Smartcoach and Exentrix again

In between busy consulting with clients, testing, lecturing and presenting, I finally found some time to write. Today was interesting: we went to our National Sports Center Papendal, at the research and development department (Innosport) and the strength and Conditioning coaches. We (re-) introduced the concept of power training and and monitoring with the Smartcoach system as well as my new toy, the Exentrix, a innovative and extremely versatile strength training machine. Both systems were developed by my good friend Dr.Marco Pozzo.
We started off defining power and distinguishing it from strength. I talked to the relationship with muscle fibre composition and showed the importance of power and of monitoring of it, every repetition, every set, every workout and throughout the long-term training process.

Relationship between fiber type and power
Relationship between fiber type and power

The best way to measure power-output at an individual base is to measure the force -velocity- and force power-curves in an easy and reliable way.
Doing so, gives us the optimal load for training and improving power output, but also the optimal amount of repetitions in a set and the optimal rest between consecutive. This is necessary since in explosive sports one wants to selectively recruit fast twitch muscle fibres, which is a paradox since it in human it is practically impossible in humans. But at least you want as many as possible of them involved in the executed movement. Otherwise one is recruiting slow fibres only and certainly in the long-term that might not be what you are looking for in explosive sports.

One might as well consider the power output  being the “real” intensity of the workout, not the load.

We believe that the first two reps within a set have a different biological effect than the last two reps, since the velocity and thus the power can drop rapidly and considerably within a set, 20%-30%, within 10 reps.
If you figure out why the velocity within a set drops, you have the core of this concept!

Power decline within a set, the red likme is at 90% of the maximum power with this load.
Power decline within a set, the red line is at 90% of the maximum power with this load.

The Exentrix is different  from all other strength training machines since: can  set the following working modes:
-isotonic, like barbell, dumbbell or weight stack equipment
-isokinetic, like Cybex, Biodex or Kin-Com
-isoinertial, like flywheel, Yo-Yo, Kinetic Box or like the Versapulley system
-aerobic, resistance like the Concept II rowing machine
-elastic, resistance like a rubberband or Theraband


2. But what I really like is that on top of that, one can also have superimposed vibration with adjustable amplitude and frequency or a random perturbation, which means a sharp sudden small pull from the system. Of course one can choose to apply these concentrically, eccentrically or both.

3. The cable can be connected to dumbbell or barbell, replace the cable of a weight stack machine or used for more functional exercises
4. concentric and eccentric loads can be adjusted independently of each other!
5. concentric and eccentric loads can be modified on-the-fly, so while exercising!
6. new programs can be custom programmed
7. one gets immediate visual feedback about every repetition, e.g. velocity, force, power, displacement, work, etc.
8. many different inputs and outputs can be connected like EMG, electronic timing, force platform, goniometers, force transducers, jump mat, light system, switches, etc.

I immediately saw the potential of this machine of which the foundations are thoroughly proven.
It is all rather abstract until you feel the machine work and the faces of the people using it, speak for themselves. One thing never fails, they all underestimate the force of the stimulus coming form that small machine.





  1. lavallee johann

    I am interested in buying this for my sport patients in my physio office (French physiotherapist). Is it possible to work on a precise ROM ? Is it possible to do hamstring curls with this device which doesn’t seem to be expensive at all considering all its possibilities ?
    Thanks for your help !!
    Best regards

    1. Hello Johann, to answer your questions, Yes, the precise range of motion can be set in the computer in cm. And with a little effort, the cable of the leg curl can be replaced by the cable of the Exentrix, giving you the resistance as set in the Exentrix instead of the weight stack. Of course I am talking about a leg curl with a cable like Technogym 😉 I hope this helps. Henk

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