Podcast #2 – Diving into Rewire with CEO and Co-Founder, Sun Sachs

Start Free with Rewire Fitness Today

What if we could practice for those most difficult moments that we’ll face in competition. For those moments when your mind begins to unravel and self-doubt starts to creep in. How could this type of practice change our lives, not only for sports but for anything that requires mental toughness?

Sun Sachs

On this episode, Ed Gibbins sits down with Sun Sachs, CEO and Co-Founder of Rewire Fitness. Sun started Rewire over a year and a half ago and we discuss his inspiration behind the product, what the system involves and its applications in sport and in life. We also discuss current affairs at Rewire including our beta program as well as some plans for the future.

Ed: Firstly, can you tell us a bit about your background? 

Sun: Yeah, of course, so I grew up in the mecca of endurance sports in the United States: Boulder, Colorado. I spent my early years in road racing as a junior and pre-junior and then as the sport of mountain biking came into being in the 80s I started to get on the mountain bike circuit. I did NORBA, downhill, slalom, cross-country, BMX and bike trials. I competed at a national level in cyclocross and I was also a bike messenger for seven years. So the way of the bike was my life, my whole lifestyle, and as I started to develop my career, I kind of shifted into different types of endurance sports like adventure races, triathlons, long-distance swimming, and more recently I’ve transitioned into doing some alpine climbing, which I’ve been really excited about – kind of growing in that experience recently. So just a lifetime and endurance sports. And then meanwhile, I also have been in software development for 25 years, so building all kinds of products many different kinds of apps since the advent of the smartphone and many web applications, working with some great team members. So it’s a combination of being a lifelong endurance athlete and software development – I’m also kind of a performance nerd!

Ed: So you’ve lived your life on two wheels and been all across the endurance world. Can you tell us how you started Rewire and why?

Sun: Yeah, so I’ve been aware of this science for quite a long time. Basically the science around Brain Endurance Training (BET). I had really just been so excited about it from when I first heard it and had been waiting for a commercial product to come to market and it really never did. One day I was on the trainer and I had this epiphany, I just thought: “Oh, this is how it could be done!” I kind of saw it as a user interface problem – like how do you do brain endurance training while you’re also doing your workout? It’s a little bit tricky. So I got together with my co-founder Cody and we developed a prototype and within a few weeks we had something working and we’ve been at this for about a year and a half really just honing in on the software and the hardware and furthering the product with beta testing. So that’s kind of how it started. 

Ed: Yeah, I mean, I think it’s really interesting how no one has sort of done anything with the mental toughness world. Every athlete knows the importance of mental toughness – when we’re talking to our athletes they say 50% to 90% of their performance (some even more) is on the mind. But, how many people actually spend time training their mind and what is there for it? So that’s what we’re going for. Can you speak a little bit more to why mental toughness is so fundamental to sports?

Sun: Yeah, of course. I mean it’s one of those things that’s almost cliche! We all know how important mental toughness is, and the traditional way to build mental toughness or resilience is to beat your body up! You can go on a five-hour ride, three-hour run – it works, but you can’t do that every day! And so, our solution is that we think of it rather than a hammer of beating your body up, it’s more like a scalpel. It’s very targeted, it targets the part of your brain that’s responsible for impulse control, for effectively managing your willpower, and your perception of effort. So what we’re essentially doing is adding more mental load to the workout, so that you adapt over time and become more resilient when you’re under fatigue. Basically, when you’re in those moments of competition or even just having a tough day, that’s when you want to be able to have that breakthrough of the wall and be able to up your game, and not have your brain be the limiter. So that’s a big part of why we develop the product. And then when you think about it, on the hardware side for sports products, at some point you can’t get a faster bike, right? You can only get so aero! At some point you just can’t put any more hours into training, what then? We’re down to the point where, with sports science which is evolved tremendously over the years, we’re down to marginal gains for athletes that take sport very seriously. What’s the new frontier? The obvious area, which has been sitting in front of us for decades, is mental performance. And so our goal is really to help athletes unleash their ultimate performance, to create opportunities for them to build their self-confidence, to build their mental resilience, and to give them practical ways to do that, with the software and the hardware combination

Ed: Definitely, when I spoke to Walter last time we spoke a little bit about David Goggins and the kind of athletes that just train their mind by pushing that body, and that’s great to a point – but bringing it into much more controlled environment is definitely needed. 
As you mentioned, you’ve been following the science for over 10 years now are there any studies have jumped out to you and really forged Rewire?

