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RT300 vs. the MyoCycle

Considering buying an FES bike and exploring your options?

The MyoCycle Home and MyoCycle Pro are medical devices that use functional electrical stimulation (FES) to help people with muscle weakness or paralysis to exercise by pedaling a stationary bike. Such devices are commonly known as FES bikes. Though the MyoCycle is relatively new, the idea of an FES bike is not. In fact, there have been several FES bikes on the market since the 1980’s, and the benefits of FES-cycling are clear. So what’s different about the MyoCycle? This guide answers that question, beginning with an explanation of how new medical devices in the US are regulated by the FDA based on the idea of substantial equivalence. From there, we explore three key aspects of an FES bike – therapy, ease of use, and affordability – and compare the MyoCycle to the RT300, the most prevalent FES bike on the market today. If you’re interested in purchasing an FES bike and are exploring your options, or if you just want to know more about FES bikes, then this article is for you.

I – Substantial Equivalence

The FDA has cleared the MyoCycle for sale in the United States. The review was part of the FDA’s 510(k) Premarket Notification process since the MyoCycle is a Class II medical device with similar devices already on the market (predicate devices). This means that the FDA reviewed MYOLYN’s claim that the MyoCycle is “substantially equivalent” to a predicate device in terms of safety and effectiveness, and they agreed.

The FDA’s 510(k) process is important and necessary for ensuring that new medical devices are safe and do what they claim to do. The process hinges on the determination of substantial equivalence, but what does that really mean? According to the FDA, a device is substantially equivalent if, in comparison to a predicate, it has the same intended use and is at least as safe and effective as the predicate.

In other words, if a medical device has 510(k) clearance from the FDA, it has been proven to be at least as safe and effective as a predicate device.

The MyoCycle 510(k) demonstrates substantial equivalence to the original RT300 (K050036). Both devices use a motorized stationary ergometer, have six channels of stimulation with similar stimulation parameters, and connect to the Internet to save and upload data and settings. While various upgrades can be added to the basic RT300 (more channels, arm-cycling, higher stimulation intensities), these all increase the cost and complexity, making them more suitable for clinical rather than home use. The design of the RT300 has changed since it was originally released, but the basic operating principles remain the same. The rest of this guide compares the MyoCycle only to the original RT300.

To summarize, the FDA has ruled that the MyoCycle is substantially equivalent to the original RT300, meaning both devices are safe and effective for their intended use.

II – Therapy

An FES bike combines two therapeutic modalities into a single system: FES and cycling. Let’s explore how the MyoCycle and the RT300 implement each of these modalities.

FES

Functional electrical stimulation (FES) uses small amounts of electrical current to cause targeted muscles to contract, enabling people with weakened or paralyzed muscles to perform functional movements. Ultimately, the effects of FES depend on the stimulation parameters and the stimulation pattern. The stimulation parameters boil down to frequency (stimulation pulses per second, usually in Hz), intensity (combination of pulse amplitude in mA and pulse width in µs), and waveform (the shape of the stimulation pulses).

The stimulation parameters on the MyoCycle and the RT300 are similar. Both devices use rectangular, charge-balanced waveforms, and the frequency used by both devices is similar. The RT300 has a wider range of parameters and higher stimulation intensities, while the MyoCycle uses parameters and intensities selected specifically to maximize cycling power output and efficiency.

The stimulation pattern determines which muscle groups are stimulated and how the stimulation changes over time. For FES-cycling, the stimulation pattern is linked to the pedal position, so a particular muscle group is ideally stimulated when that muscle group can help the pedaling motion. Stimulation patterns are typically depicted as in the figures below. In the top figure, LQ and RQ denote the left and right quadriceps while LH and RH denote the left and right hamstrings, respectively.

FES bike pedal position for quadriceps
FES bike optimization for hamstrings

From the figures, you can see that there are three basic characteristics of a stimulation pattern: muscle groups, on/off angles, and shape.

Both the MyoCycle and the entry-level RT300 use six channels of electrical stimulation. The MyoCycle is designed to target the quadriceps, glutes, and hamstrings muscle groups. The RT300 can be used with additional muscle groups, and the stimulator can be used in a standalone mode. The quadriceps, glutes, and hamstrings muscle groups are some of the biggest muscle groups in the body, and the reported benefits of FES-cycling can be had by stimulating only these muscle groups. MYOLYN recommends that customers who want to stimulate additional muscle groups buy an affordable standalone muscle stimulator, like this one.

The on/off angles for each muscle group determine when the muscles will actively pedal the ergometer. The RT300 uses default values that can be adjusted manually by a technician. The MyoCycle’s on/off angles are automatically determined for each rider based on that individual’s geometry. This is one of the most important distinctions between the MyoCycle and the RT300: MYOLYN’s proprietary algorithms for determining when and how much to stimulate the rider’s muscles. MYOLYN’s proprietary algorithms were developed by co-founder Matthew Bellman, PhD, to automatically customize the stimulation pattern for each rider. This customization is based on the rider’s geometry and optimizes the power output and efficiency of stimulating the rider’s muscles. Indeed, recent research at the Miami Project to Cure Paralysis has verified the advantages of this customization.

Cycling

Both the RT300 and the MyoCycle utilize motorized, recumbent, wheelchair-accessible, stationary cycle ergometers (powered exercise bikes that can be used from a wheelchair).

The design of the RT300 is similar to that of the THERA-Trainer tigo, manufactured in Germany. The THERA-Trainer is an “active-passive” exercise bike designed to assist riders in pedaling if they pedal below a target speed or resist them if they pedal above the target speed (loosely isokinetic). FES is added to stimulate the riders’ muscles more or less depending on how fast they pedal (more stimulation if pedaling slower, less if faster). The target speed and the behavior of the FES can be manually adjusted, and the RT300 has various workout modes.

