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Running Sensors

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''Main Article: [[RunScribe]]''
[[RunScribe]] is a small pair of [[Footpod]]'s that provide a wide variety of [[Foot Strike]] metrics. These include things like [[Impact]] G's, GCT, Braking G's, [[Pronation]], and more. I love the detailed metrics that are provided, and the insight into my running form, and possible imbalances. The main disadvantage with the RunScribe approach is that the data is not available during the run, and has to be analyzed afterward. RunScribe is rather more sophisticated than most Footpods as it not only has a 3-axis accelerometer, it also has a 3-axis gyroscope and a 3-axis magnetometer allowing it to sense far more movement. You can read about my testing at [[RunScribe]].
[[File:RunScribe.jpg|none|thumb|500px|An overview of the data from RunScribe]]
=MilestonePod=
''Main Article: [[MilestonePod]]''
[[MilestonePod]] is a vastly cheaper alternative to RunScribe, and while it doesn't provide the detailed analytics, it's a great value for money. It's also a cheap and effective way of keeping track of the mileage of your shoes, and is worth its price for that feature alone. Like [[RunScribe]] the MilestonePod doesn't provide real-time metrics, and you have to analyze the results post run. You can read about my testing at [[MilestonePod]].
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=RPM<sup>2</sup>=
RPM<sup>2</sup> (Remote Performance Measurement/Monitoring) is a pair of insoles that fit into your normal running shoes. These insoles measure pressure and use accelerometers to measure movement (a little like Sensoria). The details are not entirely clear from the web site, but they claim to measure [[Cadence]], Ground Contact Time, [[Foot Strike]], and "acceleration power". The system also claims to measure running power, though I'm not sure of the methodology. The RPM<sup>2</sup> system measure pressure in four areas (Sensoria has three), giving a [[Pronation]] measurement. There are notes that RPM<sup>2</sup> insoles are not waterproof, which is rather disconcerting, and if you run in different shaped shoes the fitment is likely to be problematic. The sizing of the insoles needs to take into account the position of the ball of the foot to ensure the sensor is in the right place. The system supports Bluetooth to connect to your phone as is common with running sensors. The RPM<sup>2</sup> can also connect to an Ant+ watch, though it's a bit of an ugly kludge. You need to have your phone with you, and then plug in the Wahoo Key adapter via a lightning-to-30 pin adapter to transmit Ant+ to a watch. The Wahoo Key and adapter are all extra bits you have to buy. The system can also be used as a power meter for cycling. Their web site is [https://www.rpm2.com Remote Performance Measurement/Monitoring].
=Kinematix TUNE=TUNE consists of two insoles and attached pods, connected by a cable as shown in the image below. This allows it to potentially gather the metrics typically associated with a Footpod, plus have data from pressure sensors in the insoles. I've not tested the TUNE, but what I can gather suggests it provides less data than you might expect. There is obviously Cadence, and they have Ground Contact Time which is shown as Swing Time and Stance Time (these are just simple calculations from and GCT.) The only metrics from the insoles appears to be the percentage of footfalls that are heel strikes (Rear Foot Strike, RFS), and something called "Stance Dynamics." It's not entirely clear what "Stance Dynamics" is except for the text "the time in propulsion during the Stance Phase." This suggests that perhaps the insole can measure sharing forces to determine how much of the Ground Contact Time is spent with the foot pushing backwards to generate propulsion. Having one device for each foot provides some insight into your symmetry which is likely to be a significant factor in injuries, but obviously that's limited to the metrics that TUNE is gathering. It looks like TUNE will provide audio coaching, but it's unclear if there will be any real-time audio feedback. They have created the option of sharing data with your coach, which is a nice option for those who work with a coach. Their website suggests that they might be adding and iWatch in the future, something I wish more running sensors would do. I'm not seeing enough data being gathered to make this device worthwhile. There are a couple of concerning caveats, the main one being that the TUNE is not waterproof. The other possible concern is that the insoles cannot be cut to size, but in practice these insoles go under your existing insoles rather than replacing them, so this might not be an issue. Overall, I'm a little underwhelmed by the amount of data that TUNE is providing, and I'm not planning on testing it at this point.[[File:KinematixTUNE.png|none|thumb|300px|The TUNE sensor.]]=Ideas For The Future =This section documents a few ideas I've had for running sensors, partly to inspire manufacturers, and partly to disclose these ideas so that they cannot be patented in the future.==Proportional Audio Feedback ==
Many running sensors will provide information on your biomechanics using an audio message. Typically, this is a spoken message such as "you're landing on your heel" or "your braking is 1.31 feet per second." I generally find these audio messages far more annoying than they are useful. The messages tend to occur too infrequently for me to get a sense of how any modifications in my form are changing the metric being measured. The spoken word means it's a little tricky to combine this with music or radio. A better approach is to have a simple signal like a beep when your metric is outside the desired level. For example, [[TgForce]] will beep when your [[Impact]] is too high, and you can combine this simple audio signal with music for the spoken word from a in audiobook or the radio. I believe that a superior approach is to have a variable audio signal that indicates how well you're doing. So instead of having a simple threshold such as 7g you'd have a range such as 5-9g. Then, when your [[Impact]] is above the lower threshold you would get an audio signal, but the audio signal would vary in one or more of volume/pitch/duration depending on where you are in the range. So a 5g [[Impact]] would produce a quiet, short, deep beep, and 9G [[Impact]] would produce a loud, longer, high-pitched beep. This way you'd get quantitive feedback on how well you're doing against your chosen metric.
==Deriving Practial Impact From Acceleration==
Often running sensors will provide a value for impact based on the acceleration measured at the foot or leg. However, the bulk of the stresses on the lower limbs comes from the acceleration of the overall body mass during landing. Therefore, I believe it would be more effective to measure the acceleration of the torso on landing to provide an estimate of the stresses on the lower limbs. I suspect that both peak acceleration and the area under the acceleration curve would provide insight into the stresses of running. Peak acceleration is fairly obvious, and I suspect is more useful than a jerk. However, it may be useful to evaluate the area under the acceleration curve, as the time spent under stress could also be a significant factor on injury rates.
==Foot Strike==
Several running sensors will measure [[Foot Strike]], though so far, I've only found RunScribe and SHFT to provide useful data. However, even these devices tend to measure the foot angle on initial contact, and I suspect that it would be far more useful to measure foot and call at the time of maximum deceleration of the torso.

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