Sun: Yeah, there’s definitely quite a few. I’ll mention one that our chief scientist did where he basically took 35 amateur cyclists and he had them trained for three months. The control group trained on a trainer three times a week and the test group basically did the same indoor training but also layered on brain training. And as you’d expect in three months of consistent training the all the athletes improved, you know on the physical side. The control group improved by 40% but the brain endurance group improved by a 120% basically a 3X Improvement in performance! And what that actually translated to was five minutes longer on a time to exhaustion test, which is basically an effort where you go until you literally can’t go any longer! Five minutes is significant, 3X is insignificant. You don’t get that from an aero helmet!

Ed:  No, you don’t! Yeah, definitely and with the Rewire team being all athletes we all understand the importance of mental toughness in sports. I know when playing rugby some of my best performances of come when I really had to use my mind in the best way. And equally the other way around when failures occurred it’s because I’ve made bad decisions at that moment and having that ability to keep focused and keep mental toughness is crucial and I think when we look at the highest level of sports and the highest athletes up there, they’ve all got a certain level of mental toughness. 

Sun: Yeah, they’ve done some comparisons in one study between amateur and elite athletes basically looking at their mental resilience. And the elite or pro athletes when under a lot of mental load, even specifically during this cognitive type of training, they had a much more realistic or accurate perception of their effort and were able to maintain their physical and mental goals. Whereas the amateur athletes just didn’t have that same level of resilience built up. What’s exciting about that is that just shows that there is something cognitively that influences performance significantly and from what the science has shown it’s something that could be trained. That’s what we aim to do: create tools for athletes. The other aspect of mental toughness, there’s another study where they basically looked at all the attributes of mental toughness. On the psychological side, there are factors that are obvious and ones that are not so obvious. So self-confidence ended up being the number one attribute for mental toughness – that’s kind of obvious. But positive cognition was the second one, and that’s basically the things you tell yourself when the going gets tough. So if you start to do a negative spiral, I would say probably all of us know how that can go. But if you can shift into more of a positive mindset and keep the motivation up, that’s really where you’re going to see great results. So with our product, we also think about it in terms of mindset and in terms of mental and physical recovery.  So not only do we have a brain endurance component. We also have a tool that will help athletes sort of reset their mind or get into a positive mindset before competition. We all have our pre-race rituals and the things that we like to do to get into a good mindset and this provides tools that will help you go through those steps that help you have a calm, ready state before competition. 

Ed: Definitely! Science, over the past 10 years, is really starting to show the importance of the brain in performance. When we look at the older studies – it’s heavily focused on physiological aspects and now it’s starting to show it’s how the brain perceives that. And how we respond to that, and how we train our minds to improve performance is really starting to get crucial. And you mentioned pre-game rituals and rituals in the game. It’s really interesting because every athlete knows the importance and uses them. For myself, I have three clicks and a tap on my leg and that would be my reset button if I encountered any bumps in the road. So we all know how our mind works and we’re just needing to start to train it now. As you said we need to ‘unleash our performance’. So you mentioned the mindset recovery component of the Rewire system, can you speak a little bit more about what that involves?

Sun: Yeah, definitely! So we combine different scientifically proven protocols that will activate your physiology for recovery and get yourself into a positive mindset. They can be used either actively or passively. So for example, you can go through an exercise where we use box breathing, used by the Navy Seals, and that actually brings your body into a parasympathetic response and you can literally see your heart rate variability (HRV) improve over that session. And then we have protocols like binaural beats so you can literally just listen in your ear buds. And it’s a two-tone frequency, which follows the phenomenon known as brain entrainment, which basically your brain hears these lower-level frequencies and it tries to mirror them. So if we want somebody to get into a relaxed state we can play a theta waves binaural beat, and it is blended into some relaxing music. So it just feels like you’re listening to calm, meditative music, while at the same time, it’s entraining your brain to be in a more relaxed state. You can use it in a variety of ways: at the end of a recovery session to help you get in the right mindset, pre-training to have a positive perspective and build your confidence, you can use it before competition with a series of different steps that you can choose from to get into you in a calm, ready state. So there’s really a lot of different ways it can be used. And the other aspect of it is we track your physiology so we have some objective and subjective measures. We measure your own perception of relaxation and then also your heart, HRV and other data points. So you really can understand what’s effective and what’s working for you. Then in the future, you can basically choose the protocols that work best for you.