The MyoCycle ergometer is custom-designed and assembled by MYOLYN, and it was designed specifically for true isokinetic FES-cycling. The MyoCycle’s motor always maintains a constant 35 rpm, providing only the amount of assistance or resistance necessary to maintain that speed (isokinetic). FES is applied based on the Level selected by the rider and the rider’s geometry – it doesn’t change with speed or resistance – so the rider is always in control of the amount of work generated by the muscles.

Both the RT300 and the MyoCycle display workout time, distance, power output, and calories burned. The main difference between the two is how power and calories burned are calculated. The MyoCycle is only commercially available cycling system that calculates active power output. This means that the MyoCycle takes the power the rider needs to produce just to move their own legs (passive power) into consideration and not just the force being applied to the pedals. This answers the question: how much work is the rider doing versus the motor? The power displayed by the MyoCycle is from the rider and only the rider.

To summarize, the RT300 and the MyoCycle both apply FES to the rider while a motorized ergometer assists or resists the pedaling, as appropriate. While the technological means for achieving this behavior differs between devices, the therapeutic effect is substantially equivalent, as both devices keep the legs moving while exercising the muscles. By doing so, both the MyoCycle and the basic RT300 are able to provide the following therapeutic benefits*:

  1. Relaxation of muscle spasms
  2. Prevention or retardation of disuse atrophy
  3. Increasing local blood circulation
  4. Maintaining or increasing range of motion

Therefore, the entry-level RT300 and the MyoCycle achieve substantially equivalent therapeutic effects, though the technological characteristics are different.

*The most recent upgrade to the RT300 added wide pulse stimulation and allows Restorative Therapies to claim that the RT300 can be used for muscle reeducation.

III – Ease of Use

Anyone who has used both an RT300 and a MyoCycle will tell you that the MyoCycle is easier to use.

The MyoCycle was designed to be as simple and easy to use as a regular exercise bike. Large buttons, simple setup, easy-to-read displays, and single-handed operation were critical design elements in making the MyoCycle fool-proof for use at home. This design allows someone with little to no experience to setup the MyoCycle very quickly. Because there are so few decisions the user has to make in setting up and using the MyoCycle, there is very little chance for user error. While this simplicity limits the flexibility of the MyoCycle, users can always get a good workout without spending a lot of time and effort on setup, and they can do so independently.

The RT300 is highly adjustable, offering a wide range of settings and flexibility for clinical use. However, greater adjustability can lead to a tuning process that is costly, time-consuming, and susceptible to user error. For this reason, patients who buy an RT300 for use at home typically have a specialist come to their home and set it up for them. Once setup is complete, many of the settings are locked so that users don’t accidentally change them. To change these settings, customers call RTI or their clinician to have them remotely change the settings over the Internet.

In contrast, the MyoCycle uses proprietary algorithms, developed by co-founder Matthew Bellman, PhD, to automatically customize the stimulation settings and stimulation pattern for each rider. This customization is based on the rider’s geometry and is aimed at maximizing the power output and efficiency of stimulating the rider’s muscles. Beyond that, MyoCycle users only need to adjust a few simple settings to get the most out of their workout.

Moreover, MYOLYN designed the entire MyoCycle from the ground up with painstaking attention to every detail that can affect usability. For example, the MyoCycle chair attachments can be easily reached and adjusted with one hand by the rider. Every detail matters, and it is the attention to detail in the design of the MyoCycle that make it such a pleasure to use.

To summarize, the MyoCycle trades flexibility for usability, enabling users to get a great workout without spending so much time and effort on setup.

IV – Affordability

The MyoCycle is, without a doubt, the most affordable FES bike on the market. In fact, even the entry-level RT300 costs substantially more than a MyoCycle, and the fully-featured RT300 costs much more. There are two main reasons, already mentioned in previous parts of this guide, for why the RT300 is so much more expensive.

The first reason has to do with design and manufacturing. MYOLYN designed the MyoCycle from the ground up to be as affordable as possible, and most of the MyoCycle is manufactured here in the USA to minimize costs without sacrificing quality.  

The second reason has to do with usability. Since the RT300 often requires setup by a trained specialist, when someone buys an RT300 for use at home, RTI typically sends a trained specialist to that person’s home, where the specialist spends hours setting the RT300 up and teaching the person how to use it. Therefore, the cost of an RT300 at home normally includes the costs associated with compensating that specialist for their time and effort. The costs are similar for clinicians who buy an RT300, but clinicians often pay RTI for extra training, especially for new clinical staff, which can cost even more. In contrast, the MyoCycle is so easy to use that anyone can set it up and use it by themselves without specialized knowledge or training.

To summarize, the MyoCycle is so much more affordable because it was designed from the ground up by the MYOLYN team to be that way.

V – Conclusions

Having compared and contrasted the key aspects of the MyoCycle vs. the RT300, we can now draw conclusions to help people who are looking to buy an FES bike to make the right choice. In terms of safety and effectiveness, the MyoCycle and the original RT300 are substantially equivalent, meaning that riders can get a great, safe workout with either device. In terms of usability, the MyoCycle is much easier to use, meaning that riders can spend less time on setup and more time on getting a great workout. In terms of affordability, there is no comparison – the MyoCycle is much more affordable. So, if you’re looking for an FES bike with all the bells and whistles and can afford the price tag, the RT300 is for you, but if you’re looking for an easy-to-use and affordable FES bike, the MyoCycle is for you.

If you’d like to learn more about the MyoCycle or how to get one, please contact us for more information.