself) and are displayed when you stand on the Withings Body Cardio. Nestled right at the bottom, is even the option to display Nike Fuel, if you are still using a device or the phone App
Different people different things. I think I would have preferred continuation of CO2 and temp monitoring and dropping the weather notification instead. Although I suppose the High/Low forecasts for the day may be of some use, plus the CO2 will have likely required a hardware sensor
What about the new metric – what about Pulse Way Velocity?
Pulse Wave Velocity (PWV)
I have ONCE seen pulse wave velocity talked about before, perhaps, in a lecture on blood pressure, as part of an obscure formula relating to arterial wall pressure. Arterial stiffness is important, and is a crucial factor in cardiac disease. But currently PWV isnt widely used outside of specialist/experimental settings. Which did cause a slightly raised sceptically eyebrow, when Withings released a device, which contains a metric which has the power to tell someone, in their home, without additional information, that an aspect of your health, specifically your cardiac health is “not optimal.”
Thus I went digging to find out a little more about PWV and it’s accuracy… so quote Jennifer:
Pulse Wave Velocity – The Science
When your heart beats, it pushes blood around the body. The pulse you feel at your wrist is literally the pressure of the blood coming out of the heart causing your artery to expand, and then relax. For that expansion to happen, we are looking for the artery to have a degree of elasticity. The artery expands, and returns to normal, in doing so, your blood pressure stays in a “normal” range.
Think about a balloon. If you put 5 breaths into the balloon, each time it will get bigger by a similar amount. However once the balloon has expanded to a certain point, it can’t stretch as far. So with each additional breath, the ballon expands a little less than before, while the pressure inside increases. There comes a point when the balloon can’t stretch any more, and the pressure inside is too great, then one more breath, and the balloon pops. Now if the ballon is left in a cupboard for a year and ages, the rubber becomes stiffer, it can’t expand as much, as so will go pop sooner.
Ss you age, your arteries will stiffen to a degree, depending on how you look after your body. So when your heart pumps, it is pushing blood into your arteries, which like the ballon, expand nicely to accommodate that pressure before relaxing back. Again is is actually what you feel with your pulse at the wrist. However if your arteries become stiff, when the heart pumps, the artery doesn’t expand as much, keeping the pressure inside the artery, causing your blood pressure to increase.
But what does this have to do with wave velocity of your pulse? Withings Body Cardio measures the time it takes for your blood to travel from your heart, to your feet – Pulse transit time – and from this Withings calculates a Pulse Wave Velocity (PWV).
The fact that Withings needs to calculate the PWV is one reason you can’t see it on your scales, only within the app
But what actually is PWV – you’ve still not explained??!
Withings has produced a nice diagram to illustrate what I have just said:
I have a feeling this image will be used a lot around the internet for Withings Body Cardio scale reviews!!
So the bottom image is what we would expect the see.
Each pulse, causing the artery to expand.
As your arteries stiffen, you get less expansion. As a result, the blood insider the vessel flows faster
This speed of flow is the crux of the metric Withings are using to approximate artery stiffness. Which is a very important statement. With their wireless blood pressure monitor Withings have a device which takes a DIRECT measurement your ACTUAL blood pressure. There is no ambiguity in what that blood pressure measurement is or what it means. With PWV, Withings are taking an indirect measurement (Pulse Transit Time) of an indirect measurement (Pulse Wave Velocity) to make inferences about arterial health.
This all sounds passable so far, especially as there are are several medical products on the market already which use indirect measuring techniques to comment on arteries stiffness. Complior®, Sphygmocor®, VaSera® are three products if you fancy a look.
It might be useful to look at the Sphygmocor device, as this is what Withings has compared themselves to during their paper “The Science Behind Body Cardio and Pulse Wave Velocity”. Just to put things into perspective, the Sphygmocor device takes 60 seconds of data to measure PWV using a blood pressure cuff and a blood vessel monitor (the stick above), whilst Withings will calculate PWV with 15 seconds of data taken through your feet.
The Withings Paper
Withings, rather than finding a few journal articles, and then shoving some tech into a product and saying it works, Withings has gone about things a different route – funding their own study – (click the image below to link to their study PDF)
Their study contains 111 people. Which is actually pretty good for a device study. Plus I cannot stress this enough, serious kudos to Withins for going out and doing this work…BUT…BUT
- Withings paid of the study
- It’s focused on selling their product
- The wording is very “pro buy this product”
- “ensure general public has access to this important measurement”
- Who is determining whether this is an important measurement Withings?
