Sensoria

The principle behind Sensoria is a cool one. They've created a stock that has built in pressure sensors underneath, and a small anklet that relays the pressure to a smart phone. This allows Sensoria to detect Foot Strike patterns with a potentially far more accuracy and an accelerometer-based system. In addition the anklet has accelerometers to measure Ground Contact Time and impact. If the sensors react fast enough, then the system could potentially detect rates of loading to see how hard the runner's landing. It's with these great expectations that I started my testing, performing a number of runs in different footwear and with different Foot Strike patterns, comparing the Sensoria against other Running Sensors, including RunScribe, the Garmin Running Dynamics, MilestonePod, and Moov Now. Sadly, my testing reveals that the system doesn't seem to work in the real world. Let me lay out the liturgy of problems:

• The biggest concern is that the system doesn't work, or at least, not reliably enough to be of any use. When I first put on the socks and anklet, the accompanying app would show in real time how much pressure was on each of the three sensors as a 'heat map' (see screen shot below). If I press my heel to the ground the heel area would light up, and if I press my forefoot to the ground the two forefoot sensors with light up on the app. This was both rather cool, and confirmation the system was working. Sadly, after only a few minutes of running the real-time display showed that the sensor was no longer responding. It's possible that this was due to sweat building up, but after only a few minutes this seems unreasonable. I contacted their support and described the problem, to which they responded with "During a long run the pressure sensor heat map and real-time visualization on your phone may be impacted by different environmental factors. However the real-time feedback algorithms and the web dashboard have been designed to provide you with accurate data." This does not seem reasonable or logical to me, but to give them the benefit of the doubt I did some further testing.
  
  

  The heat map of the Sensoria app.
• I tested the Sensoria with three different shoes (heavily cushioned, minimally cushioned, and nearly barefoot), and I tested each shoe with my normal rear foot landing, a forefoot only landing, and a forefoot first landing. My intended Foot Strike pattern was confirmed by RunScribe. You can read about the details of this testing below, but the bottom line is that the Sensoria didn't report my foot strike correctly. I think that this is a showstopper, but I'll continue to list the other issues. (I tested the Sensoria using both the left and the right sock, so I'm reasonably confident that the problem is not an isolated manufacturing issue.)
• The socks that come with the Sensoria are remarkably thick and warm, and I did not want to wear them for any length of time except in winter. They've done a good job in making the sensor pads relatively innocuous, but I found that when I was forefoot running in nearly barefoot shoes the front pads hurt my foot. You have to pay close attention when putting the Sensoria socks on to sure the sensors are in the right place, and I had to verify this each time I changed shoes. The only good news with the thick, heavy socks is that they kept the anklet in place firmly.
• The basic premise of Sensoria seems to be that you should land forefoot and that heel strike is bad. The evidence to support that idea is currently a little limited, but even if you put your target foot strike as heel, the smart phone app will nag you to land on the ball of your foot. Talking of the nagging smart phone app, I found it rather annoying rather than helpful.
• The basic package only gives you one anklet, so you don't get any balance information, but you could buy a second anklet.
• The Sensoria requires you to run with your phone, which I think is a major annoyance. While many folks are happy doing this, I find a smart phone rather cumbersome and I'd much rather have the information displayed on the watch.
• In addition to the broken Foot Strike information, the Sensoria also gives Ground Contact Time and some impact information post-run. The impact is on a scale of 1 to 10, but is not in g's (gravities). The reported Ground Contact Time by Sensoria is quite a bit higher than it should be. (See Ground Contact Time testing below.)
• Sensoria state that the anklet is "splashproof" and it should be fine in the rain. Personally, this would make me cautious about using it in heavy downpours.

1 Gallery

The anklet and charging dock are reasonably small and elegant, using nice materials and a soft finish.	The charging interface has a slightly strange punk rock look to it.	Here you can see the three sensors in the sole of the sock, and the clear label marking of this as the left sock.
This is the connector on the sock that the anklet connects to, again displaying a very 90s punk rock style.	With the sock inside out you can see the patches sewn in to cover the pressure sensors, and the outline of the wiring.	Here is a close up of the forefoot pressure sensors. This was just enough to bother my feet.
If you just pull the sock on it's easy to get the sensors slightly misplaced. I had to be careful in my testing to ensure they were in the optimum location.

