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BSX
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{{DISPLAYTITLE:BSX Lactate Threshold Monitor}}
BSX is a simple, easy to use [[Running Sensors| Running Sensor]] that estimates your [[Lactate Threshold]] (, but I don't believe its results may not be are corrector useful.) You just wear the BSX monitor in a custom calf compression sleeve that it comes with, along with the BSX app on your phone, while running on a treadmill. The BSX app tells you what pace to run at, which increases every 3 minutes until you can't continue, at which point it (probably) tells you (it's guess at) your [[Lactate Threshold]] pace. Sadly, while the BSX simple and easy to use, the results are rather dubious and it's unclear to me if it does a better job than simply using an estimate of your 10K race pace. (Important: BSX has announced a This review is for the second generation BSX; for results of their sensor and I will retest once that becomes availablethe first generation, see [[BSX Gen1]].)
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|[[File:BSX and Moxy1Front.jpg|none|thumb|x300px|The front of the BSX sensor on the left with the Moxy sensor on the right, which is an elegantly designed and aesthetically pleasing shape. I've included a Gu as my size comparison. The BSX has no buttons, inputs or display, though you can reset it with a magnet. ]]|[[File:BSX and Moxy2Back.jpg|none|thumb|x300px|A view The back of the BSX has two LEDs lower on the device and Moxy showing the infrared emitters a sensor just above. There are also four gold contacts for charging and detectorsconnection to a PC.]]|[[File:BSX Moxy Test.JPG|none|thumb|x300px|Here's my setup for testing the BSX & Moxy. I attached both sensors to my calfscalves, putting the Moxy in the same position as the BSX. I linked the Heart Rate strap to the BSX (or attempted to, repeatedly), to my watch, and to Live Recording software on the PC (initially SportTracks, then [http://www.goldencheetah.org/ Golden Cheetah].) I used the BSX app on my iPhone and linked both the BSX and the Moxy to the live recording and one of my watchwatches.]]
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=How to use the BSX Lactate Threshold Monitor=
The BSX is remarkably simple to use, especially when compared with other ways of estimating [[Lactate Threshold]]. You'll need the BSX, its calf compression sleeve, an iOS or Android device, and a treadmill.
* You'll need to have the BSX app on your iOS or Android device. <br/>[[File:BSX1a.png|none|thumb|200px|The BSX dashboard you see when you start the app.]]* If possible, limit the amount of ambient light. The updated BSX compression sleeve has light blocking material over the sensor, but I did have some issues using the BSX in full sunlight. This was a worst case scenario, with the intense sun directly hitting my calf due to me testing with my garage door open.
* Make sure the BSX is fully charged. (Seriously, you don't want it to run flat part way through this, so leave it charging until near the time you do the test.)
* Start the app and give it your details. It will want your conversational pace and your 10K pace, along with some other information about how long you've been running. <br/>[[File:BSX2a.png|none|thumb|200px|The details screen where you enter a conversational and 10K pace. I'm not sure how the app uses other fields.]]* Review the screens that tell you what paces you'll have to run. I wrote up a small card with the pace list and equivalent in MPH. I think in minutes/mile, but my treadmill works in MPH so I had to have the app set to MPH. I found it nice to know what pace I was at, as well as what the next pace would be. <br/>[[File:BSX3a.png|none|thumb|200px|These are the paces you'll have to run.]]
* Link the app to the BSX, which normally requires the BSX and phone to be close together.