- Some of the wording is a little excessively simple
- “PWV is the only stand alone measurement able to give you the whole picture of your cardiovascular health”
- IT IS IN THEIR BEST INTERESTS TO INTERPRET THE DATA FAVOURABLY.
- So anything in the study is going to be taken with a metric tonne of salt.
So given that pinch of salt, lets have a quick look at a couple of points from their paper.
Firstly, measuring the entering of blood into the aorta via the feet
The Withings Body cardio used ballistocardiography, repetitive motions within the body in a specific frequency range which have been shown to correlate with the movement of the heart, to record the movement of blood flow through the aortic valve. This is orange line above.
By comparison the blue linen the below graph is the bottom blue line is recording impedance plethysmography or phlebography, changes in electrical resistance relating the blood volume changes.
Thus the blue line is measuring repetitive vibrations, and the orange electrical changes, showing the Withings Body Cardio can record the timing of blood entering into the aorta, and then the delay between the blood arriving in the feet.
Their next graph shows a correlation between the Sphygmocor device calculations of PWV and that of the Body Cardio. OK a little more science there, they have calculated an R value for the graph of 0.7, which indicates a strong agreement between the two devices.
But this next point raises two questions. Will Withings ever make their actual DATA set public, so we can confirm that correlation? Will it be the ENTIRE data set? i.e. it does have any unfavourable data removed.
But the more important question, the is Sphygmocor device a good measure of PWV????
I mentioned earlier there ware three devices which measure PWV indirectly. Conveniently all three were compared in a paper in 2007 published in Vascular Health and Risk Management – using 20 healthy volunteers, (less than the 111 Withings patients). From this paper we can draw a few conclusions
- All three PWV devices were reliable – But that is not the same as accurate. A tape measure is reliable, if when you measure the same pencil four times, and it gives you the same measurement each time. The problem is that tape measure could be telling you a 10cm pencil is actually 200 miles long. Reliability is not the same as accuracy (which is how well something measures a true value)
- Whilst the study found all three devices to be reliable. The three devices did not agree with each other, nor alternative measures of vascular health, such as vascular ultrasound readings (known to be reliable and accurate at predicting risk of heart disease)
- Most importantly the three devices may have failed to be consistent with each other or the ultrasound readings because of using a young, healthy trial population, WITHOUT cardiovascular disease
That third point does raise an interesting point about the Withings study, of 111 volunteers. WHO WERE THEY?
We know they were in a hospital setting. They could have been 111 healthy medical students, which would be interesting given the 2007 studies difficulties with young health volunteers and PWV measurements.
However it is more likely that 111 patients, in a hospital, looking at a marker of cardiovascular health were actually patients know to have heart problems. I suggest this as an alternative 2004 study demonstrated a STRONG association between PWV and risk factors for arterial stiffness in patients who were already diagnosed with heart disease.
Basically this is a very long winded way of saying Withings has produced an interesting metric in measuring PWV. HOWEVER it may not accurate in young, fit, healthy people
Bottom line – I’m not going to worry about my “non-optimal PWV” analysis from Withings. I will however be interested to see what happens to the reading over the next few weeks.
Putting it another way. Withings could say that my PWV was 9 pink elephants. What I’ll be interested in is to see whether there is any change in the number of pink elephants in relationsion to my fitness over the next few months. But certainly I will put NO WEIGHT in the “non-optimal” reading especially given I can manage to put in a 5km run in 20:09 if I’m having a grump after work!!
Withings removal of the scales feet, leaving a single plate for the Withings Body Cardio is a great move. No more worries about where you are using the scales, as long as they are on the floor, you are sorted.
I’m not sure whether the move to rechargeable batteries was actually needed but may have merely been a side effect of moving to a “feet-less” design
Withings has always proven to make reliable scales, which provide consistent weight measurements, and that is the important thing when it comes to weight loss and tracking your body. Not so much knowing the individual values, but looking at what the trend is doing over time.
So big question would I upgrade?? If I already had something like the original Withings scale or Garmin Index probably not. However if I was in the market for a smart scale though, between this and the Garmin Index, Withings would be taking my money for a Withings Body (sans-Cardio) – given that I’m currently quite fit, biologically speaking. However if I was older, and wanted to improve my fitness, and already had a defined risk factor for cardiac disease, such as high blood pressure or diabetes, I’d certainly be thinking about putting the extra to get a Withings Body Cardio with a view to having a passing interest in the PWV reading. But I can’t state this enough, I would not be focused to the actual PWV reading, but would be interested to monitor the trend over time as I tried to improve my fitness
Any questions drop them below!