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From Fellrnr.com, Running tips
SHFT
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SHFT is a [[Running Sensors| Running Sensor]] system that analyzes your Running Form. SHFT uses two small pods, one attached to your shoe and one attached to a chest strap. These pods contain an accelerometer that measures your movement and transmits the information to a smart phone app for analysis. SHFT provides real-time audio coaching through the smart phone app as well and has more detailed analytics through either the app or their website. The SHFT system is beautifully designed, but a number of the metrics have accuracy issues and I found the audio coaching more irritating than useful.(Note that SHFT have announced the "SHFT IQ" which is a completely new system that uses a single pod and claims to use Artificial Intelligence.)
=The Pods=
The two SHFT sensor pods are lovely, with an elegant Scandinavian design style. Each part is triangular with a spring-loaded clip on the back.
The SHFT system provides a lot of metrics, but I'm concerned that not all of them are as accurate as I'd like. The SHFT system is also missing a few metrics (see below.)
* '''Power'''. There is a lot of hype around power meters for running, as power meters have revolutionized cycling. I think that running power meters are a flawed concept, and so far the implementation seems equally flawed. It's not practical for me to try to test a running power meter in absolute terms, but I did do a number of simplistic tests. Using a treadmill, I either gradually increased my pace, or gradually increase to the incline. In either case I would expect a power meter to show an increasing power output as my effort rises. As you can see below, this really doesn't happen with the SHFT system.
{| class="wikitable" style="margin-left: auto; margin-right: auto; border: none;"
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|[[File:SHFT-20170102-One.jpg|none|thumb|250px|This is the first incremental treadmill test, gradually increasing the pace over the course of the run. As you can see there's almost no increase in the power shown.]]
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|[[File:SHFT-20170102-Two.jpg|none|thumb|250px|A more dramatic variation in pace results in only a nominal improvement in the measured power.]]
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|[[File:SHFT-20170111-Three.jpg|none|thumb|250px|This is a longer test over an even greater range of paces.]]
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|[[File:SHFT-20170106-Incline.jpg|none|thumb|250px|In this test the pace is kept constant and the incline gradually increased.]]
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|[[File:SHFT-20170109-Incline2.jpg|none|thumb|250px|A second incline test.]]
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* '''Running Efficiency'''. SHFT says this is the percentage of energy used to move forward compared with overall energy expenditure. This is a really cool idea, but I have little faith in either the ability of the system to measure total energy expenditure or determine the percentage used for forward motion.
* '''Braking'''. This is a measure of how much you are breaking as you run. It's unclear if this is the deceleration measured at the foot, on the torso, or combination of the two. I wasn't able to verify this metric, even crudely, but SHFT gave me a breaking effect of around 8-18 Watts.
* '''Cadence (+ stride length)'''. As you'd expect, the measure of cadence is pretty accurate. Cadence is one of those things that fairly trivial to measure if you have a sensor on your feet or torso. It's only wrist based sensors that tend to have problems. The SHFT system will also calculate your stride length from your pace and your cadence. Unfortunately, SHFT does not get any pace information from the Footpod, relying on a GPS data from the smartphone. That means that if you run on a treadmill, your pace information is just the random noise from GPS inaccuracies, and your stride length is meaningless.
* '''Ground Contact Time (+ time in air)'''. Ground Contact Time is how long each foot spends on the ground, and this some research indicating that a lower Ground Contact Time is correlated with a better [[Running Economy]]. However, I've found no evidence so far that training can improve Ground Contact Time, and my personal suspicion is that the differences in the Running Economy are more to do with Cadence. A higher cadence will naturally result in a lower Ground Contact Time, and I'd like to see Ground Contact Time as a percentage of overall starts at time rather than an absolute value. The SHFT estimate of Ground Contact Time is too high, something I verified using [[High Speed Video Analysis]].
* '''Vertical Osculation'''. It seems intuitively obvious that excessive vertical movement is a sign of an inefficient runner, but I've not found any research indicating if there is an optimal value for [[Vertical Oscillation]]. A runners' vertical movement is partly based around the elastic properties of the leg muscles and tendons, so not all vertical motion is bad. SHFTs measurement of Vertical Oscillation, which they call "body balance" is far too low. I measured my [[Vertical Oscillation ]] using [[High Speed Video Analysis]] to be 3.5"/8.75cm, but SHFT said it was 2.2"/5.5cm. Worse, the real time display on the smartphone app showed less than 1"/2.5cm.
* '''Impact'''. SHFT calls [[Impact]] "G-Landing" and says it's "the maximum force of impact upward through the body from when the foot hits the ground to flatfoot" and they talk about this impact being "normalized." I find this all confusing on several levels, not least of which is the value displayed for my running seems a rather low at generally less than 2.0g. I'm not sure if this is the impact forces measured on the chest strap on the Footpod, or combination of the two.
* '''Landing angle'''. Unlike other systems, SHFT provides an angle of landing rather than a simple classification or in the case of [[RunScribe]] an arbitrary numeric indicator. The results look pretty good based on [[High Speed Video Analysis]].
|[[File:SHFT-LandingFFS.jpg|right|thumb|x150px|The measured angle while Forefoot landing.]]
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* '''Foot Strike'''. Based on the landing angle, SHFT gives a classification of the foot landing position into things like "neutral midfoot." The SHFT website will go even further and give a diagram of your foot showing what percentage of the time you land on what part of the foot. This looks reasonable when I tested with different foot strike patterns. (I confirmed my foot strike with [[High-Speed Video Analysis]].)
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|[[File:SHFT Landing PositionFFS.jpg|right|thumb|x150px|]]
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* '''Toe off angle'''. SHFT is unique (so far) in displaying the foot angle at toe off. It's unclear how useful this is, but I have noticed my toe off angle decreasing as I become fatigued. I evaluated this using [[High-Speed Video Analysis]], but it's tricky to confirm. The images below are from a single stride, where SHFT reported 37 degrees at toe off.
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Given the nature of the SHFT system, there are a few things that seem noteworthy by their absence. Most glaring omission is the lack of pace information, some think you get from virtually all Footpod sensors. I also think they could to rather more with impact measurement given that they're detecting it on two different body parts. I'm also concerned with the difficulty in using the SHFT system with a chest strap heart rate monitor.
=Running with One Pod=
SHFT now supports running with just one pod, but it has to be worn on the foot (I could not get any data from it on my chest.) With one pod you get Cadence, Ground Contact Time, Impact, Landing angle, Foot Strike, and Toe off angle.
=Real Time Feedback=
The only real-time feedback you get from the SHFT system is via the smartphone app. The system will provide you specific coaching (see below), and you can get it to speak metrics periodically. There is some real time display on the app itself, but the screen real estate is rather poorly used. There is a small fixed display of pace, distance, time, power, but the small font and the low contrast color makes this hard to read even on treadmill. The App will also display any or all of the available metrics, but only one is displayed at the time, and the font is a little smaller than one would like. Unlike some of the competitor systems, you have to run with your smart phone; there's no option to run with the sensors and then upload your data later.