* You can link the BSX to an Ant+ heart rate monitor, but they'll have to be close to pair. I found this to be tricky at best, and I only ever got it to work once. If the The latest BSX loses connection to has reduced the heart rate monitor, then it will tell you problems with the test is failedAnt+ communications, but only after so youshouldn've finished. Other people seem to t have had similar too many issues, and BSX have released firmware that may help, though I didn't have much luck. * Once you've finished pairing the BSX you can put it into the small pocket in the calf compression sleeve that is sold with the BSX. Make sure you use the BSX sleeve; it has light blocking material and a pouch to hold the sensor in place. <br/>[[File:BSX and Moxy.JPG|none|thumb|x300px|The BSX sensor in its calf compression sleeve. (The Moxy has to be taped on.)]]* Start the test on the app and start the treadmill. The first 3 minutes is at a walking pace, and then you'll do 3 minutes at gradually increasing paces. For instance, if you tell the BSX app that your conversational pace is 8:00 and your 10K pace is 6:30, it will give you 9:22, 8:57, 8:34, 8:13, 7:53, 7:30, 7:03, 6:40, 6:22, 6:03, 5:42, etc. * Once you've reached voluntary exhaustion, stop the treadmill and the app* (The BSX app will then tell slightly odd paces make more sense when you your Lactate Threshold pacesee them as MPH. {| class="wikitable" |- valign="top"|)<br/>[[File:BSX and Moxybsx4a.JPGpng|none|thumb|x300px200px|The BSX sensor blue partial circle gives a visual sign of how much is left on the stage. It will show a warning box in its calf compression sleeve. (The Moxy has the last 10 seconds, but I wish it would beep to be taped ongive me an audible clue.)]]|[[File:BSX1.jpg|none|thumb|x300px|The dashboard view of * Once you've reached voluntary exhaustion, stop the treadmill and the BSX app, showing previous results.]]|<br/>[[File:BSX2BSX5a.jpgpng|none|thumb|x300px200px|You have to input your conversational and 10K pace (your 10K pace If all goes well you'll see this screen showing what BSX thinks is an estimate of your Lactate Threshold.)pace]].|[[File:BSX3.jpg|none|thumb|x300px|The app shows you the paces you* You'll be running at.]]|- valign="top"|[[File:BSX4.jpg|none|thumb|x300px|You also get a display of suggested training paces based on the pace to run at, along with the time left in this stagetest. You can see your Heart Rate if the BSX has managed to link to your Ant+ heart rate monitor (I only got this to work once). You'll also see your SmO<sub>2<br/sub>, but for me it didn't bear any resemblance to reality.]]|[[File:BSX5BSX6a.jpgpng|none|thumb|x300px200px|When you're done the BSX app shows you what it thinks your Lactate Threshold is, along with other Suggested training paces.]]|[[File:BSX Failed.PNG|thumb|x300px|If you managed to get your Heart Rate monitor to pair with * One improvement over the BSX at Gen1 version is that the start, then update is more likely to tell you can get this message saying when it lost contact and has no idea what your test failedLactate Threshold pace is.]]|}==An Example Test==Here's a video However, it still appears to be more of a test I did with the BSX. I sped up the 30 minute test so it lasts less than two minutes. Notice that my SmO2 says remarkably stable throughout the testwild guess.<br/><html><iframe width="560" height="315" src="https://www.youtube.com/embed/dIlDr3kayf0" frameborder="0" allowfullscreen></iframe></html><br/>[[File:Moxy Test 20150823 0825BSX Failed.jpgpng|none|thumb|800px200px|Here is the Moxy data from the same test, showing The message when BSX fails to reach a clear decline in SmO<sub>2</sub>, which is what you'd expect. This is in stark contrast to the BSX displayconclusion.]]
=Why Measure Lactate Threshold=
The obvious question is why do you want to know your Lactate Threshold. There are several possible reasons.
=Advantages of the BSX=
* '''Simplicity'''. The BSX is vastly simpler than other methods of estimating or measuring your Lactate Threshold. There are no blood draws that accompany traditional tests, or the need to perform multiple runs on multiple days as required by the gold standards MLSS test. In addition, the BSX gives a clear and unambiguous indication of your Lactate Threshold without need for any interpretation.
* '''Training Intensity. '''The BSX sensor can be used during training to show your SmO2 value. This is a big improvement over the Gen1, which could only be used for the test.
=Concerns with the BSX=
* '''Validity'''. While the BSX gives a clear and unambiguous result, it may not be correct. See "BSX Validity" below for a list of concerns.
* '''Single Protocol'''. The BSX app supports a single protocol that uses a an incremental load test with 3 minute stages. If you want to do any other test protocol, such as longer stages or something closer to the MLSS protocol, you can't.
* '''Single User'''. The BSX is sold as a single user device, and the software does not readily support sharing the device.