2 Test runs

My first test consisted of nine runs; three with Maximalist Hoka Cliftons, three with more minimally cushioned Saucony Endorphin‏‎, and three with the near barefoot Merrell Vapor Glove. The first of each sequence was with my normal rear Foot Strike, the second was with forefoot only landing without my heel ever making contact with the ground, and the third was forefoot landing with the heel briefly touching down. I compared the Sensoria with the RunScribe and the Garmin Running Dynamics, and in the RunScribe graphs below, yellow is Ground Contact Time and blue is Foot Strike. As you can see from the table below, run scribe is reporting a Foot Strike number that is appropriate for how I was running. However, the Sensoria is reporting that time heel striking even when I'm running on my forefoot. The discrepancy between the Ground Contact Time results for the Sensoria, RunScribe, and Garmin Running Dynamics laid me to do some verification tests later using high-speed video. This testing led me to believe that the Garmin was giving the most accurate results.

Shoe	[[Foot Strike]	Sensoria % Heel	RunScribe Foot Strike	Sensoria Impact	RunScribe Impact (g's)	Sensoria GCT	RunScribe GCT	GRD GCT
Hoka Clifton	Rear	99	1.8	1.98	8.9	346	293	243
Hoka Clifton	Fore Only	66	13.0	1.44	10.8	339	273	247
Hoka Clifton	Fore First	76	10.5	1.4	9.3	368	310	256
Saucony Endorphin‏‎	Rear	83	2.6	1.84	11.5	350	284	238
Saucony Endorphin‏‎	Fore Only	83	14.2	1.35	9.3	338	269	248
Saucony Endorphin‏‎	Fore First	94	13.5	1.58	10.1	341	309	257
Merrell Vapor Glove	Rear	98	2.6	2.03	10.7	346	307	236
Merrell Vapor Glove	Fore Only	100	14.1	1.17	10.5	350	306	249
Merrell Vapor Glove	Fore First	89	14.3	1.71	11	346	310	246

2.1 Rear Strike Hokas

Both systems are clearly reporting that I'm landing on my heel as you can see below. The RunScribe system has a little more nuance, but the Sensoria seems to be doing okay. RunScribe actually rated my foot strike as 1.8 on a scale of 1 to 16, which gives a little more information than simply a percentage of the time heel striking.

Senoria Hoka Clifton Rear Foot Strike

RunScribe Hoka Clifton Rear Foot Strike

2.2 Forefoot Only Hokas

The RunScribe system is correctly reporting a forefoot landing, with a score of 13. You can see from the graph that its Foot Strike index varies a little bit, which is understandable given that an accelerometer-based system can't know if my heel is actually touching the ground on not. The Sensoria system reported I was on my heel 66% of the time, but if you look at the graph you can see how poor the data is from the underlying sensor. I've included a screenshot from the smart phone app below the screenshot of the web interface as the app seems to have data that is not quite so smoothed. It looks like the sensor is not working the tour for the first part of the run, and then only intermittently picking up my forefoot landing towards the end.

Senoria Hoka Clifton Forefoot Only

RunScribe Hoka Clifton Forefoot Only

Senoria Hoka Clifton Forefoot Only (app)

2.3 Forefoot First Hokas

In this test I am landing on my forefoot, but allowing my heel to briefly touch the ground on each foot step. Yet again, you can see good data from the RunScribe system which gives me an overall foot strike index of 10.5. In this test it looks like the Sensoria is working intermittently for the first part of the run and then giving up.

Senoria Hoka Clifton Forefoot First

RunScribe Hoka Clifton Forefoot First

2.4 Rear Strike Endorphin

While running in the rather minimally padded [[[Saucony Endorphin]] you can see that my foot strike is not quite totally on my heel. As the run progresses, the RunScribe system shows that I am passing slightly more midfoot, something that is perhaps not surprising. RunScribe rates my Foot Strike has 2.6, which is still heel striking, but not quite as much as the massively cushioned Hokas. The Sensoria graph bears little resemblance to the RunScribe, and again appears to be more noise than anything else.

