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* [[TgForce]] is a "one trick pony", but it's a great trick. It measures the impact [[Impact]] on the lower leg rather than the foot, providing great real time metrics. Sadly there are production issues at the moment that are causing the sensors to fail. * [[Moov Now]] This is a cheap and interesting sensor. Like the TgForce it can measure lower leg impact[[Impact]], but it's got software problems that have not been fixed.

* Vertical Oscillation. This is how much the torso moves up and down with each stride. It is generally believed that less Vertical Oscillation is a better, but I suspect that this is an oversimplification. It's sometimes a thought that a greater vertical oscillation will result in greater impact[[Impact]], but this is not the case. [[Impact ]] is how quickly you decelerate, so landing hard can result in less vertical movement but a shorter, more intense deceleration. It's even suggested that greater vertical oscillation will result in more braking force, but that does not seem reasonable. I believe that some are part of a runners vertical movement is likely to be elastic in nature (consider a bouncing rubber ball), some of the vertical motion will be while the runner is airborne (ballistic), and some of the vertical motion is the vertical deceleration as the runner lands. So it seems likely to me that excessive vertical oscillation is bad, but it's a tricky to know what excessive is likely to be, or how to correct it.

[[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]].

The TgForce measures just one thing; the peak impact [[Impact]] on your lower leg. While this is a far cry from the broad array of data gathered by devices like [[RunScribe]], TgForce may add some particularly valuable insight. Measuring the impact [[Impact]] that the foot can be a little misleading as the movement of your ankle can absorb a significant portion of that shock, so knowing how much of the force is transmitted to your lower leg may give a much better insight into injuries. The impact [[Impact]] that your lower leg (tibia) receives will be transmitted into your knee, so reducing that stress might be quite helpful. The companion app only runs on iOS devices, not android, which will limit the appeal for some, and unless you buy two devices, it will only measure one leg at a time. Even if you get two devices, it doesn't appear that the app readily supports this approach, unlike [[RunScribe]] that does a lot to provide side to side comparisons. That said, I really like to have real-time feedback, something that TgForce provides, either visually for use on a treadmill, or audibly outside. I've ordered a TgForce and my initial testing shows that the data from TgForce might be quite valuable, but there is a quality control problem and I've had several sensors fail. They have a fix and I should have a fully working sensor soon.[[File:TgForce1.png|none|thumb|250px|This is the real time display, showing the impact [[Impact]] of each step (from one leg) in the bar graph, plus the current and average impact[[Impact]]. There are also metrics such as total steps and [{Cadence]].]]

Moov Now is the second generation of Moov activity monitors, and is a small ankle mounted pod. It supports various sports, including cycling, swimming, boxing, and general workout routines like crunches, plank, etc. The Moov Now will also act as a general purpose activity tracker, including sleep tracking. However, it's the running functionality that I'll focus on. The Moov Now uses ankle mounted accelerometers to give a number of metrics, including [[Cadence]], [[Impact ]] (at the tibia), and "range of motion" which is how far your leg swings from the furthest forward to the furthest back. I don't see the range of motion as a particularly useful metric, as it gives no indication if you are Over striding or not. However, I like the idea of getting impact [[Impact]] metrics on the tibia (lower leg), as I suspect this is more relevant than the impact [[Impact]] measured at your foot. It seems to me that your foot could undergo massive deceleration as your forefoot touches down without necessarily generating a huge amount of stress on your ankle, and even less stress on your knee. Unlike most activity monitors, it uses a replaceable battery that should last months, which is really nice, especially if you're traveling. It's a shame the Moov Now needs to be linked to a smart phone to work, as it means taking your phone on the run. The Moov Now seems to be an interesting device given its price, especially if you are interested in the other sports that it supports. <jfs id="B01CX26IP8" noreferb="true"/>.

Like many other devices, [[Lumo Run]] uses accelerometers to measure body movement, but uniquely (so far) Lumo places the accelerometers at the small of your back. This allows Lumo to not only detect [[Cadence]] and Vertical Oscillation, but also breaking and pelvic movement. The measurement of braking force is rather different from [[RunScribe]], as Lumo measures how much your overall body slows up with each stride, rather than measuring the deceleration of your foot in touch down. I believe that both approaches are important, and give valuable insight into possible biomechanical problems. In addition, Lumo will measure how much your hips (pelvis) will drop from side to side, and how much it rotates (twists). Lumo is available Lumo Run is available for <jfs id="B01K22SOYE" noreferb="true"/>. I really wish that Lumo would measure impact[[Impact]], as it would be great to know how much of the foot strike impact [[Impact]] reaches the hips.

Zoi places sensors on both the foot and the torso. This allows it to gain a little more insight than other sensors as it knows about the movement of the foot and the torso independently. Eventually I expect to see a company produce a group of sensors placed on each foot, each knee, and the pelvis, which would give insight into the movement and impact [[Impact]] forces across most of the body. The Zoi only has one Footpod, so it doesn't give you detailed foot strike information in the way that [[RunScribe]] can, though you could see them adding that functionality in the future. The Zoi gives quite a few metrics, including [[Cadence]], Ground Contact Time, Vertical Oscillation, breaking (at the torso, not foot breaking), of [[Foot Strike]] type (fore, mid, heel), Foot impact[[Impact]], and some [[Pronation]] information. Zoi has a smartphone app that provides real time feedback and post-run analytics, but I've not seen any support for displaying metrics on a watch. Currently Zoi is on pre-order in Europe for 150 EUR. I'd like to test this system if I can get hold of one. The approach is similar to the SHFT system, though the SHFT uses a 9-axis sensor and it's not clear what the Zoi uses.

The SHFT system uses two pods, one on the chest and one on the foot, rather like the Zoi. The SHFT system includes some unusual metrics such as toe off angle and body angle, as well as Cadence, GCT, Vertical Osculation, [[Impact]], Braking, and Foot Strike. They also claim to measure power for running, something I'd need to see demonstrated in a lab to believe it's accurate and even then I'm not sure it's useful due to the impact of [[Running Economy]]. The system requires you to carry your phone, and it appears that your only feedback is via audio through the headphones which I generally find rather ineffective. It looks like there are some good post run analytics available via the app, but no sign of data export. The price of the two SHFT sensors is $300 which is a little high compared with other systems.

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 [[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 [[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 [[Impact]] would produce a quiet, short, deep beep, and 89G impact 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.