Ed: Can you explain in more detail about what the product is and how it’s working? 

Sun: Yeah, so it’s a hardware and software product where you basically have wireless buttons that you hold in your hands or attached to a training device like a bike, rowing machine or any number of different training equipment and then you use your smartphone to do cognitive tasks while you’re training. So you might get on a bike trainer and do a normal workout and while you’re doing that you’re layering on brain training by looking at your phone and answering these cognitive tasks questions. Then on the metrics side, we also track your physical performance, which is your objective metrics and then a number of cognitive metrics and lastly we compare all of that against your subjective rating of effort. That allows us to track your mental resilience over time, so you can really see a measurement of how you’re doing and how you’re improving. 

Ed: That last bit that you just mentioned about having that metric that tracks your mental toughness. I heard on a Joe Rogan podcast with Ross Edgley, the first man to swim around Great Britain, they were talking about “when are we going to get that metric that tracks our mental toughness”. That’s now! You’ve been training with the product since you first created it. How can you say it applies to sport and also life in general?

Sun: If you can do something that will prepare you for those moments in life when things feel like they’re unravelling and when they feel almost impossible to get through. If you can actually train for those moments, how would that impact sport, but also your life in general. Walter mentioned in his studies in the last podcast episode, the mental resilience really kicks in when you’re at a heightened level of fatigue. So what’s what it really is doing is preparing you for those toughest moments in life. Just imagine if you could do something that would prepare you for how to respond well when things get tough and to keep a calm mind and a positive outlook, the benefits would be profound. I’ve noticed definitely in sport it’s made the training feel easier. It’s made me a lot more confident going into a workout, hopefully soon a competition! And then in life too, I definitely have a busy lifestyle with this startup and my other responsibilities. And I’ve found a growing level of resilience having done this consistently now for the past year and a half and it’s really helped me just overall with my quality of life. 

Ed: The perception of effort part that you mentioned that’s critical! I spoke a lot with Walter about that last time, that sort of the piece of the puzzle that is going to increase your performance as you reduce your perceived exertion at the same intensity. So it’s a critical part of it. We’ve been running our second beta program for the past two months. Please can you speak a bit about that?

Sun: Yeah, we have a great group of men and women, elite and amateur athletes mostly in endurance sports. To top line some of their resumes and accomplishments: a former world duathlon champion and ultra runner, the current world record holder for Lands End to John O’ Groats, winners of prominent triathlons and we just recently started collaborating with an elite junior bike racing team in Europe and then quite a few coaches. We’re also collaborating with some organizations in your world, with elite and pro rugby teams. So we started to cross over into a lot of different sports and it’s really been interesting to see how many different types of athletes are interested in this! We’ve had applications to our beta program from strength athletes to tennis to sailing to boxing. You name the sport, athletes are interested in this! And now is really the time because you know, as we mentioned, this is the next frontier for performance and people are looking for that. They’re looking for new ways to get better and this area of performance is virtually untapped. So we’ve been excited and it’s been really helpful to have our beta athletes help us with improving the product and really making it seamless as possible for training and competition. 

Ed: So like we mentioned the majority of our current beta test is with a range of abilities of cyclists and triathletes. We will also be starting one with runners soon, can you speak about how the system is going to integrate with other sports? 

Sun: Yeah, definitely. So, we started with endurance athletes. Definitely partially based on my background and the sports that I know. But, we definitely see this to be a product that is applicable to all sports. And we’re building some foundational pieces to it. Right now, we have a lot of cognitive training that’s based on visual tasks, so in other words, you’re looking at the screen of your smartphone. But, we’re also adding audio-based tasks so athletes will be able to go out for a run with our brain training wireless buttons that they can hold in their hands and they can basically answer cognitive questions while they’re running or doing a variety of other sports: could be in the gym, out on the track, could be playing soccer, could be any number of sports. So we definitely aim to provide some tools that’ll make it easy and seamless for any athlete to use these tools. 