* '''Testing OnlyUsefulness'''. I have two concerns around the usefulness of BSX. The first issue is that [[Tempo Runs]] don't appear to be an effective form of training, so the value of knowing your Lactate Threshold seems rather limited. However, the BSX does not support any type could still be of value if it's a viable measure of use during training to monitor intensity, especially for [[High Intensity Interval Training]]. * '''Connectivity issues'''Typically, [[Heart Rate Training| Heart Rate Training suffers from drift]], so something more reliable might be useful. However, in my testing I had many problems getting found that the BSX did not seem to link to meaningfully reflect my training intensity. During either the BSX incremental treadmill tests or during [[High Intensity Interval Training]] the BSX showed a relatively stable muscle oxygenation. This is in contrast with the [[Moxy]] system that showed a heart rate monitor, better relationship between intensity and I succeeded only oncemuscle oxygenation. The indications are only noticeable change in muscle oxygenation that other users are having similar issuesI saw with BSX was during the initial transition from walking to running.
=BSX Validity=
I have a number of concerns with the validity of the results of the BSX.
* '''No independent validation'''. There is no independent validation of the results of BSX, which doesn't mean that the device it doesn't work, but it is a significant concern. There are some independent reviews (see below), but these are not really validations.
* '''Black Box'''. The BSX algorithm is proprietary and not clearly documented, which means it's hard to know if there is any scientific basis for their approach. BSX states that their algorithm is patented, but nowhere do they indicate what their patent number is. I believe it is patent US20130096403; see below for details.
* '''BSX Validation'''. BSX has performed their own validation but the results are not published. The reviews give some insight into the methodology that BSX uses, but the details are unclear. These reviews indicate that BSX did not use the gold standard of MLSS for [[Lactate Threshold]] in their validation. Instead they used an incremental treadmill test with lactate measurement from a blood draw, and relied on the rather poor Carmichael Training Systems determination of [[Lactate Threshold]]. I believe that this indicates that BSX has performed their internal validation against a seriously flawed baseline. (See [[Lactate Threshold]] for details.)
* '''3 Minute Stages'''. The BSX protocol uses an incremental test with three minute stages, which does not appear to be a valid approach for measuring blood lactate directly. This is because blood lactate takes 20-30 minutes to stabilize for a given intensity. Of course, it is possible that muscle oxygenation would not be subject to this limitation as it is measuring a very different physiological parameter, but it is another concern.
* '''%O2 DisplayMeasurement'''. In my testing, the BSX application showed measured a constant oxygen saturation level regardless of exercise intensity, typically 86 to 87%. This is in contrast to Moxy that showed a decline in oxygen saturation with increasing exercise intensity, roughly in line with the published literature. BSX has suggested that future versions of their software will present a more realistic estimate of oxygen saturation, and this problem should not indicate an issue with their validity. Personally, I find this a lack of even a relative change in oxygen saturation rather troubling.(The second generation BSX is exhibiting similar measurements to the first generation.)* '''Invalid Results'''. In my personal testing, the results of the BSX did not seem valid, but seemed to be based on what I told the application was my 10K pace combined with the pace at which I terminated the test. The BSX indicated I had a [[Lactate Threshold]] pace of between 6:10 and 8:50 depending on what 10K pace I input and what pace I terminated the test. This of course doesn't mean that the BSX couldn't detect LT for other users; it may just be that if I don't have an obvious change in SmO2, the BSX resorts to guessing. However, it means that you wouldn't know if the LT pace shown is valid or a guess. ** Tell BSX my 10K pace was 68:30 00 and terminating at 67:03 54 gives an LT pace of around 68:3017** Tell BSX my 10K pace was 67:30 and terminating at 57:43 04 gives an LT pace of around 67:1036** Tell BSX my 10K pace was 86:30 and terminating at 76:54 23 gives an LT pace of around 8:50** Tell BSX my 10K pace was 8:30 and terminating at 7:30 gives an LT pace of around 8:10* '''Exercise Ignored'''. A bigger concern is I got the same indicated [[Lactate Threshold]] pace if I tell the BSX I'm performing a test, but don't actually do any exercise. Just sitting still and terminating at the same point gives almost exactly the same result. 13
* '''Sensor Location'''. A minor concern is the location of the sensor on the calf, where it may be more affected by changes in biomechanics than using the quads.
