Where It All Started

I stumbled upon the Exerfly company back in 2021 while researching flywheel training. I was in the process of learning about flywheel resistance in general and wanted to understand if it could be a helpful tool within my training framework.  

The most common thing being said about it at the time was that it uniquely facilitated eccentric overload. I thought this was a very general thought and knew that there had to be more nuance to flywheel training in general and particularly the ability to overload the eccentric phase.

Not only did I come to find that the yo-yo nature of flywheel resistance can load both the concentric and eccentric phases equally well, but I noticed that coaches had to be very creative with their set-ups to get this eccentric “overload” they were espousing. After perusing through the landscape of companies making flywheel equipment, I discovered that none of their products overloaded the eccentric phase on their own.

That is until I found Exerfly and noticed they were advertising an eccentric motor feature that sped up the disc during the eccentric phase by a chosen percentage greater than the speed facilitated by the user during the concentric phase.  

After receiving one of the earliest versions of the motorized platform, I was able to use force plates to measure vertical ground reaction forces to confirm that the use of the eccentric motor did indeed facilitate higher force production during the eccentric phase.  

I want to be clear that flywheel resistance is a great way to load both the concentric and eccentric phases, but it is important to know that the eccentric motor is a valuable feature because we are inherently stronger eccentrically than we are concentrically. Because we are stronger eccentrically, a piece of equipment that can easily provide higher resistance during that phase is advantageous to avoid underloading it.  

Even more beneficial is the quality of Exerfly’s motor technology that allows for incremental adjustments to the intensity of the motor. Small percentage increases to the added speed from the motor can provide a safe and smooth journey through progressive overload.  

I have used plenty of equipment that allows for phase specific resistance control, and I can confidently say that Exerfly’s technology provides one of the smoothest transitions between the concentric and eccentric speeds.

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Where Flywheel Training fits

Beyond Exerfly’s build quality and the unique eccentric motor feature, I still had to gain experience and understanding of where flywheel training fit within my training framework.  

Having several years of experience using the Exerfly platform and rack mount, both with the eccentric motor, I now believe it is best used as a means for dynamic efforts to improve speed strength, or the capacity to produce force fast.  

I do not believe flywheel resistance services repetition and max efforts as well as isotonic or isokinetic resistances, for example. This is partly because flywheel resistance is self-regulating compared to the externally regulated nature of a constant load or constant speed when using isotonic or isokinetic resistance, respectively.

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Flywheel as a Dynamic Efforts Tool

By excelling as a mode of resistance for dynamic efforts, this means that flywheel training is a great way for athletes to improve their capacity to produce progressively higher forces in shorter amounts of time.  

Although, flywheel resistance is uniquely different from pneumatic, isotonic, isokinetic, and other types of resistance that are also well suited for dynamic efforts.  

I believe that flywheel resistance excels as a moderate power producing option, facilitating moderate forces at moderate velocities when comparing to ranges of forces and velocities commonly desired for dynamic efforts.  

Flywheel resistance is usually characterized by a slower amortization phase compared to pneumatic and isotonic resistance. I believe this makes it less effective for training elastic qualities that would directly transfer to plyometric capacities, especially those characterized by a fast stretch-shortening cycle.

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Bridging to Change of Direction

As I experimented further, I began to realize flywheel training may have the highest chance at servicing multi-directional speed training. By servicing, I mean that flywheel training could provide a kinetics bridge between slow to more specific fast force exercises when chasing improvements in terminal tasks like horizontal acceleration, deceleration, and change of direction.  

For example, a flywheel lateral squat seemed to come close to the kinetic fingerprint of a change of direction characterized by a foot planting outside center of mass that is meant to redirect the athlete’s momentum in another direction.  

Being able to measure the contraction time, the eccentric deceleration impulse, concentric impulse, and peak forces helped place the flywheel lateral squat in between a slower max effort and a very fast isotonic or pneumatic resistance dynamic effort. I found that flywheel resistance in general can facilitate a uniquely massive amount of impulse, or total force multiplied by contraction time, compared to other modes of resistance. Where slower max efforts provide a large impulse exposure by using very high weight lifted during a long period of time, the impulse facilitated from flywheel resistance came from moderately higher rates and peak forces over a moderately faster period of time.  

Using some outdated VBT terminology, it can be thought of as landing more in the strength speed versus the speed strength zone (I use speed strength only within my own framework to capture all faster force work).  

I found that changes of direction at higher angles from high speeds can be characterized by longer ground contact times and very high impulse. The body must efficiently attenuate eccentric forces without losing too much kinetic energy, redirect and build concentric momentum, and accelerate as fast as possible in another direction.  

This falls right in line with the characteristics of flywheel resistance and is why I see the flywheel lateral squat, for example, as a great general exercise option while an athlete is ramping towards this type of change of direction as the terminal task.  

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Exercise Application and Progression

Another exercise example I really like is a handle supported flywheel rear foot elevated split squat loaded vertically. It serves as a nice entry point into unilateral squatting dynamic efforts characterized by moderately fast contraction times, RFD, and peak forces with a massive impulse exposure.  

This unique ability to facilitate high impulse compared to other resistances may be because the flywheel continues to accelerate throughout much of the movement, forcing production of higher torque over that longer period of time.  

This rear foot elevated split squat example could be progressively overloaded during a training phase by increasing disc weight and eccentric motor speed to hopefully facilitate the production of higher RFD, peak, and average forces while trying to maintain contraction time.  

After such a phase you could move to pneumatic or isotonic resistance to make it easier to facilitate higher power outputs characterized by shorter contraction times, higher forces and velocities, and quicker transitions between the eccentric and concentric phases.  

This sort of progression could be a nice ramp into change of direction challenges characterized by more linearly oriented decelerations like a step back or a close out into a defensive slide, to use examples from basketball.

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Final Thoughts on Flywheel Training and Exerfly

Flywheel resistance certainly deserves to be thought of as a valuable training tool within your framework. As with all training methods and means, nothing is for everything and flywheel training is no different. When used appropriately, I believe it fits best as a tool for dynamic efforts, helping athletes develop the ability to produce force quickly while exposing them to high levels of impulse that can bridge toward more specific sport tasks like acceleration, deceleration, and change of direction.

Exerfly continues to provide high quality flywheel training products and still stands superior to the rest by featuring the eccentric motor. Beyond my opinions on where I think flywheel training should be placed on the training continuum, one thing is for sure, the eccentric motor serves as a way to avoid underloading a very important phase of movement that is critical to success in sport.