Ed: Definitely, I mean it is an exciting avenue that we’re in. A brand new field, and brand new kind of training and something for the future with the brain being the next frontier in marginal gains. Thanks for talking to me today Sun! I think we’ve got a really exciting future. It’s a really exciting new world that we’re exploring in terms of unlocking that next performance gain by training the mind, so I’m really excited and happy to be a part of it. And yeah, let’s keep it up! 

Sun: All right. Thank you so much, till next time!

“You have power over your mind – not outside events. Realize this, and you will find strength.”

Marcus Aurelius

Join Our Community!

Training For The Mind: Getting Comfortable With Being Uncomfortable

To the untrained eye, the reason that we exercise is to simply improve our fitness. We lift to improve our strength and build muscle and we go on long runs, swims or rides to develop our endurance. That is what, at the most basic level, training is all about – improving our athletic performance.

Sometimes I hear people disregard rest days and the importance of recovery. I usually laugh at this as the inner scientist in me cringes. At first glance, this attitude would seem to come from the false belief that improvements in our physiology occur in the gym and whilst exercising, rather than in our sleep and time spent recovering, and for the vast majority of people, it is likely to be true that they are incorrectly taking this ‘no rest’ approach with the aim of improving their fitness.

However, to some, there is more to training than simply improving fitness. To some, training is less about the body, than it is about the mind. Take David Goggins for example, he never has a rest day, and to many, this would seem crazy and futile. But, the most important thing to him when training is the development of his mental toughness. For some people, training is not about improving their body or fitness, these are just welcome bi-products. Instead, training is about the mind. Creating a high level of suffering to develop their mental toughness and themselves as a person.

‘Who on this f**king earth would be going right now? You are! I believed it enough to where my body said: “he’s not gonna stop”.’

David Goggins

I’m certainly not suggesting that you do go at 100% all the time, and you should give yourself time to rest and recover. But we can learn a lot from the mentality shown by Goggins: we should not be using science as an excuse for slacking. In that sense, you would only be cheating yourself. We should however use the science when it is correctly applied and take appropriate recovery for the our exercise. Indeed, by its very definition, you cannot recover without putting the work in first.

“At dawn, when you have trouble getting out of bed, tell yourself: “I have to go to work — as a human being. What do I have to complain of, if I’m going to do what I was born for — the things I was brought into the world to do? Or is this what I was created for? To huddle under the blankets and stay warm?”

Marcus Aurelius

If we cave in to feelings of needing to stop we our losing an internal battle with our mind, and the mind is immensely powerful. Under conditions of mental fatigue our endurance performance is shown to decrease significantly (1,2). Yet, the science shows that using Neuro Training over a 12-week programme was shown to yield 3x the improvement in athletic performance in a time-to-exhaustion trial (3). By putting our mind under uncomfortable conditions and testing our mental capacities we can break the boundaries of what was previously possible. Learn how we help athletes and those looking to level up their human performance increase their mental resilience.

“That’s one of my big things too is, you know, getting comfortable with being uncomfortable”

Laura Kline – Rewire Athlete

Related Readings:
What is Neuro-Training?
Overview of Rewire’s Neuro-Training System
Brain Endurance Training for Athletes: What You Need To Know

P.S. Try our FREE Online Mental Toughness Challenge!

Join Our Community!


1.        Marcora SM, Staiano W, Manning V. Mental fatigue impairs physical performance in humans. J Appl Physiol. 2009; 

2.        Lopes TR, Oliveira DM, Simurro PB, Akiba HT, Nakamura FY, Okano AH, et al. No Sex Difference in Mental Fatigue Effect on High-Level Runners’ Aerobic Performance. Med Sci Sport Exerc. 2020;Volume Pub. 

