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Moxy
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{{DISPLAYTITLE:Moxy Muscle Oxygen Monitor Review}}
[[File:Moxy.jpg|right|thumb|150px]]
Moxy is a device for indirectly measuring exercise intensity, and could be considered an alternative to measuring blood Lactate. I believe it's most useful as a way of evaluating the effectiveness of an athlete's [[High Intensity Interval TrainingMuscle Oxygen Saturation]]or SmO<sub>2</sub>.
=Introduction=
Moxy works by shining infrared light through the skin and into the muscle to measure how much oxygen your blood is carrying to that muscle, called [[Muscle Oxygen Saturation]] or SmO<sub>2</sub>. The idea is that a hard-working muscle will use a lot of oxygen so the blood in the muscle will have less oxygen remaining. Moxy provides a figure for the percentage of oxygenated blood compared with the overall total. (For the technically minded, Moxy is looking at the differential infrared absorption from saturated and desaturated hemoglobin.) This technique has been used in laboratories for a while, but Moxy is the first device that is practical for regular use. Moxy is a small device that is taped above the muscle, and provides real-time information to a variety of devices including many recent Garmin watches. In many ways Moxy is a similar to a heart rate monitor, measuring something that is a proxy for exercise intensity. The Moxy approach is a little different to many others because it measures a specific muscle, and while that is influenced by overall exercise intensity it does provide some uniquely muscle specific insights. The Moxy has the characteristics of a research device rather than a consumer product. It's rather expensive, and some aspects of it are a little crude, but the flip side is that a lot more effort has gone into the underlying functionality. It's not a trivial device to get the best out of, and I think it will appeal more to coaches and serious athletes than it will to the recreational runner. While measuring [[Muscle Oxygen Saturation| SmO<sub>2</sub>]] is not equivalent to measuring blood Lactate, I think it can provide a similar type of insight.
Moxy continues this open, collaborative approach to post run analysis, making its data available in a standardized format and are working with various software makers to and in support for the Moxy SmO<sub>2</sub> data. I've used SportTracks quite successfully, as well as Golden Cheetah, even though it's really focused on cycling rather than running. There's quite a few other software packages that support Moxy's SmO<sub>2</sub> data.
=Moxy, SmO2, and Lactate Threshold=
There are a couple of generally used protocols to estimate [[Lactate Threshold ]] using Moxy. I've not seen any scientific research that confirms the validity of using these protocols to estimate Lactate Threshold. This type of validation is not trivial, as most protocols for estimating Lactate Threshold from measurement of Blood Lactate are extremely flawed. Having read extensively the research available on Lactate Threshold I have a suspicion that SmO<sub>2</sub>data may actually be rather more useful for estimating an athlete's anaerobic threshold.
* '''Incremental Stress Test'''. A common approach for measuring Lactate Threshold using a finger prick based blood lactate test is the incremental stress test. The athlete starts off at a moderate pace, which is incremented every few minutes until the athlete can no longer continue. Because blood lactate levels take around 20 minutes to stabilize at a given intensity this is a flawed approach. It's unclear to me if using the same incremental stress test can be used based on SmO<sub>2</sub> or not. It's possible that the SmO<sub>2</sub>value will respond far more rapidly than Blood Lactate, overcoming that weakness. Performing an incremental stress test with Moxy is a fairly straightforward, and the Lactate Threshold should match the intensity level where SmO<sub>2</sub> values drop continuously rather than stabilize. The graph below is from the Moxy website, and shows how this should look. <br/> [[File:Moxy Incremental.jpg]]
* '''The 5-1-5 Test'''. This test is broadly similar to the incremental stress test, but rather than having just a few minutes (typically 2 or 3) at a given intensity the athlete exercise is for 5 minutes, followed by a 1 minute recovery period and another 5 minute bout. The athlete performs several of these 5-1-5 bouts at incrementing intensities. Below is another Moxy illustration showing the incrementing intensities and the SmO<sub>2</sub> values. <br/> [[File:Moxy 5-1-5.jpg]]
=Usefulness of Moxy=
There is a lot of interest in measuring [[Lactate Threshold]] in athletes. This is partly because [[Lactate Threshold ]] has shown to be an extremely good a predictor of race performance, so it can be used as a way of evaluating the effectiveness of an athlete's training regimebut measuring lactate threshold is problematic at best. A second driver for measuring Lactate Threshold is the belief that training at the intensity that matches an athlete's Lactate Threshold is particularly valuable, a type of training often called [[Tempo Runs]]. Unfortunately, the available scientific research indicates that this is actually a particularly ineffective training intensity. So, while the value of knowing your Lactate Threshold might be limited, I believe there are valid reasons for using the Moxy. The biggest reason for my perspective Another use is as an objective to measure of the effectiveness of an athlete [[High Intensity Interval Training]] (HIIT). There is a great deal of research that shows that HIIT is an extremely potent form of training, and the Moxy can be used to evaluate if an athlete is working hard enough to drive down there SmO<sub>2</sub>. In additionHowever, the readings vary with placement and with other factors, so after years of using Moxy can be used to evaluate how different muscle groups are being activatedduring HIIT, I've not found any useful insight.
=Is Moxy Accurate?=
Without laboratory grade equipment that researchers use to study SmO<sub>2</sub> I have no way of independently validating the accuracy of Moxy. However, I did do some crude validation of Moxy as part of my testing of [[BSX]]. When performing an incremental stress test, research shows that the SmO<sub>2</sub> value should arise from its resting level quite rapidly then decline as intensity increases. In my testing, Moxy consistently exhibited this behavior, while [[BSX]] never showed any correlation between exercise intensity and its value of SmO<sub>2</sub>.
[[File:BSX-Moxy LT Test.jpg|none|thumb|500px|Incremental Lactate Threshold test with both Moxy and the BSX. You can see that the SmO<sub>2</sub>value drops for the Moxy, but not the BSX]]
=Total Hemoglobin (tHb)=
Moxy can also estimate the relative blood flow to a muscle, referred to as Total Hemoglobin or tHb. This is only a relative measure, but it does give some insight to how the muscle is being activated. =Moxy and BSX=A natural comparison for Moxy is the BSX, which also claims to be an infrared based SmO<sub>2</sub>sensor. While superficially similar, the 2 devices are radically different. The most important difference is that I've found no evidence that the BSX actually works to measure SmO<sub>2</sub>. The focus of the BSX device is to estimate Lactate Threshold, some think it does seemingly on the basis of how fast you can run during an incremental treadmill test. I would suggest that the accuracy of this result is on a par with athletes 10K race time or other similar endurance test. Moxy on the other hand deemphasizes their ability to estimate Lactate Threshold, instead focusing on the other, rather more valid uses.{| class="wikitable" |- valign="top"|[[File:BSX and Moxy1.jpg|none|thumb|x300px|The BSX sensor on the left with the Moxy sensor on the right. The BSX has no buttons, inputs or display, though you can reset it with a magnet. ]]|[[File:BSX and Moxy2.jpg|none|thumb|x300px|A view of the BSX and Moxy showing the infrared emitters and detectors.]]|}