=Testing BSX=
I performed a number of tests of the BSX. Other than a few tests when my hand an issue with excessive ambient light, the BSX always provided me with an estimate of my Lactate Threshold. The answer it gave depended directly on the input I gave the app about my 10K pace. As noted above, the estimate would vary wildly. Below is the data I captured from one of the tests. You can see the sudden rise in heart rate at the three minute mark that represents the end of the initial walk and the beginning of the running, and this is followed by a steady rise in heart rate. The red line represents the muscle oxygen saturation recorded by the BSX, and you can see that it detects the change from walking to running with a small drop, but thereafter remains relatively level. There is a slight drop from the first running section through to about the 15 minute mark, after which it levels off. You see a few small dropouts, but this might be an issue with the communications from the BSX to my watch. It's hard to see from this muscle oxygenation data that there is any indication of a change that would represent a lactate threshold. In fact it's hard to believe that the BSX is even really determining muscle oxygenation. (Note: the muscle oxygenation data is recorded as cadence data for compatibility.)
[[File:BSX LT Test.jpg|none|thumb|500px|Incremental Lactate Threshold test with the BSX.]]
I did all my tests with both the BSX and the [[Moxy]] for comparison. Unfortunately, I had a battery problem with my Moxy so I don't have as many samples to show. The image below shows the rising heart rate in blue, the BSX in red, and the Moxy in green. You can see that both the BSX and the Moxy drop as I transition from walking to running, but you'll notice that the Moxy continues to drop as the intensity increases. This is what I'd expect to see from a muscle oxygenation sensor. In my testing I've always seen the Moxy detect a drop in muscle oxygenation, and never seen one from any of my BSX sensors. I have no way of verifying whether the Moxy is accurate, but I can see that it is the least functioning.
[[File:BSX-Moxy LT Test.jpg|none|thumb|500px|Incremental Lactate Threshold test with both Moxy and the BSX.]]
=Patent US20130096403=
Patent US20130096403 A1 (Apparatus and method for improving training threshold), which is a patent for determining the Lactate Threshold using an incremental stress test with an infrared sensor. I feel reasonably confident that this is the BSX patent, but I could not confirm this and BSX seem to carefully avoid any reference to the details of their patent. The patent describes an experiment using a 3 minute incremental treadmill run on 34 subjects, which looks like multiple aspects of muscle oxygenation (SmO2):
* Ray also completed a single test, and his write up includes the chart of blood lactate levels as well as some different charts from the BSX software. For the test Ray estimated his 10K pace as 6:05 min/mile pace, and the BSX indicated a Lactate Threshold pace of 6:03 min/mile, with the BSX blood test showing 5:42 min/mile. Ray's blog also includes a vaguely similar plot to the one Matt includes, showing noisy data in red. This chart is simply marked "estimated" on the Y axis and has a different scale with no units. This chart looks like a visual estimation of the breakpoint in the muscle oxygenation, something that other researchers have used. The review also includes some charts of probability, which is intriguing, but hard to interpret. You can read Ray's write up at [http://www.dcrainmaker.com/2014/09/bloodless-lactate-threshold.html http://www.dcrainmaker.com/2014/09/bloodless-lactate-threshold.html]
* Another set of reviews that BSX did not mention were performed by Gabriel Hernando of zitasport.com. Gabriel has written five articles about his experiences with BSX, mostly covering the difficulty in getting it to work. Gabriel found that the BSX gave a Lactate Threshold that compared well with his Functional Power Test from cycling. You can read Gabriel reviews at [http://blog.zitasport.com/category/crowdfunding/bsx-insight/ http://blog.zitasport.com/category/crowdfunding/bsx-insight/] (this is in Spanish, but Google can translate it reasonably well.)
=BSX Gen 2Changes=The second generation of the BSX has announced Gen 2 of their product, with the following featureschanges:* improved New hardware, not just a software upgrade. The two units look virtually identical on the outside, but I assume there is internal changes.* Improved ANT+ and BLE connectivity . This does seem to have improved quite a bit.* realReal-time muscle oxygenation recording . * improved Improved graphs and overhauled design experience . I'd say this was only a minor improvement.* automated Automated KICKR integration (during endurance tests) . This is a cycling feature, so I didn't test this.* Full download of all workout files . I couldn't see how to do this, but it's not a big deal given you can record your workout with an Ant+ compatible watch.* ANT+ broadcasting to watches and head units . This allows you to record the muscle oxygenation on most Ant+ compatible watches.I will test * Improved light blocking in the new generation when it becomes available (target October 2015)compression sleeve. The Gen 2 product will be available at This is probably quite a discount to those who purchased big deal, and you should always use the compression sleeve that comes with the original deviceBSX.