3.        Marcora SM, Staiano W, Merlini M. A Randomized Controlled Trial of Brain Endurance Training (BET) to Reduce Fatigue During Endurance Exercise. Med Sci Sport Exerc. 2015; 

Recommended Reading

Can’t Hurt Me
by David Goggins

by Marcus Aurelius

The Obstacle is the Way
by Ryan Holiday

The Joe Rogan Experience #1212 – David Goggins

The Tim Ferriss Podcast: Ryan Holiday (#4)

Why Cognitive Training is the Next Big Development in Sports


In recent decades, the application and development of science in sports has boomed. Elite teams and athletes have sports scientists working with them to push limits further than ever before.

Perhaps one of the most interesting recent examples of this is the concept of marginal gains, an idea championed by Sir Dave Brailsford, former Performance Director of British Cycling and GM of Team Ineos. Marginal gains is the concept that it is possible to increase performance by 1% in many specific areas and these tiny improvements add up to create significant overall improvement. This philosophy aided in the incredible development of Team GB’s cycling team, changing them from a laughing stock to a thriving team that won 16 Gold medals across Beijing 2008 and London 2012.

Sir Dave Brailsford (left), the pioneer of the Marginal Gains Philosophy

Brailsford made changes across a wide array of areas previously thought unimportant in order to create these marginal gains. This included the team bus layout, introduction of antibacterial hand gel to reduce infection and illness and adaptations to the warm-up. These marginal gains accumulated and the significant improvement was indicated by the medal haul.

However, one seemingly neglected area of sports science so far has been cognitive training, despite how important mental toughness is perceived to be in sports. We are forever bombarded by quotes expanding on the idea of ‘mind over matter’ but little is done to actually train the mind. We need to train the mind to be more resilient to the mental fatigue that we will inevitably face in competition to improve decision making, reduce our perception of effort and enhance positive thinking and motivation.

Some athletes have already started on a journey of cognitive training. Tom Brady has used brain training to sharpen his mind, relax his brain post-game and to improve his sleep. He also uses it to build resilience to protect against future concussions.

Cognitive tasks like a Go/NoGo task can help athletes like Brady, who are tested under extreme pressure,to make smart split-second decisions. This has been shown in a study with fencers that showed that they had better reaction times in discriminative tests but not in simple reaction tests (Di Russo et al., 2006). This demonstrates that they have the ability to make good decisions consistently under pressure. 

Response inhibition tasks like the Stroop task can help to train our mental endurance and tolerance to mental fatigue. Mental Fatigue has been shown to significantly reduce endurance performance through an increase in RPE (Marcora et al., 2009). By performing cognitive training we can increase our tolerance to mental fatigue, reducing its negative effect. In fact, using Brain Endurance Training over a 12-week programme was shown to yield 3x the improvement in athletic performance in a time-to-exhaustion trial (Staiano et al., 2015).

Cognitive training creates huge improvements in performance. Its lack of adoption so far is somewhat nice to know as it shows that there are still boundaries to break in sport and I’m sure with adoption we will see records being broken even further. It also allows the introduction of new metrics. An objective mental stress test, yielding a mental stress score, will be able to assist with athlete monitoring above and beyond current subjective measures. Perception gap, a new metric that is part of the Rewire system, is a measure of the difference between Self-Rated RPE and objective work output with data from heart rate monitors and power meters. By tracking this you can measure your mental performance over time. The goal is to reduce the perception gap when under mentally fatiguing situations so that your mind is not a limiter to achieving your true athletic potential.

If we thought marginal gains were squeezing the last bit out of human performance, we were wrong. 10 years of science has already shown that cognitive training has the potential to yield huge improvements in athletic performance. 

Buckle up and get ready for the next wave of athletes to break records and achieve new heights in athletic performance powered by new brain training solutions hitting the market over the coming years.

Studies Covered in Article for Further Reading

“Neural correlates of fast stimulus discrimination and response selection in top-level fencers”
by Francesco Di Russo, Francesco Taddei, Teresa Apnile and Donatella Spinelli
Neuroscience Letters, 2006

“Mental Fatigue impairs physical performance in humans”
by Samuele M Marcora, Walter Staiano and Victoria Manning
Journal of Applied Physiology, 2009

A Randomized Controlled Trial of Brain Endurance Training (BET) to Reduce Fatigue During Endurance Exercise” 
by Walter Staiano, Michele Merlini and Samuele M Marcora
Conference: ACSM Annual Meeting, 2015