Last week my old friend Marco Pozzo was here to give a demonstration at one of the best physiotherapy clinics in Holland.
He demonstrated one of my favorite toys in working with athletes, the Exentrix in its brand new and greatly improved version.

In my opinion, especially in elite sports, there is still a lot of performance to gain from a better understanding of the (individual) adaptation processes and their development over time, and from the integration of technologies to improve the training stimulus. One of my favorites is the use of eccentric training, especially for elite explosive athletes. Because that is what you want to present to the athlete. In many training programs the eccentric phase of movement is neglected and for sure the importance of eccentric overload, not only an eccentric contraction (you can get that walking down the street).

Raising a 20 kg dumbbell in a biceps curl is an concentric contraction, but lowering that same barbell of 20 kg demands an eccentric contraction, but does not constitute and eccentric overload, so this is not an adequate stimulus for adaptation to the eccentric contraction!

With this Exentrix one can generate almost all possible existing strength training modes: like isoinertial (like flywheel or Versapully), isokinetic ( like Cybex or Biodex), isotonic, like with normal barbells or dumbbells), elastic (like rubberbands or Theraband) and aerobic (l working with the Concept 2 rowing machines (fan-system). The load or the velocity, in case of the isokinetic mode, can be set separately for the concentric and the eccentric phase and can be changed while the athlete executes the exercise. The cable can attached to a barbell or dumbbell, but also use like in the Kaiser machines or Versapully, for functional exercises or attached to most existing exercise equipment like Technogym of Life Fitness. The cable can also be used, of course a longer one, for supra-maximal pulling or for resistance running. Also one can superimpose vibration with adjustable parameters on it, or random perturbation. Watch the video below for some of the options.

It’s basic development came from finding a more versatile alternative for the flywheel machines. These flywheel machines were developed by Per Tesch and Hans Berg for the use in microgravity conditions (space), since it principle show that it is, unlike a barbell, independent of gravity. But also it is possible to focus of the eccentric phase of the contraction. This is possible because the amount of energy that one stores into the flywheel by concentric pulling (like a yo-yo) will transfer into an eccentric directed force when the cable rolls up again and pulls back into the direction of the axis.

Yo-Yo leg curl used by Dutch Olympic Field Hockey Team men
Yo-Yo leg curl used by Dutch Olympic Field Hockey Team men

I just feel this machine is unfortunately 30 years too late for my first athletes but at least a new generation of athletes and coaches will be able to benefit from this “miracle machine”. The principles are not new at all, but it finally brings together all of these strength training modes into one extremely versatile machine

For me, the special attention for eccentric overload is:
-the eccentric phase of the muscular contraction in the Stretch-Shortening Cycle of SSC is often neglected.
-in many natural explosive movements like sprinting, some muscle’s dominant function is the eccentric phase.
-eccentric overload is a strong mechanical stimulus, since the EMG activity during eccentric contractions is low.
-despite, that eccentric contraction favors the recruitment of type II fibers.
-increase of the activation of satellite cells.
-eccentric overload is a good training stimulus for adaptation of serial and parallel elastic components of  the muscle-tendon unit, the fascia and tendons.

Now I am on my way to my training with the Exentrix myself to improve the muscles that I never possessed.

Limited bibliography, and yes, there is quite a bit more…. But these I found interesting enough to show here.

Berg, H.E; Tesch, P.A: A gravity-independent ergometer to be used for resistance training in space. Aviat. Space Environ. Med; Vol. 65, 1994, pg. 752-756.

Tesch, P.; Ekberg, A; Lindquist, D.M; Trieschmann, J.T: Muscle hypertrophy following 5-week resistance training using a non-gravity-dependent exercise system; Acta Physiol.Scand, Vol.180, No.1, 2004, pg.89-98.

Friedman-Bette, B; Bauer, T; Kinscherf, R; Vorwald, S; Klute, K; Bisschof, D; Mueller, H; Weber, M.A; Metz, J; Kauczor, H.U; Baertsch, P; Billeter, R: Effects of strength training with eccentric overload on muscle adaptation in male athletes; Eur.J.Appl.Physiol. Vol.108, 2010, pg.821-836.

Hedayatpour, N; Falla, D: Non-uniform muscle adaptations to eccentric exercise and the implications for training and sport; J.Electromyography and Kinesiology; Vol.22,2012, pg.329-333.

Isner-Horobeti, M.E; Dufour, S.P; Vautravers, P; Geny, B; Coudeyre, E; Richard, R: Eccentric exercise training: Modalities, applications and perspectives; Sports Medicine; Vol.43, 2013, pg.483-512.

Norrbrand, L; Fluckey, J.D; Pozzo, M; Tesch, P: Resistance training using eccentric overload induces early adaptations in skeletal muscle size; Eur.J.Appl.Physiol. Vol.102, 2008, pg.271-281.

LaStayo, P.C; Woolf, J.M; Lewek,M.D; Snyder-Mackler, L:; Reich, T; Lindstedt, S.L: Eccentric muscle contractions: Their contribution to injury, prevention, rehabilitation, and sport; J. Orthop. Sports Phys. Ther; Vol.33, No.10, 2003, pg.557-571.

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