Senoria Saucony Endorphin‏‎ Rear Foot Strike

RunScribe Saucony Endorphin‏‎ Rear Foot Strike

2.5 Forefoot Only Endorphin‏‎

The story continues in a similar vein when running on my forefoot with the minimally cushioned shoes. Yet again the Sensoria seems to not have any valid data.

Senoria Saucony Endorphin‏‎ Forefoot Only

RunScribe Saucony Endorphin‏‎ Forefoot Only

2.6 Forefoot First Endorphin‏‎

Another failed reading from Sensoria, which interestingly looks a lot like the graph immediately above, though that could be coincidence.

Senoria Saucony Endorphin‏‎ Forefoot First

RunScribe Saucony Endorphin‏‎ Forefoot First

2.7 Rear Strike Glove

The Merrell Vapor Glove is the closest to barefoot running of any shoe I've tried. The soul is so thin that I have to pay close attention to any debris on the road to avoid painful injury. I'd hoped that the lack of cushioning would give the pressure sensors more scope for an accurate reading, but alas the graph looks poor.

Senoria Merrell Vapor Glove Rear Foot Strike

RunScribe Merrell Vapor Glove Rear Foot Strike

2.8 Forefoot Only Glove

With so little padding in the shoe, the pressure sensors in the sock were quite uncomfortable, and I would not want to run like this very far. Yet again the Sensoria bears no resemblance to reality.

Senoria Merrell Vapor Glove Forefoot Only

RunScribe Merrell Vapor Glove Forefoot Only

2.9 Forefoot First Glove

The final test will be no surprise to anybody who's read this far. I only completed the testing to ensure I'd given Sensoria every opportunity, and for a sense of symmetry in my testing.

Senoria Merrell Vapor Glove Forefoot First

RunScribe Merrell Vapor Glove Forefoot First

2.10 Longer Run

While not a long run by any means, I tried one more time with the Sensoria, comparing it with the RunScribe, Running Dynamics, and MilestonePod. I used the Hoka Tracer with a forefoot only Foot Strike. The Sensoria reported that I was 88% heel striking, with a Ground Contact Time of 337ms and an impact of 1.01 (no units). You can see two views of this run below, one from the web and the other from the mobile app that seems to have less smoothing applied. Yet again, it looks like the pressure sensors are only giving intermittent data.

Here you can see the Sensoria is wrong most of the time.

The app seems to show the data with less smoothing, and you can see how periodically the sensor picks up the foot strike, but most of the time it's wrong.

RunScribe showed a Ground Contact Time of 291ms and a forefoot strike (13.4). You can see the graph below:

The RunScribe data reflects the true Foot Strike pattern.

MilestonePod showed 100% forefoot, Ground Contact Time of 278ms, while Running Dynamics showed Ground Contact Time of 239ms. The Moov Now reported 7.7g impact, the RunScribe 10.0, and MilestonePod gave the rate of impact as low. However, the impact figures are measured in different ways and in different positions, so it's hard to meaningfully compare them.

3 Ground Contact Time Testing

I tested Ground Contact Time by comparing multiple devices against a gold standard of high-speed video on a treadmill. I took the average of a number of strides filmed over a 10 minute period, while aiming to run as steadily as possible. As you can see the Sensoria system is wildly inaccurate, and this reflects the general trend I've seen in my other runs.

Device	Ground Contact Time (ms)	Cadence
High Speed Video	256
Sensoria	344 (+88)	175 (fluctuating wildly)
Garmin Running Dynamics	254 (-2)	176
MilestonePod	253 (-3)	177
Moov Now		178

Second test using the RunScribe system as well:

Device	Ground Contact Time (ms)	Cadence
High Speed Video	255
Sensoria	339 (+84)	178
Garmin Running Dynamics	251 (+4)	177
MilestonePod	253 (-2)	177
RunScribe	299 (+44)	178

Here's an example of the Sensoria cadence data, which reflects the wild fluctuations I saw displayed.

Sensoria cadence data