Moxy: Interview with Andri Feldmann

Andri Feldmann is Sport Scientist and doing his doctorate at the institut for sport science of the university of Bern on the subject of «NIRS and task failure prediction». He’s a co-developer of the Moxy Monitor (Fortiori Design, LLC). After completing his master’s degree, Andri Feldmann co-founded a company in Switzerland to consult coaches and athletes on how to apply Moxy to training and testing. The company was sold and now Andri Feldmann is doing his doctorate and works part-time for the DACH distributor of the Moxy Monitor (Idiag AG) on product development. 

Basics about Moxy can be read in the previous blog post.

Hi Andri, thank you very much for taking the time to talk about Moxy. You have been involved in the development and application of Moxy for several years. To the general public in the triathlon scene Moxy has only been known for a few months and is only vaguely known. Who used Moxy so far mainly?

While NIRS has been used in research for many years, the application of NIRS in applied sports settings is fairly new. Moxy Monitor is really the first athletic orientated NIRS device on the market and was launched in 2013. Considering the often-conservative nature of athletes, trainers and sport organisations it takes many years for technology to catch on. Powermeters are a good recent example. For this reason, the user field is small. Nonetheless, now there is a diverse field of users from researchers and scientists, to coaches and trainers, as well as individual athletes.

I could not say which group has the highest user rate. Because I grew up in Canada we did start with significant application in hockey, which was an excellent showcase for Moxy Monitors application in interval sports, looking at performance and recovery of the physiological system. Naturally oxygen orientated measurements tend to draw endurance athletes and cycling sport in the USA has been a large consumer as well. Recently, with my research in Bern I have been able to do research with climbers which showcases the ability to measure local muscle groups, like forearm muscles in climbers, contrasting to systemic measurements in cyclists.

Performance Tests of the German Biathlon Team in 2018.

The Norwegian triathletes have attracted a lot of attention with their pictures. How can Moxy be used in triathlon training?

I do not know how the Norwegian team uses the Moxy, but I can make some assumptions. Firstly, it can be used as a diagnostic tool, much like blood lactate or VO2 assessments. Numerous publications show that there is a relationship between these classical parameters and NIRS, therefore you can use Moxy Monitor to develop classical training zones. However, because Moxy is a real-time measure you can use this same information to identify changing training zones directly during a training to assess steady state condition or MLSS.

Other applications involve for example assessing HIIT. Unlike Heartrate, which has a considerable lag time, NIRS responds instantaneously. You can track the imbalance of O2 supply and demand during the activity portion of your HIIT and then assess your recovery.

Finally, an interesting component of NIRS is that, because it assesses O2 supply and demand, which is muscular VO2, you can make educated assumptions about VO2 limitation. Numerous clinical studies show changes in NIRS signal as a result of O2 supply limitations like cardiac output reduction, or O2 demand limitations in mitochondrial myopathy.

Can you demonstrate this with a concrete session?

A study we did in Bern two years ago I think nicely shows the strength of applying NIRS in training. There is some discrepancy between active and passive recovery during Sprint Interval Training (SIT). We decided to do repeated SIT with active and passive recovery and at the same time track NIRS. Our assumption was that which every protocol allowed muscle oxygenation as measured by NIRS to recover faster and higher would also be better suited for repeat performances. This is exactly what happened, during the active recovery NIRS did not recover as well and repeat performance was reduced. The passive recovery, counter-intuitively for many of my coaching contacts, showed a better recovery in the NIRS signal and a better repeat performance. In this example NIRS helped us understand recovery and presented itself as a suitable indicator to assess recovery during SIT.

Does the use of Moxy in triathlon make sense? If so, what added value can this bring?

Yes, it can. Firstly, adding any new technology must firstly not disrupt current performance. If a new monitor disrupts the athlete, it may just have negative consequences. The athlete must be comfortable with the new tool and understand its benefits. Essentially, there must be a trust relationship. The advantage of NIRS during endurance competition is first and foremost assessing day to day variation in performance (Tagesform). It gives you feedback about maximum steady state performance of today. While power is a great tool and works nicely together with NIRS -I would recommend using the two measures together-, if you ride 200 watts as your maximum steady state for your race because that is your experience, considering a good 10% variation in performance from day to day, you might either explode because your performance level is 180, or under performance because today it would have been 220. Then secondly, with the introduction of drafting in triathlon, NIRS can help gauge recovery in a draft and performance expenditure if you leave the draft.